Indiana CDL General Knowledge key terms

A systematic check of tires, brakes, lights, fluids, coupling devices, and cargo before driving, required by federal rule, to catch defects that could cause a breakdown or crash.

With the system fully charged and the engine off, the driver watches the gauge to confirm air loss stays within the allowed rate, proving the system holds pressure.

A buzzer and light that must activate before pressure drops below 60 psi, alerting the driver that braking power is fading and a stop is needed.

Brakes held applied by heavy springs and released by air pressure, so they set automatically when air is lost, providing emergency and parking braking.

The lever linking the brake chamber pushrod to the brake shoe; if it moves more than about an inch before the shoe contacts the drum, brakes need adjustment.

The horseshoe-shaped coupling plate on a tractor that locks onto the trailer kingpin; a firm tug test after coupling confirms the jaws are closed.

The vertical pin under a trailer's front that the tractor's fifth wheel jaws grip, transmitting pulling and braking force to the trailer.

The least legal remaining tread on a commercial vehicle: 4/32 inch on front steer tires and 2/32 inch on all other tires, measured in major grooves.

Checking tires for cuts, bulges, exposed cords, and proper inflation, since sidewall damage or underinflation can cause a blowout at highway speed.

The total ground covered from seeing a hazard to a full stop, made up of perception distance, reaction distance, and braking distance, all growing with speed.

The distance traveled while the driver's eyes and brain recognize a hazard before any physical response begins; it lengthens with fatigue or distraction.

The ground covered between recognizing a hazard and the foot reaching the brake pedal; roughly one second of travel at highway speed.

The gap kept behind the vehicle ahead; at speeds under 40 mph allow one second per 10 feet of vehicle length plus one second, and more in poor conditions.

The buffer of empty roadway kept around the vehicle on all sides so there is room to steer or brake if traffic ahead or beside suddenly changes.

Areas beside and behind a large vehicle that mirrors do not show; drivers must check mirrors and turn their heads before changing lanes or backing.

Setting flat and convex mirrors so the driver can see the sides of the vehicle, the rear wheels, and traffic behind, reducing blind spots before every trip.

The hazard created when a large vehicle swings left before turning right; drivers must watch for vehicles slipping into the open space on the right side.

The tendency of the rear wheels of a long vehicle to follow a path inside the front wheels during a turn, so the rear may strike curbs or vehicles.

Moving toward the opposite side of the road before a turn so the rear wheels clear the corner; this must be done without crowding oncoming or adjacent traffic.

Shifting technique for non-synchronized transmissions: clutch in, shift to neutral, clutch out, match engine speed, clutch in, and engage the next gear.

Shifting without using the clutch by matching engine rpm to road speed; it requires skill and can damage a transmission if done incorrectly.

Upshifting at lower rpm as the vehicle gains speed, saving fuel; the driver must still avoid lugging the engine by shifting too early.

Running the engine at too low an rpm under load, which strains components and can stall the vehicle; downshift before the engine begins to labor.

A device such as a Jake brake that slows the vehicle by restricting exhaust flow; it saves service brakes on long downgrades but may be banned locally.

Controlled braking on a long downgrade by applying the brakes firmly to drop speed, then releasing; this lets brakes cool between applications.

Loss of braking power caused by overheated drums and linings, common on long downgrades; the cure is slowing down and using a lower gear.

Restoring control by releasing the brakes to let wheels roll, steering in the direction the vehicle needs to go, and avoiding hard braking until grip returns.

Loss of traction at the drive axles, often from braking or accelerating too hard; the driver should stop braking and steer where the vehicle should travel.

Water building up under the tires so they lose contact with the pavement; it is prevented by slowing down and is cured by letting off the accelerator.

The system of tiedowns, straps, and blocking used to keep freight from shifting or falling; the number and strength of tiedowns must match the load.

The combined strength of all tiedowns holding a load; federal rules require it to be at least half the cargo weight for most loads.

Placing weight so axles are neither overloaded nor unbalanced; the steer axle must keep enough weight for control and the drive axles for traction.

A rule limiting the weight on any group of axles based on the distance between them, so trucks do not overload bridges or pavements.

Federal limits on driving and on-duty time, including a 30-minute break after 8 hours and a 14-hour on-duty window, designed to prevent driver fatigue.

An automatic system that records driving time through the engine, replacing paper logs; drivers must know how to use it and how to handle malfunctions.

Planning rest, food, and breaks so alertness stays high, since fatigue slows perception and reaction and is a leading cause of large-truck crashes.

An intersection with train tracks where drivers must slow, look and listen, avoid stopping on the tracks, and never try to beat an approaching train.

A diamond-shaped sign on a vehicle showing the class of dangerous cargo aboard, letting emergency responders identify risks after a crash or spill.

Actions after a crash: protect the scene, call for help, give first aid within training, and report the incident as required by the carrier and state.

A written record of a crash that drivers complete promptly for the carrier and police, noting time, place, vehicles, injuries, and witnesses.