Unfortunately, accidents involving trailers separating from tractors on the roadway do happen and often with tragic results. For example, an accident of this type happened in May 2013 when a trailer hauling crushed cars separated from the truck pulling it and hit a minivan heading in the opposite direction. The accident resulted in the deaths of seven people riding in the minivan.
Coupling of trailers is a basic skill required of any professional driver, so this article will review generally accepted proper coupling procedures and raise awareness to the hazards of not coupling correctly.
The following is a list of coupling procedures that are generally accepted and are offered in many state CDL training manuals. As there are differences in equipment, use these as general guidelines only and always learn the details of coupling on the equipment you are using.
- Inspect fifth wheel – Check for damage/missing parts, jaws open, and the fifth wheel greased and in the proper position
- Inspect the area and chock wheels – Make sure the area is clear and the trailer wheels are chocked
- Position tractor – Put tractor directly in front of the trailer and never back under the trailer at an angle
- Back slowly – Back up only until the fifth wheel touches the trailer, do not hit the trailer
- Secure tractor – Put on the parking brake and place transmission in neutral
- Check trailer height – Trailer should be low enough that it’s raised slightly when the tractor is backed under it (if the trailer is too low the tractor may damage it, if the trailer is too high, it may not couple correctly); check that the kingpin and fifth wheel are aligned
- Connect air lines to trailer – Connect emergency and service air lines to trailer and make sure they are safely supported so that they won’t be crushed or caught while the tractor is backing under the trailer
- Supply air to trailer – When you are sure the air pressure is normal, lock the lines
- Back under trailer – Back slowly and avoid hitting the kingpin too hard; stop when the kingpin is locked into the fifth wheel
- Check coupling for security – Raise the trailer landing gear off ground; pull tractor gently forward while the trailer brakes are locked to check that the trailer is locked onto the tractor
- Secure vehicle – Put transmission in neutral and parking brakes on, shut off engine and take keys
- Inspect coupling – Make sure there is no space between the upper and lower fifth wheel, that the fifth wheel jaws are around the kingpin, that the locking lever is in the lock position, and that the safety latch is over the locking lever
- Connect the electrical cord – Plug the electrical cord into the trailer and check air and electrical lines for damage; be sure lines will not hit any moving parts
- Raise the landing gear all the way up – Never drive with the landing gear only part way up; secure the crank handle
- Remove wheel chocks – Remove and store wheel chocks
Please beware of the hazards related to not following proper coupling procedures. Failure to follow proper coupling procedures can lead to trailer rollaway situations that may result in costly equipment damage, injuries or fatalities.