Handling Turns, Curves, and Offtracking
This domain tests whether you can predict where the rear wheels of the last trailer will go. Offtracking is the difference between the path of the front wheels and the path of the rear wheels; the rear wheels track inside the front wheels, and the longer the combination, the greater the gap.
Turning rules
- Turn wide enough that the rear wheels clear the corner, but not so wide that you enter an oncoming lane.
- Start the turn later than you would in a car. Pull forward past the corner before turning where geometry allows.
- Watch the trailer wheels in the outside mirror through the whole turn; the last trailer cuts the corner most.
- Remember swing-out: the rear of a trailer swings outward, opposite the direction of the turn, and can strike a pole or a parked car.
Curves
Slow down before the curve, hold steady speed through it, and avoid braking mid-curve. On a curve, offtracking can push the last trailer over the centerline or off the shoulder even when the tractor is perfectly placed.
Worked example
A right turn at a tight city corner. You begin the turn when the tractor clears the stop line. The tractor tracks fine, but the last trailer's tires climb the curb. Reasoning: the rear wheels follow a shorter arc, so starting early pulls them inside the corner. The fix is to pull further into the intersection first, turn later, and steer with the mirror watching the trailer wheels.
Traps that cost marks
Turning too soon and clipping the curb; swinging so wide you cross the centerline; ignoring swing-out on the outside of the turn; cutting a curve and dragging the last trailer onto the shoulder; using only the tractor's position to judge clearance.