Fifth Wheels 2. Pull the trailer air supply valve to cut off the air sup- ply to the trailer. Fontaine ® Fifth Wheels General Information 3. Chock the front and rear of the trailer tires to pre- vent the trailer from moving. WARNING On Fontaine fifth wheels, kingpin release is accom- plished by activating a manual lock control handle lo- cated on the left side (roadside) of the fifth wheel. King- pin lockup occurs when the kingpin is forced into the jaws and the lock control handle moves to the locked position. Do not use the trailer service brakes for parking; they are not designed for this purpose.
If air bleeds out of the trailer air tank during parking, the vehicle could roll causing serious personal injury or prop- erty damage. The fifth wheel top plate is bracket-mounted to the trac- tor frame in a position that best distributes the trailer load over the tractor axles. 4. Lower the trailer landing gear until the weight is re- moved from the fifth wheel. Fifth Wheel Lock Mechanism for Trailer Kingpin 5. Disconnect the tractor-to-trailer air system lines and electrical cable. Plug the air lines to prevent dirt or foreign material from entering the lines. The Fontaine fifth wheel lock mechanism for the trailer kingpin consists of a spring-loaded jaw and a sliding wedge. See Fig. 11.5 .
The jaw and wedge each have a pin permanently attached. The pin on the jaw and the pin on the wedge fit into elongated notches in the lock control handle. The notches in the handle control the limit of movement for both the jaw and wedge. The notches are arranged so that the wedge is actuated first during release of the kingpin. 6. Release the kingpin locking mechanism by pulling the kingpin lock control handle ( Fig. 11.1 ) to the outward position. 7. Slowly drive the tractor away from the trailer. During lockup, the jaw is moved first with the spring- loaded wedge being allowed to slip into place against 11.6