Trailer Couplings

Air-Suspension Dump Valve

NOTICE
Never exhaust air from the suspension while driving. When the air is exhausted, the suspension will not absorb road shocks, and components 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.
  • 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

Holland Trailer Couplings

General Information

IMPORTANT: Refer to the Holland web site (www.hollandhitch.com) for additional information.
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.
  • 1. Lock
  • 2. Cotter Pin
  • 3. Latch
  • 4. Pintle Hook
Fig. 18.2, Holland Trailer 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 positioned so that they do not rub on anything. Rubbing may wear through hoses or cables, resulting in air leaks, or exposed or broken wires, potentially affecting trailer brake or electrical systems.
6.
Connect the trailer electrical and air lines.

Trailer Release

1.
Apply the truck and trailer parking brakes.
WARNING
Do not use the trailer air supply for parking trailers not equipped with spring parking brakes. This applies the trailer service brakes only. As air bleeds from the trailer brake system, brake application is lost. This could allow the unattended vehicle to roll away, possibly resulting in serious personal injury or death.
2.
Chock the front and rear tires of the trailer.
3.
Disconnect the trailer air and electrical lines. Plug the air lines to keep them free of dirt.
4.
Take the weight of the trailer drawbar off the pintle hook.
5.
Open the latch by first removing the cotter pin, then lift up the lock and raise the latch.
6.
Slowly drive the vehicle away from the trailer.

Premier Trailer Couplings

General Information

IMPORTANT: Before operating the Premier coupling, refer to the Premier web site atwww.premier-mfg.comfor complete safety, operation, and maintenance instructions.
Trailer couplings are attached to the rear closing crossmember. The Premier trailer couplings ( Fig. 18.3 ) are designed for use with trailers having a maximum gross weight of 100,000 lbs (45 455 kg).
The Premier 2200 and 2400 trailer couplings are air adjusted couplings with a rigid pintle hook, attached to the rear closing crossmember. An air chamber, mounted forward of the coupling, operates a push rod, which pushes against a shoe inside the coupling. The shoe maintains constant pressure on the eye of the trailer drawbar when it's over the pintle hook. This takes up any slack in the trailer connection, providing smoother towing and less wear on the pintle hook. The air pressure is activated when the trailer brakes are released.
  • A. Premiere 2400 Trailer Coupling
  • B. Premiere 2200 Trailer Coupling
  • 1. Latch Lock
  • 2. Latch
  • 3. Pintle Hook
Fig. 18.3, Premiere 2200 and 2400 Trailer Couplings

Trailer Hookup

1.
Chock the trailer tires.
2.
Push the latch lock towards the mounting plate as far as possible then, while holding the latch lock in place against the mounting plate, pull the top of the latch as far as possible toward the pintle hook.
3.
While holding the latch in place, release the latch lock.
4.
Back the vehicle up until the drawbar eye is over the pintle hook, then lower the trailer.
5.
Pull the top of the latch as far as possible toward the pintle hook then, while holding the latch in position, push the latch lock towards the mounting plate.
6.
While holding the latch lock in place against the mounting plate, release the latch.
7.
Release the latch lock and make sure it is fully seated in the slot on top of the latch.
NOTICE
Always make sure the connection hanger keeps the trailer air hoses and electrical cables positioned so that they do not rub on anything. Rubbing may wear through hoses or cables, resulting in air leaks, or exposed or broken wires, potentially affecting trailer brake or electrical systems.
8.
Connect the trailer's electrical and air lines.

Trailer Release

1.
Apply the truck and trailer parking brakes.
WARNING
Do not use the trailer air supply for parking trailers not equipped with spring parking brakes. This applies the trailer service brakes only. As air bleeds from the trailer brake system, brake application is lost. This could allow the unattended vehicle to roll away, possibly resulting in serious personal injury or death.
2.
Chock the front and rear tires of the trailer.
3.
Disconnect the trailer air and electrical lines. Plug the air lines to keep them free of dirt.
4.
Take the weight of the trailer drawbar eye off the pintle hook.
5.
Push the latch lock towards the mounting plate as far as possible then, while holding the latch lock in this position, pull the top of the latch as far as possible toward the pintle hook.
6.
While holding the latch in place, release the latch lock.
7.
Slowly drive the vehicle away from the trailer.