Bench Test Procedure for Hydraulic Piston Pumps {3203, 5070} Caterpillar

Cold Planer

PM620 (S/N: FG41-UP; LB81-UP; JB91-UP; LH91-UP; 8RF1-UP)

PM622 (S/N: EL61-UP; XS61-UP; JFC1-UP; JCF1-UP; TPH1-UP)

PM820 (S/N: RL31-UP; AK51-UP; AN81-UP; TLZ1-UP)

PM822 (S/N: EE21-UP; SL81-UP; E8S1-UP; H6S1-UP)

PM825 (S/N: 6261-UP; 6271-UP; ESE1-UP)

Engine

C-10 (S/N: 3CS1-UP)

Track-Type Tractor

D3K2 (S/N: KF21-UP; KL21-UP; FT31-UP; LT31-UP; JPJ1-UP)

D4K2 (S/N: KM21-UP; KR21-UP; MT31-UP; RT31-UP)

D5K2 (S/N: KW21-UP; KY21-UP; WT31-UP; YT31-UP; RRE1-UP)

Introduction

© 2019 Caterpillar All Rights Reserved. This guideline is for the use of Cat dealers only. Unauthorized use of this document or the proprietary processes therein without permission may be violation of intellectual property law. Information contained in this document is considered Caterpillar: Confidential Yellow.

This Special Instruction includes test procedures for piston pumps. This Special Instruction also provides specifications. The technician should have a good understanding of hydraulic piston pumps. The technician should be educated in the operation of the hydraulic test bench. The test benches in this document are available through the Caterpillar Service Tool Division. Gather all necessary tooling before you need to hook up the pump. Some of the required tooling appears in a table at the end of this document. There are many possible variations of tooling that could be used. Not every possible variation can be listed.

For questions or additional information concerning this guideline, submit a feedback form in the Service Information System web site. To address an urgent need, use the following to relay your request to Caterpillar Repair Process Engineering:

• Cat dealer Technical Communicator

• Dealer Solution Network

• Caterpillar Technical Representative

• Knowledge Network (online)

Canceled Part Numbers and Replaced Part Numbers

This document may not include all Canceled part numbers and replaced part numbers. Use NPR on SIS for information about Canceled part numbers and replaced part numbers. NPR will provide the current part numbers for replaced parts.

Safety

Illustration 1	g02139237

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Personal injury or death can result from improperly checking for a leak. Always use a board or cardboard when checking for a leak. Escaping air or fluid under pressure, even a pin-hole size leak, can penetrate body tissue causing serious injury, and possible death. If fluid is injected into your skin, it must be treated immediately by a doctor familiar with this type of injury.

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Pump test pressures in this guideline may exceed the normal operating range of the hydraulic test hoses utilized when connecting the tested pump to the test bench. However, the order of magnitude of these pressures is significantly below the burst strength of the Caterpillar "XT6" product. High pressure oil can escape through improperly assembled hoses and fittings. High pressure oil can also escape through poorly maintained hoses and fittings. High pressure oil may also leak through hose that has become damaged over the life of the hose due to the pressure levels that occur during test bench operation. Personal injury or death can result from improper hose & fitting inspection or improper hose replacement procedures. Escaping fluid under pressure can penetrate body tissue causing serious injury, and possible death. Thoroughly inspect all testing hoses, fittings, and quick disconnects prior to any testing operation. Check the assembly date tag or hose assembly log date for a hose life indicator. Replace all Test Bench hoses at a minimum of every 2 years or earlier if the hose or fittings appear to be damaged.

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Hot oil and hot components can cause personal injury. Do not allow hot oil or hot components to contact skin.

Summary

This procedure is specific to the type of pump and the type of control. Refer to the test specifications and the tooling at the end of this document.

Note: A paper copy of this document may not be the latest version. Go to the Service Information System (SIS) to view the latest version.

References

Connections for the Caterpillar Hydraulic Test Center

Illustration 2	g01351819
Connections for the Test Center (1) Flow control for discharge (2) "F3" flow meter inlet (3) "F4" flow meter inlet (4) Oil supply from the auxiliary pump (5) "F3" inlet for the flow meter with flow limiter (6) "F3"outlet for the flow meter with pressure control (7) Load sensing pressure (8) Signal pressure (9) "F4" outlet for the flow meter (10) Return to tank (11) Connections for case drain (12) Oil supply

Illustration 3	g01351822
Control and Gauges for the Test Center (13) Meter for speed and torque (14) Gauge for signal pressure (15) Control for signal pressure (16) Pressure gauge for auxiliary pump (17) Auxiliary pump flow (18) "F3" discharge pressure gauge (19) "F3" discharge flow (20) "F4" discharge pressure gauge (21) "F4" discharge flow (22) Auxiliary pump flow control (23) "F3" margin pressure (24) "F3" Load control for discharge pressure (25) "F4" Load control for discharge pressure

Connections for the Caterpillar Hydraulic Test Bench

Illustration 4	g01351830
Connections for the Test Bench (26) "Flow meter 1" loop and "Flow meter 2" loop (27) Oil Supply

Illustration 5	g01351833
Connections for the test bench (28) "Flow meter 2" loop (29) "Flow meter 1" loop (30) "Flow meter 2" outlet (31) Signal pressure line (32) "Flow meter 2" inlet (33a) "Flow meter 1" outlet (33b) Auxiliary oil supply outlet (34) Auxiliary oil supply inlet (35) "Flow meter 1" inlet

Illustration 6	g01351834
Control and Gauges for the Test Bench (36) Auxiliary oil supply pressure (37) Signal pressure (38) Control for signal pressure (39) "Flow meter 1" discharge pressure (40) Control for auxiliary oil supply pressure (41) "Flow meter 2" discharge pressure (42) Auxiliary oil supply control (43) "Flow meter 2" discharge flow (44) Discharge flow for auxiliary pump (45) "Flow meter 1" discharge flow (46) "Flow meter 1" load control (47) Speed and direction control (48) "Flow meter 2" load control

Pump Illustrations

Illustration 7	g03793116
Port locations (49) Air bleed port for rear pump (50) Adjustment screw for hydraulic zero for rear pump (51) Electrical connector for displacement control for rear pump (52) Gauge port for discharge pressure for rear pump (53) Gauge port for discharge pressure for rear pump (54) Adjustment for charge pressure sequence valve (55) Gauge port for control cutoff pressure (56) Gauge port for discharge pressure for front pump (57) Gauge port for discharge pressure for rear pump (58) Electrical connector for displacement control for front pump (59) Adjustment screw for hydraulic zero for front pump (60) Air bleed port for front pump (61) Electrical connector for displacement control for front pump (62) Gauge port for stroking pressure for front pump (63) Adjustment for maximum pump displacement for front pump (64) Case drain port (65) Discharge port for front pump (66) Charge inlet port (67) Discharge port for front pump (68) Cooler outlet (69) Adjustment for crossover relief valve for rear pump (70) Adjustment for crossover relief valve for rear pump (71) Case drain port (72) Adjustment for maximum pump displacement for rear pump (73) Gauge port for stroking pressure for rear pump (74) Electrical connector for displacement control for rear pump (75) Case drain port (76) Adjustment for maximum pump displacement for front pump (77) Gauge port for stroking pressure for front pump (78) Electrical connector for control cutoff solenoid (79) Adjustment for crossover relief valve for front pump (80) Gauge port for stroking pressure for rear pump (81) Adjustment for maximum pump displacement for rear pump (82) Case drain port (83) Discharge port for rear pump (84) Gauge port for charge pressure supply (85) Discharge port for rear pump (86) Gauge port for charge pressure supply (87) Motor flushing inlet (88) Motor flushing inlet (89) Pressure port for brake release (90) Adjustment for crossover relief valve for front pump (91) Electrical connector for brake release solenoid

Illustration 8	g03793117
Port locations (49) Air bleed port for rear pump (50) Adjustment screw for hydraulic zero for rear pump (51) Electrical connector for displacement control for rear pump (52) Gauge port for discharge pressure for rear pump (53) Gauge port for discharge pressure for rear pump (54) Adjustment for charge pressure sequence valve (55) Gauge port for control cutoff pressure (56) Gauge port for discharge pressure for front pump (57) Gauge port for discharge pressure for rear pump (58) Electrical connector for displacement control for front pump (59) Adjustment screw for hydraulic zero for front pump (60) Air bleed port for front pump (61) Electrical connector for displacement control for front pump (62) Gauge port for stroking pressure for front pump (63) Adjustment for maximum pump displacement for front pump (64) Case drain port (65) Discharge port for front pump (66) Charge inlet port (67) Discharge port for front pump (68) Cooler outlet (69) Adjustment for crossover relief valve for rear pump (70) Adjustment for crossover relief valve for rear pump (71) Case drain port (72) Adjustment for maximum pump displacement for rear pump (73) Gauge port for stroking pressure for rear pump (74) Electrical connector for displacement control for rear pump (75) Case drain port (76) Adjustment for maximum pump displacement for front pump (77) Gauge port for stroking pressure for front pump (78) Electrical connector for control cutoff solenoid (79) Adjustment for crossover relief valve for front pump (80) Gauge port for stroking pressure for rear pump (81) Adjustment for maximum pump displacement for rear pump (82) Case drain port (83) Discharge port for rear pump (84) Gauge port for charge pressure supply (85) Discharge port for rear pump (86) Gauge port for charge pressure supply (87) Motor flushing inlet (88) Motor flushing inlet (89) Pressure port for brake release (90) Adjustment for crossover relief valve for front pump (91) Electrical connector for brake release solenoid

9U-5902 Rectifier Block

Illustration 9	g03793996
9U-5902 Rectifier Block Connections

Illustration 10	g03794000
9U-5902 Rectifier Block Schematic (92) High-pressure port (93) High-pressure outlet (94) High-pressure port (95) Low-pressure inlet

9U-5893 Heat Exchanger

Illustration 11	g03794004
9U-5893 Heat Exchanger Connections (96) Inlet (97) Outlet (98) Water inlet (99) Water outlet

Set up for the Front Pump

Note: Only test one pump at a time on tandem pumps. Isolate one of the pumps by connecting a hose between the discharge ports on the pump that is not being tested.

1. At least two power supplies are required to operate the solenoids on this pump. The power supplies must be able to deliver 0 mA to 1600 mA with an infinite setting in that range.

2. Connect a power supply to the solenoid (78) to operate the control cutoff valve. Connect a power supply to solenoid (58) or (61) to operate the electronic displacement solenoid.

3. Install 8T-0855 Pressure Gauges 4000 kPa (580 psi) on the gauge port for the charge pressure (84) or (86) and the gauge port for control cutoff pressure (51).

4. Install 8T-0860 Pressure Gauges 40000 kPa (5800 psi) on the gauge ports for discharge pressure (56) and (57).

5. Connect a hose from the charge inlet port (66) to the test bench auxiliary oil supply. The auxiliary oil supply should be capable of producing 4100 kPa (600 psi) and 56 L/min (14.8 US gpm).

   Note: Be sure to use XT-6ES rated hydraulic hose.

6. Connect pump discharge ports (65) and (67) to the 9U-5902 Rectifier Block high-pressure ports (92) and (94).

7. Connect the 9U-5902 Rectifier Block outlet (93) to the flow meter inlet on the test bench.

8. Connect the flow meter outlet to the 9U-5398 Heat Exchanger inlet (96) .

9. Connect the 9U-5398 Heat Exchanger outlet (97) to the low-pressure return (95) on the 9U-5902 Rectifier Block.

10. Use the rear housing case drain port (71) or (82) on tandem pumps. Fill the pump case with oil. Pour oil directly into a case drain port until the case is full.

11. Connect an in-line flow meter to the case drain port (71) or (82) and plug the unused port. Vent the case to the atmosphere. Make sure that the case drain flow is directed into the sump.

12. Do not rotate the pump in the wrong direction. The correct direction of rotation will be stated on the pump. The correct direction of rotation will also be in the test specifications. The direction of rotation is viewed from the input shaft end. Visually check the pump for proper rotation.

Adjustment for Mechanical Zero Position for the Front Pump

Note: Before performing the adjustment for mechanical zero the pump must be mechanically sound. Start rotating the pump according to Step 1 of the test specifications. Verify that all connections are tight. Listen for abnormal noise. Check for leaks around shaft seals. Check for leaks around the control valves. Be sure to sustain oil supply flow to charge inlet port (66) in Steps 1 through 5 of the mechanical zero adjustment.

1. Turn the load control on the test bench completely clockwise. Turning clockwise will allow pump discharge pressure to increase in the following steps. Start rotating the pump at the value in Step 1 of the test specifications. This unit is not equipped with a charge pump. Be sure to sustain charge pump flow to port (66) in Steps 1 through 5 of the mechanical zero adjustment. If the mechanical zero adjustment is incorrect, a discharge pressure higher than the charge pressure may occur. Increase signal current to solenoid (78) until the control cutoff valve is activated.

2. Check the gauge ports for stroking pressure (62) and (77). Ensure that the pressure differential is less than 150 kPa (22 psi). Remove adjustment screws for the locking plate.

3. Turn the adjustment screws for pump displacement (63) and (76) counterclockwise three turns.

4. Stroke the pump by supplying current to (58) until the stroking pressure at gauge port (62) is 200 kPa (29 psi) greater than at gauge port (77). Pressure should be greater at system pressure gauge port (56) for clockwise rotation. Pressure should be greater at system pressure gauge port (57) for counterclockwise rotation.

5. Slowly turn the adjustment for pump displacement (76) clockwise until the system pressure differential is less than 150 kPa (22 psi) between gauge ports (56) and (57). This procedure sets the servo piston and swashplate to mechanical zero on the (76) side of the pump. Install and tighten the adjustment screw locking plates.

6. Repeat Steps 1 through 5, but stroke the pump in the opposite direction by supplying current to (61).

7. Stop rotating the pump. Turn the load control on the test bench for pump discharge pressure counterclockwise. Allow the discharge pressure of the pump to decrease. Disconnect pressure gauges from ports (56) and (57). Reduce current to all solenoids to zero.

Adjustment for Hydraulic Zero Position for the Front Pump

1. Connect two 6000 kPa (870 psi) 8T-0856 Pressure Gauges into both gauge ports for stroking pressure (62) and (77). Increase signal current to solenoid (78) until the control cutoff valve is activated.

2. Start rotating the pump to the value listed in Step 1 of the test specifications. Turn the load control for the pump discharge pressure completely clockwise. Turning clockwise will allow pump discharge pressure to increase in the following steps. Turn the adjustment screw for the hydraulic zero (59) clockwise. Continue to turn until a pressure increase is achieved. This pressure will be seen on the gauge port for stroking pressure (62) or (77). Mark the position of the adjustment screw for the hydraulic zero (59).

   Note: Do not turn the adjustment screw for the hydraulic zero (59) more than 90 degrees in either direction.

3. Turn the adjustment screw for the hydraulic zero (59) counterclockwise until pressure increases by the same value on the opposite stroking pressure port (62) or (77). Mark the position of the adjustment screw for the hydraulic zero (59).

4. Turn the adjustment screw for hydraulic zero (59) clockwise to the midpoint of both marks. The pressure at the gauge ports for the stroking pressure (62) and (77) should differ by less than 150 kPa (22 psi).

5. Hold the adjustment screw for hydraulic zero (59) and tighten the locknut.

6. Turn the load control for the pump discharge pressure counterclockwise. Turning the load control will allow pump discharge pressure to decrease. Stop rotating the pump and allow pump pressure to dissipate. Reduce current to all solenoids to zero.

Test Procedure for the Front Pump

The ISO contamination rating of the hydraulic oil in the test bench should be ISO 16/13 or cleaner. Test bench oil should be one of the following.

• SAE 10W at 50 °C (122 °F) or

• Mobil DTE-11 at 46 °C (115 °F)

Note: The following test procedure steps correlate with the numbered steps in the test specification section according to your specific part number.

Illustration 12	g01395229
Pump flow versus EDC current

1. The following steps verify the operation of the charge relief valve. Start rotating the pump according to Step 1 of the test specifications for several minutes to bring the oil to operating temperature. This pump will require sufficient auxiliary charge flow to maintain the charge pressure value given in Step 1 of the test specifications. Verify that all connections are tight. Listen for abnormal noise. Check for leaks around shaft seals. Check for leaks around the control valves. Check the gauge port for the charge pressure (84) or (86). Compare the actual charge pressure with the value in Step 1 of the test specifications. If the charge pressure is not within the test specifications, adjust the charge relief valve. Adjust the charge relief valve by turning the adjustment screw (54) clockwise or counterclockwise accordingly.

   Note: Be sure that the front pump is mechanically and hydraulically zeroed before continuing to Step 2 of the test procedure.

2. The following steps verify the operation of the electronic displacement control and the initial point of pump stroke.

   Slowly increase the input RPM and current to the control cut-off solenoid (78) to the value listed in Step 2 of the testing specifications. Verify that the control cutoff solenoid is energized by checking for a pressure increase on the gauge port for control cutoff pressure (55). Slowly increase the current to the solenoid (58) or (61) to the value in Step 2 of the test specifications. The value listed in the test specifications is the beginning of the pump stroke. Some flow meters may not be able to read discharge flows at the initial or low flow rates. Slowly increase the solenoid current until the flow meter can read the discharge flow. This is the initial point of pump stroke.

3. Slowly increase the input RPM according to Step 3 of the test specifications. Slowly increase the current to solenoid (58) or (61) to the value in Step 3 in the test specifications. The pump should be at full stroke at this point. Record actual pump flow. The pump is to be internally inspected if the discharge flow does not match the value in Step 3 of the test specifications.

4. Slowly increase the pump discharge pressure to the value in Step 4 of the test specifications. Measure pump leakage at this point. Calculate the total loss. If the total loss is higher than the allowable value in Step 4 of the test specifications, The pump may not be mechanically feasible.

   Subtract the discharge flow in Step 4 from Step 3. The remainder is your total loss.

   Example "Step 3 flow" 162 L/min (42.8 US gpm) - "Step 4 flow" 158 L/min (41.7 US gpm) ="total loss" 4 L/min (1.1 US gpm). The "max. allowable loss" is 7.2 L/min (1.9 US gpm).

   The pump in the example is acceptable because the actual total loss is less than the maximum allowable loss.

5. Repeat Step 1 through Step 4 for the opposite side of the pump. Supply current to solenoid (58) or (61).

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Hot oil and hot components can cause personal injury. Do not allow hot oil or hot components to contact skin.

Reduce RPM and all pressure to zero. Remove the component from the test bench. Drain the oil from the pump. Plug all the ports.

Set up for the Rear Pump

Note: Only test one pump at a time on tandem pumps. Isolate one of the pumps by connecting a hose between the discharge ports on the pump that is not being tested.

1. At least two power supplies are required to operate the solenoids. The power supplies must be able to deliver 0 mA to 1600 mA with an infinite setting in that range.

2. Connect a power supply to the solenoid (78) to operate the control cutoff valve. Connect a power supply to solenoid (51) or (74) to operate the electronic displacement solenoid.

3. Install 8T-0855 Pressure Gauges 4000 kPa (580 psi) on the gauge port for the charge pressure (84) or (86) and the gauge port for control cutoff pressure (55).

4. Install 8T-0860 Pressure Gauges 40000 kPa (5800 psi) on the gauge ports for discharge pressure (52) and (53).

5. Connect a hose from the charge inlet port (66) to the test bench auxiliary oil supply. The auxiliary oil supply should be capable of producing 4100 kPa (600 psi) and 56 L/min (14.8 US gpm).

   Note: Be sure to use XT-6ES rated hydraulic hose.

6. Connect pump discharge ports (83) and (85) to the 9U-5902 Rectifier Block high-pressure ports (92) and (94).

7. Connect the 9U-5902 Rectifier Block outlet (93) to the flow meter inlet on the test bench.

8. Connect the flow meter outlet to the 9U-5398 Heat Exchanger inlet (96).

9. Connect the 9U-5398 Heat Exchanger outlet (97) to the low-pressure return (95) on the 9U-5902 Rectifier Block.

10. Use the rear housing case drain port on tandem pumps. Fill the pump case with oil. Pour oil directly into case drain port (71) or (82) until the case is full.

11. Connect an in-line flow meter to the case drain port (71) or (82). Vent the case to the atmosphere. Make sure that the case drain flow is directed into the sump.

12. Do not rotate the pump in the wrong direction. The correct direction of rotation will be stated on the pump. The correct direction of rotation will also be in the test specifications. The direction of rotation is viewed from the input shaft end. Visually check the pump for proper rotation.

Adjustment for Mechanical Zero Position for the Rear Pump

Note: Before performing the adjustment for mechanical zero the pump must be mechanically sound. Start rotating the pump according to Step 1 of the test specifications. Verify that all connections are tight. Listen for abnormal noise. Check for leaks around shaft seals. Check for leaks around the control valves. Be sure to sustain charge pump flow to charge inlet port (66) in Steps 1 through 5 of the mechanical zero adjustment.

1. Turn the load control on the test bench completely clockwise. Turning clockwise will allow pump discharge pressure to increase in the following steps. Start rotating the pump at the value in Step 1 of the test specifications. This unit is not equipped with a charge pump. Be sure to sustain charge pump flow to charge inlet port (66) in Steps 1 through 5 of the mechanical zero adjustment. If the mechanical zero adjustment is incorrect, a discharge pressure higher than the charge pressure may occur. Increase signal current to solenoid (78) until the control cutoff valve is activated.

2. Check the gauge ports for stroking pressure (73) and (80). Ensure that the pressure differential is less than 150 kPa (22 psi). Remove adjustment screws for the locking plate.

3. Turn the adjustment screws for pump displacement (72) and (81) counterclockwise three turns.

4. Stroke the pump by supplying current to (74) until the stroking pressure at gauge port (80) is 200 kPa (29 psi) greater than at gauge port (73). Pressure should be greater at system pressure gauge port (52) for clockwise rotation. Pressure should be greater at system pressure gauge port (53) for counterclockwise rotation.

5. Slowly turn the adjustment for pump displacement (72) clockwise until the system pressure differential is less than 150 kPa (22 psi) between gauge ports (52) and (53). This procedure sets the servo piston and swashplate to mechanical zero on the (72) side of the pump. Install and tighten the adjustment screw locking plates.

6. Repeat Steps 1 through 5 but stroke the pump in the opposite direction by supplying current to (51).

7. Stop rotating the pump. Turn the load control on the test bench for pump discharge pressure counterclockwise. Allow the discharge pressure of the pump to decrease. Disconnect pressure gauges from ports (52) and (53). Reduce current to all solenoids to zero.

Adjustment for Hydraulic Zero Position for the Rear Pump

1. Connect two 6000 kPa (870 psi) 8T-0856 Pressure Gauges into both gauge ports for stroking pressure (73) and (80). Increase signal current to control cutoff solenoid (78) until the control cutoff valve is activated.

2. Start rotating the pump to the value listed in Step 1 of the test specifications. Turn the load control for the pump discharge pressure completely clockwise. Turning clockwise will allow pump discharge pressure to increase in the following steps. Turn the adjustment screw for the hydraulic zero (50) clockwise. Continue to turn until a pressure increase is achieved. This pressure will be seen on the gauge port for stroking pressure (73) or (80). Mark the position of the adjustment screw for the hydraulic zero (50).

   Note: Do not turn the adjustment screw for the hydraulic zero (50) more than 90 degrees in either direction.

3. Turn the adjustment screw for the hydraulic zero (50) counterclockwise until pressure increases by the same value on the opposite stroking pressure port (73) or (80). Mark the position of the adjustment screw for the hydraulic zero (50).

4. Turn the adjustment screw for hydraulic zero (50) clockwise to the midpoint of both marks. The pressure at the gauge ports for the stroking pressure (73) and (80) should differ by less than 150 kPa (22 psi).

5. Hold the adjustment screw for hydraulic zero (50) and tighten the locknut.

6. Turn the load control for the pump discharge pressure counterclockwise. Turning counter clockwise will allow pump discharge pressure to decrease. Stop rotating the pump and allow pump pressure to dissipate. Reduce current to all solenoids to zero.

Test Procedure for the Rear Pump

The ISO contamination rating of the hydraulic oil in the test bench should be ISO 16/13 or cleaner. Test bench oil should be one of the following.

• SAE 10W at 50 °C (122 °F) or

• Mobil DTE-11 at 46 °C (115 °F)

Note: The following test procedure steps correlate with the numbered steps in the test specification section according to your specific part number.

Illustration 13	g01395229
Pump flow versus EDC current

1. The following steps verify the operation of the charge relief valve. Start rotating the pump according to Step 1 of the test specifications for several minutes to bring the oil to operating temperature. This pump will require sufficient auxiliary charge flow to maintain the charge pressure value given in Step 1 of the test specifications. Verify that all connections are tight. Listen for abnormal noise. Check for leaks around shaft seals. Check for leaks around the control valves. Check the gauge port for the charge pressure (84) or (86). Compare the actual charge pressure with the value in Step 1 of the test specifications. If the charge pressure is not within the test specifications, adjust the charge relief valve. Adjust the charge relief valve by turning the adjustment screw (54) clockwise or counterclockwise accordingly.

   Note: Be sure that the rear pump is mechanically and hydraulically zeroed before continuing to Step 2 of the test procedure.

2. The following steps verify the operation of the electronic displacement control and the initial point of pump stroke.

   Slowly increase the input RPM and current to the control cut-off solenoid (78) to the value listed in Step 2 of the testing specifications. Verify that the control cutoff solenoid is energized by checking for a pressure increase on the gauge port for control cutoff pressure (55). Slowly increase the current to the solenoid (51) or (74) to the value in Step 2 of the test specifications. This is the beginning of the pump stroke. Some flow meters may not be able to read discharge flows at the initial or low flow rates. Slowly increase the solenoid current until the flow meter can read the discharge flow. Visually check that discharge pressure until the pressure starts to rise above the charge pressure. This is the initial point of pump stroke.

3. Slowly increase the input RPM according to Step 3 of the test specifications. Slowly increase the current to solenoid (51) or (74) to the value in Step 3 in the test specifications. The pump should be at full stroke at this point. Record actual pump flow. The pump is to be internally inspected if the discharge flow does not match the value in Step 3 of the test specifications.

4. Slowly increase the pump discharge pressure to the value in Step 4 of the test specifications. Measure pump leakage at this point. Calculate the total loss. If the total loss is higher than the allowable value in Step 4 of the test specifications, The pump may not be mechanically feasible.

   Subtract the discharge flow in Step 4 from Step 3. The remainder is your total loss.

   Example "Step 3 flow" 162 L/min (42.8 US gpm) - "Step 4 flow" 158 L/min (41.7 US gpm) ="total loss" 4 L/min (1.1 US gpm). The "max. allowable loss" is 7.2 L/min (1.9 US gpm).

   The pump in the example is acceptable because the actual total loss is less than the maximum allowable loss.

5. Repeat Step 1 through Step 4 for the opposite side of the pump. Supply current to solenoid (51) or (74).

Show/hide table

Hot oil and hot components can cause personal injury. Do not allow hot oil or hot components to contact skin.

Reduce RPM and all pressure to zero. Remove the component from the test bench. Drain the oil from the pump. Plug all the ports.

Test Specifications

Tooling