NV CDL General Knowledge flashcards

36 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, brake lag distance, and braking distance. Only braking distance shrinks when brakes are applied, and it grows with the square of 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, and double the gap in rain, snow, or darkness.

Brake lag

The roughly three-quarter-second delay in an air brake system between pressing the pedal and the brake shoes contacting the drums. It adds stopping distance at every speed.

Hydroplaning speed

Tire contact with wet pavement is lost at roughly 35 mph with partially worn tires. Steering and braking become ineffective until speed drops and the tires regain contact.

Aggregate working load limit

The sum of the working load limits of all tiedowns must be at least half the cargo weight for articles over 1,100 lb, and 1.5 times the weight for lighter articles.

Securement re-check interval

Cargo and tiedowns must be inspected before driving, again within the first 50 miles, and every 150 miles or 3 hours, whichever comes first, during the trip.

Rear overhang flag rule

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.

Front overhang limit

Cargo may not extend more than 3 feet in front of the front bumper at any time, and it must never obscure lights, reflectors, or the license plate.

Governor cut-out pressure

The air compressor stops building pressure near 125 psi and restarts near 100 psi. Normal operating pressure sits between these two points on a healthy system.

Low-air warning threshold

The low-air warning must activate before pressure falls below 60 psi. Spring brakes begin to apply automatically at roughly 45 psi.

Air leak-down test

With the engine off and pressure at governor cut-out, pressure should not drop more than 3 psi in one minute for a single vehicle, or 5 psi for a combination.

Tractor protection valve

A valve that closes the tractor's air supply to the trailer when trailer pressure drops, preventing a total loss of tractor brakes in a combination vehicle.

Slack adjuster free play

On a type 30 brake chamber, the pushrod should move no more than about 1 inch when the brakes are applied. More free play means the brakes are out of adjustment.

Steering wheel free play

With power steering, free play should not exceed about 10 degrees, roughly 2 inches at the rim. More play means the steering needs repair before driving.

Tire tread minimums

Front tires need at least 4/32 inch of tread depth; all other tires need at least 2/32 inch. Cuts, bulges, or exposed cord are out-of-service defects.

Pre-trip inspection steps

The seven steps are vehicle overview, engine compartment, walk-around, brake check, start-engine check, in-cab check, and a final walk-around before driving.

Off-tracking

The rear wheels of a tractor-trailer follow a path inside the front wheels during a turn. The driver must swing wide enough to keep the trailer clear of the curb.

Push-pull steering

A steering technique with both hands on the wheel at roughly 9 and 3 o'clock, where one hand pushes and the other pulls. It keeps control through a turn.

Backing a combination

Back toward the driver's side and use a spotter whenever possible. Get out and check the area if unsure, because the blind spot behind a trailer is large.

Double-clutching

A shifting method for unsynchronized transmissions: clutch in, shift to neutral, clutch out, clutch in, shift to gear, clutch out, matching engine speed each time.

Progressive shifting

Skipping gears as the vehicle accelerates, which saves fuel and reduces wear. It is safe only when the load and grade allow the engine to pull the higher gear.

Coasting prohibition

Do not coast in neutral or with the clutch disengaged. You lose engine braking and the ability to accelerate out of trouble, and it is illegal in many states.

Retarder on slippery roads

A retarder must be switched off on slippery surfaces. Otherwise it can lock the drive wheels and cause a skid, especially on wet or icy pavement.

Twelve-to-fifteen-second scan

Look 12 to 15 seconds ahead of the vehicle. At 55 mph that is roughly a quarter mile, giving time to react to stopped traffic and road debris.

Three hazard classes

Immediate hazards are already in your path, emerging hazards are about to move into it, and atmospheric hazards are weather or visibility conditions such as fog or glare.

Mirror scan interval

Check the mirrors every 5 to 8 seconds. A vehicle that disappears from the mirror may be alongside the trailer in a blind spot, so scan systematically.

Signaling distances

Signal at least 100 feet before a turn in a city and at least 300 feet before a turn on a highway. Some states require more, so signal early.

Headlight dimming distances

Dim high beams within 500 feet of an oncoming vehicle and within 200 feet when following another vehicle. High beams reflect off fog and rain and reduce visibility.

Four-way flashers use

Use them when stopped on the shoulder, when driving slowly in a work zone, and when backing. They warn other drivers of an unusual condition ahead.

Following distance above 40 mph

Add one second to the four-second rule for each 10 mph above 40. At 60 mph that means at least six seconds, and double the gap in rain, snow, or darkness.

Passing return rule

Do not return to the right lane until you can see the passed vehicle's headlights in your mirror. A rig's rear is far behind the cab, so the gap must be large.

Downgrade gear rule

Descend a grade in a gear low enough that the engine brake alone holds your speed, roughly the same gear you would need to climb the grade.

Advisory speed signs

Yellow curve and ramp advisory speeds are set for cars. A loaded rig should go slower than the advisory, not faster, because its rollover risk is higher.

Brake failure response

Downshift, use the engine brake, pump the brakes, and apply the parking brake gradually. Do not lock the wheels, and look for an escape ramp or safe runoff.

Tire blowout response

Hold the wheel firmly, keep the vehicle straight, and slow gradually. Do not brake hard or steer sharply, which can cause a rollover, especially with a high center of gravity.

Warning triangle placement

When stopped on a highway, place triangles about 10 feet, 100 feet, and 200 feet behind the vehicle, and turn on the four-way flashers to warn traffic.