New Mexico CDL General Knowledge cheat sheet

Total stopping distance = perception distance + reaction distance + brake lag distance + braking distance; at 55 mph a loaded tractor-trailer needs roughly the length of a football field to stop.

Perception distance is the distance traveled from the moment a hazard appears until your brain registers it; at 55 mph that is about 60 feet in the typical one-second perception time.

Reaction distance is the distance traveled between seeing the hazard and pressing the brake; at 55 mph a 3/4-second reaction time equals about 60 feet.

Speed limits for a CMV in New Mexico: 75 mph on rural interstate highways and 65 mph on other rural highways unless posted otherwise; obey posted lower limits.

The posted maximum speed for a CMV on a two-lane, two-way road in New Mexico is 65 mph unless a lower limit is posted.

Follow at least one second per 10 feet of vehicle length at speeds under 40 mph, and add one extra second for speeds above 40 mph; a 60-foot rig at 55 mph needs 7 seconds.

Use the 4-second following rule minimum for any CMV, and increase to 8-10 seconds in rain, snow, ice, fog, or darkness.

Downshift before a downgrade and use the same gear you used to climb it; do not ride the brakes, and brake only hard enough to feel the slowing.

Cargo must be secured so it cannot leak, spill, blow off, fall from, or shift; aggregate working load limit of tiedowns must be at least 50% of the cargo weight.

Cargo needing tiedowns: one tiedown for articles 5 feet or less and 1,100 lb or less; two tiedowns for articles longer than 5 feet but 1,100 lb or less; three tiedowns for articles over 5 feet or over 1,100 lb.

Tiedowns must be attached to the vehicle frame or to anchor points of adequate strength, and must not be attached to the side rails or tarpaulin hooks alone.

Front-end structures must be strong enough to contain cargo; rear structures must withstand a force equal to 50% of the cargo weight.

Cargo must not obscure lights, reflectors, or the license plate, and must not extend more than 3 feet beyond the front bumper or 4 feet beyond the rear.

When cargo extends more than 4 feet beyond the rear, a red flag at least 12 inches square must be displayed in daylight and a red light at night.

Never allow anyone to ride on or in the cargo area; a person may ride in a sleeper berth that is properly secured.

Check cargo and tiedowns within the first 50 miles and again after 150 miles or every 3 hours of driving, whichever comes first.

Air pressure must build from 85 to 100 psi within 45 seconds at fast idle; if it builds slower, the system may have a leak or a faulty compressor.

With the engine off and the brakes released, pressure loss must not exceed 3 psi in one minute for a single vehicle or 4 psi in one minute for a combination.

With the brakes applied fully, leakage must not exceed 4 psi in one minute for a single vehicle or 6 psi in one minute for a combination.

The low-air warning buzzer or light must activate before pressure drops below 60 psi; the spring brakes must fully engage between 20 and 45 psi.

The safety valve must open at 150 psi; if it opens at a lower pressure, the system needs service.

Push the brake pedal when the engine is off to check the emergency spring brakes; the trailer air supply and parking brakes should pop out when pressure falls.

The air compressor is driven by the engine and governed to keep the system between roughly 100 and 125 psi.

Do not drive a vehicle with a known air brake defect; air brakes fail-safe by applying spring brakes, which can lock the wheels if pressure is lost.

Check the fifth wheel, kingpin, and coupling in the walk-around: kingpin fully seated, locking jaws closed, and the release handle secured.

Tug test: after coupling, pull forward with the trailer brakes set and the tractor in a low gear; if the trailer moves, the coupling is not locked.

Check the air lines: the emergency (supply) line is typically blue and the service line is red; the electrical cord is green; ensure no chafing or kinks.

The landing gear must be fully raised, the crank handle secured, and the trailer frame clear of the ground before moving.

The trailer hand valve (trolley valve) should be used only to test the trailer brakes, never to park or hold the vehicle.

When backing a tractor-trailer, steer with the bottom of the steering wheel in the direction you want the trailer to go, and use a helper or GOAL when possible.

The tractor protection valve keeps air in the tractor if the trailer breaks away or a line is cut, allowing a controlled stop.

Off-tracking: the rear wheels of a combination follow a shorter path than the front wheels; swing wide and check mirrors before turning.

Doubles and triples must have a converter dolly; the dolly has a fifth wheel, a pintle hook or drawbar, and its own air and electrical connections.

The rear trailer of a double or triple must have a shut-off valve on its emergency air line at the rear; the front trailer does not.

Each trailer in a double or triple set must have its own service and emergency air lines and its own electrical connection to the unit ahead.

Check the converter dolly: the pintle hook must be closed and locked, the safety chains crossed and attached, and the air lines free of kinks.

Doubles and triples have more off-tracking and sway than a single trailer; increase following distance and reduce speed in crosswinds.

When uncoupling a dolly, chock the wheels, release the spring brakes, disconnect the air lines, and lower the dolly support legs before pulling the tractor away.

The rear of the last trailer must display a red reflective triangle or a red light if it extends beyond the rear of the vehicle.

Use the trailer hand valve only for testing; never use it to hold a parked double or triple.

Tank vehicles have a high center of gravity; the center of gravity rises as the tank is filled, so rollover risk increases with partial loads.

Liquid surge: a partially filled tank has the most dangerous surge; baffles divide the tank to slow the movement of liquid.

Before driving a tanker, check the tank for leaks, the dome cover for a tight seal, and that the vent is open and unobstructed.

Check that the baffles are intact and that the tank's bulkheads are not cracked; baffle failure allows uncontrolled liquid shift.

For a tank with no baffles, the safe fill rule is to keep the load near full or nearly empty; avoid partial loads that allow surge.

Tankers must reduce speed before curves and turns; the posted curve speed is often too fast for a loaded tank.

Flammable liquid tanks must be grounded and bonded during loading and unloading to prevent static ignition.

When unloading, set the parking brakes, chock the wheels, and stay at the controls; never leave a tank unattended during transfer.

A hazardous materials endorsement requires a Transportation Security Administration threat assessment, a written test, and a valid CDL.

Placards are required for 1,001 lb or more of a hazard class in one vehicle, for any amount of a Table 2 material, and for any quantity of a Table 1 material.

The placard must show the hazard class name or number and must be placed on all four sides of the vehicle; the placard for a bulk package goes on all four sides.

The shipping paper must include the proper shipping name, hazard class, identification number, total quantity, and shipper's certification.

Emergency response information must accompany the shipping paper, and the driver must be able to reach it from the driver's seat.

Use the ERG (Emergency Response Guidebook) for initial response; the guide number is found in the yellow-bordered pages by the UN number.

Never smoke within 25 feet of a placarded vehicle, and never park within 5 feet of a roadway or within 300 feet of an open flame or bridge tunnel.

A hazardous materials load must be attended; if unattended, the vehicle must be locked and the engine off, and never left on a public street.

A school bus driver must complete a pre-trip inspection, a written test, and a skills test, and must hold the school bus (S) endorsement on the CDL.

Use the 8-light warning system: amber lights flash at least 100 feet before the stop, and red lights and the stop arm deploy when stopped.

Students must be loaded and unloaded only when the bus is stopped and the red lights are flashing; the driver must account for every student before moving.

The driver must check for students left on the bus at the end of every route and after every trip; walk to the back of the bus.

A school bus may not be refueled with students on board, and no one may smoke on a school bus.

Railroad crossings: stop at least 15 feet but not more than 50 feet from the nearest rail, open the door, and listen before crossing.

Use the bus's mirrors and a crossing gate or arm to keep students from crossing in front of the bus; students must cross at least 10 feet ahead of the bus.

A school bus must stop for a stopped school bus with flashing red lights unless on a divided highway with a physical barrier.

The pre-trip inspection covers three parts: the engine compartment, the walk-around (lights, tires, couplings), and the in-cab (brakes, gauges, steering, seat belt).

Check tire tread depth: at least 4/32 inch on the front steering tires and 2/32 inch on all other tires; check for cuts, bulges, and recaps.

Check the tire pressure with a gauge; underinflation causes heat, blowouts, and poor fuel economy, and can be a cause of out-of-service.

Check the brake system: slack adjusters should not move more than 1 inch by hand at the push rod, and the push rod should not travel more than 2 inches.

Check the lights: headlights, taillights, brake lights, turn signals, clearance lights, and reflectors must all work and be clean.

Check the steering: the steering wheel should not have more than 10 degrees of free play (about 2 inches at the rim) before the wheels move.

Check the coupling: the fifth wheel jaws closed around the kingpin, the release handle secured, and the air lines and electrical cord connected and clear.

The post-trip inspection is required after each trip; report any defect to the carrier and note it on the driver vehicle inspection report.

Start the engine and let the air pressure build to the governed range before moving; check that the parking brake holds and the warning light is off.

Use the accelerator and clutch smoothly; double-clutch to shift if the transmission is not synchronized, and do not coast in neutral.

Steering: hold the wheel with both hands, look 12-15 seconds ahead, and turn the wheel only as much as needed to make the turn.

Backing: use a helper whenever possible; if alone, use GOAL (get out and look) and back slowly with the mirrors.

When turning, swing wide enough to keep the rear wheels from hitting the curb, and check the mirrors before and during the turn.

Stopping: use the brake pedal smoothly, and come to a full stop before shifting into reverse; never shift into reverse while moving forward.

On slippery roads, reduce speed, increase following distance, and avoid sudden braking or steering; use the highest gear that will pull the load.

Parking: set the parking brake, place the transmission in the lowest gear or park, and use wheel chocks on a grade; turn the wheels into the curb when facing downhill.