BEARING 6N1078 - Caterpillar

Test Preparation - Margin Pressure
Load sense pressure can be checked in the same way as implement discharge pressure. Checking the load sense pressure will provide an accurate reading of the pressure signal that is being sent to the implement pump.
Ensure that the steering lock is engaged.
Ensure that the oil temperature is 52.5° 7.5°C (126.5° 13.5°F)
Attach a pressure gauge to pump discharge pressure tap (2) and load sensing pressure tap (3). Refer to Illustration 2 for pressure tap locations.Test Procedure - Margin Pressure
Illustration 2 g06085764
Top view of the steering control valve
(1) Steering Control Manifold
(2) Pressure Tap (Pump Discharge)
(3) Pressure Tap (Load Sensing)
The pump discharge pressure should be equal to the pressure of the load sensing signal plus margin pressure. Margin pressure should be equal to the spring force of the margin spring that is in the flow compensator valve. Margin pressure should be 1800 100 kPa (261 15 psi).
Operate the engine at HIGH IDLE. Make sure that the steering control lever is in the NEUTRAL position.
Start with the blade at ground line level or above and raise the blade.Note: The steering control lever should be moved to about 25% of the total travel distance.
Command steering in one direction. Make sure that you turn the steering wheel at a uniform rate. A second technician should observe the pressure readout on digital pressure indicator (A).
Record readout on digital pressure indicator (A). The reading that is on digital pressure indicator (A) is the margin pressure. Margin pressure is the difference between steering pump pressure and the load sense pressure (3). The margin pressure should be 1800 100 kPa (261 15 psi).Note: The pressure reading from pressure tap (2) is the steering pump pressure.
Adjust the flow compensator valve if the margin pressure is not correct.Note: If you adjust the flow compensator spool in the steering pump pressure and flow compensator valve, perform this test procedure again.Adjustment Procedure (Margin Pressure)
Illustration 3 g06085862
(4) Flow Compensator Valve
(5) Locknut
(6) Adjustment Screw
Loosen locknut (5) on flow compensator (4). Turn adjustment screw (6) clockwise to increase the margin pressure. Turn adjustment screw (6) counterclockwise to decrease the margin pressure.
After you turn adjustment screw (6), tighten locknut (5) to a torque of 17 3 N m (150 26 lb in).Test Preparation - High-Pressure Cutoff
Move the machine to a smooth, horizontal location that is away from operating machines and away from personnel.
Place the transmission direction in the NEUTRAL position.
Engage the parking brake.
Lower the work tool to the ground.
Stop the engine.
Relieve the pressure in the hydraulic system.Reference: For more information about relieving the hydraulic pressure, refer to the Service Manual module Testing and Adjusting, "System Pressure - Release" for the machine that is being serviced.
Install the steering frame lock.Test Procedure - High-Pressure Cutoff
Illustration 4 g06085764
Top view of the steering control valve
(1) Steering Control Manifold
(2) Pressure Tap (Pump Discharge)
(3) Pressure Tap (Load Sensing)
Attach a 0 to 25000 kPa (0 to 3600 psi) pressure gauge to pressure tap (2). Pressure tap (2) is on the right side of