RETARDERS.- Some tractors are equipped with a retarder that helps slow a vehicle, reducing the need for using the brakes. One common retarder is known as the "jake brake." Retarders reduce brake wear and provide another means to slow down. Retarders are controlled by the operator and are either exhaust, engine, hydraulic, or electric.

Turns

When making turns with the tractor-trailer, you must allow for the overall length of the unit. Remember: The tractor-trailer is hinged in the middle, and the trailer has a tendency to cut the corners, rather than follow the tractor. For this reason, it is necessary to make a wider turn than when turning with a straight truck.

CAUTION

Turning turn signals on well in advance of starting the turn is extremely important. This action warns other drivers that a turn is going to be made and allows them to drive safely.

RIGHT TURNS.- When performing a right-hand turn, turn slowly to give yourself and others time to avoid problems. If you cannot make the right turn without swinging into another lane, turn wide as you complete the turn, as shown in figure 7-20, view A. Keep the rear of the tractor-trailer close to the curb to stop any drivers from passing on the right. If you must cross into the oncoming traffic lane when making your turn, watch for vehicles coming towards you. Give them room to go by or stop; however, do not back up for them, because you may have a vehicle directly behind you.

Do not turn wide to the left as you start the turn to the right, as shown in figure 7-20, view B, because a following driver may think you are turning left and try to pass you on the right. Remember: If you turn too sharp while making a right turn, your trailer will ride up the curb and possibly run over obstructions (fig. 7-21).

Figure 7-21.-Incorrect right turn.

Figure 7-22.-Tractor-trailer left turn off tracking.

LEFT TURNS.- On a left turn, ensure you have reached the center of the intersection before you start the left turn. If you turn too soon, the left side of your vehicle may hit another vehicle because of off tracking (fig. 7-22).

If there are two turning lanes, always take the right-hand turn lane, as shown in figure 7-23. Do not start in the inside lane because you may have to swing right to make the left turn. You may not see vehicles on the right and cause a collision.

Backing

When backing a tractor-trailer, reverse the procedure you would use to back a bus or a straight truck; for example, if you want the trailer to go to the left, turn the steering wheel to the right. After the trailer is headed in the desired direction, turn the steering wheel slowly to the left. This puts the tractor in the same line of travel as the trailer and prevents the tractor and trailer from jackknifing. (The term jackknifing means a condition where the tractor and trailer are jammed together at an acute angle.)

Backing the trailer to the left is known as sight-side backing because you have a better view of the area into which you are backing, as shown in figure 7-24, view A. Sight-side backing is the recommended method for backing.

Reverse the sight-side backing procedures to back a trailer to the right. This is known as blind-side backing and should be done only when it is absolutely necessary. As shown in figure 7-24, view B, as the driver, you

Figure 7-23.-Left turn from right-hand lane.

cannot see the rear of your trailer or the area into which you are backing.

CAUTION

You should always use a backing guide when performing backing operations with a tractor-trailer.