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 trailer rises about 1/2 inch (13 mm).
- 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.
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Baseplate
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Bolted Stop
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Baseplate Rail
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Fifth Wheel Mount
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Slider Saddle Plate
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Safety Latch
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Operating Rod
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Operating Lever
Fig. 1, Taperloc Slide, Manually-Operated Release
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- If equipped with a manual kingpin lock release: Release
the kingpin lock mechanism by raising the safety latch to the rear
and pulling the lock operating rod out and up into the lockset position.
See Fig.. The offset of the lock control upper rod should bottom against
the plate casting above the hole. If the operating rod cannot be pulled
to the lockset position, back the tractor slightly to release the
kingpin force against the jaw.
If equipped with an air-operated kingpin lock release: Pull the air-release knob on the dash. From outside the cab, visually check that the operating rod has bottomed out against the plate casting above the hole. See Fig.. If the operating rod isn't in the unlocked position, back the tractor slightly to release the kingpin force against the jaw.
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Safety Latch
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Operating Rod (locked)
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Operating Rod (unlocked)
Fig. 2, Simplex Kingpin Locking Mechanism, 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 unlock the fifth wheel lock mechanism of a sliding type fifth wheel, the slide operating rod (see Fig.) must be in the locked position, and the slide lockpins must be in the locked position (fully inserted in baseplate rail slots). This prevents the sliding member from moving rapidly to the far forward or rearward position, which could damage the fifth wheel member or kingpin.
Important: If equipped with an air-operated lock release, you still must make a visual check of the operating rod to make sure it is in the unlocked position