8Zero Experience Carrier Database 8ABC's Updates Home
Coupling & Uncoupling
It is not hard to do… but… there is no margin for error!
Position tractor directly in front of trailer. Approach with the trailer on your left and begin turning out just as the tractor’s front bumper approaches the corner of the trailer. Use both mirrors to line up with the trailer. Try to get an even amount of trailer to show in each mirror. On a 102 wide trailer, the trailer should stick out just a little bit farther than the tires of the tractor on both sides. Remember the bobtail tractor will back just like a car.
A High Hook occurs when the trailer was too high when a tractor backed underneath it and:
The first photo shows a trailer that is too high. The second photo shows a trailer at perfect height - not too low, not too high. In truth, the first photo probably would not result in a high hook, but it is always better to be safe than to be sorry... And boy would you be sorry if you made a turn and your trailer fell off. The last photo, which is somewhat difficult to see, I admit, is of the alignment of the kingpin in relation to the fifth wheel jaws. (Click any photo to see enlarged) This kingpin is directly lined up. This photo was taken from under the trailer while the trailer was in the position shown in the second photo.
Get out of cab, check Fifth Wheel height and adjust if necessary by
cranking the trailer down with the landing gear. The trailer should be low
enough to allow it to be lifted up slightly as the tractor is backed under
Check side to side alignment of the kingpin to the Fifth Wheel jaws. If
you are more than a couple of inches off, reposition the tractor. You may
need to get underneath the trailer, directly behind the kingpin to see if
alignment is okay.
Back tractor until (slow, easy) Fifth Wheel engages kingpin and locks.
(Roll window down and listen.)
Pull gently forward twice, in first gear, to test connections.
Apply tractor brake. (Pull yellow button out.)
Get out and inspect fifth wheel jaws to ensure that they have locked
around the kingpin. Check that the release arm has gone from the out
(unlocked) position to the locked position.
Attach gladhands (airlines) and electrical cord.
Raise and secure landing gear. Crank arm in: low gear. Crank arm out: high gear. Clockwise: raise trailer. Counterclockwise: lower trailer. (Some trailers will defy these rules so if one way doesn’t work, try the other.)
Apply the brakes. (Pull out red and yellow buttons.)
Lower landing gear. When dropping a loaded trailer, you should crank the
gear down farther than if you were dropping an empty. With an empty, when
the dollies, or landing gear legs, touch the ground, crank another 3-4
turns in low gear. With a loaded trailer, when the dollies touch the
ground, crank another 6-8 turns in low gear.
Disconnect and store air lines and electrical cable.
Pull Fifth Wheel Release Arm. Some Fifth Wheels are easier to release than
others. You can buy a Fifth Wheel puller for approximately $12-$15 at most
truckstops. It is a long metal bar with a hooked end that gives you
leverage to make it easier to pull the Release Arm. They also help to keep
you cleaner. Some drivers use meat hooks as fifth wheel pullers but the
ones sold at truck stops are usually easier to use because they are
Lower the suspension by flipping the dump valve switch. (If equipped)
Pull tractor partially clear of trailer, leaving the back part of Fifth
Wheel under trailer.
Wait a moment to be sure trailer is going to stand. If a trailer has to
fall, it is better for it to do so on the frame of the tractor than on its
Pull tractor completely clear of trailer.
Flip the dump valve switch back over. (If applicable)
In the winter the Fifth Wheel can be rather tricky - it may appear to lock but may not fully do so. Make absolutely sure the jaws have locked by performing a “tug” test and by physically getting underneath the trailer to look at the jaws. Also check that the Release Arm itself goes in upon “hooking” the trailer. A tug test consists of setting the trailer brakes (on), releasing the tractor brakes, putting the transmission in a low gear and pulling forward slightly until you feel resistance. If the jaws are not locked properly, the tractor will pull out from under the trailer.
Treat other motorists as if their car carries your family... Isn't that the way you would want other
2000-2008 © Creative Curriculum FTTI, All Rights Reserved
Contact webmaster concerning reprint requests.