385B Excavator Hydraulic System Caterpillar

Gear Pump (Pilot) - Test

Usage:

385B ANS

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Illustration 1	g00854975
Pilot pump (1) Pilot pump (2) Delivery line (pilot oil) (3) 6V-9833 Cap (4) 5K-9090 O-ring seal (5) Connector (6) Pilot filter (7) 6V-9875 Connector (10) 2S-4078 O-ring seal (14) 4C-5093 Nipple assembly (15) 4C-5094 Coupler assembly (16) 4C-6461 Coupling (17) 5P-0477 Sleeve (18) 5P-0202 line (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) 4C-5086 45 Degree Coupling (24) Return port

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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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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, "Caterpillar Tools and Shop Products Guide" for tools and supplies suitable to collect and contain fluids on Caterpillar products. Dispose of all fluids according to local regulations and mandates.

Position the machine on level ground.

Stop the engine.

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

Install the following tools in accordance with the flow meter tool layout. Refer to Illustration 1.
1. Disconnect delivery line (2) from connector (5) at pilot filter (6) .
1. Install seal (4) and cap (3) to connector (5) .
1. Install seal (4) and connector (7) in the end of delivery line (2). Install nipple assembly (14) and seal (10) to connector (7) .
1. Remove plug (24) from the return port.
1. Install coupling (23) and seal (10) in return port (24). Install nipple assembly (14) and seal (10) to coupling (23) .
1. Connect flow meter (21) between connector (7) in the end of delivery line (2) and the nipple assembly at return port (24) .
1. Install multitach (45) on the engine. This is used to monitor engine speed.

Start the engine.

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Illustration 5	g00726210
(C) Display for Digging Mode (D) Key for Digging Mode

Place the machine controls at the following settings: Engine speed dial "10", AEC switch OFF, Digging Mode and Gain/Response 2 (normal). Refer to Testing and Adjusting, "Engine Performance Test" for engine rpm settings.

Place the hydraulic activation control lever in the UNLOCKED position.

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

Turn valve (46) on flow meter (21) clockwise until the pressure gauge on the flow meter shows a reading of 4120 kPa (595 psi).

Record the pilot pump flow at 4120 kPa (595 psi) in the following table.

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Table 1
Test Data For Pilot Pump Flow
Oil temperature
Engine speed (rpm)
Flow measured L/min (US gpm)
Flow corrected L/min (US gpm)
Specification for pump flow	New	90 ± 5 L/min (23.8 ± 1.3 US gpm)
Specification for pump flow	Service Limit	74 L/min (19.5 US gpm)

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

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