Iowa CDL General Knowledge Test flashcards

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

Total stopping distance

The sum of perception distance, reaction distance, and braking distance; perception and reaction together take about one second of travel at any speed.

Four-second following rule

At speeds under 40 mph, stay at least four seconds behind the vehicle ahead; add one second for each additional 10 mph of speed.

Blown front tire

Hold the steering wheel firmly, keep the vehicle straight, and slow gradually before pulling off the road; hard braking can cause loss of control.

Cargo tiedown requirement

Tiedowns must have an aggregate working load limit of at least 50 percent of the cargo weight, or 1,100 lb, whichever is greater for heavy cargo.

Overhang flag requirement

Cargo extending more than 4 feet behind the vehicle needs a red or orange flag at least 12 inches square in daylight and a red light at night.

Cargo recheck interval

Recheck cargo and tiedowns after the first 50 miles of driving, then again after every 150 miles or 3 hours of driving.

Low air pressure warning

The warning buzzer or light must activate before air pressure drops below 60 psi, alerting the driver to a loss of braking pressure.

Spring brake application

Spring brakes apply automatically when air pressure drops to between 20 and 45 psi, stopping the vehicle if pressure is lost.

Air pressure build check

With the engine at fast idle, pressure should build from 85 to 100 psi within 45 seconds; a slower build indicates a compressor or leak problem.

Off-tracking

The rear wheels of a trailer follow a path inside the path of the front wheels, so a combination vehicle turns more sharply than a straight truck.

Tractor protection valve

A valve that closes and keeps air from escaping when the trailer breaks away or the emergency line is disconnected, applying the trailer spring brakes.

Trailer hand valve use

The trolley valve should be used only to test the trailer brakes; it must never be used to park the vehicle or to stop in normal driving.

Tire tread minimums

Steering axle tires need at least 4/32 inch of tread depth; all other tires need at least 2/32 inch, and tires must be free of cuts and bulges.

Pre-trip inspection areas

The inspection covers the engine compartment, the cab and controls, and the exterior walk-around including lights, tires, brakes, and coupling.

Parking brake test

With the engine running and the vehicle stopped, set the parking brake and confirm it holds the vehicle; then release it and check the service brake.

Starting on a hill

Use the parking brake to hold the vehicle while releasing the clutch and accelerating, then release the parking brake once the vehicle begins to move.

Coasting prohibition

Do not coast with the clutch in or the transmission in neutral; you lose engine braking and the ability to accelerate quickly.

Pulling off the road

Signal, check mirrors, slow down, and pull as far off the road as possible; turn on the four-way flashers if the vehicle is a hazard.

Double-clutching

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

Downshifting on a grade

Select a lower gear before starting down a grade and use the engine brake or retarder; do not rely on the service brakes alone.

Missed gear procedure

Do not force the shift; return the transmission to neutral, match engine speed, and try the shift again.

Twelve-second scan

Look at least 12 to 15 seconds ahead of the vehicle, about a quarter mile at highway speed, to spot hazards early.

High beams at night

Use high beams when there is no oncoming traffic; switch to low beams when meeting or following another vehicle to avoid blinding the other driver.

Hazard clues

Brake lights, turn signals, and drivers looking over their shoulders indicate a driver may change lanes or turn; watch for these clues.

Phone use while driving

Texting or using a hand-held phone is prohibited for commercial drivers; if a call is necessary, pull off the road and stop first.

Drowsy driving

Fatigue slows reaction time and judgment much like alcohol; take breaks and do not drive when tired.

Cab distraction control

Before driving, set the GPS, adjust mirrors and seats, and secure loose items so you do not need to reach for them while moving.

Following distance formula

Allow at least one second for each 10 feet of vehicle length at speeds under 40 mph, and add one second for speeds above 40 mph.

Being passed

When another vehicle passes, maintain speed and keep to the right; do not speed up or move into the passing lane.

Merging onto a highway

Use the acceleration lane to match traffic speed and merge smoothly; do not stop at the end of the ramp unless it is necessary.

Skid recovery

Take your foot off the accelerator and steer in the direction you want the vehicle to go; do not brake hard during the skid.

Fog driving

Use low beams and fog lights in fog; high beams reflect off the fog and reduce visibility.

Hazardous materials placards

Placards must be displayed on both sides and both ends of the vehicle for the hazard class being carried, showing the class number and name.

Hazmat shipping paper

The shipping paper must accompany the shipment and include the proper shipping name, hazard class, UN identification number, and total quantity.