Mack T31321, T313L21 And T313Lr21 Shifting Instructions - Mack Granite GU Series Operator's Handbook Manual

218 OPERATION
5. Move the dash-mounted compound NEUTRAL control valve to the ON
position, which moves the synchro clutch to a NEUTRAL position.
6. Engage the PTO.
7. Move the main box shift lever to the desired ratio.
8. Release the clutch pedal to engage the clutch.
9. Operate the PTO-driven load.
When disengaging the PTO —
1. Depress the clutch pedal to disengage the clutch.
2. Move the main box shift lever to NEUTRAL.
3. Disengage the PTO.
4. Move the dash-mounted compound NEUTRAL control valve to the OFF
position, which moves the synchro clutch back to LO range.
5. Move the shift lever to the desired main gear box ratio.
6. Release the parking brakes.
7. Release the clutch pedal to engage the clutch.
MACK T31321, T313L21 and T313LR21 Shifting
Instructions
CAUTION
Make sure air pressure is at least 90 psi and unit is at operating temperature before
making range shifts. Always start in LO range. This also applies to dynamometer
testing. When the truck is stationary, do NOT shift into HI range and then start
moving the truck. Otherwise, damage to the synchronizer may result.
The T313(L)(LR)21 is a range-shifted transmission with 12 forward highway
speeds and an extra LO gear in the LO range. LO and HI ranges are
controlled by an air-shift range selector.