Page 66 - Georgia Commercial Drivers Manual 2020
P. 66
7SECTION : DOUBLES AND TRIPLES
Connect Converter Dolly to Front Trailer • Apply converter gear spring brakes or chock »» Locking jaws around the shank, not the
• Back first semitrailer into position in front wheels. head of kingpin.
of dolly tongue. • Release pintle hook on first semi-trailer. »» Release arm properly seated and safety
• Hook dolly to front trailer. • Slowly pull clear of dolly. latch/lock engaged.
• Lock pintle hook.
• Secure converter gear support in raised po- Never unlock the pintle hook with the dolly • Check fifth wheel (upper).
still under the rear trailer. The dolly tow bar may »» Glide plate securely mounted to trailer
sition. fly up, possibly causing injury, and making it frame.
Connect Converter Dolly to Rear Trailer very difficult to re-couple. »» Kingpin not damaged.
• Make sure trailer brakes are locked and/or
7.2.3 – C oupling and Uncoupling • Air and electric lines to trailer.
wheels chocked. Triple Trailers »» Electrical cord firmly plugged in and se-
• Make sure trailer height is correct. (It must cured.
Couple Tractor/First Semitrailer to Second/ »» Air lines properly connected to glad
be slightly lower than the center of the fifth Third Trailers hands, no air leaks, properly secured with
wheel, so trailer is raised slightly when dolly • Couple tractor to first trailer. Use the method enough slack for turns.
is pushed under.) »» All lines free from damage.
• Back converter dolly under rear trailer. already described for coupling tractor-semi-
• Raise landing gear slightly off ground to trailers. • Sliding fifth wheel.
prevent damage if trailer moves. • Move converter dolly into position and cou- »» Slide not damaged or parts missing.
• Test coupling by pulling against pin of the ple first trailer to second trailer using the »» Properly greased.
second semitrailer. method for coupling doubles. Triples rig is »» All locking pins present and locked in
• Make visual check of coupling. (No space now complete. place.
between upper and lower fifth wheel. Lock- Uncouple Triple-trailer Rig »» If air powered, no air leaks.
ing jaws closed on kingpin.) • Uncouple third trailer by pulling the dolly »» Check that fifth wheel is not so far forward
• Connect safety chains, air hoses, and light out, then unhitching the dolly using the that the tractor frame will hit landing gear,
cords. method for uncoupling doubles. or cab will hit the trailer, during turns.
• Close converter dolly air tank petcock and • Uncouple remainder of rig as you would any
shut-off valves at rear of second trailer (ser- double-bottom rig using the method already Landing Gear
vice and emergency shut-offs). described. • Fully raised, no missing parts, not bent or
• Open shut-off valves at rear of first trailer
(and on dolly if so equipped). 7.2.4 – Coupling and Uncoupling otherwise damaged.
• Raise landing gear completely. Other Combinations • Crank handle in place and secured.
• Charge trailer brakes (push “air supply” knob • If power operated, no air or hydraulic leaks.
in), and check for air at rear of second trailer The methods described so far apply to the Double and Triple Trailers
by opening the emergency line shut-off. If air more common tractor-trailer combinations. • Shut-off valves (at rear of trailers, in service
pressure isn’t there, something is wrong and However, there are other ways of coupling
the brakes won’t work. and uncoupling the many types of truck-trailer and emergency lines).
and tractor-trailer combinations that are in use. »» Rear of front trailers: OPEN.
7.2.2 – Uncoupling Twin Trailers There are too many to cover in this manual. »» Rear of last trailer: CLOSED.
Uncouple Rear Trailer You will need to learn the correct way to couple »» Converter dolly air tank drain valve:
• Park rig in a straight line on firm level and uncouple the vehicle(s) you will drive ac-
cording to the manufacturer and/or owner CLOSED.
ground. specifications. • Be sure air lines are supported and glad
• Apply parking brakes so rig won’t move.
• Chock wheels of second trailer if it doesn’t 7.3 – Inspecting Doubles hands are properly connected.
and Triples • If spare tire is carried on converter gear
have spring brakes.
• Lower landing gear of second semitrailer Use the seven-step inspection procedure de- (dolly), make sure it’s secured.
scribed in Section 2 to inspect your combina- • Be sure pintle-eye of dolly is in place in pintle
enough to remove some weight from dolly. tion vehicle. There are more things to inspect
• Close air shut-offs at rear of first semitrailer on a combination vehicle than on a single ve- hook of trailer(s).
hicle. Many of these items are simply more of • Make sure pintle hook is latched.
(and on dolly if so equipped). what you would find on a single vehicle. (For • Safety chains should be secured to trailer(s).
• Disconnect all dolly air and electric lines and example, tires, wheels, lights, reflectors, etc.) • Be sure light cords are firmly in sockets on
However, there are also some new things to
secure them. check. These are discussed below. trailers.
• Release dolly brakes.
• Release converter dolly fifth wheel latch. 7.3.1 – Additional Checks 7.3.2 – Additional Things to Check
• Slowly pull tractor, first semitrailer, and dolly Do these checks in addition to those already During a Walk-around Inspection
forward to pull dolly out from under rear listed in Section 2, Step 5: Do Walk-around In- Do these checks in addition to subsection 5.3,
semitrailer. spection. Inspecting Air Brake Systems.
Uncouple Converter Dolly Coupling System Areas
• Lower dolly landing gear. • Check fifth wheel (lower). 7.4 – D oubles/Triples
• Disconnect safety chains. Air Brake Check
»» Securely mounted to frame.
»» No missing or damaged parts. Check the brakes on a double or triple trailer
»» Enough grease. as you would any combination vehicle. Sub-
»» No visible space between upper and lower section 6.5.2 explains how to check air brakes
on combination vehicles. You must also make
fifth wheel. the following checks on your double or triple
trailers
64 2019-2020 GEORGIA COMMERCIAL DRIVERS MANUAL
