Pulling Double and Triple Trailers: Tracking, Turns, and Offtracking
Pulling Double and Triple Trailers: Tracking, Turns, and Offtracking
This domain tests how a multi-trailer combination follows a curve and how to steer through turns without clipping curbs, poles, or signs. Expect questions on offtracking and on which trailer to watch in the mirrors.
Tracking and offtracking
- The rear wheels of every trailer follow a shorter path than the tractor's front wheels. This is offtracking.
- The longer the combination and the more trailers, the greater the offtracking. A triple cuts the corner more than a double, and the last trailer cuts it most.
- Watch the tires of the last trailer in the mirrors through every turn.
Turn technique
- Approach wide enough to clear the corner but stay in your lane; do not swing into oncoming traffic.
- Begin the turn later than you would in a car so the rear trailer clears the curb.
- Take right turns slowly and check the right mirror repeatedly; the last trailer is the unit that hits things.
- Check the mirrors again before accelerating out of the turn.
Plan ahead
- A loaded double or triple cannot practically be backed as a unit. Choose routes and entrances that let you drive forward out of trouble.
Worked example
A right turn from a two-lane road into a narrow street: the tractor's front wheels clear the corner and the first trailer clears, but the second trailer's right tires track inside the first trailer's path and clip the curb. Reasoning: the driver started the turn too early. The fix is to begin steering later, swing wider within the lane, and watch the second trailer's tires pass the corner in the right mirror.
Traps
- Watching only the first trailer and forgetting the last one.
- Turning early, then over-swinging into the adjacent lane to compensate.
- Assuming the mirrors show everything; check the blind spots before the lane change that follows the turn.