Peterbilt Medium Duty Trucks Operator's Manual after 1-07

Operating the Transmission
During Normal Driving
If you want to shift directly into any gear other than first or
reverse, depress the clutch pedal only far enough to release
the clutch. Pushing the clutch to the floor applies the clutch
brake and could cause gear hang-up.
CAUTION: Be careful not to apply the clutch
brake while the vehicle is moving. The purpose
of the clutch brake is to stop the transmission so
that you can shift into a starting gear without
grinding gears. Applying the clutch brake when
the vehicle is moving causes a braking effect on
the drivetrain and shortens the service life of the
clutch brake.
Double Clutching
Whether you are upshifting or down shifting, it is best to double
clutch. Double clutching is easier on the transmission and
on the engine, helping your vehicle match engine speed with
driveline speed and achieving clash-free shifts.
To double clutch:
Operating Instructions
1. Push the clutch pedal down to disengage the clutch.
2. Move the gear shift lever to Neutral.
3. Release the pedal to engage the clutch. This lets you
control the rpm of the mainshaft gears, allowing you to
match the rpm of the mainshaft gears to those of the output
shaft.
• Upshifts: let the engine and gears slow down to the
rpm required for the next gear.
• Downshifts: press accelerator, increase engine and
gear speed to the rpm required in the lower gear.
4. Now quickly press the pedal to disengage the clutch and
move the gear shift lever to the next gear speed position.
5. Release the pedal to engage the clutch.
More Transmission Tips
“Riding” the Clutch
The clutch is not a footrest. Do not drive with your foot resting
on the clutch pedal. It will allow your clutch to slip, causing
excessive heat and wear—damage could result.
– 70 – Y53-6008 Medium Duty (R10/06)