Driving Combination Vehicles: Turns, Braking, and Skids
Driving a combination vehicle requires planning because the unit is long, heavy, and slow to respond. In turns, the trailer off-tracks toward the inside of the turn, so you must swing wide and watch the trailer's rear wheels in the mirrors. Braking must be smooth and progressive; hard braking can cause the trailer to push the tractor or jackknife. Know that the trailer brakes should be used with the tractor brakes, and that a light application early is safer than a late hard stop. Skids: a drive-wheel skid is corrected by releasing the brakes and steering in the direction you want to go; a trailer skid is corrected by releasing the brakes and, if needed, accelerating slightly to pull the trailer straight. Traps: thinking you can steer out of a jackknife, braking hard on a curve, or forgetting that the trailer's weight and length increase stopping distance. Another trap is cutting a turn too tight and hitting a curb or object with the trailer. Rule of thumb: slow down before the turn, not in it, and look ahead to plan the swing. Worked example: if the trailer starts to swing out during a stop, release the brakes to let the wheels roll and regain traction, then reapply smoothly.