Description: This section explains the coupling devices used to connect the air lines. We'll discuss cleaning the couplers and rubber seals before connecting. Why should you connect the glad hands at a 90 degree angle? What happens if you cross the air lines?
This infographic demonstrates the coupling and uncoupling items that you will need to inspect during the Pre-Trip Inspection portion of your CDL Skills Test.
During your CDL skills test you will be asked to explain to the examiner how you know the items associated with the connection of the truck and trailer are in good safe working condition.
CDL College Inforgraphic Download
Lesson: Coupling and Uncoupling
You'll learn the proper procedures coupling and uncoupling a semi-truck and trailer. We'll cover
the proper inspection procedures that you'll be asked to perform on your CDL Driving Test.
Air/Electric Lines
- Listen for air leaks.
- Check that air hose and electrical lines are not cut, chafed, spliced.
- Make sure air and electrical lines are not
- pinched, or dragging against tractor parts
- Check that electrical plug is firmly locked in place on both tractor and trailer.
- Check that air connectors are sealed on both tractor and trailer.
- Mounting Bolts. Look for loose or missing mounting clamps, bolts, or nuts.
- Locking Jaws. Look into fifth wheel gap and check that jaws are fully closed around the kingpin.
- Fifth Wheel Skid Plate. Check fifth wheel skid plate for proper lubrication and mounted to the platform. Also ensure that all bolts are secure and not missing.
- Platform. Check for cracks or breaks in the platform that supports the fifth wheel skid plate.
- Make sure the release arm is in engaged position and the safety latch is in place.
Kingpin/Apron/Gap
- Check that the kingpin is not bent.
- Make sure the visible part of the apron is not bent,
- cracked, or broken.
- Check that the trailer is laying flat on the fifth wheel
- skid plate (no gap).
Sliding Fifth Wheel Locking Pins
- If equipped, look for loose or missing pins in the slide mechanism of the sliding fifth wheel. If air powered, check for leaks.
- Make sure locking pins are fully engaged.
- Check that the fifth wheel is positioned properly so that the tractor frame will clear the landing gear during tuns.