Trailer Couplings

Air-Suspension Dump Valve

The air-suspension height switch may be used to aid in connecting or disconnecting from a trailer. 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.
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.
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.

Holland Trailer Coupling

General Information

The Holland PH-10RP41 trailer coupling is designed for use with trailers having a maximum gross weight of 10,000 lb. See Fig. 19.1 . It is a rigid-type pintle hook, used only on tractor applications, and is fastened to the rear closing crossmember of the vehicle. It is a non-air-adjusted coupling.
  • 1. Lock
  • 2. Latch
  • 3. Pintle Hook
Fig. 19.1, Holland PH-10RP41 Trailer Coupling

Operation

Trailer Hookup

1.
Chock the front and rear tires of the trailer.
2.
Lift the lock and raise the latch.
3.
Back up the vehicle, until the drawbar eye is over the pintle hook.
4.
Lower the trailer, until the drawbar eye rests on the pintle hook.
5.
Close the latch.
NOTICE
Always make sure the connect-hanger/support 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.
Hook up the trailer electrical and air lines.
7.
Remove the chocks from the trailer's tires.

Trailer Release

1.
Apply the tractor 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 out dirt.
4.
Take the weight of the trailer drawbar off the pintle hook.
5.
Open the latch by lifting up the lock and raising the latch.
6.
Slowly drive the vehicle away from the trailer.