freightliner Cargo Manual page 114

Fifth Wheels
the jaw. A timing bracket ensures that the wedge and
jaw are moved at the correct time.
Placing the lock control handle in the unlocked position
moves the wedge away from the jaw. This action un-
locks the jaw so that it can be moved by the trailer king-
pin. When the tractor is moved out from under the
trailer, the kingpin moves the jaw until the kingpin is out
of the mechanism. With the jaw in the unlocked posi-
tion, the lock control handle will remain in the unlocked
position until manually moved by the operator.
During coupling (Fig. 11.5), the motion of the kingpin
entering the jaw will actuate the jaw and wedge. The
jaw will move behind the kingpin, followed by the
wedge. The purpose of the wedge is to reinforce the
jaw and take up slack around the pin. Any wear on the
jaw is immediately taken up by the wedge so there is
no slack in the connection.
Fifth Wheel Locking Operation
Locking the Fifth Wheel Lock Mechanism
1. Chock the front and rear of the trailer tires to pre-
vent the trailer from moving.
2. The kingpin lock mechanism must be fully open,
the fifth wheel plate must be completely lubricated
with chassis grease. For lubrication instructions,
refer to Group 31 of the Cargo Maintenance
Manual .
11.7
2
1
3
B
01/04/95
NOTE: Kingpin correctly entering the lock. Note how the
steel tongue allows lock halves to close completely
around the neck and shoulder of the kingpin.
A. Unlocked Position
B. Locking
1. Wedge
2. Jaw
Fig. 11.5, Fontaine Kingpin Lock Mechanism
A
C
f310184c
C. Locked
3. Trailer Kingpin