Bench Test Procedure for Gear Pumps {5073} Caterpillar

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Introduction

© 2016 Caterpillar All Rights Reserved. This guideline is for the use of Caterpillar 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 gear pumps. The technician should have a good understanding of hydraulic gear pumps. The technician should be educated in the operation of the hydraulic test bench. All the necessary tooling should be gathered before you begin to test the pump. 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 website. In order to address an urgent need, use the following to relay your request to Caterpillar Repair Process Engineering:

• Cat Dealer Technical Communicator

• Dealer Solution Network

• Cat Technical Representative

• Knowledge Network (on-line)

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

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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.

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) in order to view the latest version.

References

Contamination Control

New gear pumps have a break-in time. During the break in time, the gear teeth cut into the housing. A large amount of contamination is created. An additional filter is recommended on the output of the pump. The additional filter will stop the contamination from entering the test bench. 9U-6989 Head and 9U-6984 Filter Element are recommended for this application.

Mounting and Drive Configurations

There are many possibilities for mounting a gear pump. Caterpillar has two bolt and four bolt mounting plates available. The mounting plates fit pumps with SAE A, B, C, D, E, or F mounting flanges. Refer to Special Instruction, REHS1761, "Required Tooling for Bench Testing Hydraulic Components" in order to see the available mounting plates. Many other mounting plates will need to be fabricated. Fabricated tooling will need to be built according to the mounting flange of the pump that will be tested.

There are several types of drive shafts that can be used on gear pumps. On pumps with spline, taper, and keyed shafts refer to Special Instruction, REHS1761, "Required Tooling for Bench Testing Hydraulic Components" for the required drive shaft adapter. A drive adapter must be fabricated for tang type shafts.

Multiple Pump Suctions

Many times, multiple gear pumps are stacked in the same housing. A suction manifold may be required to supply oil to all the pump inlets. Because of the tremendous amount of possible variations, Caterpillar does not offer a suction manifold. The dealer must fabricate a suction manifold in order to accommodate the specific gear pump.

Break-in Procedures

Procedure for Aluminum Body Gear Pumps

Illustration 2	g01042717

The oil in the test bench should be one of the following.

• SAE 10W at 60° C (140° F) or

• Mobil DTE-11 at 46° C (115° F)

1. Start rotating the pump at 600 RPM. Listen for abnormal noise. Verify that all connections are not leaking. Check for leaks around shaft seals.

2. Slowly increase the speed to 2000 RPM over a 2 minute period.

   Note: Refer to Illustration 1 for the following steps.

3. Slowly increase the pressure from 0 psi to 500 psi above the relief valve pressure of the system in a 30 second period.

4. Cycle the pressure between the relief valve pressure of the system plus 500 psi and 0 psi 90 times in a 60 second period. Use the load valve on your test bench in order to cycle the pressure.

5. After the break-in procedure has been performed test the volumetric efficiency. Use the applicable Test Instruction that is provided later in this document.

Procedure for Iron Body Gear Pumps

Illustration 3	g01421689

1. Start rotating the pump at 600 RPM. Listen for abnormal noise. Check all connections for leaks. Check for leaks around shaft seals.

2. Slowly increase the speed to 1200 RPM over a 2 minute period.

   Note: Refer to Illustration 2 for the following steps.

3. Increase the pressure from 0 psi to 500 psi at a rate of approximately 100 psi per second.

4. Keep the pressure constant for approximately 3 seconds.

5. Increase the pressure by 250 psi at a rate of approximately 100 psi per second.

6. Continue this pattern by increasing the pressure by 250 psi. After each increase, keep the pressure constant for approximately 3 seconds. Continue increasing the pressure in 250 psi increments until the pressure is 500 psi above relief pressure.

7. After the break-in procedure has been performed test the volumetric efficiency. Use the applicable Test Instruction that is provided later in this document.

Test Instructions

Generic Test Instructions

1. Rotate the pump at machine rated rpm. If you do not know the rated speed, rotate at 2000 RPM. Listen for abnormal noise. Verify that all the connections are not leaking. Check for leaks around shaft seals.

   Run the pump for at least 5 minutes in order to raise the temperature of the oil and purge the system of air.

2. Rotate the pump at 2000 RPM. Load the pump to 100 psi. Record the flow rate of the pump.

3. Rotate the pump at 2000 RPM. Load the pump to 1000 psi. Record the flow rate of the pump.

4. Divide the flow rate at Step 3 by the flow rate at Step 2 and multiply this number by 100. This is the volumetric efficiency of the pump.

   No more than 10% volumetric loss is acceptable for gear pumps.

   Note: Pumps with an output of equal to or less than 20 gpm at 2000 rpm are allowed up to 15% volumetric loss.

Limited Horsepower Instructions

Note: This procedure is for test benches that cannot rotate the tested pump at 2000 RPM with a 1000 psi load.

1. Start rotating the pump at 1000 RPM. Listen for abnormal noise. Verify that all the connections are not leaking. Check for leaks around shaft seals.

   Run the pump for at least 5 minutes in order to raise the temperature of the oil and purge the system of air.

2. Rotate the pump at 1000 RPM. Load the pump to 100 psi. Record the flow rate out of the pump.

3. Rotate the pump at 1000 RPM. Load the pump to 1000 psi. Record the flow rate out of the pump.

4. Rotate the pump at 2000 RPM. Load the pump to 100 psi. Record the flow rate out of the pump.

5. Use the formula in Illustration 1 to calculate the volumetric loss.

Illustration 4	g01046377