HYDRAULICS
8M-74
Traction Circuit Flow Test
Set up flow meter to perform a tee test (Figure 8M-18).
Figure 8M-18. Flow Meter Tee Test Setup
Traction Pump Test
1. Shut off the engine and remove ignition key.
2. Disconnect and remove traction control cable from
traction pump.
3. Install fabricated hydro lock linkage through cable
mounting bracket and secure to traction pump
control arm.
4. Disconnect hoses and tee fittings from the forward
and reverse ports on the traction pump
(Figure 8M-19).
5. Connect the “IN” ports of the flow meter to the for-
ward pressure port on the traction pump and onto
the disconnected forward traction hose
(Figure 8M-19).
6. Connect the “OUT” ports of the flow meter to the
reverse pressure port on the traction pump and
onto the disconnected reverse traction hose
(Figure 8M-19).
7. Install blocking disc at the flow meter tee fittings to
block the hoses that are connected to the forward
and reverse pressure hoses (Figure 8M-19).
8. Open the tester load valve, set the parking brake,
start the engine, and advance the engine speed to
full throttle.
9. Adjust the hydro lock linkage until 10 gpm (37.8
lpm) is obtained (in the forward direction) on the
flow meter and secure linkage so that flow is main-
tained at 10 gpm (37.8 lpm). Read and record flow
A) on Flow Test Report 3.
10.Slowly close tester load valve until a reading of
2000 psi (138 Bar) is obtained. Read and record
flow B) on Flow Test Report 3.
11.Continue to close load valve until zero flow is
obtained. Record forward high pressure relief
valve pressure C) on Flow Test Report 3.
Conclusion
• If leakage is less than 1 gpm (3.8 lpm), traction
pump is not at fault.
• If leakage is 1 to 2 gpm (3.8 to 7.5 lpm), traction
pump is marginal.
• If leakage is 2 gpm (7.5 lpm) or more, traction pump
is faulty.
• STEP 11, pressure of 3500 psi (241 Bar) should
have been observed. If pump passed leakage test
and the 3500 psi (241 Bar) could not be achieved,
the forward high pressure relief valve is at fault.
NOTICE
Before performing this test, make sure the tow
valve is closed located on the side of the trac-
tion pump.
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