374D Excavator Hydraulic System Swing Pump - Test - Constant Horsepower Flow Control Caterpillar

Introduction

This test measures the flow capabilities of the swing pump under a load. The pump output flow will be measured at specified pressures.

Required Tools

Illustration 1	g02571852
198-4240 Digital Pressure Indicator Gp

Illustration 2	g02535237
348-5430 Multi-Tool Gp

Machine Preparation

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 onto the hydraulic tank. Attach an air supply hose onto the assembly. Apply 276 to 414 kPa (40 to 60 psi). This procedure will pull a vacuum on the hydraulic system.

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Illustration 3	g02175794
Tool layout for swing pump (1) 8T-4193 Bolt (2) 5P-8077 Half Flange (3) Delivery line (swing pump) (4) Swing pump (5) 1P-3705 Rectangular Seal (6) 7I-7132 Cover (9) 174-4356 Pump Adapter (10) 2S-4078 O-Ring Seal (11) 174-4360 90 degree Elbow (12) 3J-1907 O-Ring Seal (13) 9S-4191 Plug (14) 4C-5093 Nipple Assembly (15) 4C-5094 Coupler As (16) 4C-6461 Coupling (17) 5P-0477 Sleeve (18) 5P-0202 Hose (19) 9U-6807 45 degree Coupling (20) 6K-6307 O-Ring Seal (21) 4C-9910 Portable Hydraulic Tester (Flow meter) (22) 9U-5229 Union (23) 2P-1415 Collet (24) Return port (return line for hydraulic cooling package)

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NOTICE
Care must be taken to ensure that fluids are contained during performance of inspection, maintenance, testing, adjusting, and repair of the product. Be prepared to collect the fluid with suitable containers before opening any compartment or disassembling any component containing fluids. Refer to Special Publication, NENG2500, "Dealer Service Tool Catalog" for tools and supplies suitable to collect and contain fluids on Cat products. Dispose of all fluids according to local regulations and mandates.

5. Disconnect delivery line (3) from swing pump (4) .

6. Install seal (5), half flanges (2) and cover (6) to the end of delivery line (3) by using bolts (1) .

7. Remove the plug from return port (24) .

8. Install the tools in accordance with the flow meter tool layout. Refer to Illustration 3.

9. Install the Multi-Tool Gp on the engine to monitor engine speed.

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Illustration 4	g02176085
Lower compartment under the main control valve Pilot manifold (27) Pressure tap

10. Connect a 34,450 kPa (5,000 psi) pressure sensor to pressure tap (27) at the pilot manifold.

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Illustration 5	g02175833
Swing pump (28) Pressure tap

11. Connect a 41,368 kPa (6,000 psi) pressure sensor to pressure tap (28) at the swing pump to monitor the delivery pressure of the swing pump.

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.

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Illustration 6	g01919740
Monitor and keypad (A) Engine speed (B) Gain/Response (C) AEC switch (D) Gain/Response switch

2. Place the machine controls at the following settings:
   • Engine speed dial "10"

   • AEC switch OFF

   • Gain/Response "AVS" (normal mode)

   Refer to Testing and Adjusting, "Engine Performance - Test (Engine Speed)" for engine rpm settings.

3. Place the hydraulic lockout lever in the UNLOCKED position.

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

5. Check the pilot oil pressure at pressure tap (27). The pressure reading should indicate 4120 ± 100 kPa (600 ± 15 psi). If the pilot oil pressure is not within the specification, adjust the pilot relief valve. Refer to Testing and Adjusting, "Relief Valve (Pilot) - Test and Adjust" for information concerning the adjustment of the pilot relief valve.

6. Move the joystick for swing to the FULL SWING position.

   Note: This action will upstroke the pump for full flow and must be held through the duration of the test.

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Illustration 7	g02731153
Portable hydraulic tester (flow meter) (21) Portable hydraulic tester (flow meter) (32) Valve

7. Turn valve (32) on portable hydraulic tester (21) clockwise. Record pump flow at each of the following pressures in Table 2. Use the pressure gauge at pressure tap (28) to monitor the delivery pressure of the swing pump.

Worksheet

Illustration 8	g02178494
P-Q characteristic curve

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

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