Stanley Black & Decker GTR20 Testing & Troubleshooting, General, Testing The Hydraulic Circuit

TESTING & TROUBLESHOOTING

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 5 GPM OR 10 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 5 or 10 gpm de- pending on which flow you are testing.

7.With the engine at the programed speed, the test flow gauge should read 4-6 gpm/15-23 lpm or 9-11 gpm/34- 41.6 lpm.

8.Slowly turn the restrictor valve clockwise while watch- ing the pressure gauge. The flow rate should stay at 4-6 gpm/15-23 lpm or 9-11 gpm/34-41.6 lpm as the pressure gauge reaches 2100-2200 psi/148-155 bar.

9.At 2100-2200 psi/148-155 bar, the relief valve should be- gin to open. The pressure at which the relief valve just be- gins to open is commonly referred to as the "cracking pres- sure". 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 manifold as- sembly. 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 clock- wise to raise the pressure and counterclockwise to reduce the pressure.

c. Tighten the nut and retest.

GTR20 User Manual ◄ 17