Air-Suspension Dump Valve
NOTICE
Never exhaust air from the suspension while
driving. When the air is exhausted, the suspen-
sion will not absorb road shocks, and compo-
nents may be damaged.
The air-suspension dump valve may be used to aid
in connecting or disconnecting from a trailer. When
the valve switch is set to LOWER, the air-suspension
dump valve deflates the air springs to lower the rear
of the vehicle. See
Fig. 18.1. In the AUTO position,
the automatic ride-control valves operate for normal
driving.
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 reinflating.
Holland Trailer Couplings
General Information
IMPORTANT: Refer to the Holland web site
(
www.hollandhitch.com) for additional informa-
tion.
The Holland trailer coupling (Fig. 18.2) is designed
for use with trailers having a maximum gross weight
of 49,000 lbs (22 226 kg). It is a swivel-mount pintle
hook designed for heavy-duty construction, utility,
and off-road applications. It is fastened to the rear
closing crossmember of the vehicle and is a non-air-
adjusted coupling.
Trailer Hookup
1.
Chock the trailer tires.
2.
Remove the cotter pin, then lift the lock and raise
the latch.
3.
Back the vehicle up until the drawbar eye is over
the horn of the pintle hook.
4.
Lower the trailer until the drawbar eye rests on
the pintle hook.
5.
Close the latch, then insert the cotter pin.
NOTICE
Always make sure the connection hanger keeps
the trailer air hoses and electrical cables posi-
tioned so that they do not rub on anything. Rub-
bing may wear through hoses or cables, resulting
in air leaks, or exposed or broken wires, poten-
tially affecting trailer brake or electrical systems.
6.
Connect the trailer electrical and air lines.
Trailer Release
1.
Apply the truck and trailer parking brakes.
1
2
3
4
01/05/2012 f611158
1. Interaxle Lock Switch
2. Fifth Wheel Slide Switch
3. Rearmost Axle Differential Lock Switch
4. Air-Suspension Dump Switch
Fig. 18.1, Axle and Suspension Switches
Trailer Couplings
18.1
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