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CATERPILLAR ELPHINSTONE PTY. LTD.
R2900 LHD BRAKING SYSTEM MODULE FO R M N O . 9EL920 9EL92033-00 00 FO R U SE IN SER VIC E TR AIN IN G G U ID E:C EP L R2 900 LH D - July 1998
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Service Training Module R2900 Brake Module CATERPILLAR ELPHIN STONE PTY. LTD.
List of Contents Caterpillar Elphinstone Machine List of Contents ...................... ................................. ...................... ...................... ...................... ...................... ...................... ...................... ...................... .......................... .......................... ............. .. 2 Important Safety Notice ...................... ................................. ...................... ...................... ...................... ...................... ...................... ...................... ........................... .......................... .......... 3 R2900 Braking System Overview ...................... ................................. ...................... ...................... ...................... ...................... ...................... .......................... ...................... ....... 4 Introduction ...................... ................................. ...................... ...................... ..................... ..................... ...................... ...................... ...................... ............................. ............................. ................. ...... 5 Braking System Block Schematic ...................... ................................. ...................... ...................... ...................... ...................... ...................... .......................... ..................... ...... 6 Braking System Component Location ...................... ................................. ...................... ...................... ...................... ...................... ...................... ........................... ................ 7 Location of Brake System Components ..................... ................................ ...................... ...................... ...................... ...................... ...................... ......................... .............. 8 Accumulator Charging Valve Valve (Accumulator Fully Charged - Cut-Out Cycle) .............................. ......................................... ............... .... 9 Accumulator Charging Valve Valve (Accumulator Being Charged - Cut-In Cycle) ...................... ................................. ...................... ........... 10 Location of Brake System Components ..................... ................................ ...................... ...................... ...................... ...................... ...................... ....................... ............ 11 Service Brake Control Valve (Released Position) ..................... ................................ ...................... ...................... ...................... ...................... ................... ........ 13 Service Brake Accumulator ...................... ................................. ...................... ...................... ...................... ...................... ...................... ...................... .......................... ................... .... 15 Wheel Brake (Parking Brake Released) ..................... ................................ ...................... ...................... ...................... ...................... ...................... ....................... ............ 16 Wheel Brake (Parking Brake Released - Ser vice Brake Applied) ...................... ................................. ...................... ...................... ................ ..... 17 System Operation (Parking Brake Engaged) .............................. ......................................... ...................... ...................... ...................... ...................... ................. ...... 18 System Operation (Parking Brake Released) ..................... ................................ ...................... ...................... ...................... ...................... ......................... .............. 20 System Operation (Service Brakes Applied) ...................... ................................. ...................... ...................... ...................... ...................... .......................... ............... 21 Towing Brake Release System ................................................................................................................ 22 Towing Brake Release System Operation (Towing (Towing Brake Release Activated) ..................... ................................ .................... ......... 23 Brake Pressure Test Points ...................................................................................................................... 25 Brake Electrical System ...................... ................................. ...................... ...................... ...................... ...................... ...................... ...................... ............................. ........................ ...... 26 System Operation (Power (Power Supply) ...................... ................................. ...................... ...................... ...................... ...................... ...................... ............................ ................... .. 28 System Operation (Relay Latched and Parking Brake Engaged) ...................... ................................. ...................... ...................... ................ ..... 29 System Operation (Parking Brake Released) ..................... ................................ ...................... ...................... ...................... ...................... ......................... .............. 30 Parking Brake CMS Component Location ...................... ................................. ...................... ...................... ...................... ...................... ...................... .................. ....... 31 System Operation CMS (Parking Brake Released) ................................ ........................................... ...................... ...................... ...................... ................ ..... 33 Stop Light and Residual Brake Pressure Light Circuit Components ..................... ................................ ...................... ...................... ............. .. 34 System Operation (Stop Light/Residual Brake Pressure Circuit) ...................... ................................. ...................... ...................... ................. ...... 35 Electric Brake Release System ..................... ................................ ...................... ...................... ...................... ...................... ...................... ............................ ......................... ........ 36 System Operation (Electric Brake Release) ...................... ................................. ...................... ...................... ...................... ...................... .......................... ............... 37 Practical Tasks ......................................................................................................................................... 38 Theory Assessment ...................... ................................. ...................... ...................... ...................... ...................... ...................... ...................... ............................ ............................ ............. .. 39 Theory Assessment Answers ...................... ................................. ...................... ...................... ...................... ...................... ...................... ...................... .......................... ............... 41 Theory Assessment ...................... ................................. ...................... ...................... ...................... ...................... ...................... ...................... ............................ ............................ ............. .. 42 Theory Assessment Answers ...................... ................................. ...................... ...................... ...................... ...................... ...................... ...................... .......................... ............... 44 Serviceman’s Handouts ..................... ................................ ...................... ...................... ...................... ...................... ...................... ...................... ......................... ......................... ........... 45 Page 2
Service Training Module R2900 Brake Module CATERPILLAR ELPHIN STONE PTY. LTD.
List of Contents Caterpillar Elphinstone Machine List of Contents ...................... ................................. ...................... ...................... ...................... ...................... ...................... ...................... ...................... .......................... .......................... ............. .. 2 Important Safety Notice ...................... ................................. ...................... ...................... ...................... ...................... ...................... ...................... ........................... .......................... .......... 3 R2900 Braking System Overview ...................... ................................. ...................... ...................... ...................... ...................... ...................... .......................... ...................... ....... 4 Introduction ...................... ................................. ...................... ...................... ..................... ..................... ...................... ...................... ...................... ............................. ............................. ................. ...... 5 Braking System Block Schematic ...................... ................................. ...................... ...................... ...................... ...................... ...................... .......................... ..................... ...... 6 Braking System Component Location ...................... ................................. ...................... ...................... ...................... ...................... ...................... ........................... ................ 7 Location of Brake System Components ..................... ................................ ...................... ...................... ...................... ...................... ...................... ......................... .............. 8 Accumulator Charging Valve Valve (Accumulator Fully Charged - Cut-Out Cycle) .............................. ......................................... ............... .... 9 Accumulator Charging Valve Valve (Accumulator Being Charged - Cut-In Cycle) ...................... ................................. ...................... ........... 10 Location of Brake System Components ..................... ................................ ...................... ...................... ...................... ...................... ...................... ....................... ............ 11 Service Brake Control Valve (Released Position) ..................... ................................ ...................... ...................... ...................... ...................... ................... ........ 13 Service Brake Accumulator ...................... ................................. ...................... ...................... ...................... ...................... ...................... ...................... .......................... ................... .... 15 Wheel Brake (Parking Brake Released) ..................... ................................ ...................... ...................... ...................... ...................... ...................... ....................... ............ 16 Wheel Brake (Parking Brake Released - Ser vice Brake Applied) ...................... ................................. ...................... ...................... ................ ..... 17 System Operation (Parking Brake Engaged) .............................. ......................................... ...................... ...................... ...................... ...................... ................. ...... 18 System Operation (Parking Brake Released) ..................... ................................ ...................... ...................... ...................... ...................... ......................... .............. 20 System Operation (Service Brakes Applied) ...................... ................................. ...................... ...................... ...................... ...................... .......................... ............... 21 Towing Brake Release System ................................................................................................................ 22 Towing Brake Release System Operation (Towing (Towing Brake Release Activated) ..................... ................................ .................... ......... 23 Brake Pressure Test Points ...................................................................................................................... 25 Brake Electrical System ...................... ................................. ...................... ...................... ...................... ...................... ...................... ...................... ............................. ........................ ...... 26 System Operation (Power (Power Supply) ...................... ................................. ...................... ...................... ...................... ...................... ...................... ............................ ................... .. 28 System Operation (Relay Latched and Parking Brake Engaged) ...................... ................................. ...................... ...................... ................ ..... 29 System Operation (Parking Brake Released) ..................... ................................ ...................... ...................... ...................... ...................... ......................... .............. 30 Parking Brake CMS Component Location ...................... ................................. ...................... ...................... ...................... ...................... ...................... .................. ....... 31 System Operation CMS (Parking Brake Released) ................................ ........................................... ...................... ...................... ...................... ................ ..... 33 Stop Light and Residual Brake Pressure Light Circuit Components ..................... ................................ ...................... ...................... ............. .. 34 System Operation (Stop Light/Residual Brake Pressure Circuit) ...................... ................................. ...................... ...................... ................. ...... 35 Electric Brake Release System ..................... ................................ ...................... ...................... ...................... ...................... ...................... ............................ ......................... ........ 36 System Operation (Electric Brake Release) ...................... ................................. ...................... ...................... ...................... ...................... .......................... ............... 37 Practical Tasks ......................................................................................................................................... 38 Theory Assessment ...................... ................................. ...................... ...................... ...................... ...................... ...................... ...................... ............................ ............................ ............. .. 39 Theory Assessment Answers ...................... ................................. ...................... ...................... ...................... ...................... ...................... ...................... .......................... ............... 41 Theory Assessment ...................... ................................. ...................... ...................... ...................... ...................... ...................... ...................... ............................ ............................ ............. .. 42 Theory Assessment Answers ...................... ................................. ...................... ...................... ...................... ...................... ...................... ...................... .......................... ............... 44 Serviceman’s Handouts ..................... ................................ ...................... ...................... ...................... ...................... ...................... ...................... ......................... ......................... ........... 45 Page 2
Service Training Module R2900 Brake Module CATERPILLAR ELPHIN STONE PTY. LTD.
IMPORTANT IMPORTANT SAFETY SA FETY NOTICE The course content and subject matter is current at the time of publication. Specifications, torques, pressure settings, measurements, adjustments, illustrations and other items can change at any time. Always refer re fer to the machine specific service manual, parts book and updates prior to performing repairs and adjustments. Caterpillar Elphinstone Pty Ltd cannot anticipate every possible circumstance that might involve a potential hazard. The warnings in this module are therefore not inclusive. If a procedure, tool, device or work method not specifically recommended by Caterpillar Elphinstone Pty Ltd is to be used, you must satisfy yourself y ourself that it is safe for yourself and others. You should also ensure that the machine will not be damaged or made unsafe by the procedures you choose.
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Service Training Module R2900 Brake Module CATERPILLAR ELPHIN STONE PTY. LTD.
R2900 Braking System Overview Module Description Aims: T he aim o fthis t tr raining m o d u le is t to o p ro vid e p articip ants w ith th e o p eratio n alkn kno o w led g e an d d iag n o st sti ic sk ski ills n ec eces essa sar ry t to o trou b lesh eshoo oo t the R 29 00 B raking S ystem .
Nominal Duration: T he m o d ule is des d esi ig n ed so th at m o st o fthe traine nees es w illac acq q u ire th th e kn k n o w led g e in o ne 4 h o ur se sessi ssio n .T h e len g th o ftim e ac act tu ally t tak aken en to co m p let ete e the m o d u le w illvar vary y d ep en d ing o n fac act to rs su ch as th e tea each chi in g m et eth h o d u sed , th e traine e’ s kno w led g e and sk ski ills at a t en try,an d th e ind ivid u altrain ee’ s ab a b ility.
Pre-Requisites: M ec echa han n ica cal l trad es esm m an - sh sho o u ld h ave co m p let eted ed a B as asi ic H yd ydr rau lic an a n d E lec ect trica cal l Training P ro g ram (p refer err red b u t n o t essen tial).
Learning Outcomes: A s a resu sul lt o fst stu ud yin g th is m o d u le, p articip an ts s sh h o uld b e ab le to : 1 . D em o nst nstr rat ate e an a n u nd er erst stan and d ing o f the fun ct cti io n and a nd o p er erat ati io n o fthe b raking system an and d its co m p o ne nent nts. s. 2 . U se and an d und un d erst erstand an d the b raking system sch schem em ati atic. 3 . Tr Trac ace e th e o ilflo w th ro u g h th e b rak aki in g syst system em d u ring allm o d es o fo p er erat ati io n . 4 . A p p ly this op o p er erat ati io n alkn kno o w led g e to to tro u b lesh o o t a ser s eri ies o f b rak aki ing syst system em p ro b lem s. 5 . U se th th e S er ervi vice M an u alan d P ar art ts B o o k to a assi ssist w ith t tr ro ub les esho ho o ting .
Assessment: Tasks: P ar art a rt A : P rac act tica cal lTest Tests. s. P ar art a rt B : T he heo o ry Assessm A ssessm en ent t (True ue/ /Fa Fal lse Test) Test).
Resource Requirements: • R 2 90 90 0 L H D . • Fu lly eq uip p ed classr assro o o m w ith w hite b o ar ard d an and d o ver verhe head ad p ro jec ect to r. • Training M o d ule and a nd ha hand nd o ut m at ater eri ial. • H yd ydr rau aul lic pr p ressu essur re gaug ga ug es. • S ervi ervice M anua an ual l. • P arts B oo k. • Too To o ls fo r pract prac ticaltasks. sk s.
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Service Training Module R2900 Brake Module CATERPILLAR ELPHIN STONE PTY. LTD.
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Introduction
Introduction:
T h is p resen es en tati atio n d iscu sc u sse sses s th th e syst system em o p erat erati io n an d ad ju sti stin g p roced oc edur ures es for the R 16 00 LH D B raking S ystem . G rap hical ca l sym b o ls and a nd sec sect tio nal na l view d raw ing s w ill b e use used d w hen he n d iscu sc u ssin g syst system em s op op eratio n s. S yst ystem em s w illb e exp exp lained b y tracin g o ilflo w fro m the tank, an k, th ro ug h th e syst system em , and an d b ack ac k to th e tank. an k.
• Schema Schematic tic colou colourr code: code:
T h e co c o lo ur co d es fo r h ydr yd rau lic o ilu sed se d thro u g h o u tthis pr p resen se n tatio n ar a re as fo fo llo w s: R ed e d - S ystem o r high p ressur essure. e. O range a n g e - P ilo t p ressu es sur re. B lue u e - B lo cked ck ed o r trap p ed o il. G reen e e n - T ank an k or o r retu etu rn o il
• Testing esting & Adjustin Adjusting g procedures:
N O T E : A fo llo w the p ro ced ce d ures ures in the the S ervi ervice M an ua l w he n A lw ays fo tes est tin g an d /o r ad ju st sti in g th e mm ac h in e b rak aki in g syst system em .
• Servic Servicema eman’ n’s s Handouts: Handouts:
G ive eac e ach h tr train ee a co c o p y of o f th e re releva evan t ser se rvicem ce m an ’ s ha h an d o u ts, su sup p p lied w ith th is tr train in g m o d u le.
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Service Training Module R2900 Brake Module CATERPILLAR ELPHIN STONE PTY. LTD.
WHEEL BRAKE
PARKING BRAKE CONTROL VALVE
PILOT RELIEF VALVE FILTER
SERVICE BRAKE ACCUMULATOR SERVICE BRAKE CONTROL VALVE
ACCUMULATOR CHARGING VALVE
BRAKE AND PILOT PUMP ACCUMULATOR CHARGE RELIEF VALVE TANK
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Braking System Block Schematic • Block Schematic - Parking brake system - Service brake system • Other Brake System Features: - Towing brake release system • The pump draws oil (green) from the tank and sends flow (red) to the various control valves • The parking brake is spring engaged and hydraulically released • The service brake is hydraulically applied
This block schem atic o f the R 29 00 LH D braking system show s the com ponents and oilflow . There are tw o b rake controlsystem s on the m achine: the p arking brake system and the service b rake system . A n optional feature of the brake system is the tow ing brake release system . The b rake and pilot pum p oil (red ) flow s to the accum ulator ch arging valve. T he valve divides the o ilflow ofthe b rake and pilotpum p,priority is given to the service brake circuit. W hen the p arking brake control valve is activated,pum p oilis d irected into the parking brake section of the w heelbrakes to release the brakes. B rake and pilot pum p oilflow s through the accum ulator charging valve to the service brake accum ulator. W hen the service brake controlvalve is activated, accum ulator oil goes to the service brake section of the w heelbrakes. The w heel brakes are d ual-piston, outboard, w et-disc brakes located in the w heel ends. E ach w heel brake has a parking brake piston and a service brake p iston. The p arking brake is spring engaged and hydraulically released. The service b rake is hydraulically applied. Page 6
Service Training Module R2900 Brake Module CATERPILLAR ELPHIN STONE PTY. LTD.
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Braking System Component Location • Identify components (1) Hydraulic tank (2) Parking brake control valve (3) Service brake accumulator (4) Accumulator charge relief valve (5) Pilot oil filter (6) Pilot relief valve (7) Front wheel brakes (8) Service brake control valve (9) Rear wheel brakes (10) Accumulator charging valve (11) Brake and pilot pump (12) Electric brake release pump
The hyd raulic brake system consists o f: hyd raulic tank (1), parking brake co ntrol valve (2), service brake accum ulator (3), accu m ulator charge relief valve (4), pilot oilfilter (5), pilot relief valve (6), front w heel brakes (7), service brake control valve (8), rear w heel brakes (9), accum ulator ch arging valve (10),brake an d pilot pum p (11)an d electric brake release p um p (12) . Th ere are fou r w heel brakes on the m achine. Each w heel brake has tw o sections; a p arking brake section and a service brake section. The parking b rake is oilpressure released and sp ring applied. The service brake is oil pressure applied an d sp ring released. The service b rake can be used w hen the brake is released.
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Service Training Module R2900 Brake Module CATERPILLAR ELPHIN STONE PTY. LTD.
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1 3 1. Hydraulic tank. 2. Hydraulic oil filters.
3. Brake and pilot pump.
5 6 4
4. Accumulator charging valve.
5. Pilot relief valve. 6. Pilot oil filter. 4
Location of Brake System Components • Hydraulic filters are mounted inside the hydraulic tank
• Brake and pilot pump is part of a two section gear type pump • Accumulator charging valve divides oil flow with priority given to the braking system • Pilot relief valve controls the pressure in the pilot system • Pilot oil filter is fitted with a bypass valve
The hydraulic tan k (1)is located on the right hand side ofthe m achine. The hyd raulic oilfilters (2)are m ounted inside the hyd raulic tank. There is a byp ass valve for the filter elem ents. W henever the restriction through the filters is too high, the byp ass valve w illopen. The b rake and pilot pum p (3) is part of a tw o section p um p, w hich is m ounted on the left hand rear of the torque converter updrive tran sfer housing. The brake and pilot pum p (3)supplies oilto the p ilot steering system , brake system and pilot hyd raulic system . The accum ulator charging valve (4) is located on the left hand inside w all of the rear fram e. The valve d ivides the oil flow from the b rake and pilot pum p, priority is given to the brake circuit. The p ilot system relief valve (5) is m ounted on the rear fram e cross beam . The pilot oilfilter (6)is m ounted behind the reliefvalve m anifold. The p ilot relief valve controls the p ressure in the p ilot oilsystem . The pilotoilfilter (6),filters the pilotoiland is fitted w ith a byp ass valve w hich w illopen w henever the resistance to the flow of oilthrough the filter is too high.
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Service Training Module R2900 Brake Module CATERPILLAR ELPHIN STONE PTY. LTD.
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Accumulator Charging Valve (Accumulator Fully Charged - Cut-Out Cycle) • Accumulator charging valve (accumulator fully charged cut-out cycle) (1) Pilot valve spool (2) Upper limit check ball (3) Pilot valve spring (4) Lower limit check ball (5) Check valve (6) Orifice (7) Passage (8) Chamber (9) Charging valve spool (10) Spring (11) Spool stop • Accumulator charging valve in CUT-OUT cycle: • Accumulator does not need oil; the ACV directs all pump oil to the pilot circuit
W ith the engine running, oil from the b rake p um p goes into the accum ulator charging valve (A C V). If the brake accum ulator does not need oil,the A C V directs alloilfrom the brake pum p to the pilot circuit. W hen the brake accum ulator need s oil,the A C V divides the pum p flow . The A C V w illdirect a percentag e of pum p o ilto the accum ulator. The rem ainder of the pum p oilw illflow to the pilot circuit. W hen the o ilpressure in the accum ulator reaches the cut out pressure of the accu m ulator ch arging valve, the accu m ulator is fully charged w ith oil. O il from the brake and pilot pum p enters the A C V . This oil passes through a d rilled passage in valve spool(9) to ch am ber (8). P ressure w illincrease in cham ber (8)and m ove valve spool(9) to the right. The valve sp ool(9)is now held against sp oolstop (11)and pum p oilw illflow to the pilot circuit. O il pressure in the accum ulator m oves check valve (4) to the right against pilot valve sp ool(1). O ilpressure in the accum ulator is retained by check balls (4)and (5). Page 9
Service Training Module R2900 Brake Module CATERPILLAR ELPHIN STONE PTY. LTD.
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Accumulator Charging Valve (Accumulator Being Charged - Cut-In Cycle) • Accumulator charging valve (accumulator being charged cut-in cycle) (1) Pilot valve spool (2) Upper limit check ball (3) Pilot valve spring (4) Lower limit check ball (5) Check valve (6) Orifice (7) Passage (8) Chamber (9) Charging valve spool (10) Spring (11) Spool stop • Accumulator needs oil; the ACV divides pump flow to accumulator and pilot circuit • Accumulator will charge until CUT-OUT pressure is reached
B rake application w ill cause the oil pressure in the accum ulator to decrease. W hen the pressure d ecreases to the cut-in p ressure, pilot valve sp ring (3)w illunseat check b all(4). A t the sam e tim e, check b all (2)seats. P ilotvalve sp ool(1)allow s o nly one ofthese check balls to be seated at a tim e. W hen check b all(4) is unseated , pressure from the accum ulator flow s through passag e (7). T he oilenters the cham ber behind valve spool(9). The spring (10) and the accum ulator oil pressure balance the pum p pressure in cham ber (8) acting on the o pposite end of valve spool(9). This m eans that the p um p pressu re is alw ays highe r than the accum ulator pressure. P um p p ressure flow s through orifice (6), past check valve (5), and out to the accum ulator. W hen the a ccum ulator is fully charged , the o il pressure in the accum ulator w illseat check b all(4). The pilot valve sp ool(1)w illunseat check b all(2)and allow pressure in the cham ber behind valve spool(9) to return to tank. Valve spool(9) w illnow m ove to the right and direct brake charge pum p oilto the pilot circuit.
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Service Training Module R2900 Brake Module CATERPILLAR ELPHIN STONE PTY. LTD.
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1 1. Parking brake control valve.
2. Accumulator charge relief valve.
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4 3. Brake control pedals.
4. Service brake accumulator. 7
Location of Brake System Components • Parking brake control valve solenoids are energised to release the parking brake • Accumulator charge relief valve protects the service brake system if the accumulator charging valve fails
• Brake pedals regulate the pressure at the wheel brakes
• Service brake accumulator supplies oil at a constant pressure to the service brakes
The parking brake controlvalve (1)is located on the lefthand inside w all of the rear fram e. W hen the parking brake co ntrolknob (in operator’ s station)is m oved to the released position, the solenoids o f the parking brake controlvalve are energised. O il flow s to the p arking brake sections of the w heel brakes. O ilpressure then releases the p arking brake. The accu m ulator ch arge relief valve (2) is m ounted on the left han d inside w allofthe rear fram e. The reliefvalve protects the service brake system if the accum ulator charging valve fails. The b rake control ped als (3) reg ulate the p ressure at the b rakes. A s the p osition of the p ed al ch an ges, the pressure at the brakes also changes. The service b rake accum ulator (4) is m ounted on the inside left han d w all of the rear fram e. The accum ulator stores hydrau lic o il under pressure an d supplies oil at a co nstant pressure range to the service brake system . Continued
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Service Training Module R2900 Brake Module CATERPILLAR ELPHIN STONE PTY. LTD.
• Service brake control valve modulates the pressure to the wheel brakes, depending on position of the pedals
The brake pedalis co nnected to the service brake controlvalve. The service brake controlvalve is supplied w ith oil from the service brake accum ulator.The service b rake controlvalve w illm odulate this pressure dep ending on the p osition of the p ed als.
• Left pedal applies the brakes first then neutralises the transmission
N O TE: The brake and transm ission neutraliser control pedal (left side pedal) applies the brake first then neutralises the transm ission.
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Service Training Module R2900 Brake Module CATERPILLAR ELPHIN STONE PTY. LTD.
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Accumulator Oil Pressure
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Tank Oil Regulated Oil Pressure
3 TO W H E EL BRAKES
4 TA N K
FROM A C C U M U LA T O R TO W H E EL BRAKES
FROM A C C U M U LA TO R
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Service Brake Control Valve (Released Position) • Service Brake Control Valve: (1) Service brake control valve (2) Springs (3) Return port (4) Spool (5) Spool (6) Spring • The service brake control valve modulates (regulates) the pressure to the service brake • The further the pedal is depressed, the greater the pressure at the service brake
The service brake co ntrolvalve is a dual pressure reducing valve w ith tw o indep en den t output pressures. The valve is directly below the service brake p edal. The service brake co ntrol valve m odulates p ressurised oil from the accum ulator to the service brake section o f the w heel brakes. The position of the b rake p ed al cau ses a sp ecific p ressure at the b rakes. A s the p osition of the p ed al ch an ges, the p ressure at the service brakes also change. Ifone braking circuit fails, the second braking circuit rem ains functional due to the m echanicalcontact betw een the tw o spools (4) and (5). W ith the engine running, oilflow s from the service brake accum ulator to service b rake control valve (1) through tw o inlet ports. W hen the operator pushes on the brake ped al, springs (2) cause spools (4) and (5) to overcom e the force of spring (6) and m ove d ow n. Continued
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Service Training Module R2900 Brake Module CATERPILLAR ELPHIN STONE PTY. LTD.
• When the control spools move down, accumulator pressure oil flows to the wheel brakes • The service brake control valve reduces (modulates) the oil pressure to the wheel brakes
W hen sp ool(4)m oves d ow n, oilfrom the accum ulator port flow s past the spoolto the front brake p ort. The oil flow s into the oil line to the front service b rakes and applies the front brakes. S pool(4) is on top of spool(5) and as spool(4)m oves d ow n it causes spool(5) to also m ove dow n. A s spool(5) m oves dow n, oilfrom the accum ulator port flow s past the sp oolto the rear brake port. The oil flow s into the oil line to the rear service brakes and applies the rear brakes. Internal m etering p assages red uce o il pressure to each axle. The service brake control valve m eters oil to the rear brakes at a h igher pressure than the front brakes. W hen the o perator releases the b rake p ed al, spring (6) forces sp ools (4)an d (5)up. N ow the oilflow ing from the accu m ulators is blocked at the spool. W hen the sp ools m ove up, the return p orts are open. The oil in the service b rake ports can now flow into the return ports. O ilin the front an d rear brake oillines is now vented back to the hydrau lic tan k.
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Service Training Module R2900 Brake Module CATERPILLAR ELPHIN STONE PTY. LTD.
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Pressure Oil Nitrogen Gas
1
4 3
5
6
9
Service Brake Accumulator • Service Brake Accumulator (1) Accumulator (2) Nitrogen charging valve (3) Piston (4) Nitrogen gas chamber (5) Pressure oil chamber (6) Oil pressure outlet •
The accumulator supplies oil under pressure to the service brakes
•
The gas chamber above the piston has a charge of dry nitrogen gas
•
Pump oil pushes the piston up and causes compression of the dry nitrogen gas
The service brake accum ulator supplies oil under pressure to the service b rake control valve. There is a nitrogen charge in the accum ulator. Th e accum ulator has a sealed piston (3) that m oves up and dow n inside the bore of the accum ulator. The cham ber (4) ab ove the p iston has a charge o fdry nitrogen gas. The charge o fdry nitrogen gas is put into the accum ulator through valve (2). O ilfrom the pum p and accum ulator charging valve co m es throu gh port (6) into cham ber (5). W hen the pressure in the accum ulator reaches the cut-out pressure o f the accu m ulator ch arging valve, the supply of oilto the accum ulator is stopped by the accum ulator charging valve.
Page 15
Service Training Module R2900 Brake Module CATERPILLAR ELPHIN STONE PTY. LTD.
1 Parking Brake Oil Pressure
3
2
5
4 6
9 7
8
10
Wheel Brake (Parking Brake Released) • Wheel Brake (parking brake released) (1) Parking piston (2) Service piston (3) Outer casing (4) Springs (5) Wheel hub (6) Annular passage (7) Steel plates (8) Friction discs (9) Brake pack •
•
When the parking brake is released, oil pressure moves the parking piston to the left away from the brake pack When the parking brake is applied, springs move the parking piston to the right against the brake pack
The o uter casing (3)is bolted to the axle housing w hich does not turn. There are splines on the inside o f the o uter casing (3). S plines on the circum ference ofthe steelplates (7)fit in the sp lines ofthe outer casing (3). This keeps the steelplates (7) stationary. The w heel hub (outer housing of the final drive) (5) has splines on its outer circum ference. These sp lines fit into the sp lines o n the inside of friction discs (8). B oth w heelhub (5)and friction discs (8)turn together. W hen the parking brake is released, oilflow s through a port in the en d plate to annular passage (6). T he o ilpressure m oves parking piston (1) to the left, com pressing sp rings (4), until the piston contacts the end plate. This relieves the p ressure from the b rake pack. Friction discs (8) an d w heel hub (5)are free to rotate. W hen the p arking brake is engag ed,the o ilin the annular passage (6)is dum ped to tank. W hen the oil pressure drops, the parking p iston is m oved to the right by springs (4)untilit contacts service piston (2)and forces it into contact w ith b rake p ack (9). This holds the rotating discs to the stationary p lates an d locks w heelhub (5)to the axle housing. Page 16
Service Training Module R2900 Brake Module CATERPILLAR ELPHIN STONE PTY. LTD.
1
Parking Brake Oil Pressure Service Brake Oil Pressure
2
3
4
5 9 6
7
8
11
Wheel Brake (Parking Brake Released - Service Brake Applied) • Wheel Brake (1) Parking piston (2) Service piston (3) Outer casing (4) Springs (5) Pull rods (6) Annular passage (7) Steel plates (8) Friction discs (9) Brake pack • When the service brake is applied, the service piston moves to the right against the brake pack
W hen the service brake ped al is d ep ressed , oil und er pressure flow s through a port in the end plate into an nular passage (6). The p ressure ofthe oilm oves service piston (2)to the rightagainst the brake pack (9). S prings (4) are ten sioned by p ullrods (5)as the service piston m oves. This causes friction betw een the steel plates (7), w hich are held stationary b y o uter casing (3), and friction discs (8)w hich turn w ith the rotation ofthe w heels. This friction causes the w heels to turn slow er or stop. The am ount of brake application d ep ends on the position o f the brake ped al. G rooves cut in the faces o fthe friction discs (8)allow cooling oilto flow betw een the p lates and discs. The cooling oil w ill constantly flow betw een the plates and discs in either the service brake applied or released positions.
• Cooling oil will constantly flow between the brake pack in both the brake applied and brake released position Page 17
Service Training Module R2900 Brake Module CATERPILLAR ELPHIN STONE PTY. LTD.
FRONT WHEEL BRAKES SERVICE BRAKE CONTROL VALVE
REAR WHEEL BRAKES SERVICE BRAKE ACCUMULATOR
PILOT RELIEF VALVE
PARKING BRAKE CONTROL VALVE
ACCUMULATOR CHARGING VALVE
T M O L E I P T S Y O T S
ACCUMULATOR CHARGE RELIEF VALVE
STEERING PUMP
BRAKE AND PILOT PUMP
TANK
12
System Operation (Parking Brake Engaged) • Braking system shown with engine running, parking brake applied and service brakes released • The brake and pilot pump supplies oil to the accumulator charging valve and pilot system • The accumulator charging valve keeps the pressure in the service brake accumulator within a constant range • The service brake accumulator stores oil pressure for operation of the service brakes
This sch em atic show s the braking system w ith the eng ine run ning, the parking brake engag ed and the service brake released . O il from the b rake and pilot pum p flow s to the accum ulator charging valve and the p ilot relief valve. The accum ulator charging valve keeps the p ressure in the service b rake accu m ulator w ithin a co nstant range. The pilot relief valve controls the pilot oilpressure to the parking brake circuit. The brake and pilot pum p also supplies oil to the hyd raulic im plem ent and steering pilot system s. The p um p oil flow s throug h the accum ulator charging valve to the service brake accum ulator. A piston in the service brake accum ulator is held against the oilintake end by dry nitrogen g as. The service b rake accum ulator stores hydraulic oil pressure for operation of the service brakes. W hen the service b rake accum ulator is fully charged , the accum ulator charging valve directs its p um p oilflow to tank. O ilflow is blocked by the service brake co ntrolvalve. Continued
Page 18
Service Training Module R2900 Brake Module CATERPILLAR ELPHIN STONE PTY. LTD.
• Two solenoid control valves control the operation of the parking brake
The parking brake co ntrolvalve co nsists o ftw o solen oid co ntrolvalves. W hen the solenoids are d e-energised , pum p oil is blocked at the controlvalves. The p arking brake section of the w heelbrakes is open to tank through the parking b rake control valve. The parking b rakes are applied by sp ring pressure.
Page 19
Service Training Module R2900 Brake Module CATERPILLAR ELPHIN STONE PTY. LTD.
FRONT WHEEL BRAKES SERVICE BRAKE CONTROL VALVE
REAR WHEEL BRAKES SERVICE BRAKE ACCUMULATOR
PILOT RELIEF VALVE
PARKING BRAKE CONTROL VALVE
ACCUMULATOR CHARGING VALVE
T M O L E I P T S Y O T S
ACCUMULATOR CHARGE RELIEF VALVE
STEERING PUMP
BRAKE AND PILOT PUMP
TANK
13
System Operation (Parking Brake Released) •
•
Braking system shown with engine running, parking brake released and service brakes released The pilot relief valve controls the oil pressure in the parking brake circuit
•
When the parking brake control is moved to the released position, the parking brake solenoid control valves are energised
•
Pressure oil is sent to the parking brake section of the wheel brakes
W hen the p arking brake control in the cab is m oved to the released position, pow er is sen t to en ergise the parking brake solen oid control valves. O ilfrom the brake and pilot pum p flow s through the pilot reliefvalve to the parking brake control valve. The pilot relief valve controls the m axim um pressure in the p arking brake circuit. O il flow s to the p arking brake section o f the w heel brakes. The oil pressure causes the p arking brake piston to retract, releasing the parking brake.
Page 20
Service Training Module R2900 Brake Module CATERPILLAR ELPHIN STONE PTY. LTD.
FRONT WHEEL BRAKES SERVICE BRAKE CONTROL VALVE
REAR WHEEL BRAKES SERVICE BRAKE ACCUMULATOR
PILOT RELIEF VALVE
PARKING BRAKE CONTROL VALVE
ACCUMULATOR CHARGING VALVE
T M O L E I P T S Y O T S
ACCUMULATOR CHARGE RELIEF VALVE
STEERING PUMP
BRAKE AND PILOT PUMP
TANK
14
System Operation (Service Brakes Applied) • Braking system shown with engine running, parking brake released and service brakes applied • The accumulator charging valve charges the service brake accumulator with pressure oil • When the brake pedal is depressed, pressure oil moves the service brake piston to apply the brakes • The further the pedal is depressed, the greater the pressure at the wheel brakes
O il from the brake and pilot pum p flow s throug h the accum ulator ch arging valve to the service b rake accu m ulator. The service brake accum ulator stores h ydraulic oil pressure for the operation of the service brakes. W hen the service brake accum ulator is fully charged w ith oil, the accum ulator charging valve sends the pum p oil flow to tank. The service brake controlvalve is in the circuit from the service b rake accum ulator to the service b rakes. W hen the brake ped al is pushed , oil from the service brake accu m ulator goes to the service brake section of the w heel brakes. The service brake control valve is a tan dem type valve p roviding sp lit system braking. In the event of a failure in either the front or rear brake system , the other portion of the valve w illcontinue to function. A fter the service brakes have been activated severaltim es, the volum e of oil in the service b rake accum ulator is reduced. The p iston in the service brake accum ulator m oves d ow n tow ards the oilend untilthere is a decrease in pressure. The accum ulator ch arging valve cuts in sen ding oilfrom the brake and pilot pum p to the accum ulator. Page 21
Service Training Module R2900 Brake Module CATERPILLAR ELPHIN STONE PTY. LTD.
1 2
3 2. Brake release sequence valve. 3. Shuttle valves.
1. Brake release cylinder.
5
4
4. Check valve.
5. Towing hook. 15
Towing Brake Release System • Towing brake release system components: (1) Brake release cylinder (2) Towing brake release sequence valve (3) Shuttle valves (4) Check valve (5) Towing hook • The towing brake release system allows release of the parking brake in the event of a machine fault • The towing brake release system is activated when the towing brake release cylinder piston is moved up
The tow ing brake release system allow s the operator to release the parking brakes if the b rakes are applied due to a m achine fault. W hen the brakes are released , the m achine can be tow ed to a service area. The system is activated by a tow ing ho ok (5) com pressing the tow ing brake release piston in the m achine tow ing bar.
The tow ing b rake rake release system m ust only be activated b y a tow ing ho ok secu rely attache attache d to the recovery m achine . The tow ing ho ok m ust ust b e securel se cu rely attache d to the tow ing b ar of the inop erative m achine p rior to activating the release system . Failure to d o so m ay resu lt in the tow ed m achine m oving , causing serious p erso nal injury o r d eath. W he n the m achine ha s b een tow ed to a saf sa fe p lace, en sure tha t it is p arked on aa leve evel lsurfac e a nd that the w hee ls are b locked secu sec urel rely so the m achine can n ot m ove p rior to aan nyy service w ork b eing p erform ed oon n the m ach ine. E nsure nsu re the ino p perati erative m achine can nnoot t m ove b efore d isco nn ecting the tow ing ho ok. Page 22
Service Training Module R2900 Brake Module CATERPILLAR ELPHIN STONE PTY. LTD.
FRONT WHEEL BRAKES SERVICE BRAKE CONTROL VALVE
SERVICE BRAKE ACCUMULATOR
REAR WHEEL BRAKES PILOT RELIEF VALVE
PARKING BRAKE CONTROL VALVE
ACCUMULATOR CHARGING VALVE
T M O L E I P T S Y O T S
SHUTTLE VALVE TOW BRAKE RELEASE CYLINDER
ACCUMULATOR CHARGE RELIEF VALVE BRAKE RELEASE SEQUENCE VALVE
STEERING PUMP
BRAKE AND PILOT PUMP
L E A C N R R O E F T X E
TANK
16
System Operation (Towing Brake Release Activated) •
•
•
The towing brake release system is activated by the towing brake release cylinder piston The piston creates oil pressure as it moves up and this pressure releases the parking brake section of the wheel brakes When the towing brake piston moves down, the parking brakes apply
The tow ing b rake release system is an attachm ent ofthe parking b rake circuit. W hen the tow ing brake release system is activated, the p iston in the tow ing brake release cylinder is com pressed ag ainst spring pressure. Th e p iston m oves up and covers the tank port. M ovem entof the piston now creates o il pressure w hich is directed, via a shuttle valve, to the parking brake section of the w heelbrakes to release the brakes. W hen the tow ing brake release cylinder piston is released, the sp ring m oves the piston d ow n. T he oilpressure in the w heelbrakes decreases and the parking brakes apply. D uring norm al operation, w hen the operator releases the parking brake, the p arking brake controlvalve sen ds oilpressure to the w heel brakes. The oil pressure also activates the brake release seq uence valve. The sequence valve o pens the tow ing brake release cylinder to tank. Continued
Page 23
Service Training Module R2900 Brake Module CATERPILLAR ELPHIN STONE PTY. LTD.
• Brake release sequence valve disables towing release system during normal machine operation • Check valve replenishes oil in the brake system when required • Tank port prevents hydraulic lock between shuttles and deactivated piston
W ith the brake release sequence valve o pen to tank the tow ing brake release system is d isab led during no rm al m achine o peration. The check valve rep lenishes oil in the brake release system w hen required. W hen the tow ing brake release cylinder is in the deactivated position, the sp ring cham ber is connected to the hydraulic tank port. This prevents a pressure increase (hydraulic lock) behind the shuttle valves so the parking brakes can be released .
Page 24
Service Training Module R2900 Brake Module CATERPILLAR ELPHIN STONE PTY. LTD.
3
1
2
1. Pilot pressure test point.
2. Accumulator charging valve pressure test point. 3. Accumulator charge relief valve.
1 2
17
Brake Pressure Test Points • Identify components (1) Pilot pressure test point (2) Accumulator charging valve pressure test point (3) Accumulator charge relief valve
The pilot pressure test point (1)is located on the pilot oilfilter. The test point is used for checking the p ilot pressure in the p arking brake, steering and im plem ent hydraulic system . The p ressure p oint (2) located in the pressure m anifold, below the brake accum ulator is for checking the C U T- IN ,C U T- O U T pressures o f the accum ulator charging valve. The accum ulator charge reliefvalve (3)can o nly be tested and set on a test bench.
• Testing & adjusting procedures Always follow the procedures in the Service Manual when testing and adjusting the machine
Page 25
Service Training Module R2900 Brake Module CATERPILLAR ELPHIN STONE PTY. LTD.
1
3
2
1. Parking brake control switch.
2. Service brake oil low pressure switch (CMS). 3. Service brake oil low pressure switch (B.A).
5
4
6
4. Parking brake relay.
5
7
5. Solenoids. 6. Parking brake low oil pressure switch. 7. Parking brake pressure switch (remotes). 18
Brake Electrical System • The parking brake is engaged and released by the parking brake control switch • When the service brake oil pressure is in the operating range, the parking brake can be released • If service brake oil pressure falls below the operating range, the parking brake will apply
The p arking brake system is controlled by parking brake controlsw itch (1) in the cab. The standard parking brake controlsw itch is a pull-toap ply type. W hen the sw itch is pulled out, the b rakes w ill apply. C ertain m ining reg ulations req uire m achines to be eq uipped w ith a push-to-ap ply parking brake controlsw itch. W hen the sw itch is pushed in, the brakes are applied. W hen the service b rake oilpressure is in the o perating range, service brake low oil pressure sw itches (2) and (3) w ill close. S w itch (3) w ill provide an earth for parking brake relay (4). If the p ark b rake control sw itch is in the engaged position, the relay (4)w illenergise and “ latch” . If the engine is started w ith parking brake control sw itch (1) in the release position, the brakes w illnot release as the parking brake relay w illno t be latched . The sw itch m ust be m oved to the engaged position to latch the relay. W hen the p arking brake controlsw itch is m oved to the release position, pow er is supplied to park b rake so lenoid controlvalves (5) toContinued release
Page 26
Service Training Module R2900 Brake Module CATERPILLAR ELPHIN STONE PTY. LTD.
• The Caterpillar Monitoring System monitors the service brake oil pressure
If service brake oilpressure falls b elow the operating range, sw itch (3) w ill open. The p arking brake relay w ill open an d interrupt pow er to solenoids (5). The p arking brake w illapply.
• If the service brake oil pressure falls below the normal operating range, the Caterpillar Monitoring System will initiate a category 3 warning
S ervice brake low oilpressure sw itch (2)is for the C aterpillar M onitoring S ystem . W hen brake oil pressure falls below the norm al operating ran ge, the sw itch w ill open, cau sing a categ ory three w arning. The C aterpillar M onitoring S ystem alert indicator w illcom e on,the fault light w illflash and the fault alarm w illso und.
• The parking brake low oil pressure switch is an input of the transmission electronic control - the signal tells the control when the parking brake is engaged • The transmission electronic control sends the parking brake low oil pressure switch signal to the Caterpillar Monitoring System over the Cat data link
The parking brake low oilpressure sw itch (6)is an inputofthe electronic transm ission control. W hen the p arking brake is engag ed , the sw itch sends a signal to the transm ission control. The control shifts the tran sm ission to neu tral. The transm ission control also sends the parking brake status to the C aterpillar M onitoring S ystem over the data link. W hen the p arking brake is engaged, the alert indicator for the parking b rake flashes on the C aterpillar M onitoring S ystem . If the op erator selects FO R W A R D or R E VER S E w hile the parking brake is en gag ed , the C aterpillar M onitoring S ystem initiates a category 3 w arning . P arking brake pressure sw itch (7)is p art ofthe optionalrem ote control system .
Page 27
Service Training Module R2900 Brake Module CATERPILLAR ELPHIN STONE PTY. LTD.
PARKING BRAKE RELAY 87
30
B C A PARKING BRAKE CONTROL SWITCH
BRAKE CONTROL 10 A
+ 24v
REMOTE CONTROL 10 A
1 2
0 1 1
REMOTE CONTROL SWITCH
PARKING BRAKE SOLENOIDS 1 2
8 14 13
1 2 3
27 22 28 18 37 38
POWER SUPPLY FROM BRAKE CONTROL CIRCUIT BREAKER
SERVICE BRAKE LOW OIL PRESSURE SWITCH 1 2 3
1 2 3
TRANSMISSION PRESSURE SWITCH ABA
POWER SUPPLY FROM REMOTE CONTROL CIRCUIT BREAKER
GROUND CIRCUIT
19
System Operation (Power Supply) • Key on engine not running
• Power is supplied from brake control circuit breaker to parking brake relay
• Loop wire fitted when optional impending brake application is not required
• Power supplied to terminal 30 on brake relay from remote control circuit breaker
This schem atic show s the w ires that have battery voltag e w ith the key sw itch in the o n position, and the p arking brake control sw itch in the brake engag ed position (engine off). P ow er is then supplied from the brake co ntrol circuit breaker to the parking brake co ntrolsw itch . W ith the sw itch in the engag ed position pow er is available atthe p arking brake relay w hich cannotbe energised because w ith the engine off there is no system pressure. The service brake low oil pressure sw itch and the A B A sw itch (A utom atic B rake A pplication)contacts are therefore open,interrupting the ground circuit for the parking brake relay. NOTE: Ifthe A B A transm ission oilpressure sw itch (optional)is n ot fitted a loop w ire is fitted to the three pin plug to com plete the circuit to the brake charge p ressure sw itch (as show n). P ow er is supplied to term inal30 on the parking brake relay through the rem ote co ntrolsw itch (optional)from the rem ote co ntrolsystem circuit breaker. Page 28
Service Training Module R2900 Brake Module CATERPILLAR ELPHIN STONE PTY. LTD.
PARKING BRAKE RELAY 87
30
B C A PARKING BRAKE CONTROL SWITCH
BRAKE CONTROL 10 A
+ 24v
REMOTE CONTROL 10 A
1 2
0 1 1
REMOTE CONTROL SWITCH
PARKING BRAKE SOLENOIDS 1 2
8 14 13
1 2 3
27 22 28 18 37 38
POWER SUPPLY FROM BRAKE CONTROL CIRCUIT BREAKER
SERVICE BRAKE LOW OIL PRESSURE SWITCH 1 2 3
TRANSMISSION PRESSURE SWITCH ABA
1 2 3
POWER SUPPLY FROM REMOTE CONTROL CIRCUIT BREAKER
GROUND CIRCUIT
20
System Operation (Relay Latched and Parking Brake Engaged) • With engine running transmission and brake oil pressure will increase • With both switches closed the parking brake relay will latch
W ith the engine running the transm ission oil pressure w ill rise. The transm ission pressure (A B A ) sw itch (if fitted) w illclose. A t the sam e tim e the brake oilpressure w illincrease.The service brake low oil pressure sw itch w ill close. W ith both sw itches in the closed position the parking brake relay circuit is com pleted to ground an d the parking brake relay w illlatch.
Page 29
Service Training Module R2900 Brake Module CATERPILLAR ELPHIN STONE PTY. LTD.
PARKING BRAKE RELAY 87
30
B C A PARKING BRAKE CONTROL SWITCH
BRAKE CONTROL 10 A
+ 24v
REMOTE CONTROL 10 A
1 2
0 1 1
REMOTE CONTROL SWITCH
PARKING BRAKE SOLENOIDS 1 2
8 14 13
1 2 3
27 22 28 18 37 38
POWER SUPPLY TO ENERGISE PARK BRAKE SOLENOIDS
SERVICE BRAKE LOW OIL PRESSURE SWITCH 1 2 3
TRANSMISSION PRESSURE SWITCH ABA
1 2 3
POWER SUPPLY FROM REMOTE CONTROL CIRCUIT BREAKER
GROUND CIRCUIT
21
System Operation (Parking Brake Released) •
Parking brake relay is latched by power from remote circuit breaker
•
Once relay is latched, parking brake can be released
P ow er is supplied from the rem ote circu it breaker to latch the parking brake relay.
O nce the p arking brake relay is latched and the p arking brake sw itch is m oved to the released position, pow er is directed to parking brake solenoids. The parking brake solenoids are energised and the parking brakes are released .
Page 30
Service Training Module R2900 Brake Module CATERPILLAR ELPHIN STONE PTY. LTD.
1
2
1. Parking brake low oil pressure switch.
2. Impending brake application switch.
6
3
4 5 4. Parking brake low oil pressure alert indicator. 5. Service brake low oil pressure aler t indicator. 6. Impending brake application alert indicator.
3. Service brake low oil pressure switch (C.M.S). 22
Parking Brake CMS Component Location
• CMS display area alerts the operator to any abnormal machine conditions • Brake system uses three switches and alert indicators
• Parking brake pressure switch activates the parking brake alert indicator on the CMS dash when parking brakes are applied.
The display area of the C M S sho w s the operator the cond ition o f the m achine system s and alerts the o perator to any ab no rm al m achine conditions that m ay exist. In the C M S electricalbrake system three sw itch es an d alert indicators are used . a. P arking brake low oilpressure sw itch . b. S ervice brake low oilpressure sw itch . c. Im pending b rake application. The parking brake pressure sw itch (1) is located below the brake release controlvalve on the left hand inside w allof the rear fram e. The parking brake pressure sw itch via the electronic tran sm ission co ntrolm odule, activates the alert indicator (4)on the C M S pan elw hen the parking brake is en gag ed . W hen the parking brake is released the p ark b rake p ressure sw itch w ill open. The p arking brake light on the C M S panelw illthen g o out. Continued
Page 31
Service Training Module R2900 Brake Module CATERPILLAR ELPHIN STONE PTY. LTD.
• Park/ing brake released, switch will open and park brake alert indicator will deactivate
The parking brake pressure sw itch sen ds a signalto the transm ission co ntrol m odule. W hen the em ergency /parking brake is applied , this sw itch w ill close, causing the transm ission to neutralise. W hen the parking brake is relea sed , the tran sm ission w ill resum e norm al operation.
• The parking brake pressure switch sends a signal to the transmission control module.
The service brake low oilpressure sw itch (3)is located on the left hand inside w allof the rear fram e.
• Service brake low oil pressure switch.
W hen the m achine is started the brake system oilpressure increases. W hen the pressure reaches the setting of sw itch (3) its contacts w ill close cau sing the low brake oilpressure light (5) on the C M S panelto go ou t. Th e p arking brake can no w be released. If the service b rake oil pressure d ecreases to below the setting of sw itch (3) its contacts w illopen and the service brake low oilpressure light on the C M S panel w ill co m e o n, w arning the o perator of low service brake oilpressure.
• Switch for impending brake application light. (IBA)
The im pending brake application sw itch (2) (optional) is located on back of the hyd raulic pilot filter housing above the torque converter. If the transm ission oilpressure falls b elow the setting of sw itch (2), the im pending brake application light (6)on the dash w illillum inate w arning the operator of the abnorm alcondition.
Page 32
Service Training Module R2900 Brake Module CATERPILLAR ELPHIN STONE PTY. LTD.
PARKING BRAKE LOW OIL PRESSURE SWITCH C B A 10 11 1 2 3
27 36 3 9 5
PARK BRAKE SWITCH N.C PARKBRAKE SWITCH N.O CAT DATA LINK CAT DATA LINK + GROUND ELECTRONIC TRANSMISSION CONTROL
SERVICE BRAKE LOW OIL PRESSURE SWITCH CMS
1 2 3
1 2 3
1 2 3 4
23 24 35 33 2
CAT DATA LINK + CAT DATA LINK BRAKE OIL PRESSURE IMPENDING BRAKE APP. GROUND COMPUTERISED MONITORING SYSTEM
IBA CMS SWITCH
CAT DATA LINK CIRCUIT
SERVICE BRAKE LOW OIL PRESSURE SWITCH CMS CIRCUIT
IMPENDING BRAKE APPLICATION CIRCUIT
PARKING BRAKE LOW OIL PRESSURE SWITCH CIRCUIT
23
System Operation CMS (Parking Brake Released) • Parking brake can not be released until brake and transmission have system pressure
• CAT Data Link allows the transmission control to receive and send information to the computerised monitoring system • Loop wire fitted when optional impending brake application is not fitted
The parking brake cannot be released un tilthe brake and transm ission oilpressure increases. This increase in p ressure w illcause the service brake low oilpressure sw itch an d im pen ding brake application (I.B .A .) sw itch (if fitted) to close, causing the alert indicators on the C M S dash to go out. W hen the p arking brakes are released the parking brake low oilpressure sw itch closes sending a signal to the electronic transm ission control. Th is sign alis then com m unicated to the C M S on the C A T controldata link causing the parking brake light to go out. The C A T data link is b idirectional, allow ing the transm ission controlto receive and send inform ation. The p urpose ofthe data link is to en able the tran sm ission control to co m m unicate w ith the C om puterised M onitoring S ystem (C M S ). The data link is not a single visible com ponent as it consists o f internal control circuits and connecting w iring harness. NOTE: W hen the im pending brake application is not fitted a loop w ire is fitted to co m plete the circu it to ground (as show n ab ove). Page 33
Service Training Module R2900 Brake Module CATERPILLAR ELPHIN STONE PTY. LTD.
1
2
1. Stop light switch.
2. Stop light.
3
4 3. Rear brake pressure switch.
4. Residual brake pressure light. 24
Stop Light and Residual Brake Pressure Light Circuit Components • Identify components: (1) Stop light switch (2) Stop light (3) Residual brake pressure switch (4) Residual brake pressure light • Operating the machine with the residual pressure will cause overheating of the brakes and may severely shorten the service life of brake components
The com ponents of this circuit are; stop light sw itch (1), stop light (2), rear brake pressure sw itch (3) and residualbrake pressure light (4). The stop light sw itch (1) is m ounted in the front brake circuit at the outlet of the brake controlvalve. Ifthe m achine is equipped w ith a residualbrake p ressure o ption a rear brake pressure sw itch (3)is also fitted. W hen the service brakes are applied the stop light (2)w illillum inate. NOTE: O perating the m achine w ith residualpressure w illcause overheating of the b rakes and m ay severely sh orten the service life of b rake com ponents.
Page 34
Service Training Module R2900 Brake Module CATERPILLAR ELPHIN STONE PTY. LTD.
STOP/TAIL LAMP CAB +24V
T S
9
15A
FRONT BRAKE PRESSURE SWITCH
3 1 2
1 2 1 2 REAR BRAKE PRESSURE SWITCH
3 TO FRONT LIGHT SWITCH POWER SUPPLY RESIDUAL BRAKE PRESSURE LIGHT
STOP LIGHT CIRCUIT 25
System Operation (Stop Light/Residual Brake Pressure Circuit) • When the service brakes are applied will close the brake pressure switches and completes the circuit to the stop/tail light
W hen the service brakes are ap plied oil pressure w illclose the brake pressure sw itches and com pletes the circu it to the stop/taillam p P ow er w illnow be supplied to illum inate the stop light. If the m achine is equipped w ith a residualbrake pressure circuit a rear brake pressure sw itch is also fitted (as sh ow n).
•
W hen the service b rake is applied the b rake o il pressure rises above the setting ofresidualbrake pressure sw itches. The sw itches w illclose com pleting the circuit to the residual brake pressure light. P ow er w ill now be supplied to illum inate residualbrake pressure light.
Machine equipped with a residual brake pressure circuit are fitted with a rear brake pressure switch and light
Ifthe residualbrake oilpressure rem ains in the w heelbrakes ab ove the setting of the sw itches after the b rakes have been released, the light w illrem ain illum inated. A lso the rear brake light w illillum inate.
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Service Training Module R2900 Brake Module CATERPILLAR ELPHIN STONE PTY. LTD.
1
2 1. Brake release pump.
3
3. Brake release pump switch.
2. Brake release pump solenoid.
4
4. Park brake control switch. 26
Electric Brake Release System • Brake Release Circuit Components: (1) Brake release pump (2) Brake release pump relay (3) Brake release switch (4) Park brake control switch • The brake release circuit allows the operator to release the parking brake • The pump is activated by a switch located on the circuit breaker board.
The electric brake release circuit allow s the operator to release the parking b rake if the b rake is ap plied due to a m achine fau lt. W hen the brakes are released , the m achine can be tow ed to a service area. The electric b rake release circuit is controlled by a sw itch located on the circuit breaker board in the operator’ s station. The electric brake release circuit uses an electric hyd raulic pum p to supply oilto the parking brake circuit and the service brake circuit. W hen the brake system is fully charged , the operator m ust use the parking brake co ntrolsw itch to release the brakes. B ecause the service brake circuit is charged w ith oil, the service brake can b e used to stop the m achine during tow ing , etc.
• An electric hydraulic pump charges the parking brake circuit and service brake circuit Page 36
Service Training Module R2900 Brake Module CATERPILLAR ELPHIN STONE PTY. LTD.
BRAKE RELEASE SWITCH
+24V
BRAKE RELEASE RELAY 6
15A
BRAKE CONTROL
MOTOR
S
G
BRAKE RELEASE MOTOR
FUSE 675A
POS
NEG
POS
12 VOLT BATTERIES
BAT MTR
MOTOR
NEG
DISCONNECT SWITCH
BRAKE RELEASE MOTOR CIRCUIT
RELAY POWER SUPPLY
27
System Operation (Electric Brake Release) • Explain operation
The ab ove electrical schem atic sh ow s the b rake release pum p activated. W hen the brake release toggle sw itch is held in the on position, pow er from the brake controlcircuit breaker energises the brake release relay. Then pow er is supplied from the 675 am p fuse to activate the brake release pum p’ s electricalm otor.
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Service Training Module R2900 Brake Module CATERPILLAR ELPHIN STONE PTY. LTD.
1. Electrical faults.
1. Bleed down oil pressure. 28
Practical Tasks • Bleed down oil pressure in the brake system
Task 1 1:Each trainee w illbe req uired to successfully bleed dow n the o il pressure in the b rake system . 1. Find the p roced ure in S ervice M anual. 2. Fo llow the p rocedure and successfully com plete the task.
• Electrical Faults.
Task 2 2: Trainer to place a series of electricalfaults on the m achine. 1. P lace a faulty p arking brake relay in the circuit. 2. R em ove w ire E L3 32 -B R from parking brake controlsw itch. Each trainee w illbe required to successfully 1. Fault find the electricalfaults, using the electricalschem atic and service m anual. 2. R ectify the faults, test and start m achine.
• Service manual.
A lw ays check the S ervice M anual for the correct ad justing procedure and sp ecifications. A lw ays follow the procedures contained in the S ervice M anual w hen testing an d/or adjusting the m ach ine.
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Service Training Module R2900 Brake Module CATERPILLAR ELPHIN STONE PTY. LTD.
R2900 LHD Braking System Theory Assessment Directions: Multiple Choice. Read each statement carefully and circle the letter(s) of the correct answer(s) * Reference to notes and other literature is allowed. Q .1. E ach w heel hee lb rake has: A . O ne section B . Tw o sections C .Fo ur sections D .N ine sections
Q .2. The The pparki arking b rake is: A . O ilap plied an d sp ring released B . O ilap plied and released C .O ilreleased and spring ap plied D .P ed alco ntrolled
Q .3. The Th e b rake and p pi ilot p um p is a: pum A . C entrifug alpum p B .P iston p um p C .Vane pum p D .G ear pum p
Q .4. The accu ac cu m ul ulator ch arging ng valve d ivides n the: d es the oilflow b etw ee een A . P ilot and transm ission system s B . B rake and pilot system s C .B rake and hydraulic system s D .P ilot and oilco oling system s
Q .5. The Th e ac acc cum ator charge relief valve lim its m axim um oilp ressure in the : cuum m ulator pressur A . P ilot system B . P arking brake system C .A ccum ulator charging circuit D .M ain hydraulic circuit Continued
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Service Training Module R2900 Brake Module CATERPILLAR ELPHIN STONE PTY. LTD.
Q .6. The service brake supp p lies oilun under d er pprressur e to: to: b rake ac cu m ulator sup und essure A . The parking brake co ntrolvalve B . The service brake controlvalve C .The accum ulator charging valve D .The pilot relief valve
Q .7. The service brake olvalve is o p erated erated b y a: b rake contr control perated by A.Lever B . S w itch C .Pedal D .S olenoid
Q .8. The service b rakes rake s aare: ar re: e: A . Electronically applied B . S pring ap plied an d oilreleased C .O ilap plied and released D .O ilap plied an d sp ring released
Q .9. The accum ulator charging valve gives ppri p riority o ilflow to: A . The brake system B . Th e b rake and pilot system s C .The hyd raulic system D .The tran sm ission controlvalve
Q .10. The The service b rake accum ulator is ch arged w ith: acc um ul A . C om pressed air B .O xygen C .H ydrogen D . D ry nitrogen
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Service Training Module R2900 Brake Module CATERPILLAR ELPHIN STONE PTY. LTD.
R2900 Braking System Theory Assessment Answers Q.1. B. Q.2. C. Q.3. D. Q.4. B. Q.5. C. Q.6. B. Q.7. C. Q.8. D. Q.9. A. Q.10. D.
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Service Training Module R2900 Brake Module CATERPILLAR ELPHIN STONE PTY. LTD.
R2900 LHD Brake Electrical System Theory Assessment Directions: Multiple Choice. Read each statement carefully and circle the letter(s) of the correct answer(s) * Reference to notes and other literature is allowed. Q .1. The The p arking b brake rake is contr co ntrolled b y: A . A sw itch on the pilot co ntrolvalve B . A sw itch on the m ain dash panel C .A sw itch on the circuit breaker board D .The transm ission electronic co ntrolm odule
Q .2. W he n the parki brake rake sw itch is m oved to the en gag ed posi p arking b p osition: A . The front w heelbrakes release B . The rear parking brakes release C .The service b rakes apply D .A llthe w heelbrakes are activated
Q .3. The The b rake oilp r essure sw itch es ar e located on: brake ressur are A . The B . The C .The D .The
inside left w allof the rear fram e inside right w allof the rear fram e rad iator guard right w allof the front fram e
Q .4. The p parki arking b rake r elay is located : rel A . B ehind the p ilot controlvalve B . U nd er the S TIC steer co ntrolvalve C .B ehind the C M S dash D .U nd er the o perators seat
Q .5. The p arking b brake rake r el elay ay control controls the: parki rel A . S ervice brake application B . R elease of the parking b rake C . R elease of the service b rakes D . Transm ission gear selection
Continued
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Service Training Module R2900 Brake Module CATERPILLAR ELPHIN STONE PTY. LTD.
Q .6. The parki s are m ounted o n the: p arking b rake solen oid ds A . M ain im plem ent controlvalve B . B rake system relief valve C .Transm ission hydrau lic co ntrols D .H ydrau lic brake release co ntrolvalve
Q .7. W hen rem rem ote con contr tr olis fi fitted to the m achine: trol A . Tw o extra solenoid controlvalves are fitted B . O ne extra so lenoid controlvalve is fitted C .Three extra solenoid controlvalves are fitted D .Five extra so lenoid controlvalves are fitted
Q .8. W hen the tran sm ission o il p ressure rise s the: A . P arking brake sw itch w illopen B . A B A sw itch (if fitted)w illopen C .A B A sw itch (if fitted)w illclose D .P arking brake sw itch w illclose
Q .9. W hen the se rvice b rake o ilpr eases ease s to w orking p r essure: e: servi brake p ressure incr ncrease ressur A . T he brake charge pressure sw itch w illclose B . The parking brake relay w illunlatch C . T he brake ch arge pressure sw itch w illopen D . The service b rakes w illapply
Q. .10. 10.The eel b rake r elea se ppum um p is activated b y: .10.The lectric bbrake rel ease A. B. C. D.
The rem ote controls The parking b rake sw itch A tog gle sw itch m ou nted o n the dash A toggle sw itch m ounted on the circuit breaker board
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Service Training Module R2900 Brake Module CATERPILLAR ELPHIN STONE PTY. LTD.
R2900 Brake Electrical System Theory Assessment Answers Q.1. B. Q.2. D. Q.3. A. Q.4. C. Q.5. B. Q.6. D. Q.7. B. Q.8. C. Q.9. A. Q.10. D.
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Service Training Module R2900 Brake Module CATERPILLAR ELPHIN STONE PTY. LTD.
3 ?
Serviceman’s Handout No. 1 Braking System Component Location (1) (2) (3) (4) (5) (6) (7) (8) (9) (10) (11)
Brake and pilot pump Accumulator charging valve Pilot oil filter Pilot relief valve Brake system relief valve Accumulator Service brake control valve Wheel brakes Parking brake release solenoid Hydraulic tank Electric pump
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Service Training Module R2900 Brake Module CATERPILLAR ELPHIN STONE PTY. LTD.
3
2 1 4
5 6 7
9 10
8
11 5
Serviceman’s Handout No. 2 Accumulator Charging Valve (Component Location) (1) (2) (3) (4) (5) (6) (7) (8) (9) (10) (11)
Spring Check valve Spool stop Pilot valve spool Pilot valve spring Chamber Charging valve spool Orifice Upper limit check ball Lower limit check ball Passage
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Service Training Module R2900 Brake Module CATERPILLAR ELPHIN STONE PTY. LTD.
Park Brake Oil Pressure
10
Wheel Brake (Parking Brake Released) Serviceman’s Handout No.3 (1) (2) (3) (4) (5) (6) (7) (8) (9)
Parking piston Service piston Outer casing Springs Wheel hub Annular passage Steel plates Friction discs Brake pack
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Service Training Module R2900 Brake Module CATERPILLAR ELPHIN STONE PTY. LTD.
FRONT WHEEL BRAKES SERVICE BRAKE CONTROL VALVE
REAR WHEEL BRAKES
SERVICE BRAKE ACCUMULATOR
PARKING BRAKE PILOT RELIEF VALVE
CONTROL VALVE
ACCUMULATOR CHARGING VALVE
T M O L I E P T S Y O T S
ACCUMULATOR CHARGE RELIEF VALVE
STEERING
BRAKE AND
PUMP
PILOT PUMP
TANK
12
Serviceman’s Handout No. 4 System Operation (Parkimg Brake Engaged) (1) Pressure oil (2) Pilot oil (3) Tank oil
Page 48
Service Training Module R2900 Brake Module CATERPILLAR ELPHIN STONE PTY. LTD.
FRONT WHEEL BRAKES SERVICE BRAKE CONTROL VALVE
REAR WHEEL BRAKES
SERVICE BRAKE ACCUMULATOR
PARKING BRAKE PILOT RELIEF VALVE
CONTROL VALVE
ACCUMULATOR CHARGING VALVE
T M O L I E P T S Y O T S
ACCUMULATOR CHARGE RELIEF VALVE
STEERING
BRAKE AND
PUMP
PILOT PUMP
TANK
13
Serviceman’s Handout No. 5 System Operation (Parking Brake Released) (1) Pressure oil (2) Pilot oil (3) Tank oil
Page 49
Service Training Module R2900 Brake Module CATERPILLAR ELPHIN STONE PTY. LTD.
FRONT WHEEL BRAKES SERVICE BRAKE CONTROL VALVE
REAR WHEEL BRAKES
SERVICE BRAKE ACCUMULATOR
PARKING BRAKE PILOT RELIEF VALVE
CONTROL VALVE
ACCUMULATOR CHARGING VALVE
T M O L I E P T S Y O T S
ACCUMULATOR CHARGE RELIEF VALVE
STEERING
BRAKE AND
PUMP
PILOT PUMP
TANK
14
Serviceman’s Handout No. 6 System Operation (Service Brakes Applied) (1) Pressure oil (2) Pilot oil (3) Tank oil
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Service Training Module R2900 Brake Module CATERPILLAR ELPHIN STONE PTY. LTD.
FRONT WHEEL BRAKES
SERVICE BRAKE CONTROL VALVE
SERVICE BRAKE ACCUMULATOR
REAR WHEEL BRAKES PILOT RELIEF VALVE
PARKING BRAKE CONTROL VALVE
ACCUMULATOR CHARGING VALVE
T M O L E I P T S Y O T S
SHUTTLE VALVE
TOW BRAKE RELEASE CYLINDER ACCUMULATOR CHARGE RELIEF VALVE BRAKE RELEASE SEQUENCE VALVE
STEERING PUMP
BRAKE AND PILOT PUMP
L E A C N R R O E F T X E
TANK
16
Serviceman’s Handout No. 7 System Operation (Towing Brake Release Activated) (1) Pressure oil (2) Pilot oil (3) Tank oil
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Service Training Module R2900 Brake Module CATERPILLAR ELPHIN STONE PTY. LTD.
PARKING BRA KE RELAY 87
30
B C A PARKING BR AKE CONTROL SWITCH
BRAKE CONTROL 10 A
REMOTE CONTROL
+ 24v
10 A
1 2
0 1 1
REMOTE CONTROL SWITCH
PARK BRAKE SOLENOIDS 1 2
8 14 13
1 2 3
27 22 28 18 37 38
POWER SUPPLY FROM BRAKE CONTROL CIRCUIT BREAKER
SERVICE BRAKE LOW 0IL PRESSURE SWITCH 1 2 3
TRANSMISSION PRESSURE SWITCH ABA
1 2 3
POWER SUPPLY FROM REMOTE CONTROL CIRCUIT BREAKER
GROUND CIRCUIT
19
Serviceman’s Handout No 9 System Operation (Power Supply)
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Service Training Module R2900 Brake Module CATERPILLAR ELPHIN STONE PTY. LTD.
PARKING BRA KE RELAY 87
30
B C A PARKING BR AKE CONTROL SWITCH
BRAKE CONTROL 10 A
REMOTE CONTROL
+ 24v
10 A
1 2
0 1 1
REMOTE CONTROL SWITCH
PARK BRAKE SOLENOIDS 1 2
8 14 13
1 2 3
27 22 28 18 37 38
POWER SUPPLY FROM BRAKE CONTROL CIRCUIT BREAKER
SERVICE BRAKE LOW 0IL PRESSURE SWITCH 1 2 3
TRANSMISSION PRESSURE SWITCH ABA
1 2 3
POWER SUPPLY FROM REMOTE CONTROL CIRCUIT BREAKER
GROUND CIRCUIT
20
Serviceman’s Handout No. 10 System Operation (Relay Latched and Parking Brake Engaged)
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Service Training Module R2900 Brake Module CATERPILLAR ELPHIN STONE PTY. LTD.
PARKING BRAKE PRESSURE SWITCH C B A 10 11 1 2 3
27 36 3 9 5
PARK BRAKE SWITCH N.C PARKBRAKE SWITCH N.O CAT DATA LINK CAT DATA LINK + GROUND ELECTRONIC TRANSMISSION CONTROL
SERVICE BRAKE LOW OIL PRESSURE SWITCH CMS
1 2 3
1 2 3
1 2 3 4
23 24 35 33 2
CAT DATA LINK + CAT DATA LINK BRAKE OIL PRESSURE IMPENDING BRAKE APP. GROUND COMPUTERISED MONITORING SYSTEM
IBA CMS SWITCH
CAT DATA LINK CIRCUIT
IMPENDING BRAKE APP, CIRCUIT
SERVICE BRAKE LOW OIL PRESSURE SWITCH CMS CIRCUIT
PARKING BRAKE LOW OIL PRESSURE SWITCH CIRCUIT
21
Serviceman’s Handout No. 11 System Operation CMS (Parking Brake Released)
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Service Training Module R2900 Brake Module CATERPILLAR ELPHIN STONE PTY. LTD.
STOP/TAIL LAMP CAB +24V
9
15A
FRONT BRAKE PRESSURE SWITCH
3 1 2
1 2 1 2 REAR BRAKE PRESSURE SWITCH
T S
3 TO FRONT LIGHT SWITCH POWER SUPPLY RESIDUAL BRAKE PRESSURE LIGHT
STOP LIGHT CIRCUIT
25
Serviceman’s Handout No. 12 System Operation (Stop Light and Residual Brake Circuit)
Page 55