GTR20B01 User
Manual ◄ 17
GENERAL
Tests and adjustments should be performed periodically
to ensure the power unit is operating at maximum ef-
ficiency. Stanley Circuit Tester (part number 04182) is
recommended. This tester can be used to isolate prob-
lems in both the engine and hydraulic system prior to
any power unit disassembly.
TESTING THE HYDRAULIC CIRCUIT
The following tests can be performed to ensure that the
hydraulic pump is supplying the correct flow and pres
-
sure and that the system relief valve is operating prop-
erly.
During these tests, make sure the engine is warm and
operating smoothly. If test results are not as specified,
refer to the troubleshooting table in this section for pos-
sible causes.
TESTING THE 4 GPM OR 8 GPM CIRCUIT
To test the circuit, proceed as follows:
1. Set the flow selector switches to the OFF (center) po
-
sition.
2. Set the throttle control switch to AUTO-OFF position.
3. Connect the Stanley Circuit Tester across two hose
ends (where the tool would normally be connected).
4. Fully open the tester restrictor valve (counterclock-
wise).
5. Start the engine and allow it to run until warm.
6. Switch the flow selector switch to 4 or 8 gpm depend
-
ing on which flow you are testing.
7. With the engine at the programed speed, the test flow
gauge should read 4 gpm/15 lpm or 8 gpm/30 lpm.
8. Slowly turn the restrictor valve clockwise while watch-
ing the pressure gauge. The flow rate should stay at
4 gpm/15 lpm or 8 gpm/30 lpm as the pressure gauge
reaches 2100-2200 psi/148-155 bar.
9. At 2100-2200 psi/148-155 bar, the relief valve should
begin to open. The pressure at which the relief valve just
begins to open is commonly referred to as the "crack
-
ing pressure". At the "cracking pressure," the flow rate
should start to drop because the relief valve is allowing
fluid to bypass to the hydraulic reservoir. The "cracking
pressure" is preset at the factory and if it is not within the
above range, the relief valve must be re-set as follows:
a. The relief valve is located on the right side of the unit
just behind the dash panel. It putrudes out from the man-
ifold assembly. Use a open end or box end wrench to
loosen the nut on the relief valve.
b. Use an Allen wrench to adjust the relief valve. Turn
clockwise to raise the pressure and counterclockwise to re-
duce the pressure.
c. Tighten the nut and retest.
TESTING THE CIRCUIT
