JLG TF6-42 Service Manual - Manuale (Pagina 730)

T12000 ID 04/99 7-2
Troubleshooting guide
7.2.2 Transmission pressure checks
Transmission problems can be isolated by the use of pressure tests. When the stall test indicates slipping
clutches, then measure clutch pack pressure to determine if the slippage is due to low pressure or clutch
plate friction material failure.
In addition, converter charging pressure and transmission lubrication pressure can also be measured.
7.2.3 Mechanical and electrical checks
Prior to checking any part of the system for hydraulic function (pressure testing), the following mechanical
and electrical checks should be made:
• Check the parking brake and inching pedal for correct adjustment.
• Be sure all lever linkage is properly connected and adjusted in each segment and at all connecting points.
• The controls are actuated electrically. Check the wiring and electrical components.
• Be sure that all components of the cooling system are in good condition and operating correctly.
The radiator must be clean to maintain the proper cooling and operating temperatures for the engine and
transmission. Air clean the radiator, if necessary.
• The engine must be operating correctly. Be sure that it is correctly tuned and adjusted to the correct idle
and maximum no-load governed speed specifications.
7.2.4 Hydraulic checks
Also, before checking the transmission clutches, torque converter, charging pump, and hydraulic circuit for
pressure and rate of oil flow, it is important to make the following transmission fluid check:
Check oil level in the transmission. The transmission fluid must be at the correct (full level).
All clutches and the converter and its fluid circuit lines must be fully charged (filled) at all times.
Note
T
HE TRANSMISSION FLUID MUST BE AT OPERATING TEMPERATURE OF
82 - 93 °C (180 - 200 F)
TO OBTAIN
CORRECT FLUID LEVEL AND PRESSURE READINGS .
D O NOT ATTEMPT TO MAKE THESE CHECKS WITH COLD OIL .
To raise the oil temperature to this specification it is necessary to either operate (work) the vehicle or run the
engine with converter at “stall” (Refer to 7.2.1 “Stall test”).
CAUTION
B E CAREFUL THAT THE VEHICLE DOES NOT MOVE UNEXPECTEDLY WHEN OPERATING THE ENGINE AND
CONVERTER AT STALL RPM
.