New Test For Margin Pressure On Implement Hydraulic Pump Caterpillar

New Test For Margin Pressure On Implement Hydraulic Pump

Usage:

EXCAVATOR365B (9PZ1-UP),
365B L (4XZ1-UP) EXCAVATORS

Problem:

The procedure to check the margin pressure on the implement pump that is included in the Test and Adjust Module is not conclusively providing the same results. The following procedure will provide consistent and repeatable results, whether the machine is in the HPC-ON configuration or the HPC-OFF configuration. The new procedure eliminates the subjective interpretation of the instruction to "slowly modulate".

Solution:

IMPLEMENT PUMP MARGIN PRESSURE TEST AND ADJUST

Margin pressure is the differential pressure between pump discharge pressure and the load sensing signal pressure on the ON configured machine. Margin pressure on the OFF configured machine is the differential pressure between the pump discharge pressure and the true load signal pressure. Each implement pump needs to be isolated and checked separately by disconnecting the POWER SHIFT signal from the pumps not being checked.

1. Start the engine and warm the hydraulic oil to a temperature of 50 C (122 F).

2. Shut the engine off.

3. Install the 1U-5796 Pressure Differential Gauge Group between the implement pump pressure test port (front or rear pump) on the rear of the pump group and the load sensing signal/true load signal circuit test port on the regulator of the pump that is being tested.

4. Isolate the test pump by disconnecting the power shift signal pressure from the pump that is not being tested. April 12, 2000 Component Code: 5070

5. Start the engine and set the engine speed to the dial position "1".

6. Use the VIDS and bring the BOOM UP solenoid current parameter into view on the VIDS message center

7. Increase the engine speed to the dial position "10".

8. Slowly activate the BOOM UP function until the BOOM UP SOLENOID CURRENT reading is 1 Ampere. Hold the joystick in order to maintain the 1 Amp current reading. Observe the reading for the test pump margin pressure on the 1U-5796 Pressure Differential Gauge Group.

9. The MARGIN PRESSURE reading for the test pump, under the above condition, should be 1960 1 100 kPa (285 1 15 psi). If necessary, make an adjustment to the test pump margin pressure using the margin pressure adjustment screw.

NOTE: Always make pressure adjustments on the pressure rise.

10. Reduce engine speed, lower the boom to the ground, and shut the engine off.

11. Repeat Steps 3 through 9 in order to test the second pump.

12. After the margin pressure has been adjusted on the second pump, reconnect the power shift signal pressure line to the second pump.