The document provides instructions for testing and adjusting the pressure of the piston pump steering system. It describes checking the pressure using a digital pressure indicator connected to the pressure tap on the steering check and relief valve. If the pressure is not within the specified range of 21270 ± 350 kPa, the procedure provides steps to adjust the high-pressure cutoff valve by loosening a locknut and turning an Allen screw. Potential leakage sources are also identified if the pressure does not increase as expected.
The document provides instructions for testing and adjusting the pressure of the piston pump steering system. It describes checking the pressure using a digital pressure indicator connected to the pressure tap on the steering check and relief valve. If the pressure is not within the specified range of 21270 ± 350 kPa, the procedure provides steps to adjust the high-pressure cutoff valve by loosening a locknut and turning an Allen screw. Potential leakage sources are also identified if the pressure does not increase as expected.
The document provides instructions for testing and adjusting the pressure of the piston pump steering system. It describes checking the pressure using a digital pressure indicator connected to the pressure tap on the steering check and relief valve. If the pressure is not within the specified range of 21270 ± 350 kPa, the procedure provides steps to adjust the high-pressure cutoff valve by loosening a locknut and turning an Allen screw. Potential leakage sources are also identified if the pressure does not increase as expected.
The document provides instructions for testing and adjusting the pressure of the piston pump steering system. It describes checking the pressure using a digital pressure indicator connected to the pressure tap on the steering check and relief valve. If the pressure is not within the specified range of 21270 ± 350 kPa, the procedure provides steps to adjust the high-pressure cutoff valve by loosening a locknut and turning an Allen screw. Potential leakage sources are also identified if the pressure does not increase as expected.
0 2 3C 6 Cat erp ater Con illa pill fide r: ar I nc. ntia lG ree Illustration 1 (1) Pressure and flow compensator valve g00638711 n (2) Flow compensator valve (3) High-pressure cutoff valve Pressure and flow compensator valve (1) is mounted to the case of the steering piston pump. The steering piston pump is mounted on the front side of the pump drive.
Illustration 2 g06085098 777E series truck (4) Steering check and relief valve (SS) Pressure tap for the steering system
PSP Illustration 3 202 -0002 g00638712
3 AA 777D series truck
/0 (4) Steering check and relief valve
01: 1 E6 (SS) Pressure tap for the steering system
5 /2 5 Steering check and relief valve (4) is on the frame behind the right front suspension cylinder.
2. Operate the engine at HI IDLE. Turn the steering wheel to the right or turn the steering wheel to the left until the steering cylinder stop is reached. Then, continue turning the steering wheel against the stop. Hold the steering wheel in this position for 3 seconds and then release the steering wheel. Continue this step until the oil in the steering system reaches at least 38 °C (100 °F).
3. Check the steering system pressure by installing a 198-4240 Digital Pressure Indicator with the 198-4238 Pressure Sensor at pressure tap (SS) for the steering system. Pressure tap (SS) is on steering check and relief valve (4) behind the left front suspension cylinder.
4. Operate the engine at HI IDLE. Turn the wheels to the right or the left and keep turning the steering wheel. Check the pressure while you are turning the steering wheel. The pressure setting of the high-pressure cutoff valve is 21270 ± 350 kPa (3100 ± 50 psi).
5. If the pressure needs to be adjusted, stop the engine.
6. Remove nut (5) from setscrew (6) on high-pressure cutoff valve (3). 7. Loosen locknut (7) of high-pressure cutoff valve (3).
8. With an allen wrench, rotate setscrew (6) clockwise by 1/4 turn to raise the pressure. Rotate setscrew (6) counterclockwise by a 1/4 turn to lower the pressure. Each 1/4 turn of setscrew (6) changes the pressure approximately 1313 kPa (190 psi).
9. Repeat Steps 1 through 9 until the pressure setting is correct.
Personal injury or death can result from improperly checking for
a leak.
PSP Always use a board or cardboard when checking for a leak. Escaping air or fluid under pressure, even a pin-hole size leak,
- can penetrate body tissue causing serious injury, and possible
202 0002 death.
3 AA If fluid is injected into your skin, it must be treated immediately
01: /0 by a doctor familiar with this type of injury.
1 E6 53: /2 5 RE 11+ 10. If the pressure is low, and if the pressure does not increase with this method, there is excessive leakage in the system. Use the following steps to locate the leak.
0 2 6 12. If the setting of the backup relief valve for the primary steering is correct, disassemble spool (3) of pressure and flow
3 Cat erp Cater compensator valve (1) for high-pressure cutoff. Check spool (3) for sticking. Replace the entire pressure and flow compensator valve (1) if the spool is damaged or the bore is damaged.
Con illa pill
13. If high-pressure cutoff valve (3) is not sticking and the bore is not damaged, disassemble steering check and relief valve (4).
fide r: ar I a. Check the secondary steering check valve. Check the seat of the secondary steering check valve to be sure that primary steering oil is not leaking into the secondary steering system.
ntia nc. b. Check the steering pump oil pressure switch. Check the seal to be sure that primary steering oil is not leaking from the
lG steering check and relief valve.
ree c. Check the pressure reducing valve to be sure that primary steering oil is not leaking to the steering hydraulic tank.
0 6 The steering system pressure will drop to low-pressure standby when the steering wheel is not turned.
Cat 2 3C 4. Operate the engine at LO IDLE. Check the steering system pressure by installing a 8T-0860 Pressure Gauge 40000 kPa
ater (5800 psi) at the pressure tap (SS) for the steering system. Pressure tap (SS) is on the steering check and relief valve behind
erp the left front suspension cylinder.
Con illa pill
Note: The pressure gauge needs to withstand the maximum pressure from the steering piston pump.
fide r: ar I 5. The pressure of the steering system will drop to low-pressure standby when the steering wheel is not turned. The low-
nc. pressure standby should not exceed 2510 ± 440 kPa (364 ± 64 psi).
ntia 6. If the low-pressure standby is less than 2070 kPa (300 psi) after three cycles of the steering system, stop the engine.
lG 7. Remove nut (5) from setscrew (6) on flow compensator valve (2).
ree n 8. Loosen locknut (7) of flow compensator valve (2).
9. With an allen wrench, rotate setscrew (6) clockwise by 1/4 turn to raise the pressure. Rotate setscrew (6) counterclockwise by a 1/4 turn to lower the pressure. Each 1/4 turn of setscrew (6) changes the pressure approximately 400 kPa (60 psi).
10. Repeat Steps 1 through 9 until the pressure setting is 2510 ± 440 kPa (364 ± 64 psi). If the pressure cannot be adjusted, check flow compensator valve (2). The spool may be sticking. Replace the entire pressure and flow compensator valve (1) if the spool or the bore is damaged.
