Stanley Black & Decker MHP3 Testing & Troubleshooting, General, Testing the Hydraulic Circuit

TESTING & TROUBLESHOOTING

GENERAL

Tests and adjustments should be performed periodically to ensure the TracHorse is operating at maximum ef- ficiency. Stanley Circuit Tester (P/N 04182) is recom- mended. This tester can be used to isolate problems in both the engine and hydraulic system prior to any Tra- cHorse 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 given in this section for possible causes.

TESTING THE 5 GPM EHTMA TYPE C CIRCUITS

To test either of the two circuits, proceed as follows:

1.Set both Circuit Control Levers to the OFF (down) position. Push the Combiner Knob IN to separate the two circuits.

2.Connect the Stanley Circuit Tester across two hose ends (where the tool would normally be connected) of one circuit.

3.Fully open the tester restrictor valve (counter clock- wise).

4.Start the engine and allow it to run until warm.

5.Pull the engine throttle control completely OUT so that the engine is running at full RPM.

6.Move the Circuit Control Lever for the circuit to be tested to the ON (up) position.

7.With the engine at high speed, the test flow gauge should read 4–5 gpm/15–19 lpm.

8.Slowly turn the restrictor valve clockwise while watching the pressure gauge. The flow rate should stay at 4–5 gpm/15–19 Ipm 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 re- lief valve just begins to open is commonly referred to as the “cracking pressure”. At the “cracking pres- sure”, the flow rate should start to drop because the relief valve is allowing fluid to bypass to the hydrau- lic reservoir. The “cracking pressure” is preset at the factory and if it is not within the above range, the relief valve must be reset as follows:

a.Access to the relief valves can be gained through the front of the dash behind the two plugs (item 54, major assy). Use a socket and ratchet wrench to loosen the locknut on the re- lief valve.

b.Use an Allen wrench to adjust the relief valve. Turn clockwise to raise the pressure and coun- terclockwise to reduce the pressure.

c.Tighten the locknut and test for 2100–2200 psi/148–155 bar as described above.

d.Repeat the above test with the hoses and tester connected to the other circuit.

TESTING THE 10 GPM EHTMA TYPE D CIRCUIT

The 10 gpm circuit is formed when the combiner knob is pulled out and both circuit control levers are set to the ON (up) position. This allows the output of both pump sections to be combined at one set of fittings to provide 10 gpm/38 Ipm flow to a single tool. To test the circuit, proceed as follows:

1.Perform Steps 1 through 5 under “Testing The 5 gpm EHTMA Type C Circuits”. Make sure a tool and hoses ARE NOT CONNECTED to the other tool cir- cuit.

2.Pull the combiner knob OUT to combine the two cir- cuits.

3.Raise both control levers to the ON position.

4.With the engine at high speed, the test flow gauge should read 9–10 gpm/34–38 lpm as the pressure gauge reaches 2100–2200 psi/148–155 bar.

5.Perform Step 9 under “Testing The 5 gpm EHTMA

Type C Circuits”.

ADJUSTING TRACK TENSION

•The track tension is adjusted with the unit lifted off the ground. Between the drive wheel and front idler wheel, there are 3 smaller rollers.

•Once the unit is lifted off the ground, adjust the track tension to achieve 3/8” to ½” sag below the center small roller.

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