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3.4
Pump flow at rated pressure can now be checked against the pump manufacturer's
specifications. The decrease in flow from the minimum pressure to maximum
pressure determines the pump condition. Typically a worn or damaged pump will lose
20 - 30 percent. A pump that delivers low flow at both minimum and maximum
pressure indicates suction problems. Blocked suction filters and pump cavitation
problems can also be checked by recording the pump flow at various engine speeds.
3.5
The tester can be used at several points in the circuit and the machine can be used
under its normal working conditions to evaluate the performance of the circuit
elements, such as pump, control valve, cylinder and hydraulic motor.
Overall System
Pump
4.0 Test B - 'TEE' Test (See Drawing A2) using DHT or DHCR
4.1
A 'Tee' must be installed at one point between the pump and control valve then
connected to the "IN" port of the Tester. The "OUT" port of the tester is connected
back to the tank. Make sure the loading valve is open. Note: Typically an elbow may
be changed to a 'Tee' in most hydraulic circuits and the 'Tee' can be capped with a
steel cap when not used for testing.
4.12 Pump Test. Disconnect and plug connection to control valve and proceed as in
paragraph 3.2; 3.3 and 3.4.
4.2
Overall System and Relief Valve Test (See drawing A2)
(For relief valve integral with directional control valves)
4.21 Connect control valve to 'Tee'. Operate control valve to extend the cylinder to
end of stroke.
4.22 Close the Tester loading valve while watching pressure and flow meter reading.
Pressure will increase until relief valve opens at which point flow reading will
return to zero. Note or record pressure at this point. Adjust the relief valve if the
pressure is below the recommended setting.
Test Hose
Relief Valve
'Tee' Test
Tee Connection
Drawing A2
Cylinder
DHT
8
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