Medium Duty Operator's Manual - Peterbilt Motors Company

Preventive Maintenance
As the clutch pedal is depressed further, with harder pressure,
the release yoke moves the release bearing away from
the engine. This causes the clutch plate to release from the
driven disks in the clutch. This is called release travel. And
finally, on 9-, 10-, and 11-speed transmissions, as the pedal
is pushed to the last 1/2 to 1 inch of travel, the release bearing
contacts and engages the clutch brake. This is called
clutch brake squeeze. When the clutch wears, the release
bearing gradually moves toward the engine, decreasing free
pedal and free travel. When all free pedal and free travel are
gone, the clutch requires adjustment.
The clutch is adjusted by turning an adjustment ring that is
built into the clutch. When the ring is turned, the release
bearing moves back toward the transmission, restoring free
pedal and clutch free travel. Under normal clutch wear this is
the only adjustment needed. Do not attempt to change any
other component. See the Medium Duty Maintenance Manual
for details.
Clutch Adjustment — Normal Wear
Transmission and Clutch
Clutch pedal free travel is usually 1 3/4 in. to 2 in. (34 to 51
mm). This should be your guide for determining whether your
truck needs clutch adjustment. Also, if it becomes increasingly
difficult to shift into gears, or the truck creeps with the
clutch pedal depressed, your clutch needs adjustment. See
the Medium Duty Maintenance Manual for the proper
adjustment procedures.
Some vehicles have automatic clutch adjustment. If yours
doesn't have this feature, adjustment will have to be done by
a trained certified mechanic. Have the adjustment done
before clutch pedal free travel is reduced to the minimum
allowable 1/2 in. (13mm).
Clutch Linkage
The Medium Duty is equipped with a rod and lever mechanical
clutch linkage. Lubricate each pivot point on the clutch
linkage.
Medium Duty (R05/09) Y53-6008A – 235 –