DC CDL General Knowledge flashcards

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

Air brake leak test

With the engine off and full pressure, release the parking brake and hold the service brake; pressure loss must not exceed 3 psi in one minute for a single vehicle or 5 psi per minute for a combination.

Low air pressure warning

A warning device must activate before air pressure drops below 60 psi, and the spring brakes must automatically engage between 20 and 45 psi.

Slack adjuster pushrod stroke

A pushrod stroke of more than about 1 inch on a standard brake chamber indicates the brakes are out of adjustment and the vehicle is out of service.

Steering wheel play limit

Steering wheel free play must not exceed 10 degrees on a power steering system or 10 degrees on a manual system before the vehicle is placed out of service.

Double-clutching procedure

Press the clutch, shift to neutral, release the clutch, press the clutch again, and shift to the next gear; the intermediate release matches engine and transmission speeds.

Backing with a spotter

Before reversing, get out and look, back on the driver's side when possible, and use a spotter who stays visible in the mirror; stop if the spotter disappears from view.

Off-tracking in turns

The rear wheels of a tractor-trailer cut the corner and track inside the front wheels' path; the longer the wheelbase, the greater the off-tracking.

Following distance rule

Allow at least 1 second per 10 feet of vehicle length at speeds under 40 mph, plus 1 extra second; above 40 mph add 1 second per 10 feet of length.

Aim high in steering

Look 12-15 seconds ahead in city traffic and about a quarter mile ahead on the highway to identify hazards early and keep the vehicle centered.

First response to a hazard

When a hazard develops, slow down or stop first; swerving risks rollover and loss of control, so it should be the last resort.

Total stopping distance

Total stopping distance equals perception distance plus reaction distance plus braking distance; at 55 mph the vehicle travels about 60 feet per second.

Braking distance and speed

Braking distance increases with the square of speed, so doubling speed from 30 to 60 mph roughly quadruples the braking distance.

Downhill braking technique

Use a lower gear and engine braking before the descent, and apply the brakes in short, firm applications to avoid overheating and brake fade.

Skid recovery technique

Stop braking, steer in the direction of the skid, and do not accelerate until the vehicle is under control again.

Front-wheel skid response

A front-wheel skid means the vehicle is not responding to steering; release the brake and let the front wheels regain traction before steering.

Tire blowout response

Hold the steering wheel firmly, keep the vehicle straight, and slow gradually without hard braking; then move off the road to a safe spot.

Brake failure response

If the brakes fail, downshift to a lower gear, use the parking brake gradually, and look for an escape ramp or uphill grade.

Passing safely

Pass only when the lane ahead is clear and you can see far enough ahead to complete the pass safely; never pass on a hill or curve with limited sight distance.

School bus red lights

When a school bus displays flashing red lights and an extended stop arm, traffic in both directions must stop, except on divided highways where oncoming traffic may proceed.

Cyclist passing clearance

Cyclists have the same rights as motor vehicles; many states require at least 3 feet of clearance when passing a cyclist.

CDL blood alcohol limit

The legal limit for commercial drivers is a blood alcohol concentration of 0.04 percent, lower than the 0.08 percent limit for non-commercial drivers.

Hours-of-service driving limit

Driving is limited to 11 hours after 10 consecutive hours off duty, and a 30-minute break is required after 8 hours of driving.

Refusing a blood alcohol test

A CDL holder who refuses a blood alcohol test is disqualified for at least one year, and longer if carrying hazardous materials.

Federal weight limits

The limits are 20,000 pounds on a single axle, 34,000 pounds on a tandem axle group, and 80,000 pounds gross vehicle weight on the Interstate System.

Tiedown working load limit

Tiedowns must have a working load limit of at least half the weight of the cargo, and the aggregate WLL must be at least half the cargo weight.

Cargo securement checks

Cargo must be checked within the first 50 miles of driving and every 150 miles or 3 hours thereafter.

Hazmat placard requirement

Placards must be displayed on all four sides of a vehicle carrying hazardous materials in quantities requiring placarding.

Shipping papers location

Shipping papers must be within reach of the driver while seated and must include the proper shipping name, hazard class, UN number, and quantity.

Railroad crossing stop distance

Commercial vehicles must stop 15-50 feet from the nearest rail at railroad crossings unless the crossing is marked as exempt.

Stalled on railroad tracks

If the vehicle stalls on the tracks, get everyone out and move away from the tracks immediately; never stay in the vehicle.

Pre-trip inspection timing

The pre-trip inspection must be completed within the 24 hours before driving, and the driver must sign a report certifying the vehicle is safe.

Accident reporting to carrier

Report the accident to the carrier immediately and file a written report within the time required by the state, often 24-72 hours.