How to Shift a Big Truck

Large diesel-powered dump trucks and tractor-trailer trucks pose a significant challenge when learning how to operate the shifting mechanism, especially when you're familiar only with shifting a small, manual-transmission-style passenger vehicle. Large trucks have a "synchronized transmission," which means that you shift the gears at timed intervals based on the revolutions-per-minute (rpm) gauge. Every truck has different timings, so you must familiarize yourself with the manufacturer's operating guidelines for the vehicle. Once you're familiar with the guidelines, you're ready to drive the rig.

Things You'll Need

• Operating manual for make and model of truck

Instructions

Level Highway

1. Study the operating manual for the truck you plan to operate, and pay close attention to the recommended rpm shifting pattern for both low- and high-rpm readings. Studying the manual ensures you're prepared to coordinate your shifting pattern with the manufacturer's transmission synchronization settings. It also familiarizes you with the gear shift lever pattern.

2. Allow the truck to idle at normal idle speed. Depress the clutch fully to the floor of the vehicle, and then place the gear shift lever into first gear.

3. Gently release the clutch while applying only light pressure to the accelerator to get the vehicle moving. Then press down the accelerator to bring the vehicle's rpm reading on the rpm gauge to the manufacturer's recommendation, which for many rigs is around 2,100 rpm.

4. Apply light pressure on the shift lever, pushing or pulling it in the direction of neutral. Then let off the accelerator, allowing the shift lever to slide into neutral while the accelerator is released. Watch the rpm gauge and allow it to reach the manufacturer's recommended "low" rpm for shifting into the next-higher gear.

5. After going through all the gears, and while in the last gear, pull up or press the vehicle's gear divider lever or switch, which is located on the shifter knob or on the gear shifter stick (if the vehicle has a divider). Then let off the accelerator while allowing the shifter to return to neutral again. Move the shifter over to the first-gear position, and go through all of the gears again until maximum speed is reached.

6. Downshift the vehicle by following steps 1 to 5 in reverse.

Uphill and Downhill

1. Let off the accelerator and press the clutch down rapidly to the floor in one swift movement.

2. Move the shifter lever into the neutral position, and allow the rpm gauge to drop to the recommended reading before shifting into the next higher or lower gear.

3. Depress the clutch again and shift into the next higher or lower gear.

Tips & Warnings

• When shifting while going uphill, the double-clutching technique greatly eases any difficulty, as the speed of the vehicle may slow at a faster rate than the rpm drops.

• Never shift when going downhill, as loss of vehicle control can result. Select a gear that permits the vehicle's engine to assist in "braking" the descent, and brake judiciously, using the "stab" braking method of pressing down the brake to drop the speed by 15 mph and then letting off the brake, repeating as needed. Never hold the brake pedal down continuously when going downhill when driving a vehicle with an air-brake system.

References

• Car and Driver: Shifting a Semi-Truck Basics
• Shifting an 18-Speed Transmission (PDF)

Resources

• Video Resource: Real-Life Shifting Example
• Video Resource: Shifting the Eaton 10-Speed Transmission