Page 59 - Georgia Commercial Drivers Manual 2020
P. 59
6SECTION : COMBINATION VEHICLES
Step 2. Inspect Area and Chock Wheels Step 9. Lock Trailer Brakes • After raising landing gear, secure the crank
• Make sure area around the vehicle is clear. Pull out the “air supply” knob or move the handle safely.
• Be sure trailer wheels are chocked or spring
tractor protection valve control from “normal” • When full weight of trailer is resting on tractor:
brakes are on. to “emergency.” »» Check for enough clearance between rear
• Check that cargo (if any) is secured against of tractor frame and landing gear. (When
Step 10. Back Under Trailer tractor turns sharply, it must not hit land-
movement due to tractor being coupled to • Use lowest reverse gear. ing gear.)
the trailer. • Back tractor slowly under trailer to avoid hit- »» Check that there is enough clearance be-
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. Remove and store wheel chocks in a safe
cause you might push the trailer sideways
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.
looking down both sides of the trailer. • Pull tractor gently forward while the trailer 6.4.2 – U ncoupling
Tractor-Semitrailers
Step 4. Back Slowly brakes are still locked to check that the trailer
• Back until fifth wheel just touches the trailer. is locked onto the tractor. The following steps will help you to uncouple
• Don’t hit the trailer. safely.
Step 12. Secure Vehicle
Step 5. Secure Tractor • Put transmission in neutral. Step 1. Position Rig
• Put on the parking brake. • Put parking brakes on. • Make sure surface of parking area can sup-
• Put transmission in neutral. • Shut off engine and take key with you so
port weight of trailer.
Step 6. Check Trailer Height someone else won’t move truck while you • Have tractor lined up with the trailer. (Pull-
• The trailer should be low enough that it is are under it.
ing out at an angle can damage landing gear.)
raised slightly by the tractor when the tractor Step 13. Inspect Coupling
is backed under it. Raise or lower the trailer • Use a flashlight, if necessary. Step 2. Ease Pressure on Locking Jaws
as needed. (If the trailer is too low, the tractor • Make sure there is no space between upper • Shut off trailer air supply to lock trailer
may strike and damage the trailer nose; if the
trailer is too high, it may not couple correctly.) and lower fifth wheel. If there is space, some- brakes.
• Check that the kingpin and fifth wheel are thing is wrong (kingpin may be on top of the • Ease pressure on fifth wheel locking jaws by
aligned. closed fifth wheel jaws, and trailer would
come loose very easily). backing up gently. (This will help you release
Step 7. Connect Air Lines to Trailer • Go under trailer and look into the back of the the fifth wheel locking lever.)
• Check glad hand seals and connect tractor fifth wheel. Make sure the fifth wheel jaws • Put parking brakes on while tractor is push-
have closed around the shank of the kingpin. ing against the kingpin. (This will hold rig
emergency air line to trailer emergency glad • Check that the locking lever is in the “lock” with pressure off the locking jaws.)
hand. position.
• Check glad hand seals and connect tractor • Check that the safety latch is in position over Step 3. Chock Trailer Wheels
service air line to trailer service glad hand. locking lever. (On some fifth wheels the catch Chock the trailer wheels if the trailer doesn’t
• Make sure air lines are safely supported must be put in place by hand.)
where they won’t be crushed or caught while • If the coupling isn’t right, don’t drive the have spring brakes or if you’re not sure. (The air
tractor is backing under the trailer. coupled unit; get it fixed. could leak out of the trailer air tank, releasing its
emergency brakes. Without chocks, the trailer
Step 8. Supply Air to Trailer Step 14. C onnect the Electrical Cord and could move.)
• From cab, push in “air supply” knob or Check Air Lines
Step 4. Lower the Landing Gear
move tractor protection valve control from • Plug the electrical cord into the trailer and • If trailer is empty, lower the landing gear
the “emergency” to the “normal” position to fasten the safety catch.
supply air to the trailer brake system. until it makes firm contact with the ground.
• Wait until the air pressure is normal. • Check both air lines and electrical line for • If trailer is loaded, after the landing gear
• Check brake system for crossed air lines. signs of damage.
»» Shut engine off so you can hear the brakes. makes firm contact with the ground, turn
»» Apply and release trailer brakes and listen • Make sure air and electrical lines will not hit crank in low gear a few extra turns. This will
any moving parts of vehicle. lift some weight off the tractor. (Do not lift
for sound of trailer brakes being applied trailer off the fifth wheel.) This will:
and released. You should hear the brakes Step 15. Raise Front Trailer Supports »» Make it easier to unlatch fifth wheel.
move when applied and air escape when (Landing Gear) »» Make it easier to couple next time.
the brakes are released.
»» Check air brake system pressure gauge for • Use low gear range (if so equipped) to begin Step 5. Disconnect Air Lines and
signs of major air loss. raising the landing gear. Once free of weight, Electrical Cable
• When you are sure trailer brakes are work- switch to the high gear range.
ing, start engine. • Disconnect air lines from trailer. Connect air
• Make sure air pressure is up to normal. • Raise the landing gear all the way up. (Never line glad hands to dummy couplers at back
drive with landing gear only part way up as it of cab or couple them together.
may catch on railroad tracks or other things.)
• Hang electrical cable with plug down to pre-
vent moisture from entering it.
• Make sure lines are supported so they won’t
be damaged while driving the tractor.
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