D400E Series II Ejector Truck Steering, Suspension, and Ejector Body Hydraulic Systems Caterpillar

Pump Flow - Test

Usage:

This test is designed to tell if a pump is operating within the design parameters.

Park on a level surface. Apply the parking brake. Shut of the engine.

For any pump test, the pump flow at 690 kPa (100 psi) will be larger than the pump flow at 6900 kPa (1000 psi) if the pump is operating at the same rpm. The pump flow is measured in L/min (US gpm).

The difference between the pump flow of the two operating pressures is the flow loss.

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Table 1
Method for determining flow loss
	Pump flow at 690 kPa (100 psi)
-	Pump flow at 6900 kPa (1000 psi)
	Flow loss

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Table 2
Example of determining flow loss
	217.6 L/min (57.5 US gpm)
-	196.8 L/min (52.0 US gpm)
	20.8 L/min (5.5 US gpm)

Flow loss is used as a measure of pump performance. Flow loss is expressed as a percentage of pump flow.

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Table 3
Method of determining percent of flow loss
Flow loss (L/min or US gpm)	×	100	=	Percent of flow loss
Pump flow at 690 kPa (100 psi)

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Table 4
Example of determining percent of flow loss
20.8 L (5.5 US gal)	×	100	=	9.5%
217.6 L/min (57.5 US gpm)

If the percent of flow loss is more than 10%, the pump performance is inadequate.

Note: The values in the examples are not set values for any specific pump or for any specific pump condition. Refer to the Specifications for the specific machine.

Test On The Machine

Install a 5P-3600 Hydraulic Flow Meter on the pressure side of the pump. Run the engine at high idle. Measure the pump flow at 690 kPa (100 psi), and at 6900 kPa (1000 psi). Use these values in the following formula (table 5).

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Table 5
Method of determining percent of flow loss
Flow loss (L/min or US gpm)	×	100	=	Percent of flow loss
Pump flow at 690 kPa (100 psi)

Test On The Bench

If the test bench can be run at 6900 kPa (1000 psi) and at full pump rpm, determine the percent of flow loss by using the following formula (table 6).

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Table 6
Method of determining percent of flow loss
Flow loss (L/min or US gpm)	×	100	=	Percent of flow loss
Pump flow at 690 kPa (100 psi)

If the test bench can not be run at 6900 kPa (1000 psi) or at full pump rpm, run the pump shaft at 1000 rpm. Measure the pump flow at 690 kPa (100 psi) and at 6900 kPa (1000 psi). Use these values in the top portion of the following formula (table 7). For the bottom part of the formula, run the pump shaft at 2000 rpm. Measure the pump flow at 690 kPa (100 psi).

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Table 7
	Pump flow at 690 kPa (100 psi)
-	Pump flow at 6900 kPa (1000 psi)	×	100	=	Percent of flow loss
	Pump flow at 690 kPa (100 psi) and at 2000 rpm	×	100	=	Percent of flow loss

Case Drain Test

Another parameter of the steering pump that can be checked is the case drain pressure. This can be done in the following way:

Stop the engine and relieve the pressure in the hydraulic system. Install the steering frame locks. Refer to Operation and Maintenance Manual, SEBU7379, "Install Steering Frame Locks".

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Illustration 1	g00703620
The location of the piston pump (steering) (1)

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Illustration 2	g00587227
(1) Port for the case drain of the piston pump (steering) (1)

Install a 700 kPa (100 psi) pressure gauge on case drain port (1). Vent the hydraulic tank by loosening the cap.

Start the engine and articulate the machine into one of the steering frame locks. Continue to articulate the machine into the steering frame lock and observe the pressure gauge.

The pressure should be zero or near zero. If the pressure is excessively high, the piston pump (steering) is probably worn. An excessive pressure would be above approximately 100 kPa (15 psi). Replace the pump. Refer to Disassembly and Assembly, "Piston Pump (Steering) - Remove and Install".