Combination Vehicles

Coupling and Uncoupling

Knowing how to couple and uncouple correctly is basic to safe operation of combination vehicles. Wrong coupling and uncoupling can be very dangerous. General coupling and uncoupling steps are listed below. There are differences between different rigs, so learn the details of coupling and uncoupling the truck(s) you will operate.

Coupling Tractor-Semitrailers

Step 1: Inspect Fifth Wheel

Check for damaged/missing parts.
Check to see that mounting to tractor is secure, no cracks in frame, etc.
Be sure that the fifth wheel plate is greased as required. Failure to keep the fifth wheel plate lubricated could cause steering problems because of friction between the tractor and trailer.

Check if fifth wheel is in proper position for coupling:

Wheel tilted down toward rear of tractor.
Jaws open.
Safety unlocking handle in the automatic lock position.
If you have a sliding fifth wheel, make sure it is locked.
Make sure the trailer kingpin is not bent or broken.

Step 2: Inspect Area and Chock Wheels

Make sure area around the vehicle is clear.
Be sure trailer wheels are chocked or spring brakes are on.
Check that cargo (if any) is secured against movement due to tractor being coupled to the trailer.

Step 3: Position Tractor

Put the tractor directly in front of the trailer. Never back under the trailer at an angle because you might push the trailer sideways and break the landing gear.
Check position, using outside mirrors, by looking down both sides of the trailer.

Step 4: Back Slowly

Back until fifth wheel just touches the trailer -- Don’t hit the trailer.

Step 5: Secure Tractor

Put on the parking brake.
Put transmission in neutral.

Step 6: Check Trailer Height

The trailer should be low enough that it is raised slightly by the tractor when the tractor is backed under it. Raise or lower the trailer as needed. If the trailer is too low, the tractor may strike and damage the trailer nose. If the trailer is too high, it may not couple correctly.
Check that the kingpin and fifth wheel are aligned.

Step 7: Connect Air Lines to Trailer

Check glad hand seals and connect tractor emergency air line to trailer emergency glad hand.
Check glad hand seals and connect tractor service air line to trailer service glad hand.
Make sure air lines are safely supported where they won't be crushed or caught while the tractor is backing under the trailer.

Step 8: Supply Air to Trailer

From cab, push in “air supply” knob or move tractor protection valve control from the “emergency” to the “normal” position to supply air to the trailer brake system.
Wait until the air pressure is normal.
Check brake system for crossed air lines.
Shut engine off so you can hear the brakes.
Apply and release trailer brakes and listen for sound of trailer brakes being applied and released. You should hear the brakes move when applied and air escape when the brakes are released.
Check air brake system pressure gauge for signs of major air loss.
When you are sure trailer brakes are working, start the engine.
Make sure air pressure is up to normal.

Step 9: Lock Trailer Brakes

Pull out the “air supply” knob or move the tractor protection valve control from “normal” to “emergency.”

Step 10: Back Under Trailer

Use lowest reverse gear.
Back tractor slowly under trailer to avoid hitting the kingpin too hard.
Stop when the kingpin is locked into the fifth wheel.

Step 11: Check Connection for Security

Raise trailer landing gear slightly off ground.
Pull tractor gently forward while the trailer brakes are still locked to check that the trailer is locked onto the tractor.

Step 12: Secure Vehicle

Put transmission in neutral.
Put parking brakes on.
Shut off engine and take the key with you so someone else won't move truck while you are under it.

Step 13: Inspect Coupling

Use a flashlight, if necessary.
Make sure there is no space between the apron on the trailer and the fifth wheel skid plate. If there is space, something is wrong (kingpin may be on top of the closed fifth wheel jaws, and trailer would come loose easily).
Go under trailer and look into the back of the fifth wheel. Make sure the fifth wheel jaws have closed around the shank of the kingpin.
Check that the fifth wheel locking lever is in the “lock” position.
Check that the safety latch is in position over locking lever (on some fifth wheels the catch must be put in place by hand).
If the coupling isn’t right, don’t drive the coupled unit, get it fixed.

Step 14: Connect Electrical Cord/ Check Air Lines

Plug the electrical cord into the trailer and fasten the safety catch.
Check both air lines and electrical line for signs of damage.
Make sure air and electrical lines will not hit any moving parts of the vehicle.

Step 15: Raise Trailer Landing Gear

Use low gear range (if so equipped) to begin raising the landing gear. Once free of weight, switch to the high gear range.
Raise the landing gear all the way up. Never drive with landing gear only part way up as it may catch on railroad tracks or other things.
After raising landing gear, secure the crank handle safely.
When the full weight of the trailer is resting on tractor: Check for enough clearance between rear of tractor frame and landing gear (when the tractor turns sharply, it must not hit the landing gear). Check that there is enough clearance between the top of the tractor tires and the nose of the trailer.

Step 16: Remove Trailer Wheel Chocks

Remove and store wheel chocks in a safe place.

The following steps will help you to uncouple safely:

Step 1: Position Vehicle

Make sure surface of parking area can support weight of trailer.
Have tractor lined up with the trailer (pulling out at an angle can damage landing gear).

Step 2: Ease Pressure on Locking Jaws

Shut off trailer air supply to lock trailer brakes.
Ease pressure on fifth wheel locking jaws by backing up gently. (This will help you release the fifth wheel locking lever).
Put parking brakes on while tractor is pushing against the kingpin. (This will hold the vehicle with pressure off the locking jaws).

Step 3: Chock Trailer Wheels

Chock the trailer wheels if the trailer doesn’t have spring brakes or if you're not sure. (The air could leak out of the trailer air tank, releasing its emergency brakes. Without chocks, the trailer could move).

Step 4: Lower the Landing Gear

If the trailer is empty, lower the landing gear until it makes firm contact with the ground.
If the trailer is loaded, after the landing gear makes firm contact with the ground, turn crank in low gear a few extra turns. This will lift some weight off the tractor. (Do not lift trailer off the fifth wheel). This will: Make it easier to unlatch fifth wheel. Make it easier to couple next time.

Step 5: Disconnect Air Lines and Electrical Cable

Disconnect air lines from trailer. Connect air line glad hands to dummy couplers at back of cab or couple them together.
Hang electrical cable with plug down to prevent moisture from entering it.
Make sure lines are supported so they won’t be damaged while driving the tractor.

Step 6: Unlock Fifth Wheel

Raise the release handle lock.
Pull the release handle to “open” position.
Keep legs and feet clear of the rear tractor wheels to avoid serious injury in case the vehicle moves.

Step 7: Pull Tractor Partially Clear of Trailer

Pull tractor forward until fifth wheel comes out from under the trailer.
Stop with the tractor frame under the trailer (prevents trailer from falling to ground if landing gear should collapse or sink).

Step 8: Secure Tractor

Apply parking brake.
Place transmission in neutral.

Step 9: Inspect Trailer Supports

Make sure the ground is supporting the trailer.
Make sure the landing gear is not damaged.

Step 10: Pull Tractor Clear of Trailer

Release parking brakes.
Check the area and drive tractor forward until it clears.

Coupling a Pintle Hook

Step 1: Inspect Pintle Hook

Before operating, check for worn, damaged, or missing parts, and make sure mount is secure.
If the pintle hook is not secured to the mounting surface, the pintle hook could separate from the vehicle which, if not avoided, could result in death or serious injury.

Step 2: Unlock Lock Pin and Open Latch

Unlock and remove the tethered lock pin, if applicable.
Lift the lock handle away from the vehicle until the lock clears the lock seat on the hook body.
Open the latch by rotating the latch assembly up toward the vehicle until the latch is in its most upright position, then release the lock handle.

Step 3: Lower Drawbar into Place

Position the drawbar eye over the horn of the pintle hook and lower it into place.

Step 4: Lock Pintle Hook

Push the latch closed. When correctly locked, the lock handle will rotate and move up until it is flush with the top of the latch.
Insert the tethered lock pin through the latch and lock holes, and close the tethered wire lock pin, if applicable.
Failure to correctly lock the latch can result in separation of the trailer and vehicle which, if not avoided, could result in death or serious injury.

Uncoupling a Pintle Hook

Step 1: Park on Level Surface

Park the trailer on a firm level surface and block trailer tires.

Step 2: Disconnect Electrical Connector, Breakaway Brake Switch and Safety Chains

Disconnect electrical connector.
Disconnect breakaway brake switch lanyard.
Disconnect safety chains from tow vehicle.

Step 3: Unlock the Coupler

Unlock the coupler and open it.

Step 4: Check Ground Surface for Correct Support

Before extending jack, make certain the ground surface below the jack pad will support the tongue load.

Step 5: Rotate Jack Handle

Rotate jack handle to extend the jack and transfer the weight of the trailer tongue to the jack.

Step 6: Raise Trailer Coupler

Raise the trailer coupler above the tow vehicle hitch.

Step 7: Drive Forward

Drive tow vehicle forward.

Coupling a Drawbar

Step 1: Remove Safety Lock screw and Rotate Safety Cover Bar

Remove safety lock screw (2), recover and keep the relative self-locking nut (12) aside then also loosen safety lock screw (2a) and turn out the adjustment screw (3) by at least five turns.
Rotate the safety cover bar (4) outwards so that it is completely open.

Step 2: Reverse Truck

Reverse truck very slowly until the ball cup drawbar eye (6) is in position exactly above the drawbar coupling ball (5).

Step 3: Lower the Drawbeam

Lower the drawbeam until the ball cup drawbar eye (6) lies completely covering the drawbar coupling ball (5).

Step 4: Rotate the Safety Cover Bar

Rotate the safety cover bar back inwards (4) and fit in safety lock screw (2) together with its self-locking nut.
Tighten in both the lock screws (2, 2a) together with their relative self-locking nuts (12, 12a) at a 350 to 400 Nm torque wrench setting.

Step 5: Adjust the Adjustment Screw

Adjust the adjustment screw (3) until a 0.3 - 0.5 mm vertical clearance between the guard disk (13) and the ball cup (6) is reached. Lock setting with counter nut (11).
In the event that the safety cover bar (4) will not perfectly lodge into its seating appropriately, travel is strictly forbidden.

Step 6: Protect Coupling Ball and Anchor Edge onto Ball

Protect the part that is still visible of the coupling ball (5) with the rubber dust proof bellows protection cover (7).
Accurately anchor the edge directly onto the ball itself.

Step 7: Lubricate the Drawbar Eye

Lubricate the inside of the drawbar eye ball cup (6) directly through the grease nipple (18).

Uncoupling a Drawbar

Step 1: Turn Trailer Brake On

Make sure that the trailer brake is on.

Step 2: Remove Cover and Loosen Screws

Remove the rubber dust proof bellows protection cover (7).
Loosen the adjustment screw (3) and the counter nut (11).
Loosen safety lock screw (2a) and remove safety lock screw (2) together with its self-locking nut (12).

Step 3: Rotate Safety Cover Bar and Lift Trailer Drawbeam

Rotate the safety cover bar (4) outwards so that it is completely open.
Lift the trailer drawbeam until the drawbar coupling ball (5) is fully visible, then travel forward with the trailer very slowly.
Rotate the safety cover bar inwards (4) until it lodges back in its housing.

Step 4: Lock Safety Screw and Tighten Self-Locking Nut

Fit in safety lock screw (2) and tighten in self-locking nut (12).

Coupling a Gooseneck Hitch

If you are hooking up a Gooseneck or a fifth wheel hitch, the procedure is a little different from a receiver and ball, but it is not more difficult.

Step 1: Open the Latch & Lubricate the Gooseneck Ball

Open the clamp latch on the Gooseneck coupler.
Make sure that the Gooseneck ball is properly lubricated.

Step 2: Position Coupler and Latch the Clamp

Position the trailer's coupler directly over the ball and lower the Gooseneck trailer into position and latch the clamp.

Step 3: Attach Safety Chains

Attach your safety chains. Remember that all trailers are required by law to have safety chains.

Step 4: Connect Trailer Light Wiring

Connect your trailer light wiring to your vehicle's connector.
Check all of your lights, including your brake lights.

Step 5: Lower and Stow the Trailer Jacks

Completely lower and stow the trailer jacks, allowing the weight to settle onto the tow vehicle.

Uncoupling a Gooseneck Hitch

Step 1: Remove Safety Pin and Clip

Simply remove safety pin and clip.

Step 2: Rotate Handle and Raise Trailer off Ball

Rotate handle to this position and raise trailer off ball. Coupler will return to load position automatically.

Step 3: Install Safety Pin and Clip

Install safety pin and clip.

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