349D2 MHPU Mobile Hydraulic Power Unit Hydraulic System Gear Pump (Pilot) - Test Caterpillar

Specification

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

Note: Specifications for flow rates are based on an engine speed of 1800 rpm. To get more accurate test results, measured flow should be corrected with the following calculation.

Introduction

The pilot pump is a gear pump that supplies oil flow to the pilot system. The pilot pump is located inside the main pump compartment and mounted externally to the main pump. This test is used to measure pump flow at the pilot pump.

Required Tools

Illustration 1	g01623868
Tooling (B) 198-4240 Digital Pressure Indicator Gp

Illustration 2	g02535237
Tooling (C) 348-5430 Multi-Tool Gp

Illustration 3	g03774482
(1) Pilot pump (2) Pilot line (delivery line from the pilot pump) (3) Swing motor (4) Makeup line (swing motor)

Reference: Refer to Tool Operating Manual, NEHS1087 for operating instructions for the 348-5430 Multi-Tool Gp.

Note: Use Software License Card, NETG5049 with part number 348-5430 Multi-Tool Gp.

Machine Preparation

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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.

1. Position the machine on level ground.

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 (F) 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.

5. Install the following tools in accordance with the flow meter tool layout and the circuit diagram. Refer to Illustration 3.

   1. Remove pilot line (2) from the connector at pilot pump (1).

   2. Install seal (D12) and plug (D13) to the end of pilot line (2).

   3. Install seal (D12) and elbow (D11) to the connector at pilot pump (1).

   4. Install seal (D4), coupling (D10), seal (D4), and nipple assembly (D5) to elbow (D11).
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      Illustration 4	g03774483
      Swing motor (3) Swing motor (4) Makeup line (D16) Elbow (D17) Tee

   5. Disconnect makeup line (4) from the connector at swing motor (1).

   6. Assemble and install seals (D15), tee (D17), swivel elbow (D16), and coupling (D14) to the connector at swing motor (1).

   7. Connect portable hydraulic tester (D1) and test hoses between couping (D10) at pilot pump (1) and coupling (D14) at swing motor (3).
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   Illustration 5	g03774480
   Pilot filter (5) Pressure tap (pilot)

6. Connect a 41368 kPa (6000 psi) pressure gauge (B2) to pressure tap (5) for pressure of pilot pump (1).

7. Install tooling (C) to monitor the engine speed.

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

Test Procedure

1. Start the engine.

2. Place the machine controls at the following settings: engine speed dial "10" and AEC switch OFF. Refer to Testing and Adjusting, "Engine Performance - Test (Engine Speed)" for engine rpm settings.

3. Increase the hydraulic oil temperature to 55° ± 5°C (131° ± 9°F).
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   Illustration 6	g03774485
   (D1) Portable hydraulic tester (flow meter) (6) Valve

4. Turn valve (6) on portable hydraulic tester (D1) clockwise until the pressure gauge on the portable hydraulic tester shows a reading of 4100 ± 500 kPa (595 ± 73 psi).

5. Record the pilot pump flow at 4100 ± 500 kPa (595 ± 73 psi) in Table 1.

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