Illinois CDL Doubles and Triples flashcards

32 cards. Read the term and the definition here. The deck at the top of this page is optional.

Converter dolly inspection points

Check the dolly frame, drawbar eye, pintle hook latch, safety chains, fifth wheel jaws and grease, axle and springs, brake chamber and slack adjuster, shut-off valves, tires and mud flaps before every trip.

Pintle hook latch check

The latch must close fully over the drawbar eye, the safety pin must be in place, and the hook throat must show no cracks, deep grooves or elongation from wear.

Fifth wheel gap check

After coupling, no daylight should show between the fifth wheel plate and the trailer apron, the jaws must be closed around the kingpin, and the release handle must be latched.

Dolly air line routing

Lines from the lead trailer to the dolly and from the dolly to the rear trailer must sit in the dummy couplers, be free of kinks, and clear of the frame, tires and exhaust.

Converter dolly definition

A towed unit with a frame, one or two axles, a drawbar eye and a fifth wheel that supports the kingpin of a second trailer, turning a single trailer into a double.

Gladhand color code

Red is the emergency or supply line that charges trailer tanks and releases spring brakes; blue is the service line that carries the brake application signal from the treadle valve.

Dead-end shut-off valves

Hand valves at the rear of each trailer and on the dolly that seal unused gladhands. Left open, they bleed supply air away and the trailer spring brakes apply.

Dolly safety chains

Secondary attachments between the dolly and the lead trailer that catch the drawbar if the pintle hook fails; route them so they neither drag on the road nor limit full turns.

Dolly fifth wheel load

The dolly fifth wheel carries the vertical kingpin load of the rear trailer and transmits it through the dolly frame and drawbar to the lead trailer; the dolly carries no cargo.

Emergency line loss result

If the emergency red line loses pressure or separates, trailer supply air escapes, the tractor protection valve closes, and the trailer spring brakes apply automatically.

Combination static leak test

With the system fully charged and the engine off, released brakes may lose no more than 4 psi in one minute; with the pedal fully applied and held, no more than 6 psi.

Low air pressure warning

The warning buzzer and light must activate before system pressure falls below 60 psi; the trailer spring brakes normally pop out between 20 and 45 psi.

Tractor protection valve

A valve controlled by the red trailer air supply knob that seals the tractor's air system and applies the trailer spring brakes during a breakaway or major leak.

Trailer spring brake test

With the system charged, pulling out the red knob should set the trailer brakes with an audible exhaust; pushing it in should release them once supply pressure rebuilds.

Seven-way pin colors

White is ground, brown is tail and marker, yellow is left turn, green is right turn, red is stop, blue is auxiliary, and black is ABS power.

Trailer ABS lamp

The trailer ABS lamp should light at key-on and go out once the vehicle exceeds about 5 mph; a lamp that stays on signals a fault on that unit.

Light check on each unit

With doubles or triples, check clearance, tail, turn, stop and four-way flashers on the tractor, the lead trailer and the last trailer separately before moving.

Dragging electrical cord

A seven-way cord that drags or rubs the frame or dolly wears through insulation, causing short circuits, blown fuses and loss of trailer lighting.

Fifty percent WLL rule

The total working load limit of all tiedowns used on an article must be at least half the weight of that article, and every component must be marked.

One or two tiedown rule

Articles up to 5 feet long and 1,100 pounds need one tiedown; two are required when the article is up to 5 feet and 2,200 pounds, or over 5 feet up to 1,100 pounds.

Ten-foot tiedown formula

For articles longer than 10 feet or heavier than 2,200 pounds, use at least one tiedown per 10 feet of length rounded up, with aggregate working load limit of 50 percent of the weight.

Tiedown recheck intervals

Cargo securement must be rechecked within the first 50 miles of travel and again every 3 hours or 150 miles, whichever comes first.

Cargo forward movement

Cargo must be blocked, braced or tied so it cannot shift forward against the cab or headboard, or rearward and sideways, during braking and turns.

Tug test after coupling

With the trailer brakes set, pull forward gently in the lowest gear; the combination should hold firm. A clunk or movement means the jaws are not locked.

Trailer too high hazard

If the trailer apron sits above the fifth wheel plate, the kingpin can ride over the plate and the trailer drops when pulled; check the gap before backing under.

Doubles coupling order

Latch the dolly to the lead trailer's pintle hook, attach the chains and air lines, charge the system, then back the dolly's fifth wheel under the rear trailer's kingpin.

Doubles uncoupling order

Set the brakes, disconnect the rear trailer's lines and cord, release its fifth wheel, pull clear, then unhook the dolly's lines, chains and pintle hook.

Fifth wheel release handle

After coupling, the release handle must be pushed fully in with its safety latch engaged; a partly open handle lets the jaws open while the vehicle is on the road.

Off-tracking definition

The tendency of the rear wheels of the last trailer to follow a path inside the front wheels during a turn, increasing with more trailers and sharper turns.

Rearward amplification

The last trailer in a set swings farther sideways than the tractor during sudden steering; it is greatest with triples and smallest with a single trailer.

Right turn with doubles

Swing wide enough for the last trailer's tires to clear the curb without crossing into another lane, and check the right mirror for the rear trailer and pedestrians.

Downgrade snub braking

Choose a gear that holds a safe speed at the top of the grade and brake in short, firm applications; continuous light braking overheats drums and causes fade.