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A better understanding of the plates locking and un-locking operation can be obtained by viewing the working parts
from the underside of the plate. The Fifth Wheel Plate {A} can be removed and turned over to view the workings of the
mechanism. Refer to the drawings in (Figure 2) for the parts identication.
1. To open the locking mechanism, lift and pull the Release Handle out until the Lock Catch engages the Lock Jaw
Assembly. (see below).
2. As the trailer king pin moves into the plate, it will contact the Lock Lever, forcing the Lock Catch to disengage the Lock
Jaw Assembly, allowing the Main Spring to close the Lock Jaw Assembly behind the King Pin. The King Pin must be
fully engaged in the plate slot or the Lock Jaw Assembly will not seat properly, and the Handle Catch would not then
engage the inner side wall of the plate. To be certain that the Lock Jaw Assembly has closed fully, attempt to pull the
Release Handle without rst lifting it. To discourage theft or pranksters, place a padlock through the obround hole
above the Release Handle.
CAUTION: DO NOT ATTEMPT TO TRIP THE LOCK MECHANISM WITH YOUR HAND. USE A PROBE DEVICE
TO SIMULATE THE KING PIN ACTION
CLOSED -- LOCKED POSITION OPEN -- UNLOCKED POSITION
OPENING THE JAW ASSEMBLY
FIFTH WHEEL PLATE OPERATION
Lock Lever
Lock Catch
Lock Jaw Assembly
OPEN
CLOSED
LIFT UPWARD AND
PULL OUT WITH
FORCE UNTIL LOCK
CATCH ENGAGES
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