e c i v r e S
Function Maintenance Inspection Troubleshooting
ZF
® Servocom RAS (Rear Axle Steering) version of PAUL Nutzfahrzeuge GmbH Danziger Str. 49 D-94036 Passau GERMANY Tel.: 0049/851-95538-0 Fax.: 0049/851-54193
ZF Lenksysteme GmbH D-73522 Schwaebisch Gmuend Telephone elephone (07171) 31-0 31-0 Fax (07171) 31-4396 31-4396 8352 W 5/00 e
Contents / System description / Notes
Contents: Page
1
Functional description . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2
2
Safety instructions . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5
3
Maintenance . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5
4
Inspection . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 6
5
Disassembly of the ZF-Servocom RAS . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 7
6
Installation of the ZF-Servocom RAS . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 8
7
Charging with gas . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 9
8
Filling with oil . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 10
9
Bleeding . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 10
10 Settings and tightening torques . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 11 11 Special tools . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 12 12 Troubleshooting . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 13
System description: !
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The ZF-Servo ZF-Servocom com RAS is a rear rear axle axle steeri steering ng system system which which hydro hydrosta static ticall allyy transmi transmits ts the steeri steering ng movement of the front axle to the rear axle (as in the case of a hydraulic braking system). The hydrostatic power is transmitted from the master cylinder (front axle) via hydraulic connections to the centering cylinder (rear axle).
Notes: !
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This manual is exclusively intended to supplement the existing instructions for operation, maintenance and inspection of the ZF-Servocom steering systems. All the work described here should be carried out within the framework of routine maintenance and inspection of the ZF-Servocom. All the settings and test values or dimensions listed are standard values which apply for all versions.
Exception:
The individual vehicle manufacturers may prescribe different values. Please take note of the service information circulars and the spare parts list!
ZF-Servocom RAS
1
Function
1
Funct Functiona ionall descri descripti ption on
1.1 Mechanical Mechanical design
1 2
ZF ZF -Servocom Mast aster cyli ylinder with pres pressu sure re limi limiti ting ng valv valve e and and repl replen enis ish hing ing vavl vavle e
3 4 5 6 7
Ce Centering cylinder Hydr ydraulic accu accum mulato ator Hydr Hydrau auli licc line liness Pres Pressu surre swit switch ch Conn Connec ecti ting ng rod rod
1.2 Function Function
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The steering movement is transmitted from the ZF-Servocom or front axle steering (1) mechanically via a connecting rod (7) and hydraulically via hydraulic lines (5) to the master cylinder (2) which is mounted on the front axle or vehicle chassis. The master cylinder (2) hydrostatically transmits the steering movement via hydraulic lines (5) to the centering centering cylinder cylinder (3) on the trailing trailing axle. This axle is steered by the centering cylinder cylinder via the piston piston rod. The hydraulic accumulator (4) improves the rigidity of the hydrostatic transmission system and acts permanently on the two centering pistons which are integrated into the centering cylinder (3). Pressure limiting valves are installed in the master cylinder (2) in order to protect the hydrostatic system against impermissibly high pressures which could damage the system. The master cylinder (2) also includes replenishing valves to prevent the formation of a vacuum in the unpressurized cylinder area and thus facilitate the steering movement. The pressure switch (6) monitors the system pressure and is connected to a pilot lamp.
Additional information for versions with cut-off valve (8): The cut-off valve (8) (see figure on page 18) connects the lines L1 and L2 in case of breakdown of the hydraulic assistance of the front axle steering gear. This produces the fact that the ZF-Servocom RAS does not co-steer and that no additional actuating forces are required at the front axle steering gear.
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ZF-Servocom RAS
Function 1.3 Function Function when travelling travelling straight straight ahead
Operating pressure - front axle steering
System pressure
Accumulator pressure (gas-charged)
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The master cylinder (2) is designed so that the cylinder areas Z1 and Z2 are connected when travelling straight ahead and when the steering angle is less than 5 o. This ensures that the four cylinder areas Z3, Z4, Z5 and Z6 in the centering cylinder (3) are pressurized by the hydraulic accumulator (4), thus holding the trailing axle in position for travel straight ahead.
Short-circuiting cylinder areas Z1 and Z2 and centering the trailing axle additionally ensures that the master master cylinder cylinder and centering cylinder cylinder (3) are synchroni synchronized. zed. This compensates compensates any hydrostatic hydrostatic offsets which may occur, for example as a result of minute leaks.
ZF-Servocom RAS
3
Function 1.4 Functio Function n when when steer steering ing to the right right
Operating pressure - front axle steering / return flow Operating pressure - front axle steering System pressure / return flow System pressure Accumulator pressure (gas-charged)
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Cylinder space Z7 in the master cylinder (2) is pressurized by the ZF-Servocom or front axle steering (1) and displaces the piston rod to the right.
This pressurizes the hydraulic fluid in cylinder space Z1, as well as in cylinder space Z6 via hydraulic lines (5) if the steering angle is greater than 5 o.
The piston rod of the centering cylinder (3) is consequently displaced to the left and the trailing axle is steered to the left.
ZF-Servocom RAS
Safety instructions / Maintenance
2
Safe Safety ty inst instru ruct ction ionss
Attention: !
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Lines and connections, etc. must not be opened until the system pressure of the ZF-Servocom RAS has been relieved. The bleeder valves must be opened slowly to bleed the system. Note that at least the system pressure is still present in the hydrostatic system even when the engine has been switched off. The front front axle axle steeri steering ng must not not be actuated actuated when connecti connection onss or lines, lines, etc. on the rear rear axle axle steering system have been opened, since the high resultant pressures may cause injuries.
3
Maint intena enance
3.1
Mainte Maintenan nance ce inter interva vals ls
The maintenance intervals which apply for the ZF-Servocom steering system or which are specified by the vehicle manufacturer also apply for the ZF-Servocom RAS. Note any other or additional intervals specified by the vehicle manufacturer.
3.2
Mainte Maintenan nance ce work work
Check oil level ZF-Servocom RAS: The oil level cannot cannot be checked. checked. This is also unnecessar unnecessaryy, since oil cannot be lost during during normal normal operation and when the ZF-Servocom RAS is in good condition. ZF-Servocom (front axle steering): Check oil level in oil tank. If the oil level exceeds the maximum permitted, this may be due to a leak in the master cylinder.
Check for external leaks Hydraulic Hydraulic lines, lines, connection connections, s, master cylinder cylinder,, centering centering cylinder cylinder and hydrauli hydraulicc accumulato accumulatorr must be visually inspected for leaks. There must not be any visible leakage. Only the piston rods of the master and centering cylinders may be coated with a film of oil. The formation of drops is not permissible.
Check bellows Check that the bellows is seated correctly and undamaged. The bellows must not be twisted.
ZF-Servocom RAS
5
Inspection 4
Ins Inspect ection
4.1
Inspect Inspection ion inter interva vals ls
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The same inspection intervals apply for the ZF-Servocom RAS as for the ZF-Servocom steering.
Note any other or additional intervals specified by the vehicle manufacturer.
4.2 4.2
Inspe Inspect ction ion wo work rk
4.2.1 Carry out the maintenance work described in section 3.2.
Spindle A
Bleeder valve Tool [1]
Connection
Valve B 4.2.2 Check system pressure on hydraulic accumulator
Remove cap on hydraulic accumulator. Slightly loosen the hexagon socket head screw of connection A2 (back off approx. one-quarter turn anticlockwise).
Screw tool [1] onto connection A2 by hand with the union nut.
Turn pressure gauge so that it can be read off conveniently.
Close valve B.
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Turn spindle spindle A of tool [1] to the left until the pointer pointer on the pressur pressure e gauge gauge begins to move. Then give it one more full turn.
ZF-Servocom RAS
Inspection !
Read Read off the system system pressu pressure re.. Requi Required red:: 15 +1/-3 +1/-3 bar (see (see note note on page page 1).
Note: If the system pressure corresponds with the required value, the accumulator pressure need not be checked as described in section 4.2.3 since it will invariably be correct in such cases.
Tighten the hexagon socket head screw with spindle A in order to close the valve.
Unscrew the union nut and remove tool [1].
Tighten the hexagon socket head screw with a torque of 25 Nm and leak-test the valve with sealing spray or soapy water. Refit the cap. Tool [2]
Valve 4.2.3 Check hydraulic accumulator pressure
Connect tool [2] to connection A1. Turn the valve anticlockwis anticlockwise e with tool [2] to relieve relieve the system pressure pressure.. At the same time, check whether the pilot indicator installed in the cab switches at a remaining pressure of 2...5 bar.
Connect tool [1] to connection A2 as described in section 4.2.2.
Read off the accumulator accumulator pressur pressure. e. Required Required:: 10 +1/-3 bar (see note on page 1).
Note: If the accumulator pressure does not correspond to the required value, the accumulator pressure must be increased as described in section 7 or the hydraulic accumulator replaced.
Close Close the valve of tool tool [2] by turning turning clockwis clockwise. e.
Check whether the oil tank of tool [2] has been filled (oil grade see section 6.1).
Build Build up the system pressure pressure with tool [2] by actuating actuating the hand hand pump. Required Required:: 15 +1/-3 bar (see note on page 1).
Remove tool [1] as described in section 4.2.2.
Close the valve of the hydraulic accumulator as described in section 4.2.2.
Remove tool [2].
4.2.4 Check cut-off valve (8) and switch relay (9)
Connect cable plug of the signal sensor (10) to earth.
Steer the steering wheel so that the steering output shaft angle is bigger than 5 o.
The ZF-Servocom RAS must not co-steer.
If the ZF-Servocom RAS co-steers, the failure must be removed - see troubleshooting.
ZF-Servocom RAS
7
Disassembly / Installation 5
Disass Disassemb embly ly of of the the ZF-Ser ZF-Servoc vocom om RAS Attention: Note the safety instructions in section 2.
5.1
Maste Masterr and cent center ering ing cylinde cylinders rs
Mark connections and installed position of cylinders.
Disconnect master and centering cylinders and drain oil.
5.2
Hydra Hydraulic ulic accumu accumulat lator or
Unscrew union piece from hydraulic accumulator.
Release catches and remove hydraulic accumulator.
6
Insta Installa llati tion on of the the ZF-Ser ZF-Servo voco com m RAS RAS
6.1
Maste Masterr and cent center ering ing cylinde cylinders rs
6.1.1 Preparing cylinders for installation
Move piston rod to middle position. Tool [4] Tool [3]
Master cylinder
Centering cylinder
Mount tool on piston rod so that bevel on left-hand side (see arrow on tool) positively engages the bevel at the end of the piston piston rod. rod. Move piston piston rod until the right-hand right-hand side side of the tool (tool (tool [3]) or the shoulder (tool [4] - see marking on tool) contacts the face end of the cylinder. Fill master and centering cylinders with oil.
Oil grade: Only oil grades approved by the vehicle manufacturer (e.g. Pentosin CHF 11S) may be used in the ZF-Servocom ZF-Servocom RAS (without (without ZF-Servocom ZF-Servocom steering). steering). The oil must not be mixed with other other grades. Attention: In the case of the master cylinder, only ports L1, L2 and L3 in the centre of the cylinder (see diagram on page 6) may be filled with the above oil grade. The external ports L4 and L5 must be filled with the oil grade used in the ZF-Servocom or front axle steering. 6.1.2 Installation instructions
Screw ball joint onto piston rod.
Attention: Note values X and Y for the minimum screw depth.
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ZF-Servocom RAS
Installation / Charging with gas Value X
Value Y
Cylinder pipe
Piston rod
Value alue X (pis (pisto ton n rod rod):
Mast Master er cyli cylind nder er:: Centeri Centering ng cyli cylind nder: er:
max. max. 13 mm (for (for 834 8346 974 163:m 63:max ax.. 31.5 1.5 mm) mm) max. max. 31.5 31.5 mm mm
Valu alue Y (cyl (cylin ind der pipe): e):
Mas Master ter cyl cylind inder: er: Centeri Centering ng cylin cylinder der::
max. ax. 14 mm max. max. 19 mm
Oil the mating faces and screw thread of the ball joint.
Turn the steered wheels into the exact straight-ahead position.
Install the master and centering cylinders so that the line connections point upwards.
Screw the ball joint mounted on the cylinder pipe onto the frame (master cylinder) and axle (centering cylinder) and lock it in place. Tig Tightening torque:Cla :Clamp: 45...50 Nm Castellated Castellated nut: 250...280 250...280 Nm (for 8346 974 163: 210...230 210...230 Nm)
Move piston rod to middle position as described in section 6.1.
Oil the screw thread and mating face.
After connection to the piston rod, fit the ball joint into the wheel steering lever by twisting and turning.
Attention: Note values X and Y. Tighten (torque see above) and secure the clamp and castellated nut. Check sealing edges, sealing faces and sealing rings of the connections for signs of damage. Connect the piping so that it is oil-tight.
Following the installation of the centering and the master cylinder, the chassis geometry must be measured and readjusted, if necessary.
6.2 Hydraulic Hydraulic accumulator accumulator
Insert hydraulic accumulator in union piece and secure it.
Tighten union piece (Ermeto GE) with a torque of 80+10 Nm.
7
Char Ch argi ging ng with with gas gas
Connect tool [1] to connection A2 as described in section 4.2.2.
Attention: Only Only nitrogen nitrogen may be used as the charging charging gas. Explosion Explosion hazard! hazard! Only nitrogen cylinders with pressure reducing valve and relief valve may be used.
Connect charging hose to tool [1] and nitrogen cylinder.
ZF-Servocom RAS
9
Charging with gas / Filling with oil / Bleeding !
Set pressure reducing valve to 10+1 bar (see note on page 1).
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Slowly open the shutoff valve on the nitrogen cylinder.
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Open valve B of tool [1].
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Spindle A Tool [1] Valve B
When the accumulator pressure reaches 10+1 bar (see note on page 1), close the shutoff valve on the cylinder and valve B on tool [1]. Check the accumulator pressure again after waiting 5 minutes, during which time the temperature is equalized.
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Remove tool [1] as described in section 4.2.2.
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Close the valve of the hydraulic accumulator as described in section 4.2.2.
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Filli illing ng with with oil oil
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Oil grade: Only oil grades approved by the vehicle manufacturer (e.g. Pentosin CHF 11S) may be used in the ZF-Servocom ZF-Servocom RAS (without (without ZF-Servocom ZF-Servocom steering). steering). The oil must not be mixed with other other grades.
DC-No.: A00 198 924 03 10 !
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Amount of oil: Approx. 6 litres are required to fill the complete ZF-Servocom RAS (without ZF-Servocom steering or front axle steering). Move master cylinder to middle position (see section 6.1). Connect Connect tool [2] to connection connection A1. Fill the oil tank of tool [2] with oil (oil grade as above) in order order to avoid pumping air. In order to facilitate the filling and subsequent bleeding process, it is advisable to open some of the bleeder valves of lines L3, L1 and L2 (see diagram on page 6) and to close them again when oil emerges.
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Increase the system pressure to 15+1 bar (see note on page 1) by actuating the hand pump.
9
Bleed leedin ing g
9.1 ZF - Servocom Servocom RAS RAS !
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Connect Connect tool [2] to connection connection A1. Fill the oil tank of tool [2] with oil (oil grade as above) in order order to avoid pumping air. Actuate the hand pump of tool [2] to build up pressure and ensure that the system is pressurized during the entire bleeding process.
ZF-Servocom RAS
Bleeding / Settings and tightening torques !
Open the highest bleeder valve in line L3 until air bubbles no longer escape; then reclose it so that it is oil-tight.
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Open the other bleeder valves in line L3 and then reclose them so that they are oil-tight.
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Bleed lines L1 and L2 as described above.
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Bleed the cylinder ports and then reclose them so that they are oil-tight.
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Check the system pressu pressure. re. Required Required:: 15+1 bar (see note on page 1)
9.2 ZF-Ser ZF-Servocom vocom or front axle steering and corresponding corresponding circuit of master cylinder !
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Start the engine. Open the bleeder valves or ports of lines L4 and L5 until air bubbles no longer escape; then reclose them so that they are oil-tight.
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Turn the steering from one limit position to the other several times.
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This allows any remaining air in the oil to escape via the oil tank.
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The oil level in the oil tank may rise by 1...2 cm when the engine is switched off and the system has been fully bled.
9.3 Bleed Bleed the ZF-Serv ZF-Servocom ocom RAS again as described in section section 9.1 !
Check the system system pressur pressure. e. Required Required:: 151 bar (see note on page 1)
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Remove tool [2].
10 Settin Settings gs and tighte tightening ning torques torques - Settings:
Accu Accumu mula lato torr pres pressu sure re::
Chec Check: k: Char Charg ging: ing:
10+1/ 0+1/-3 -3 bar bar (see (see note note on page page 1) 101 bar (see note on page 1)
System tem pressure:
Check: ck: Char Charg ging: ing:
15+1/-3 /-3 bar (se (see note on page 1) 151 bar (see note on page 1)
Value X:
Master cylinder: Cen Centeri terin ng cyli cylin nder: er:
max. 13 mm (for 8346 974 163max. 31.5 mm) max. ax. 31.5 mm
Value Y:
Master cylinder: Cen Centeri terin ng cyli cylin nder: er:
max. 14 mm max. ax. 19 mm
- Tightening torques:
Hydraulic accumulator:
Hexagon socket head screw Union piece (Ermeto GE)
Master and centering cylinders:
Clamp 45...50 Nm Castellated nut 250...280 Nm (for (for 8346 8346 974 974 163 163:: 210.. 210...23 .230 0 Nm)
ZF-Servocom RAS
25 Nm 80+10 Nm
11
Special tools tools 11 Special Special tools tools Note: The special tools listed below refer to the standard version and the design version on the basis of which the entire manual has been compiled. compiled. Other tools may consequent consequently ly be required required for the particular particular unit unit in question. Part. No.
Tool [1] Test device
7016 798 516
Tool [2] Hydraulic unit for filling with oil
7418 798 563
Tool [3] Gauge for master cylinder
8346 798 301 (For 8346 974 163: 8346 798 303)
Tool [4] Gauge for centering cylinder
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8346 798 302
ZF-Servocom RAS
12 Troubleshoot Troubleshooting ing This troubleshooting procedure presupposes that there no defects in the front axle steering!
The applicated letters a nd nd numbers ( e. e.g. 2, L5) refer to the illustration are on page 17.
Attention: Note the safety instructions in section 2.
Fault Pressure switch indicator lights up when vehicle power supply is switched on
Cause !
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Pressure switch indicator lights up when vehicle power supply is switched on although RAS is functioning correctly Indicator does not light up although RAS is not functioning correctly
1 3
1 4
Oil tank indicator lights up while steering
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Internal leak in master cylinder (2) Hydraulic accumulator (4) defective
Internal leak in centering cylinder (3) oil leaking from L3 to A3 Press switch (6) defective
Contact of pressure switch (6) is sticking
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Indicator defective
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Electric lead defective
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Fault Synchronization error. Rear axle does not centre back to the precise strai raight-a t-ahead positio tion - only when stationary - also when driving - in one direction - in both directions
Loss of oil; external leak in system
Check
Internal leak in master cylinder (2) - oil leaking leaking fro from L5 to L2 or from from L4 to L1
Cause !
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Mechanical connecting elements between axle (ball joints, piston rod, steering knuckle, etc. etc.)) and cyli ylinder are stiff, bent, with backlash
Air in RAS steering system
Geometry of rear axle not OK System pressure too low, external leak
Gas pressure of accu accum mulator (4) (4) too low Internal leak in centering cyl cylinder (3) - oil leakin king from L3 to A3
Middle position of master and and/or /or cen centeri terin ng cyli cylin nder offset in relation to straight-ahead position of wheels
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Check steering system for exter na nal leaks (visual examination) and system pressure - required: 15+1-3 bar (see note on page 1) Check oil level in oil tank (is too high) Check maximum pressure in hydraulic accumulator - required: 10 +1/ -3 bar (see note on page 1) Open screw plug A3 - oil must not emerge Check correct functioning of pressure switch as directed by vehicle manufacturer Check correct functioning of pressure switch as directed by vehicle manufacturer Check correct functioning of indicator Check wiring for continuity with the aid of a mult multii-pu purp rpos ose e meas measur urin ing g inst instru rume ment nt Check system pressure (is too high) - required: 15+1 15+1-3 -3 bar bar (see (see note note on pag page 1)
Remedy !
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Visual examination of mechanical connecting elements
Bleed steering system and chec check k sys system tem press essure - requ equired: ed: 15 +1 -3 bar (see (see note on page age 1) Check rear axle for specified axle values Check steering system for external leaks (visual examination) and check exis existi ting ng syst system em press ressur ure e - requ requir ired ed:: 15 +1 -3 bar (s (see note on page age 1) Check accumulator pressure - required: 10+1-3 1-3 bar (se (see note on page 1) Remove screw plug (A3) - oil must not eme emerge rge from the the open cyl cylinder port.
Set wheels to straight-ahead position. Chec Check k mid middle positio tion of piston ton rod in master and centering cylinders
Seal or replace cylinder Charge hydraulic accumulator with nitrogen or replace it. 101 bar (see note on page 1) - see operating instructions
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Seal or replace centering cylinder
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Replace pressure switch
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Replace pressure switch
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Replace indicator
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Check !
Eliminate cause of leak. Fill system with oil 151 bar (see note on page 1) and bleed it. See operating instructions.
Replace wiring or repair break in conn connect ectio ion n Seal or replace cylinder
Remedy !
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Replace defective parts
Fill Fill syst system em with with oil oil 151 bar (see (see note on page age 1) and and bleed eed it (see (see operat eratin ing g inst instru ruct ctio ion ns) Set axle values values as directed directed by vehicle manufacturer Repair leak Fill with oil 151 bar (see note on page page1) 1) and and bleed leed syst system em (see (see operat eratin ing g inst instru ruct ctio ion ns) Charge hydraulic accumulator with nitro trogen 10+1 bar (se (see note on page 1) or replace it (see operating instructions) Seal or replace cylinder
Set cylinders to middle position with whee wheells in strai traig ght-ah t-ahea ead d positio ition n. See operating instructions for setting
1 4
Fault Synchronization error. Rear axle does not centre back to the precise strai raight-a t-ahead positio tion - only when stationary - also when driving - in one direction - in both directions
Cause !
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Mechanical connecting elements between axle (ball joints, piston rod, steering knuckle, etc. etc.)) and cyli ylinder are stiff, bent, with backlash
Air in RAS steering system
Geometry of rear axle not OK System pressure too low, external leak
Gas pressure of accu accum mulator (4) (4) too low Internal leak in centering cyl cylinder (3) - oil leakin king from L3 to A3
Middle position of master and and/or /or cen centeri terin ng cyli cylin nder offset in relation to straight-ahead position of wheels
Fault
Synchronization Synchronization error Rear axle remains in straight-ahead position and does not turn - only when stationary - also when driving - in one direction - in both directions
Cause
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Air in RAS steering system
Too little oil in the RAS system. External leak in piping or in master and/or centering cylinder
Leak in control system of mast master er cylin cylinde derr (2) (2) - oil oil leaki leaking ng from L1 or L2 to L3
Leak in main cylinder part of cen centeri terin ng cyli cylin nder (3) (3) - oil leak leakiing fro from L1 to L2 or vice vice versa
Check !
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Visual examination of mechanical connecting elements
Bleed steering system and chec check k sys system tem press essure - requ equired: ed: 15 +1 -3 bar (see (see note on page age 1) Check rear axle for specified axle values Check steering system for external leaks (visual examination) and check exis existi ting ng syst system em press ressur ure e - requ requir ired ed:: 15 +1 -3 bar (s (see note on page age 1) Check accumulator pressure - required: 10+1-3 1-3 bar (se (see note on page 1) Remove screw plug (A3) - oil must not eme emerge rge from the the open cyl cylinder port.
Set wheels to straight-ahead position. Chec Check k mid middle positio tion of piston ton rod in master and centering cylinders
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Check
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Check steering system for external leaks
Check oil leakage at cylinder ports L1 to L3 or L2 to L3, L3, as appr approp opri riat ate. e. Turn front axle in the corresponding direction to be checked. Unscrew and seal line L1 to L3 or L2 and L3. Set system pressure of RAS in line L2 or L1 to 20 bar on Minimess port. Measure leakage oil at open cylinder ports for approx. 1 minute. No more than 0.02 dm 3 /min oil may emerge emerge from both ports ports taken together. Set wheels to straight-ahead positio tion and and chec check k oil leaka eakag ge at cyl cylind inder ports rts L1 or L2, as appropriate.
Replace defective parts
Fill Fill syst system em with with oil oil 151 bar (see (see note on page age 1) and and bleed eed it (see (see operat eratin ing g inst instru ruct ctio ion ns) Set axle values values as directed directed by vehicle manufacturer Repair leak Fill with oil 151 bar (see note on page page1) 1) and and bleed leed syst system em (see (see operat eratin ing g inst instru ruct ctio ion ns) Charge hydraulic accumulator with nitro trogen 10+1 bar (se (see note on page 1) or replace it (see operating instructions) Seal or replace cylinder
Set cylinders to middle position with whee wheells in strai traig ght-ah t-ahea ead d positio ition n. See operating instructions for setting
Remedy
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Check steering system for external leaks (visual examination) and existing system pressure - required: 15+1-3 bar (see note on page 1)
Unscrew line L1 or L2 from cylinder and seal it. Set system pressure to 20 bar via connection A1. Oil must not emerge from the open cylinder port. 1 5
Remedy
Eliminate cause of infiltrated air. Fill system with oil 151 bar (see note on page 1) - see operating instructions Eliminate cause of leak. Fill system with oil 151 bar (see note on page 1) and bleed it
!
Seal or replace cylinder
!
Seal or replace cylinder
Fault
Synchronization Synchronization error Rear axle remains in straight-ahead position and does not turn - only when stationary - also when driving - in one direction - in both directions
Cause
!
!
!
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Air in RAS steering system
Too little oil in the RAS system. External leak in piping or in master and/or centering cylinder
Leak in control system of mast master er cylin cylinde derr (2) (2) - oil oil leaki leaking ng from L1 or L2 to L3
Leak in main cylinder part of cen centeri terin ng cyli cylin nder (3) (3) - oil leak leakiing fro from L1 to L2 or vice vice versa
Check
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!
!
!
Check steering system for external leaks
Remedy
!
Check steering system for external leaks (visual examination) and existing system pressure - required: 15+1-3 bar (see note on page 1) Check oil leakage at cylinder ports L1 to L3 or L2 to L3, L3, as appr approp opri riat ate. e. Turn front axle in the corresponding direction to be checked. Unscrew and seal line L1 to L3 or L2 and L3. Set system pressure of RAS in line L2 or L1 to 20 bar on Minimess port. Measure leakage oil at open cylinder ports for approx. 1 minute. No more than 0.02 dm 3 /min oil may emerge emerge from both ports ports taken together. Set wheels to straight-ahead positio tion and and chec check k oil leaka eakag ge at cyl cylind inder ports rts L1 or L2, as appropriate.
Eliminate cause of infiltrated air. Fill system with oil 151 bar (see note on page 1) - see operating instructions Eliminate cause of leak. Fill system with oil 151 bar (see note on page 1) and bleed it
!
Seal or replace cylinder
!
Seal or replace cylinder
Unscrew line L1 or L2 from cylinder and seal it. Set system pressure to 20 bar via connection A1. Oil must not emerge from the open cylinder port. 1 5
Fault
Cause
1 6 !
!
Leak from main cylinder part of cent center erin ing g cyli cylind nder er (3) (3) to centering cylinder part - oil leaking fro from L1 to L3
Lines no longer allow oil to pass through
Check
!
!
Set wheels to straight-ahead position and and chec check k oil oil leak leakag age e at cyli cylind nder er port port L3. Unscrew crew and and seal line L3. L3. Set system pressure of RAS to 20 bar via connection A1. Oil must not emerge from the open cylinder port. Check piping and hoses for signs of damage. Measure system pressure at the corresponding end of the piping.
Remedy
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Seal or replace cylinder
!
Replace damaged piping
Additional information for versions with cut-off valve (8) ZF-Servocom RAS No function
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Defective Defective cut-off cut-off valve (8)
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Defective switch relay (9)
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Defective signal sensor (e.g.flow rate indicator)
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Start the engine. Interrupt connection between main power supply and cut-off valve Switch on ignition (engine off) Take off main power supply plug from cut-off valve (8). Measure voltage. Nominal value: main power supply volt voltag age. e. Start Start engi engine ne.. Meas Measur ure e volt voltag age. e. Nominal value: 0V Check switching function.
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!
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If ZF-Servocom RAS does not function replace cut-off valve (8).
Replace switch relay (9). No main power supply voltage => repl replace ace swit switch ch rela relayy (9) (9) Replace signal sensor
Legend to diagrams on page 17/18: 1 2 3 4 5
front axle steering masterzylinder centering cylinder hydraulic accumulator hydraulic lines
A, B, C, D, E, X, Y, T, W, V
6 pr pressure switch 7 connecting rod 8 cut-off valve 9 switch relay 10 signal sensor A2 (e. (e.g. flow rate rate indicat cator)
L1/L2 hydrostatic connecting line to master - and centering cylinder L3 pressure line L4/L5 connecting line from front axle steering to mastercylinder A1 connection tube (oil side) connection tube at hydraulic accumulator (gas side) A3 clo closing screw crew (ce (centeri ering cyl cylinder) (E) bleeder valve conn connect ectio ion n iden identi tifi ficat catio ion n stic sticke ked d up at the the aggr aggreg egate atess
Fault
Cause
1 6 !
!
Check
Leak from main cylinder part of cent center erin ing g cyli cylind nder er (3) (3) to centering cylinder part - oil leaking fro from L1 to L3
Lines no longer allow oil to pass through
!
!
Set wheels to straight-ahead position and and chec check k oil oil leak leakag age e at cyli cylind nder er port port L3. Unscrew crew and and seal line L3. L3. Set system pressure of RAS to 20 bar via connection A1. Oil must not emerge from the open cylinder port. Check piping and hoses for signs of damage. Measure system pressure at the corresponding end of the piping.
Remedy
!
Seal or replace cylinder
!
Replace damaged piping
Additional information for versions with cut-off valve (8) ZF-Servocom RAS No function
!
Defective Defective cut-off cut-off valve (8)
!
!
Defective switch relay (9)
!
!
Defective signal sensor (e.g.flow rate indicator)
!
Start the engine. Interrupt connection between main power supply and cut-off valve Switch on ignition (engine off) Take off main power supply plug from cut-off valve (8). Measure voltage. Nominal value: main power supply volt voltag age. e. Start Start engi engine ne.. Meas Measur ure e volt voltag age. e. Nominal value: 0V Check switching function.
!
!
!
!
If ZF-Servocom RAS does not function replace cut-off valve (8).
Replace switch relay (9). No main power supply voltage => repl replace ace swit switch ch rela relayy (9) (9) Replace signal sensor
Legend to diagrams on page 17/18: 1 2 3 4 5
front axle steering masterzylinder centering cylinder hydraulic accumulator hydraulic lines
A, B, C, D, E, X, Y, T, W, V
6 pr pressure switch 7 connecting rod 8 cut-off valve 9 switch relay 10 signal sensor A2 (e. (e.g. flow rate rate indicat cator)
L1/L2 hydrostatic connecting line to master - and centering cylinder L3 pressure line L4/L5 connecting line from front axle steering to mastercylinder A1 connection tube (oil side) connection tube at hydraulic accumulator (gas side) A3 clo closing screw crew (ce (centeri ering cyl cylinder) (E) bleeder valve conn connect ectio ion n iden identi tifi ficat catio ion n stic sticke ked d up at the the aggr aggreg egate atess
Version without cut-off-valve (8)
1 7
Version without cut-off-valve (8)
1 7
FILLING PORT CONNECTOR "E"
Company instruction
PAUL NUTZFAHRZEUGE
BLEEDING GUIDE FOR ZF-SERVO ZF -SERVOCOM COM
1.
Lift vehicle frame on front side.
2.
Move steering straight ahead.
3.
Stop engine during bleeding. bleeding .
4.
Connect hydraulic pump to non return valve beneath centering cylinder (see photo).
5.
Increase system pressure to 15 bar with hydraulic pump.
6.
Attention: Use only Pentosin CH11S (DC-No.: A00 198 03 10), 10), complete filling appr. 6 ltr.
7.
Loose slightly cap nut of pressure switch (close to master cylinder), hydraulic line L3 and release air. Close cap nut.
8.
Bleeding MINIMESS-connectors by turns (hydraulic (hydraulic line L1 and L2).
9.
Increase in between system pressure to appr. 15 bar. Minim Minimum um pressure during bleeding > 10 bar.
10.
Star engine an steer slowly 5 times left to right to left.
11.
Stop engine and steer straight ahead.
12.
For oil calming down wait appr. 10 minutes.
13.
Repeat bleeding procedure for hydraulic hydraulic line L1 and L2.
14.
Increase hydraulic hydraulic system pressure to 15 bar.
15.
Final performance control.
Sheet metal thickness = 3 mm
Adjustment tools
