Group 170
Preventive Maintenance
Test Driving
67
Check After Start
Check Clutch Operation
Note: For further information refer to literature in Func-
tion Group 4.
Read through the road test section to become familiar
with what needs to be checked before taking the vehi-
cle on the road. Do not read while operating the
vehicle-loss of vehicle control may occur.
Start the test drive by checking clutch pedal play and
clutch operation. Clutch pedal play should be 4 to 10
mm (0.15 to 0.40 in.), which is the clearance between
the pedal plunger and the piston in the master cylinder.
On VN/VHD vehicles with clutch brake, check function
by depressing clutch pedal to within 6 to 12 mm (1/2 to 1
in.) from the floor while engaging a gear. There should
be no grating of the engagement teeth when the clutch
brake is engaged.
Check Parking Brake and Clutch Slip
Note: For further information refer to literature in Func-
tion Groups 4 and 5.
Check for parking brake holding power and also for
clutch slippage by engaging direct gear, not allowing the
engine speed to go above 1000 rpm and attempt to
drive off with the parking brake still applied. The parking
brake should hold the vehicle stationary while letting the
clutch up slowly to the point where the engine almost
stalls or stops.
If the clutch slips or the truck moves forward during this
operation, note on form for later inspection of either the
clutch or spring brake operation.
Release parking brake and start driving. Check that the
parking brakes are released quickly and that no brake
drag can be felt.
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