349D2 MHPU Mobile Hydraulic Power Unit Hydraulic System Main Pump (Flow) - Test - Hydraulic Power Caterpillar

Specification

High-Power Mode

Note: Certain machines will default to "Economy Mode" at machine startup. Change to "High Hydraulic Power Mode" before performing the test procedure.

Hydraulic Power Conversion

Introduction

This test measures two pump flow to the boom cylinders at the boom foot. The test uses a load valve at the boom foot to simulate normal machine operating pressure to determine machine performance. Both pumps are tested for output flow at specified pressures. If the results from this test are not within the specification, refer to Testing and Adjusting, "Main Pump (Flow) - Test (Constant Horsepower Flow Control)" to isolate any problem with the pumps.

Illustration 1	g01721640
(A) Message display (B) Monitor

Illustration 2	g03400941
The electronic control module is located in the compartment behind the cab. (C) Alarm lamp (D) Electronic control module

Note: Before starting main pump flow tests, check message display (A) on monitor (B) and alarm lamp (C) on electronic control module (D) for normal operation. If no faults are present, perform the operational checks. Refer to Testing and Adjusting, "Operational Checks".

Note: If the operational checks (cycle time) indicate that slow speed of an implement is common to the circuits of one pump, the problem is most likely in the hydraulic system. Then perform the pump flow tests. Refer to Testing and Adjusting, "Main Pump (Flow) - Test (Hydraulic Power)".

Note: The engine, the fuel, or the working altitude may be the problem if the operational checks indicate that slow speed of an implement is common to both pump circuits.

Note: Perform the following procedures before testing the main pump flow.

• Set the pilot pressure to the specifications in Testing and Adjusting, "Relief Valve (Pilot) - Test and Adjust" for the machine.

• Set the main relief valve to specifications. Refer to Testing and Adjusting, "Relief Valve (Main) - Test and Adjust" for the machine.

Required Tools

Illustration 3	g03402023
Tooling (A) 198-4240 Digital Pressure Indicator Gp

Illustration 4	g03400942
Flow meter tool layout at boom foot (1) Connector (boom cylinder lines) (3) Boom cylinder (4) Line (boom cylinder head end) (5) Line (boom cylinder rod end) (6) Line (boom cylinder rod end) (7) Line (boom cylinder head end)

Machine Preparation

1. Position the machine on level ground in the service position.

2. Stop the engine.

3. Release the pressure in the hydraulic system. Refer to Testing and Adjusting, "Hydraulic System Pressure - Release".

4. Attach 311-1362 Vacuum Cap onto the hydraulic tank. Attach an air supply hose onto the assembly. Apply 276 kPa to 414 kPa (40 psi to 60 psi). This procedure will pull a vacuum on the hydraulic system.
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   Illustration 5	g03400969
   Pump compartment (29) Pressure tap (delivery pressure for drive pump) (30) Pressure tap (delivery pressure for idler pump)

5. Connect 41368 kPa (6000 psi) pressure sensors to pressure tap (29) and pressure tap (30) for delivery pressure from both pumps.

6. Install the following tools in accordance with the flow meter tool layout.

   1. Disconnect line (6) and line (7) from boom cylinder (3).

   2. Install O-ring seal (10) and plug (11) to the end of line (6) and line (7).

   3. Install cap (2) on connector (1) for the boom cylinder lines.

   4. Disconnect line (4) and line (5) from boom cylinder (3).

   5. Install cap (2) on connector (1) for the boom cylinder lines.

   6. Install O-ring seal (10), connector (12), O-ring seal (13), and nipple assembly (14) to the end of line (4) and line (5).

   7. Remove 311-1362 Vacuum Cap and install the filler plug for the hydraulic tank.

   8. Connect portable hydraulic tester (21) and the test hoses between nipple assembly (14) on line (4) and nipple assembly (14) on line (5).

      Note: To avoid damage to the flow meter, make sure that the direction of oil flow is correct. The proper direction of flow is from line (4) for the boom cylinder head end, through flow meter (21), and return through line (5) for the boom cylinder rod end.

Test Procedure

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To prevent personal injury or equipment damage from failure of the hydraulic test equipment or associated circuit components because of blocked pump flow, make sure that the test equipment valves are fully open before starting the engine.

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To prevent personal injury and/or equipment damage from failed lines or components while the hydraulic test equipment is returned to the open flow position, slowly open the hydraulic test equipment valve while monitoring the pump flow. If pump flow does not increase as the valve is opened, shut the engine off and determine what is preventing the pump from upstroking.

1. Start the engine.

2. Place the machine controls at the following settings: engine speed dial "1" and AEC switch OFF.

3. Place the hydraulic activation control lever in the UNLOCKED position.

4. Move the joystick for the boom to the full BOOM RAISE position. Hold the joystick for the boom in this position.

5. Slowly increase engine speed to speed dial "10".

6. Override fan speed to 970 rpm.

   1. Enter "Service" Menu.

   2. Enter password "9992".

   3. Select "Override Parameters".

   4. Override "Desired Fan Speed" to 970 rpm.

7. Increase the hydraulic oil temperature to 55° ± 5°C (131° ± 9°F).

8. Record pump flow at each of the following pressures in Table 1. Confirm the delivery pressure of the drive pump at pressure tap (1) and the idler pump at pressure tap (2).
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   Illustration 6	g03401009
   Portable hydraulic tester (flow meter) (21) Portable hydraulic tester (flow meter) (31) Valve

9. Turn valve (31) on portable hydraulic tester clockwise. Record the following items for each measuring point:

   • Drive Pump Pressure

   • Idler Pump Pressure

   • Measured Flow

   Note: Flow measurements must be done only during pressure rise.

10. Return the joystick for the boom to the NEUTRAL position.

11. Stop the engine.

12. Calculate the hydraulic power using the average pump pressure and the measured flow. Refer to Table 2 for Metric (kW) and English (hp) calculations.

13. Let the hydraulic oil cool to 55° ± 5°C (131° ± 9°F) and repeat the test.

    Note: If second test results differ from first test, then run a third test.

14. Release the pressure in the hydraulic system. Refer to Testing and Adjusting, "System Pressure - Release".