Page 56 - 2021-2022 Commercial Drivers Manual

SECTION 6 : COMBINATION VEHICLES

Step 2. Inspect Area and Chock Wheels Step 9. Lock Trailer Brakes • After raising landing gear, secure the crank

handle safely.
• Make sure area around the vehicle is clear. Pull out the “air supply” knob or move the

tractor protection valve control from “normal” • When full weight of trailer is resting on tractor:

• Be sure trailer wheels are chocked or spring to “emergency.” » Check for enough clearance between rear

brakes are on.
of tractor frame and landing gear. (When

• Check that cargo (if any) is secured against Step 10. Back Under Trailer tractor turns sharply, it must not hit land-
movement due to tractor being coupled to ing gear.)

the trailer. • Use lowest reverse gear. » Check that there is enough clearance be-

• Back tractor slowly under trailer to avoid hit- tween the top of the tractor tires and the
Step 3. Position Tractor ting the kingpin too hard. nose of the trailer.
• Put the tractor directly in front of the trailer. • Stop when the kingpin is locked into the fifth Step 16. Remove Trailer Wheel Chocks
(Never back under the trailer at an angle be- wheel.
cause you might push the trailer sideways Remove and store wheel chocks in a safe
and break the landing gear.) Step 11. Check Connection for Security place.

• Check position, using outside mirrors, by • Raise trailer landing gear slightly off ground. 6.4.2 – Uncoupling

looking down both sides of the trailer.

• Pull tractor gently forward while the trailer Tractor-Semitrailers
brakes are still locked to check that the trailer
Step 4. Back Slowly The following steps will help you to uncouple
is locked onto the tractor. safely.
• Back until fifth wheel just touches the trailer.

Step 12. Secure Vehicle

• Don’t hit the trailer. Step 1. Position Rig
• Put transmission in neutral.

Step 5. Secure Tractor • Make sure surface of parking area can sup-

• Put parking brakes on. port weight of trailer.

• Put on the parking brake.
• Shut off engine and take key with you so • Have tractor lined up with the trailer. (Pull-

• Put transmission in neutral. someone else won’t move truck while you ing out at an angle can damage landing gear.)
are under it.
Step 6. Check Trailer Height Step 2. Ease Pressure on Locking Jaws
Step 13. Inspect Coupling

• The trailer should be low enough that it is • Shut off trailer air supply to lock trailer

raised slightly by the tractor when the tractor • Use a flashlight, if necessary. brakes.
is backed under it. Raise or lower the trailer • Make sure there is no space between upper • Ease pressure on fifth wheel locking jaws by

as needed. (If the trailer is too low, the tractor and lower fifth wheel. If there is space, some- backing up gently. (This will help you release
may strike and damage the trailer nose; if the thing is wrong (kingpin may be on top of the the fifth wheel locking lever.)
trailer is too high, it may not couple correctly.)
closed fifth wheel jaws, and trailer would

• Check that the kingpin and fifth wheel are come loose very easily). • Put parking brakes on while tractor is push-
aligned. ing against the kingpin. (This will hold rig
• Go under trailer and look into the back of the with pressure off the locking jaws.)

fifth wheel. Make sure the fifth wheel jaws
Step 7. Connect Air Lines to Trailer
have closed around the shank of the kingpin. Step 3. Chock Trailer Wheels
• Check glad hand seals and connect tractor • Check that the locking lever is in the “lock” Chock the trailer wheels if the trailer doesn’t

emergency air line to trailer emergency glad position. have spring brakes or if you’re not sure. (The air
hand. could leak out of the trailer air tank, releasing its

• Check that the safety latch is in position over

• Check glad hand seals and connect tractor emergency brakes. Without chocks, the trailer
service air line to trailer service glad hand. locking lever. (On some fifth wheels the catch could move.)
must be put in place by hand.)
• Make sure air lines are safely supported • If the coupling isn’t right, don’t drive the Step 4. Lower the Landing Gear

where they won’t be crushed or caught while coupled unit; get it fixed.
tractor is backing under the trailer. • If trailer is empty, lower the landing gear

until it makes firm contact with the ground.

Step 8. Supply Air to Trailer Step 14. Connect the Electrical Cord and
Check Air Lines • If trailer is loaded, after the landing gear
• From cab, push in “air supply” knob or makes firm contact with the ground, turn

move tractor protection valve control from • Plug the electrical cord into the trailer and crank in low gear a few extra turns. This will
the “emergency” to the “normal” position to fasten the safety catch. lift some weight off the tractor. (Do not lift
supply air to the trailer brake system. • Check both air lines and electrical line for trailer off the fifth wheel.) This will:
signs of damage. » Make it easier to unlatch fifth wheel.

• Wait until the air pressure is normal. » Make it easier to couple next time.

• Make sure air and electrical lines will not hit

• Check brake system for crossed air lines.
» Shut engine off so you can hear the brakes. any moving parts of vehicle. Step 5. Disconnect Air Lines and

» Apply and release trailer brakes and listen Step 15. Raise Front Trailer Supports Electrical Cable

for sound of trailer brakes being applied (Landing Gear)

and released. You should hear the brakes • Disconnect air lines from trailer. Connect air
move when applied and air escape when • Use low gear range (if so equipped) to begin line glad hands to dummy couplers at back

the brakes are released. raising the landing gear. Once free of weight, of cab or couple them together.

» Check air brake system pressure gauge for switch to the high gear range. • Hang electrical cable with plug down to pre-

signs of major air loss. vent moisture from entering it.
• Raise the landing gear all the way up. (Never

• When you are sure trailer brakes are work- drive with landing gear only part way up as it • Make sure lines are supported so they won’t

ing, start engine. may catch on railroad tracks or other things.) be damaged while driving the tractor.
• Make sure air pressure is up to normal.

57