Louisiana CDL General Knowledge key terms

A systematic check of a commercial vehicle's critical parts, including brakes, tires, lights, coupling devices, and fluid levels, performed before driving to confirm the vehicle is safe and legally roadworthy.

The formal walk-around and in-cab examination required to obtain and keep a commercial driver's license, covering engine compartment, exterior components, and brake system checks in a fixed sequence.

A sequence of checks confirming air pressure builds, holds, and releases properly, including static leak tests, warning buzzer activation, and the emergency spring brake application at low pressure.

Parking and emergency brakes held engaged by heavy springs and released by air pressure; they apply automatically when system pressure drops too low, stopping the vehicle if air is lost.

A temporary loss of stopping power caused by overheated brake drums or linings, common on long downgrades, corrected by slowing down and using a lower gear rather than riding the brakes.

A device such as an exhaust brake or Jacobs brake that slows the vehicle using engine compression, reducing reliance on wheel brakes during long descents and helping prevent overheating.

Changing to a lower gear so the engine helps control speed, especially on downgrades or before entering curves, done at the proper speed to avoid over-revving or damaging the transmission.

A shifting technique for non-synchronized manual transmissions: press the clutch, shift to neutral, release the clutch, match engine speed, press the clutch again, and engage the next gear.

Shifting a non-synchronized transmission without using the clutch by matching engine and road speed; it requires skill, and many employers and licensing tests expect proper clutch use instead.

The total distance traveled from the moment a hazard is noticed until the vehicle stops, equal to perception distance plus reaction distance plus braking distance, all increasing with speed.

The distance a vehicle travels while the driver recognizes a hazard and decides to act; it grows with speed and with fatigue, distraction, or poor visibility.

The gap kept behind the vehicle ahead, commonly at least one second per ten feet of vehicle length at speeds under 40 mph and one second per ten feet plus one second above that.

The safety margin kept around the vehicle on all sides, including front, rear, and lateral gaps, giving room to steer or stop if traffic, debris, or another driver creates a sudden hazard.

The large blind spots around a commercial vehicle, at the sides, directly behind, and in front, where smaller vehicles can disappear from the driver's view and should not linger.

Setting flat and convex mirrors so the driver can see the sides, rear, and trailer wheels of the vehicle, checked before every trip and used frequently while driving and turning.

The hazard created when a large vehicle swings left before a right turn and a smaller vehicle moves into the open space on the right; drivers should check mirrors and turn slowly and wide.

The tendency of the rear wheels of a long vehicle or trailer to follow a tighter path than the front wheels, so turns must be made wide enough to keep the rear from hitting curbs or vehicles.

Loss of tire contact with the road when water builds up under the tires; prevention includes slowing down, keeping tires properly inflated, and avoiding standing water.

Regaining control after tires lose traction: stop braking, steer in the direction the rear is sliding, and avoid sudden acceleration until the vehicle straightens out.

A dangerous condition where a tractor and trailer fold at the coupling, often after hard braking or skidding on slippery roads, which can be prevented by smooth braking and steering.

Side-to-side movement of a trailer, often caused by improper cargo weight distribution, high speed, or wind; the driver should ease off the accelerator and avoid hard braking.

Using tiedowns, straps, chains, and blocking to keep cargo from shifting or falling; loads must be balanced, within weight limits, and secured to meet federal and state requirements.

Placing cargo so weight is balanced across axles and kept low, avoiding an overloaded rear or a light steer axle that reduces steering control and braking effectiveness.

A place where a road meets train tracks; commercial drivers must slow down, look and listen, and stop when required, never blocking the tracks or stopping on them.

The practice of scanning far ahead and to the sides for changing conditions such as work zones, weather, pedestrians, and stopped traffic, so the driver can act before a hazard becomes an emergency.

An evasive action such as a controlled stop or steering around an obstacle, performed without hard braking that could cause a skid or jackknife when traction is limited.

Physical and mental tiredness that slows reaction time and judgment; drivers should get enough rest, take breaks, and stop driving when drowsy rather than relying on caffeine or open windows.

Federal rules limiting driving and on-duty time and requiring rest periods, designed to reduce fatigue-related crashes; drivers must log their time accurately.

The percentage of alcohol in the blood, used to define legal impairment; commercial drivers are held to a stricter limit than other drivers and face serious penalties for exceeding it.

The legal principle that by driving on public roads a person agrees to submit to alcohol or drug testing when lawfully requested, with refusal carrying license penalties.

A directive that a driver or vehicle may not operate because of a serious safety violation, such as excessive hours or defective brakes, until the problem is corrected.

Signaling intentions to other road users through turn signals, brake lights, four-way flashers, horn, and lane position, giving others time to react to the vehicle's movements.

Fundamental driving skills including smooth acceleration, steering, braking, and backing, performed so the vehicle stays stable and predictable in traffic and tight spaces.

Choosing a safe speed for conditions and maintaining room around the vehicle, adjusting for weather, traffic, road grade, and load so there is time to react.