Handling Combination Vehicles (Offtracking, Turns, Backing)
What this domain tests
This domain tests offtracking, wide turns, swept path, mirror use, backing, pull-up maneuvers, and spotter communication.
Core rules
- Offtracking means the rear wheels of the trailer follow a path inside the tractor's front wheels. The longer the wheelbase, the greater the cut-in.
- Approach turns wide enough to keep the trailer tires clear of the curb, but not so wide that you enter opposing lanes.
- Use both mirrors continuously through a turn; watch the trailer's side and rear.
- For backing, get out and look, use a spotter, and pull up when unsure. Back toward the driver's side when possible.
- Do not oversteer; smooth corrections prevent trailer swing.
Worked example
You make a right turn at an intersection. The tractor clears the curb, but the trailer's right rear tires are tracking toward it. You should stop, pull up if needed, and complete the turn with a wider arc after checking the mirror. The reasoning: the trailer's rear axles cut inside the tractor's path, so watching only the tractor's front is insufficient.
Traps that cost marks
- Turning too tight and clipping the curb with trailer tires.
- Backing without a spotter or without getting out to look.
- Oversteering and causing trailer swing.
- Ignoring the trailer in the mirrors during a turn.