66
Twin Disc, Incorporated
Troubleshooting
Power Transmission System Operator’s Manual #1020510
Failed Clutch Solenoid
If there is partial or full pressure on a clutch that is not selected, then
remove and inspect the selector valve assembly. Replace the selector
valve if necessary.
Failed Clutch Pack
DO NOT GET NEAR THE DRIVESHAFTS FOR THIS TEST!
If the oil level is correct but the oil well fracturing rig output
driveshaft will not rotate, start the engine and while at low idle,
shift out of N into D, and then R. With the help of an assistant if
necessary, observe the drive shaft between the converter and
transmission. Use a mirror under the oil well fracturing rig if
necessary.
When the range selector is in the
N
position the drive shaft between the
converter and the transmission should be rotating. If the input drive shaft
is not rotating when in the
N
position, the transmission is locked-up
internally or the torque converter is not transmitting power. When
N
is
deselected, the input drive shaft should come to a stop quickly. If
R
is
selected, three clutches are deliberately engaged, thus stalling the torque
converter. If the input drive shaft stops and the output driveshaft does
not move when
D1
is selected, the transmission may be locked-up
internally, or the oil fracturing pump may be locked up. If the drive shaft
does not come to a stop when shifted out of
N
, and the output driveshaft
does not rotate, one or more of the transmission clutches are not engaged
properly. Further testing is required to identify the problem.
Install pressure test fittings at each clutch pressure test port.
test port locations in Operation.
Go to Test 8 of the control system tests.
With the engine running, verify that the pressure at each clutch is at full
pressure when selected and at zero pressure when not selected.
If no problems are found during the clutch pressure test, it is likely that a
clutch pack has failed. Dark or burnt smelling oil is an indication of a
failed clutch. A clutch pack may be seized, causing the clutch to be
locked up, or the clutch pack may be worn out causing it to slip. The
transmission must be removed to repair either condition.
Summary of Contents for TA-90-8501
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