Coupling and Uncoupling Trailers

Coupling and uncoupling tractors and trailers can present serious hazards if precautions are not taken. Failure to follow proper procedures can cause tractor runaway or trailer rollaway situations that result in costly equipment damage or serious, even fatal injuries.


• Trailer brakes not functioning properly

• The ground underfoot is not firm enough to support the trailer

• Trailer wheels are not chocked

• Slippery surfaces while climbing onto the trailer

• Landing gear collapses and the trailer drops to the ground

• Trailer kingpin set too shallow or the tractor frame may be too long

Prior to Coupling

• Ensure parking area is level and firm enough to support trailer and landing gear

• Ensure room is available to maneuver the vehicle safely, and surrounding area is unobstructed

• Make sure enough light is available to perform procedure safely

• Inspect the fifth wheel for damaged or missing parts, and grease the wheel plate as required

• Check to see if the fifth wheel is in the proper position for coupling (ensure the wheel is tilted down toward the trailer, jaws are open, safety unlocking handle is in the automatic lock position and trailer kingpin is not damaged)

• Ensure trailer wheels are chocked or brakes are on, and that cargo is secured

When Coupling Trailers

• Reverse tractor slowly in a straight line until the fifth wheel touches the trailer

• Stop, put the parking brake on. Turn off the engine and remove the keys.

• Raise or lower the trailer until the kingpin and fifth wheel are aligned

• Attach tractor emergency and service air lines to the trailer. Make sure the air lines are safely supported while the tractor is backing under the trailer.

• From the cab, supply air to the trailer brake system. When you are sure the trailer brakes are working, be sure to lock them.

• Back under the trailer using the lowest reverse gear. Stop when the kingpin is locked into the fifth wheel.

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

• Put on the parking brakes, shut off the engine and remove the key. Inspect the coupling. Ensure there is no space between the upper and lower fifth wheel; the fifth wheel jaws are around kingpin; the locking lever is in the “lock” position and that the safety latch is in position over the locking lever

• Plug/connect the electrical line and check electrical and air lines for damage. Be sure lines will not hit any moving parts of the vehicle

• Raise trailer supports (landing gear). Never drive with landing gear only part-way up. After raising the landing gear, support the crank handle

• Remove and store wheel chocks in a safe place

• Complete all necessary visual and functional checks before moving the unit


When uncoupling, follow the coupling procedure in reverse. Trailer coupling and uncoupling is also a common cause of back and shoulder injuries. Drivers need to avoid awkward body positioning when raising/lowering landing gear, operating fifth wheel locking pins, etc. Various manufacturers have also developed tools to assist the driver with stubborn fifth wheel locking pins. For more information on avoiding strains and sprains, go to the Sentry Safety Library at and refer to “Truck Driver MSDs-Strains, Sprains and Musculoskeletal Disorders” (75-260L). For more information on coupling and uncoupling procedures, refer to your equipment manufacturer’s instructions and the Commercial Drivers License (CDL) Manual. The model CDL Manual is produced by the American Association of Motor Vehicle Administrator.

Sentry Insurance is committed to helping you protect your business by providing resources to manage loss-producing situations and prevent accidents. For additional information visit, or call 1-877-832-1835.


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