Arkansas CDL General Knowledge Test key terms

A systematic check of a vehicle's critical parts, completed before driving, to confirm they are present, secure, and working. It covers tires, brakes, lights, fluid levels, coupling devices, and cargo securement so defects are found while the vehicle is stopped.

A written record of defects found during a pre-trip or post-trip inspection. The driver prepares it each day, and the motor carrier must review and certify repairs before the vehicle is used again.

A parked test where the driver charges the system, shuts off the engine, and watches the air gauge for pressure loss. Static loss must stay within the limit stated in the CDL manual, and a tractor-trailer combination is tested with the brakes applied as well.

The speed at which the compressor raises tank pressure from about 85 to 100 psi at normal engine speed. A slow rate signals a compressor, governor, or leak problem that must be corrected before the vehicle is driven.

A buzzer and light that activate when system pressure falls below roughly 60 psi. The driver must stop and find the leak, because spring brakes will begin applying and stopping distance grows quickly.

Parking and emergency brakes held engaged by heavy springs and released by air pressure. If air pressure is lost, they apply automatically, which is why the vehicle cannot be moved until pressure is restored.

A test where the driver applies the parking brake, releases the service brake, and gently pulls against it in a low gear to confirm the vehicle holds. It proves the parking brake can stop and hold the loaded vehicle.

The pressure at which the compressor stops pumping, typically around 125 psi. Knowing this value helps a driver confirm the compressor and governor are cycling normally during an inspection.

The lever that links a brake chamber pushrod to the brake shoe. Its travel distance shows how much adjustment remains; too much travel means the brakes are out of adjustment and stopping power is reduced.

The maximum allowable pushrod travel for a brake chamber, measured with the brakes applied and air pressure stable. A reading beyond the limit means the brake must be adjusted before the vehicle is operated on the road.

A controlled braking method for vehicles without antilock brakes: press the brake pedal fully, release when wheels lock, then press again. It is used only on slippery surfaces when the vehicle must be slowed quickly.

Braking as hard as possible without locking the wheels, keeping steering control while producing maximum stopping force. It is the preferred technique on dry pavement for vehicles without antilock brakes.

A condition where a braked wheel stops turning and slides on the road surface. Steering and directional control are lost, and tire flat spots may result, so the driver should ease off and reapply braking.

An electronic system that rapidly releases and reapplies brake pressure to prevent wheel lock-up during hard braking. It helps maintain steering control, but it does not shorten stopping distance on all surfaces.

The grip between tires and the road surface that allows acceleration, steering, and braking. It drops sharply on wet, icy, or loose surfaces, so speed and following distance must be reduced to match conditions.

Loss of tire contact with the road when water builds up under the tread. Steering and braking become ineffective, so the driver should ease off the accelerator and avoid hard braking until grip returns.

The gap between your vehicle and the one ahead, measured in seconds by counting as the rear of the lead vehicle passes a fixed object. One second per ten feet of vehicle length plus one second is the minimum rule.

The safety margin kept around a vehicle on all sides so there is room to stop or steer away from trouble. It is maintained by choosing lanes, adjusting speed, and avoiding travel beside other large vehicles.

Areas around a vehicle that the driver cannot see in the mirrors. Large vehicles have large blind spots to the sides, rear, and directly in front, so mirrors must be checked often and lanes changed cautiously.

Setting the flat and convex mirrors so the driver can see the sides of the vehicle, the rear tires, and the traffic lane alongside. Proper adjustment is checked before each trip and readjusted after coupling or loading.

The hazard created when a large vehicle turns right and the rear wheels track inside the front wheels, threatening a vehicle or cyclist on the right. Drivers should swing wide, go slow, and check mirrors throughout the turn.

The tendency of a trailer's rear wheels to follow a shorter path than the tractor's front wheels in a turn. It is why a driver must allow extra room and watch the trailer in the mirrors during turns.

The outward movement of a vehicle's rear end or trailer when turning, which can strike nearby objects or vehicles. Drivers must check clearance before turning and keep the rear of the vehicle in view.

The horseshoe-shaped coupling plate on a tractor that locks onto the trailer kingpin. The locking jaws must be checked for a firm grip, and the release handle should be secured, before any trailer is moved.

The vertical pin under a trailer that locks into the tractor's fifth wheel. The coupling is complete only when the jaws close around the kingpin and the safety latch is engaged.

A check after coupling where the driver pulls gently forward against the locked trailer brakes to confirm the fifth wheel is secure. Any movement of the trailer relative to the tractor means the coupling failed.

The couplers that join the tractor's air lines to the trailer's air lines. They must be sealed, locked, and free of leaks so the trailer brakes and emergency system work properly.

The use of tiedowns, straps, chains, and blocking to keep a load from shifting, falling, or blowing off. The number and strength of tiedowns depend on the weight and length of the cargo.

The combined strength rating of all tiedowns used to secure a load. It must be at least half the weight of the cargo, and each tiedown must be rated and in good condition.

Placing cargo so weight is spread correctly over the axles and kept low and centered. Poor distribution can overload an axle, lighten the steering axle, or make the vehicle unstable in turns.

A crash in which a vehicle tips onto its side, most often caused by taking a curve too fast, especially with a high center of gravity. Drivers prevent it by slowing before curves and keeping loads low.

The required stop for certain vehicles, including those carrying hazardous materials or passengers, before crossing tracks. The driver stops, listens, looks both ways, and crosses only when the way is clear.

Moving a vehicle in reverse, which is the most dangerous routine maneuver because visibility is limited. Drivers should back only when necessary, use a helper or spotter, and get out to check the path first.

A person positioned outside the vehicle to guide a driver during backing. The driver and spotter agree on hand signals first, and the driver stops immediately if the spotter is no longer visible.

A shifting method for vehicles without synchronized transmissions: clutch in, shift to neutral, clutch out, clutch in again, then shift into the next gear. It matches engine and transmission speed to avoid gear clash.

Shifting without using the clutch by matching engine rpm to road speed. It requires skill and is not recommended for beginners, because a missed match can damage the transmission or cause a loss of control.

A device such as an exhaust or compression brake that slows the vehicle without using the service brakes. It helps control speed on long downgrades but may be prohibited in some areas and can cause skids on slick roads.

A downhill braking technique where the driver applies the brakes firmly to reduce speed, then releases them to let them cool. It prevents brake fade on long grades and is used with a low gear.

The loss of stopping power when brakes overheat from continuous use, such as riding the pedal down a long grade. The cure is to slow down, use a lower gear, and let the brakes cool.