Fifth Wheels 8. After lockup is completed, connect the tractor-to- trailer air system lines and the electrical cable to the trailer. Take care to prevent dirt or foreign mate- rial from entering the air system lines. 13. The load distribution on the front steering axle and rear drive axle(s) will have a direct effect on the steering control of the vehicle. Determine the front and rear axle weights by weigh- ing the vehicle on scales designed for this purpose. 9. Charge the air brake system with air. Make sure that the air connections do not leak. 10.
With the trailer wheels chocked and the brakes set, check for clearance between the kingpin and the fifth wheel jaws by moving the tractor forward and backward against the locked kingpin. There should be no slack between the tractor and the trailer. If slack is present, uncouple the trailer. The maximum axle weight ratings are given on the Federal Motor Vehicle Safety Standard (FMVSS) label or Canadian Motor Vehicle Safety Standard (CMVSS) label attached to the left rear door post of the tractor. The desired load on the axle is no less than 80 percent of the maximum axle weight rating, but in no case should the axle load exceed the maximum axle weight rating given on the FMVSS or CMVSS label.
For adjustment instructions, refer to the applicable manufacturer’s service information. WARNING WARNING Eliminate slack between the trailer and the tractor. Incorrect fifth wheel adjustment could cause the trailer to disconnect, possibly resulting in serious personal injury or death. Do not overload any tractor axle by improperly loading the trailer. This could cause erratic steering and loss of vehicle control, possibly resulting in serious personal injury or death. 11. Retract the trailer landing gear, and secure the ratchet handle. Unlocking the Fifth Wheel Lock Mechanism 12. Remove the chocks from the trailer tires. 1. Apply the tractor parking brakes. 2.
Pull the trailer air supply valve to cut off the air sup- ply to the trailer. 11.9