Unlocking the Fifth Wheel Lock Mechanism
- Apply the tractor parking brakes.
- Pull the trailer air supply valve to cut off the air supply to the trailer.
- Chock the front and rear of the trailer tires to prevent the trailer from moving.
- Lower the trailer landing gear until the weight is removed from the fifth wheel.
- 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.
- Release the kingpin locking mechanism by lifting the safety
latch and pulling the lock control handle to the unlocked position.
See Fig..
Note: Make sure the safety latch is down when the control handle is locked.
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Unlocked
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Locked
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Safety Latch
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Lock Control Handle
Fig. 1, Fontaine Fifth Wheel, Locking and Unlocking
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- Slowly drive the tractor away from the trailer.
Warning: Do not use the trailer air supply for parking trailers not equipped with spring parking brakes. This applies the trailer service brakes only. As air bleeds from the trailer brake system, brake application is lost. This could allow the unattended vehicle to roll away, possibly resulting in serious personal injury or death.
Notice: Before attempting to lock or unlock the fifth wheel lock mechanism of a sliding type fifth wheel, the slide release pull handle, if so equipped, and the slide locking wedges must be in the locked position. This prevents the sliding member from moving rapidly to the far forward or rearward position, which could damage the fifth wheel member or kingpin.