Operation5. Back tractor squarely under trailer, engaging fifth wheeljaws on trailer kingpin. Always back slowly, making suretrailer is neither too high nor too low. Avoid backingunder trailer from an angle.6. Connect service and parking brake hoses and trailerlight connector. Refer to the Warning located in theTractor-Trailer Connections information. Use athree-point stance when connecting and disconnectingtrailer.7. Inspect fifth-wheel jaws to be sure they have closed ontrailer kingpin and the trailer plate is resting securely onthe fifth wheel.8. Be sure the coupler release lever is in the lockedposition.9. Charge trailer brake system. Set trailer brakes, eitherwith the hand valve or tractor protection valve. Pullagainst trailer for an additional check of hook-up. Do notpull hard enough to damage or strain the equipment.10. Set tractor parking brakes and fully raise trailer landinggear. Refer to Brakes segment of this section forOperation of Parking Brakes and Trailer Brakes.11. Check operation of all trailer lights and correct faultylights.Un-Hook1. Try to keep tractor and trailer in straight line.2. Apply tractor and trailer parking brakes.3. Lower trailer landing gear, making sure it is on solid,level ground. The weight of trailer must be on landinggear.4. Block trailer wheels.5. Disconnect brake hoses and light cords. Be sure hosesand cords are clear.6. Pull coupler release lever to disengage fifth wheel jaws.7. Release tractor parking brakes.8. Pull out from trailer slowly, allowing landing gear to takeload gradually.Fifth Wheel Jaw Unlock ControlYour vehicle may be equipped with an optional FifthWheel Jaw Unlock feature. A guarded switch mountedin the cab allows the operator to unlock the fifth wheeljaw from inside the vehicle. There are two availableversions for the system, with monitoring or withoutmonitoring. The version with monitoring capabilitiesincludes additional indicators to show the driver fifthwheel jaw status.NOTE: Fifth Wheel Jaw Unlock is only operational whenvehicle is stationary, parking brake is set, and ignitionswitch is in the RUN position.NOTE: Outside (roadside), mechanical jaw releasemechanism is still operable regardless of in-cab control.199
