Ohio CDL Doubles and Triples Endorsement Test flashcards

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

Coupling order for doubles

Connect tractor to lead trailer, then converter dolly to lead trailer, then rear trailer to the dolly. Check each coupling before moving to the next.

Pull test after coupling

Set the trailer brakes, release the tractor parking brake, and pull gently forward. If the tractor moves, the kingpin is not locked.

Uncoupling order for doubles

Drop the rear trailer first, then the converter dolly, then the lead trailer. Chock wheels and lower landing gear before releasing the fifth wheel.

Gladhand color coding

Emergency (supply) gladhands are usually on the driver's side and service gladhands on the passenger's side. Matching colors helps prevent cross-connection.

Converter dolly brakes

The dolly has its own spring brakes that set when air pressure drops. Chock or set them before detaching the dolly.

Inspect every coupling point

On doubles and triples, check the tractor fifth wheel, dolly fifth wheel, and each trailer kingpin. A single missed lock can drop a trailer.

Test each trailer's brakes

Apply the trailer brakes separately and confirm each trailer holds. One dead trailer brake circuit lengthens stopping distance and can cause a jackknife.

Air leak check

Charge the system and listen at every gladhand and dolly connection. Watch the gauge for pressure drop that indicates a leak.

Light and cord inspection

Confirm stop, turn, and clearance lights work on every trailer. Check that the electrical cord is not dragging, chafed, or disconnected.

Offtracking with doubles

The rear trailer cuts a tighter path than the tractor. Swing wide on turns and watch the rear trailer in the mirrors through the whole turn.

Right turn with doubles

The rear trailer may track inside the curb line. Pull forward until the tractor clears the corner before turning to avoid dragging the trailer over the curb.

Backing doubles

Only the rear trailer responds directly to steering, and the dolly can jackknife quickly. Avoid backing; if unavoidable, back slowly with a spotter.

Following distance

Increase following distance with multiple trailers. A common rule is one second per 10 feet of combination length plus two seconds.

Crossing tracks or bridges

Keep the combination straight when crossing railroad tracks or narrow bridges so no trailer cheats off-line and strikes the structure.

Stopping distance with doubles

Stopping distance grows with each added trailer because total weight rises while tractor braking effort stays the same. Brake earlier and allow more room.

Smooth brake application

Apply brakes progressively, not with a hard stab. A sudden hard brake can swing the rear trailer or jackknife the combination.

Engine braking on downgrades

Downshift and use engine braking to control speed. Continuous service brake use overheats tractor brakes and reduces stopping ability.

Trailer hand valve use

The trolley valve is for testing trailer brakes only. Do not use it for parking or for normal stopping.

Dolly air connections

The dolly's air lines connect to the lead trailer's rear gladhands, and the rear trailer's lines connect to the dolly's gladhands.

Cross-connected air lines

Cross-connected lines can release trailer brakes when they should apply, or keep them applied and dragging. Match color-coded lines carefully.

Dolly safety chains

Check the dolly's safety chains and locking pins. A dolly that separates from the lead trailer can cause a serious crash.

Dolly brake test

After connecting all air lines, charge the system and confirm the dolly's brakes apply and release with the tractor's brake pedal before moving.

Trailer sway correction

Release the accelerator and steer straight ahead. Do not steer into the sway or brake hard, which can worsen the swing.

Drive-wheel skid recovery

Release the brakes and steer in the direction you want the front of the tractor to go. Keep steering smooth until traction returns.

Steer-wheel skid recovery

Release the brakes and steer in the direction the rear of the tractor is sliding. Avoid overcorrecting once the tires regain grip.

Jackknife response

Release the brakes and steer to straighten the combination. Do not accelerate out of a jackknife; that worsens the angle.

Trailer tire blowout

Hold the steering wheel firmly, ease off the accelerator, and avoid hard braking until the combination slows. Then move to a safe location.

Gross combination weight

GCW is the total weight of tractor, all trailers, cargo, fuel, and driver. It must not exceed the tractor's rated GCW.

Axle weight ratings

Each axle has a maximum weight rating, and each trailer has a GVWR. No axle or trailer may exceed its rating.

Load the lead trailer heavier

When possible, put more weight on the lead trailer than the rear trailer. A light lead trailer with a heavy rear trailer increases sway.

Bridge formula

The bridge formula limits the weight carried on a group of axles based on the distance between them. Check it before loading.

Secure cargo per trailer

Secure cargo on each trailer independently. A shifting load on one trailer changes weight distribution and can affect the whole combination.