Assignment on opening up of complete cylinder unit including crosshead bearing, connecting rod bearing, & main bearing for continuous machinery survey
Compiled by P.H.D.R. SSA!"HA #$arine %ngineer Sri an'a(
Content
). Planning
*. Safety precautions
+. verhauling & calibration procedure
-. Spare parts used
. References
). Planning Information requested prior to survey 1. Refer class status report 2. Consult technical manager and discuss intended procedure 3. Check spare parts inventory and order if necessary. In this case it has to be taken into account R.O. after !nishing the "ob too. #. Inform master $ork schedule% &iscuss $ith chief o'cer and arrange any support if necessary (. )revious survey report% engine running hours $hen survey $as carried out% &etails of recoded clearances% details of any possible marking on pin% bearing condition. *. +ifting gear condition including engine room crane and test certi!cates has to be checked and make sure conditions are satisfactory in advance to prevent accidents% unnecessary delays% damages and personnel in"uries.
/*. Safety precautions 1,
Inform company% con!rm duration of port stay and take permission
2, -ake immobiliation certi!cate from port authority. -his process may take some times therefore early inform to authority $ill avoid delays 3, Read the manual and have a toll bo/ meeting $ith everyone involved in the "ob. &iscuss the procedure. #,
)repare important tools and spares to be used in this operation
(, 0 risk assessment of all personnel doing the operation to be prepared and documented *,
hut main engine starting air
,
ngage turning gear to the main engine crankshaft
4,
Open indicator cocks of all cylinders
5, 16,
top main engine lube oil pump after cooling do$n of engine Open crank case doors of fore and aft unit
11, Open crank case doors of that unit in $hich maintenance is to be carried out. 12, )ut blo$er and ventilate the crankcase thoroughly as it is an enclosed space.
13,
)repare enclosed space entry checklist.
1#,
0fter su'cient ventilation $earing proper )) enter C7C
1(. efore start the "ob checked condition of high pressure hydraulic pump and hoses al$ays used proper safety equipment $hen handling the unit.
/+. verhauling & calibration procedure %ach procedure has prepared as they have been carried out separately 0hile safety precautions are given above as they are similar to all process more or less.
Procedure for Cylinder head and piston overhauling and calibration 1. et blocking device A on the main 2. 3. #. (.
starting valve in the +OC8& position. ngage turning gear 1. Close fuel oil inlet valve C. Close cooling $ater inlet valve D. Close cooling $ater outlet valves % and
2. *. Open cooling $ater drain cocks 3 and H. . hut o9 the control air and safety air
supply. 4. :ent the manoeuvring system through the ball valve. 5. 0lso shut o9 the air supply on the reduction unit for the hydraulic7pneumatic e/haust valve% and vent the system.
&ismantling of cylinder cover carried out according to the manufactures instruction given in maintenance manual al$ays under supervision of responsible engineer. 0ll the O;rings and sealing rings $ere rene$ed $ith original spares. )hotographs of all parts before and after cleaning $ere taken to attach survey report Condition of seating faces% condition of cooling spaces should be carefully checked. 'ciency of cooling $ater treatment process evaluated by the condition of cooling spaces. 0ll mountings of the cylinder cover $ere removed and valve bores reconditioned as described in the maintenance manual. 0fter the grinding% cleaned the bore and seating carefully% and checked that the seating is not damaged.
0fter removing the piston from the cylinder and place it on the piston support. !ote4
It is recommended to replace all the piston rings $henever a piston is removed from the engine. 2ree ring gap5
efore dismantling the piston rings% measure the free ring gap of all the piston rings.
Radial ring 0idth5
=easure the radial $idth of the rings. >ote do$n the results Ring grooves5
Clean the ring grooves and check them for burn marks or other deformation. =easure the ring grooves $ith a calliper gauge% Clearance in piston ring grooves? -he ma/imum vertical height in a $orn ring groove must not e/ceed the value stated in &ata. -he groove is also $orn out if there is no chromium layer. If the ring grooves are $orn out% the piston cro$n must be reconditioned% contact =0> @< &iesel 07 for advice. Piston top template5
Check that the piston top template is permanently marked $ith the piston top centre diameter &62A#4. Check that the centre area C has been marked o9% and $rite the ma/imum permissible burn a$ay rate on the template. =ark the outer part of the template R for ring area% and $rite the ma/imum permissible burn a$ay rate for the ring shaped area. Piston cro0n top5
Clean the piston cro$n and check the burn a$ay by means of the template. For maximum permissible burn away on the piston top centre area
Check the burn a$ay on the $hole circumference of the piston cro$n top. If the burn a$ay e/ceeds the values given in &ata% contact =0> @< for advice. >ote do$n the results for later reference.
Calibration of piston rod stu6ng bo7 1. 0fter the piston rod stu'ng bo/ has been dismantled% check the follo$ing clearances? Bppermost scraper ring and sealing rings Clearance at ring ends scraper ring,. -otal clearance scraper ring,. &62; 25, Clearance at ring ends sealing rings,. -otal clearance sealing rings,. &62; 25, Lowermost scraper rings
Clearance at ring ends. -otal clearance. &62;36, -he ring clearances stated in &ata apply to ne$ rings. 0s a general guide% it is recommended D depending on the overhauling intervals and oneEs o$n e/perience D to replace sealing rings and scraper rings $hen the speci!ed clearance values &62;25 and &62;36 have been halved. 2. Farter springs?
Fenerally% it is recommended to rene$ the springs $hen the sealing rings and scraper rings are rene$ed. -he springs can be checked as follo$s? )lace the springs on the table% measure +o Gree length,% and compare $ith &ata. If a spring is e/tended more than 4H from the value given in data% it must be discarded.
Procedure for crosshead bearing overhauling and calibration Gollo$ing procedure $as follo$ed $hen carrying out crosshead bearing removal of a =0> =C;C engine?
1. -urn the crank thro$ to 56 before &C. 2. Check the bearing clearance by inserting feeler gauge b7$ bearing cap and crosshead "ournal e/actly ne/t to the landing surface of the piston rod foot.
-he $ear limit for a cross head bearing shell is limited to (6H reduction of the oil $edge length +,.J +K16mmL 3. -urn the crankshaft do$n enough to give access to nuts and scre$s on piston rod. #. =ount t$o chain blocks on the top of the crankcase for suspending the piston rod. (. +oosen and remove the locking $ire and scre$s on the piston rod foot.
*. =ount the lifting eye bolt on each side of the piston rod foot. . -urn the crosshead to -&C. 4. Mook the chain blocks to the eye bolt on the piston rod foot. 0nd turn the crosshead do$n so that piston is no$ suspended on the chain blocks. 5. -urn to &C. 16.=ount the hydraulic "ack on the crosshead bearing cap nut and loosen them. J)ressure? 1(66;1*(6 barsL 11.=ount the lifting attachment on the head of the connecting rod. 12.uspend the t$o chain blocks from the lifting brackets in the ath$art ship direction.
13.=ount the 2 eye bolts on the top of the cross head bearing cap. 1#.
1.-urn the crosshead up until the piston rod lands on the crosshead. nsure that the guide ring in the crosshead !ts correctly in the centre hole of the piston rod. 14.&o not remove the chain blocks or the lifting eye bolts.
15.-urn the crosshead to -&C and attach the chain blocks to the lifting arrangement and haul it tight. 26.=ount the four supports for the guide shoes on the crosshead guide. 21.Carefully and slo$ly turn the crankshaft to$ards to e/haust side and make sure the crosshead guide sits on the supports. 22.-urn the crank thro$ to$ards &C slo$ly $hile follo$ing $ith the chain blocks% thus continuously supporting the connecting rod.
23.In case it is necessary to remove the lo$er bearing shell% tilt the connecting rod to$ards the door on the cam shaft side $ith means of chain blocks.
2#.&ismount the locking scre$s and turn the bearing shell so far up that an eye bolt can be mounted. +ift the bearing shell out. -op clearance in crosshead bearing?;=a/? 6.25mm% =in? 6.1mm
"he procedure for opening and calibration of connecting rod bearing $A! 1&8 Chec'ing Cran'pin 1earing
-he bottom clearance bet$een the "ournal and a ne$ bearing shell is the result of a summation of the production tolerances of the bearing assembly components. 1. Open the crankcase door at the relevant cylinder.
2. -urn the crank concerned to &C. 3. =easure the clearance in the crankpin bearing by inserting a feeler gauge at the bottom of the bearing shell in both sides. . #. -he di9erence bet$een the actual clearance measurement and the measurement recorded in the 0d"ustment heet or the clearance noted for a ne$ bearing installed later, must not e/ceed 6.1 mm. If so% the crankpin bearing must be disassembled for inspection. (. -he $ear limit for the crankpin bearing shells is based on an evaluation of the bearing condition at the time of inspection. 0n average $ear rate of 6.61 mm per 16%666 hours is regarded as normal.
"he procedure for opening and calibration of main bearing 1. =ake sure that the main bearing measuring tool depth gauge, is calibrate and set to N6E. 2. Open the scre$s of lube oil pipe connection and insert the depth gauge and measure the clearance bet$een upper bearing keep and "ournal.
3. Compare this reading $ith the earlier reading in the record or the ne$ bearing #. (. *. .
reading. >o$ disconnect the lube oil pipe line. -urn the crank thro$ so that it is to$ards the e/haust side. >o$ mount the hydraulic "acks and loosen the main bearing stud nuts. =ount the lifting tool for main bearing keep and lift the keep using a pulley
and a $ire rope. 4. >ote the marking on the main bearing keep before lifting for correct direction of the keep. 5. Fuide the keep safely outside $ith a help of another chain block and place it on a $ooden base once it is out. 16.=ount the tool for lifting the upper bearing shell and place it safely outside. 11.)lace the strong back cross piece, support on the bed plate so that its ends rest on the cross girders. 12.=ount the hydraulic "ack on the cross piece placing it such that it lies beneath the crank $ebs. 13.=ount a dial gauge on the ad"acent main bearing so that the lift of the crank shaft can be recorded. 1#.>o$ $ith hydraulic pressure 1(66;1*(6 bar, lift the crankshaft corresponding to the main bearing clearance to the ad"acent main bearing% and check the lift $ith the help of a dial gauge. 1(.Remove the lock scre$s from the lo$er shell. 1*.)lace the dismantling tool on the lo$er bearing shell such that the ap enters the oil groove. 1.)ull the bearing shell round and up so that it lies on the "ournal and take it out safely.
-op =ain bearing clearance? ma/; 6.(4mm% min; 6.#6mm
Checking the bearing edges *. earing edges can be checked $ith a PfeelerQ that is able to follo$ the bearing edge against the "ournal the $hole $ay round on each side. If $hite metal is missing at the edge% the tip of the PfeelerQ $ill enter the hole% thus locating the damage. In most cases this hole can be seen by the naked eye as a dark spot $hen using a strong ashlight. -he >o. 1 and the t$o aft most main bearings are more di'cult to access on the $hole circumference on each side% but it is often possible to bend the PfeelerQ to suit the situation and thus reach as far round as possible.
be bent to an angle of appro/. *( to form a Pfeeler tipQ. Frind the tip smooth to obtain the shape and dimension sho$n on the sketch. >ote that the thickness of the $hite metal is appro/. 1.( mm% $hich is $hy the tip should be less than 1.2 mm thick% and bigger than the ma/. -op clearance. 0t the other end of the tip% a PhandleQ should be made by bending a hook or similar in the same direction as the tip. 4. If there is too large a di9erence in the crankshaft deection readings autolog, check the clearance in the individual bearings. earing clearance checks should also be carried out during time;based overhauls and surveys. If there is a suspicion of a damaged bearing% it is recommended to edge check the bearing% $ithout opening up. 5. efore measuring% check that the feeler blades are in good condition. -he feeler is inserted along the crank thro$. o$ the feeler blade is pushed ma/. 26 mm into the gap. 16. -he clearance is measured at both the fore and the aft part of the bearing. 11. -he di9erence bet$een the actual clearance measurement and the measurement recorded in the ad"ustment sheet or the clearance noted for a ne$ bearing installed later, must not e/ceed 6.16 mm
/-.Spare parts used &escription
)art number
RO at biginin g of month
used
RO
Cylinder Cover O;ring Fasket pring Mousing Fasket Fasket Fasket
)iston )iston )iston )iston
assembly ring >o. 61 ring >o. 626# ring >o. 63
)iston stu'ng bo/ O;ring Gitted bolt Gitted bolt +emella for scraper ring Farter spring
)56161;613; 12* )56161;613; 1(1 )56161;613; 14 )56163;666#; 626 )56163;666#; 632 )56163;666#; 12
2 1 2 1 1 1
1 2 1
2 2 # 4 2
/. Reference5
=0> @< =C;C ngine maintenance manual Class >8 C= urvey guidance
Image credit?
