How To Hook Up A Set Of Doubles

vii.2 Coupling and Uncoupling

Knowing how to couple and uncouple correctly is basic to the safe operation of doubles and triples. Wrong coupling and uncoupling tin be very dangerous. Coupling and uncoupling steps for doubles and triples are outlined below.

Coupling Twin Trailers

Secure 2nd (rear) trailer:

If the second trailer does not take spring brakes, drive the tractor shut to the trailer, connect the emergency line, charge the trailer air tank, and disconnect the emergency line. This will set the trailer emergency brakes (if the slack adjusters are correctly adapted). Chock the wheels if you lot have whatever doubt most the brakes.

Couple tractor and first semitrailer equally described before:

A converter gear or dolly is a coupling device of one or 2 axles and a fifth wheel by which a semitrailer tin be coupled to the rear of a tractor-trailer combination forming a double bottom rig.

Circumspection: For the safest handling on the road, the more than heavily loaded semi-trailer should be in first position behind the tractor. The lighter trailer should be in the rear.

Position converter dolly in front of second (rear) trailer:

Release dolly brakes by opening the air tank petcock. (Or, if the dolly has spring brakes, use the dolly parking brake control.)
If the distance is not too great, bicycle dolly into position by manus so it is in line with the kingpin.
Or, apply the tractor and outset semitrailer to selection upwardly the converter dolly:
- Position combination every bit close equally possible to converter dolly.
- Movement dolly to rear of first semi-trailer and couple information technology to the trailer.
- Lock pintle hook.
- Secure dolly back up in raised position.
- Pull dolly into position as close as possible to nose of the second semitrailer.
- Lower dolly support.
- Unhook dolly from offset trailer.
- Wheel dolly into position in front end of second trailer in line with the kingpin.

Connect converter dolly to forepart trailer:

Dorsum outset semi-trailer into position in front of dolly tongue.
Hook dolly to front trailer.
- Lock pintle hook.
- Secure converter gear support in raised position.

Connect converter dolly to rear trailer:

Make certain trailer brakes are locked and/or wheels chocked.
Make sure trailer height is correct (it must be slightly lower than the middle of the fifth bicycle, and so trailer is raised slightly when dolly is pushed nether).
Back converter dolly under rear trailer.
Raise landing gear slightly off ground to prevent damage if trailer moves.
Test coupling by pulling against pin of number ii semi-trailer.
Brand visual check of coupling no space between upper and lower 5th wheel. Locking jaws closed on kingpin).
Connect condom chains, air hoses and lite cords.
Close converter dolly air tank petcock and shut-off valves at rear of 2d trailer (service and emergency shut-offs).
Open up shut-off valves at rear of first trailer (and on dolly if so equipped).
Heighten landing gear completely.
Charge trailers (push "air supply" knob in) and check for air at rear of second trailer by opening the emergency line shut-off. If air pressure is non there, something is wrong and the brakes volition not work.

It isn't very probable you will connect to a trailer without leap brakes, only a question about this still comes up from fourth dimension to fourth dimension on the written exam.

While you don't necessarily need to memorize the definition of a converter gear or dolly, y'all should take a solid understanding of what its purpose is.

This is very important to think! Always have the heaviest trailer closest to the tractor. There is a very expert take a chance this will show upwards on the written exam.

Written exam questions ordinarily refer to trailer height positioning. The trailer should enhance slightly when the dolly is pushed under it.

You lot should always cheque the emergency line shut off valve instead of the service line shut off valve. The service line shut off valve will non accept whatsoever air escaping it unless somebody is depressing the restriction pedal or the trailer hand valve is engaged. It's better practice to check the emergency line.

Doubles:

Refers to pulling ii trailers at the aforementioned time, otherwise known every bit "pups" or "pup trailers" considering they're only about 28 feet long. Nonetheless there are some states that allow doubles that are each 48 feet in length.

HOS:

Hours Of Service

HOS refers to the logbook hours of service regulations.

OWI:

Operating While Intoxicated

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