2. Pull the trailer air supply valve to cut off the air sup-
ply to the trailer.
3. Chock the front and rear of the trailer tires to pre-
vent the trailer from moving.
WARNING
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.
4. Lower the trailer landing gear until the weight is re-
moved from the fifth wheel.
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.
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.
Fontaine
®
Fifth Wheels
General Information
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.
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.
Fifth Wheel Lock Mechanism for
Trailer Kingpin
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.
During lockup, the jaw is moved first with the spring-
loaded wedge being allowed to slip into place against
Fifth Wheels
11.6
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