Couple and Uncouple Your Cargo Trailer

*The following instructions should only be used as guidelines and are not meant to replace manufacture or trailer dealer’s instructions.


Coupling Your Trailer

A secure coupling (or fastening) to the tow vehicle is essential. A loss of coupling may result in serious injury or death. Therefore, you must understand how to properly couple your cargo trailer to your tow vehicle.



The following parts are involved in making a secure coupling between the trailer and the tow vehicle:

  • Coupling: That part of the trailer connecting mechanism by which the connection is actually made to the trailer hitch. This does not include any structural member, extension of the trailer frame, or brake controller.
  • Hitch: That part of the connecting mechanism including the ball support platform and ball and those components that extend and are attached to the towing vehicle, including bumpers intended to serve as hitches.
  • Weight distributing hitch (equalizing hitch): A mechanical device that connects the trailer to the towing vehicle and by means of leverage applied to the trailer and towing vehicle structure, when properly adjusted, distributes the imposed vertical load at the hitch and coupling connection between structures of the towing vehicle and the trailer.
  • Weight carrying hitch: A mechanical and/or structural device that connects the trailer to the towing vehicle and that does not employ features designed to redistribute the load imposed at the hitch and carrying connection.
  • Safety chains or cables: Chains or cables permanently attached to the trailer such that if the coupler connection comes lose, the safety chains or cables can keep the trailer attached to the tow vehicle. With properly rigged safety chains or cable, it is possible to keep the tongue of the trailer from digging into the road pavement, even if the coupler-to-hitch connection comes apart. Some states do not allow safety cables. Therefore, it may be wise to check with the state police to see if your state has any restrictions on the use of safety cables, if your trailer is so equipped.
  • Trailer lighting (and braking) connector: A device that connects electrical power from the tow vehicle to the trailer. Electricity is used to turn on brake lights, running lights, and turn signals as required. In addition, if your trailer has a braking system, the electrical connector will also supply power to the trailer brakes from the tow vehicle.
  • Break-away switch: If the trailer becomes uncoupled from the towing vehicle, the break-away switch lanyard, attached independently to the tow vehicle, will pull a pin in the emergency electrical break-away switch on the trailer. The break-away switch is activated by a separate battery supply in the trailer such as to energize the trailer brakes independently of the towing vehicle. It is important to check the state of charge of the emergency break-away battery before each trip. Simply pull the pin out of the switch by hand and then try to pull the trailer forward. If you feel a significant drag force, then the brakes are activated. Be sure to re-insert the pin in the break-away switch. Also, be sure to allow enough slack in the break-away switch lanyard such that the switch will only activate (pin pulls out) if the trailer becomes uncoupled from the tow vehicle.
  • Jack: A device on the trailer that is used to raise and lower the trailer tongue. On larger trailers it is sometimes called the “landing gear”. They are common on gooseneck cargo trailers.




Use an adequate tow vehicle and hitch

If you do not use the proper tow vehicle, and one that is matched to the Gross Vehicle Weight (GVRW) of your trailer, you could cause an accident that can cause serious injury or death. If you already have a tow vehicle, you should know your vehicle tow rating, and Gross Combination Weight Rating (GCWR) and make certain the trailer’s rated capacity is less than or equal to the tow vehicle’s rated towing capacity. If you already have, or plan to buy a trailer, make certain that the tow rating of the tow vehicle is equal or greater than the GVWR of the trailer, and that the GCWR will be within limits.



Before coupling your trailer to the tow vehicle

Be sure the size and rating of the hitch ball match the size and rating of the coupler. Couplers and hitch balls are rated with the rating and size.



Wipe the hitch ball clean and inspect for any damage by feeling for cracks, flat spots, or pits.



Rock the hitch ball to make sure the ball is tight to the hitch, and visually check to make sure the ball nut is solid against the lock washer and hitch frame.

Clean the inside of the coupler by wiping it inside and outside and inspect it visually for cracks and deformations. Make sure to feel inside the coupler for worn spots or pits.

Check the coupler and make sure it is tightly attached to the tongue of the trailer. All coupler bolts and nuts should be tight against the trailer frame.


Raise the coupler so that its bottom is above the hitch ball. It is best to use the trailer tongue jack if you have one.


Prepare the hitch and coupler

Lightly lubricate the hitch ball and inside of the coupler with automotive bearing grease.

Check to make sure the coupler is still above the hitch ball so that the ball can slide under the coupler.

Open the coupler lock. Ball couplers have a locking mechanism with an internal moving clamp like piece, and an outside wheel, handle, or latch.

In the open position, the clamp underneath the coupler opens, allowing the coupler to drop fully onto the hitch ball.



Coupling the trailer to the tow vehicle

Backing up the tow vehicle

Check once again to make sure the coupler is higher than the hitch ball.

It is best to have help in backing up your tow vehicle to the cargo trailer.

Trying to do this alone can be dangerous and result in serious injury or death!

One person slowly and carefully backs up the tow vehicle while the other person directs them into position. For safety, the person guiding should stand just to the outside of the tow vehicle to prevent them from being crushed between the tow vehicle and the trailer.

The person guiding should direct the driver so that the hitch ball is under the coupler. Make sure again that the coupler is still higher than the hitch ball. If it needs to be raised, make sure to have the driver put the vehicle in park before walking behind the vehicle.

When the trailer ball is centered under the coupler, crank the tongue jack to lower the trailer until the ball is all the way down onto the hitch ball. If needed, rock the trailer just enough until the couplers falls into place over the hitch ball.

If the coupler will not go all the way down on the ball, your hitch ball may be too large.  Stop what you are doing and double check to make sure you have properly matched the hitch ball with the size indicated on the coupler.

Lower the lock on the top of the coupler until it is locked into place. Sometimes couplers can look like they are locked so look closely to make sure that it closes into position fully. You should not be able to lift the coupler off the hitch ball when it is when it’s in place.

If there is a lot of slack and the coupler look loose over the hitch ball, your hitch ball may be too small. Stop what you are doing and double check to make sure you have properly matched the hitch ball with the size indicated on the coupler.

Be sure to insert a pin or lock into the hole on the locking mechanism. Locks are best so that no one can steal your trailer or unlock the coupler without your knowledge.

If the pin or lock will not line up with the hole, this may mean that the coupler latch is not fully locked into place.

To make sure that it is secure, use your trailer jack and try to raise the trailer no more than 1 inch. It should raise the rear of your tow vehicle slightly as you do this if it is properly connected.




If the coupler cannot be secured to the hitch ball, do not tow the trailer.

Lower the trailer until its entire tongue weight is held by the hitch. Continue retracting the jack to its fully retraced position.

Make sure the jack is all the way up, otherwise you may bend your jack by hitting a pot hole or dip in the road.

Attach the safety chains

Check the safety chains and hooks for damage or wear. Replace worn or damaged safety chains and hooks before towing.

Crisscross the chains underneath the coupler so if the trailer uncouples, the safety chains can hold the tongue up above the road.

Loop around a frame member of the tow vehicle or to holes provided in the hitch system. Do not attach them to an interchangeable part of the hitch assembly.

Attach the “S” hooks by hooking them from underneath the holes, not from the top. Make sure to provide enough slack to permit tight turns, but not so long that the chains drag on the road.

s hooks




Attach and test electric break-away brake system

If the coupler or hitch fails, a properly connected and working break-away brake system will apply electric brakes on the trailer. The safety chains will keep the tow vehicle attached and as the brakes are applied at the trailer’s axles, the trailer/tow vehicle will come to a controlled stop.

The break-away break system includes a battery, a switch, a pull-pin, and a lanyard. Read and follow the instruction provided to you by the brake manufacturer. If you do not have these instructions contact your trailer dealer.

The break-away brake system may be fitted with a charging capability that draws power from the tow vehicle. If the electric system on your tow vehicle does not provide power to the break-away brake battery, you must periodically charge the battery to keep the break-away brake system in working order.


Connect the pull-pin lanyard to the tow vehicle so that the pull-pin will be pulled out before all of the slack in the safety chains is taken up (see break-away brake system, figure). Do not connect the pull-pin cable to a safety chain or to the hitch ball or hitch ball assembly. This would prevent the break-away break system from operating when it’s needed.

To test the break-away brake battery, remove the pull-pin from the switch and try and pull the trailer forward. You should feel the trailer resisting being towed, but the wheels will not necessarily be locked. If the brakes do not function, do not tow the trailer until the brakes or the battery have been repaired.

Immediately replace the pull-pin back into the switch. The breakaway brake system battery discharges rapidly when the pull-pin is removed.



Do not tow the trailer with the break-away brake system ON (pin pulled out) because the brakes will overheat which can result in permanent brake failure.


If you do not use your trailer for several months, or during winter months:

  • Store the battery indoors and;
  • Charge the battery periodically as needed.

Replace the break-away break battery according to the intervals specified by the battery manufacturer.

Connect the electrical cables (plug)

Connect the trailer lights to the tow vehicles using the electrical connector(s).

Check to make sure all lights are operating.

  • Clearance and running lights (turn on tow vehicle headlights)
  • Break lights (have someone step on the tow vehicle’s brake pedal)
  • Turn signals (operate tow vehicles turn signal lever for both directions)

Check electric brakes for proper operation using brake controller mounted in the cab of tow vehicle.

If your cargo trailer has electric brakes, your tow vehicle will have an electric brake controller that sends power to the trailer brakes. Before towing the trailer on the road, you must operate the brake controller while trying to pull the trailer forward to make sure the electric brakes operate.

While towing the trailer at less than 5 M.P.H., manually operate the electric brake controller in the tow vehicle cab. Do not do this on the road. You should feel the operation of the trailer brakes.



You should review our Safe Cargo Trailer Towing Guidelines

Uncoupling the ball hitch trailer with the tongue jack

Follow these steps to uncouple your ball hitch trailer from the tow vehicle

  • Make sure trailer is parked on a flat surface.
  • Block trailer tires to prevent the trailer from rolling, before jacking up the trailer.
  • Disconnect the electrical connector.
  • Disconnect the brake-away break switch lanyard.
  • Disconnect the safety chains from the tow vehicle.
  • Unlock the coupler and open it.
  • Before extending the jack, make certain the ground surface below the jack pad will support the tongue load. Do not use the jack on bear ground. Make sure to place a piece of wood or metal underneath the jack pad.
  • Rotate the jack handle (or crank) clockwise. This will slowly extend the jack and transfer the weight of the trailer tongue to the jack.

Trailer with gooseneck coupler and drop-leg jack

A gooseneck coupler on the trailer connects to a gooseneck hitch that you must have installed in the bed of the tow vehicle, normally in the center. This system of coupling a trailer to a tow vehicle permits the tow vehicle to turn to sharper angles than are possible with a bumper hitch system. A gooseneck coupler consists of a tube in an inverted “U” shape and a gooseneck ball receiver. “Trailer with a gooseneck hitch coupler” figure shows a trailer with a gooseneck coupler.

Contact your trailer dealer for more information on coupling and uncoupling your cargo trailer.


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