freightliner 108SD, Driver Manual

Page: 128 / 192

Fifth Wheels, General
Information
WARNING
Do not use any fifth wheel that fails to operate
properly. Doing so may cause loss of vehicle
control, possibly resulting in severe personal in-
jury or death.
Air-Suspension Dump Valve
The air-suspension dump valve may be used to ad-
just the vehicle height in order to aid with coupling to
or uncoupling from a trailer. See
Fig. 17.1 . When the
switch is set to LOWER, the air-suspension dump
valve deflates the air springs to lower the rear of the
vehicle. In the AUTO position, the automatic ride-
control valves operate for normal driving.
WARNING
Never exhaust air from the suspension while
driving. The suspension will not absorb road
shocks, possibly damaging components, and ve-
hicle handling may be compromised. This could
result in loss of vehicle control, possibly result-
ing in severe personal injury or death.
NOTICE
Do not operate the vehicle over uneven ground
such as ramps, speed bumps, curbs, etc. with
the air springs deflated. Doing this may lead to
air bag separation from the piston, preventing the
suspension air springs from inflating.
Fifth Wheel Lubrication
WARNING
Keep the fifth wheel plate lubricated to prevent
binding between the tractor and trailer. A binding
fifth wheel could cause erratic steering and loss
of vehicle control, possibly resulting in personal
injury or death.
The standard fifth wheel plate must be kept well lu-
bricated with chassis grease to prevent friction and
binding between the vehicle fifth wheel plate and the
trailer.
For a low-lube fifth wheel plate, inspect the condition
of the low-lube pads. There should be no damaged
or missing pieces. Slight puckering at the outside
edges is normal.
For lubrication instructions, see Group 31 of the
108SD and 114SD Maintenance Manual .
Fifth Wheel Coupling
Fifth wheel coupling is activated with the lock control
handle located on either the right or left side of the
fifth wheel. Coupling is complete when the kingpin
has been forced into the jaws and the lock control
handle has moved to the locked position.
NOTICE
Some fifth wheels may be mounted on sliding
rails. Before attempting to couple a trailer to a
sliding fifth wheel, the slide feature must be
locked to prevent the top plate from sliding rap-
idly forward or rearward, causing damage to the
fifth wheel or kingpin.
Fontaine and Holland Fifth Wheels
Coupling
1. Chock the front and rear trailer tires.
2.
Ensure the fifth wheel jaw is fully open and the
operating rod is in the unlocked position. See
Fig. 17.2 or Fig. 17.3 .
3. Make sure the fifth wheel top plate is tilted so the
ramps are as low as possible.
10/26/2001 f610597
Fig. 17.1, Air-Suspension Dump Valve
Fifth Wheels
17.1