Figure 7-18.Electrical connector.
. Check the rear of the tractor frame and the
landing gear for enough clearance to make turns.
. Ensure there is enough clearance between the top
of the tractor tires and the nose of the trailer.
Step 14. Remove trailer wheel chocks
o Remove and store wheel chocks in a safe place.
The basic steps for uncoupling a tractor from a
trailer are as follows:
Step 1. Position tractor and trailer
Ensure the parking area surface can support the
weight of the trailer.
Ensure the tractor is lined up with the trailer, if at
all possible, because pulling out at an angle can
bend and damage the landing gear.
Step 2. Ease pressure on locking jaws
Shut off trailer air supply or engage the trailer
hand valve to lock the trailer brakes.
Ease pressure on the locking jaws by backing up
gently. (This procedure helps you release the fifth
wheel locking lever.)
Apply the parking brakes while the tractor is
backing; this holds the tractor in place with the
pressure of the kingpin off the locking jaws.
Step 3. Lower the landing gear
l Chock the trailer wheels.
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 the
crank in low gear a few extra turns; this lifts some
weight off the tractor suspension.
NOTE: Do not lower the landing gear so low that
it lifts the trailer off the fifth wheel because doing this
makes it harder to couple and uncouple.
Step 4. Disconnect electrical cable
Disconnect the electrical cable and hang the
cable with the plug down to prevent moisture
from entering it.
Ensure the electrical cable is supported so it will
not be damaged while driving the tractor.
Step 5. Unlock fifth wheel
Raise the safety catch over the locking pin (if so
Pull the release handle to the open position.
Keep legs and feet clear of the rear
of the tractor wheels to avoid injury
should the tractor move.
Step 6. Pull tractor partially clear of trailer
Pull tractor forward until the fifth wheel comes
out from under the trailer.
Stop with the tractor frame underneath the trailer.
This prevents the trailer from falling to the
ground if the landing gear should collapse or
Step 7. Secure tractor
Apply the parking brake.
Disengage the trailer hand valve to release trailer
Place the manual transmission in neutral; in park,
if an automatic transmission.