Kentucky CDL General Knowledge cheat sheet

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

Perception distance is the distance traveled from seeing a hazard until the brain recognizes it; reaction distance adds the time to move the foot to the brake.

Speed limits posted for cars apply to trucks unless a lower truck limit is posted; adjust speed for curves, rain, snow, fog, and heavy traffic.

Following distance rule: at least one second per 10 feet of vehicle length below 40 mph, plus one extra second when over 40 mph (a 60-foot rig at 55 mph needs 7 seconds).

Use the 4-second minimum following distance for speeds under 40 mph and add one second for each 10 mph above 40.

Hydroplaning begins at speeds as low as 30 mph when tires have low tread or the road has standing water; release the accelerator and avoid hard braking.

Skids: steer in the direction you want the front of the vehicle to go; for a rear-wheel skid, turn the wheel toward the skid.

On downgrades, shift to a lower gear before starting down; do not use the brakes continuously or they will fade (overheat).

Cargo must be secured so it cannot shift, leak, or fall; the aggregate working load limit of tiedowns must be at least 1.5 times the cargo weight for cargo over 1,100 lbs.

At least one tiedown for cargo up to 5 feet long and 1,100 lbs; two tiedowns for cargo 5 to 10 feet long or over 1,100 lbs; a fourth tiedown for every additional 10 feet.

Front-end structure and rear-end structure (or header board) must withstand a load of 0.5 g deceleration forward and 0.5 g acceleration rearward.

Tiedowns must be attached to the vehicle frame or to anchor points rated for the load; never attach to side rails or reflectors that are not rated.

Cargo must not extend more than 3 feet beyond the front bumper or more than 4 feet beyond the rear of the vehicle without a red-orange flag or marker.

Overlength rear projections of 4 feet or more require flags or markers during daylight; at night use a red light visible for 500 feet.

Check cargo securement within the first 50 miles and every 150 miles or 3 hours thereafter, and after any emergency stop.

Gross vehicle weight rating (GVWR) and axle weight limits must not be exceeded; steer axle weight affects steering control and braking.

Before loading, check that the bus is free of riders, that emergency exits operate, and that interior lights and stop arm work.

Standees are not allowed above 40 mph or on any bus without standee rails; never allow riders to stand forward of the standee line.

The standee line is a line at least 2 inches wide on the floor, no more than 6 inches behind the driver's seat, marking where passengers may stand.

Carry no more riders than the bus is designed for; count riders during loading and unloading to avoid leaving a passenger behind.

Do not allow riders to carry on hazardous materials, including gasoline, propane, or large amounts of flammable liquid.

At railroad crossings, stop the bus 15 to 50 feet before the nearest rail, open the door, listen, and look both ways before proceeding.

After unloading, walk to the rear of the bus and check for sleeping or left-behind passengers, especially children.

Use the 4-way flashers and stop arm only as required by state law; turn off the flashers before moving again.

Air brake system must have a warning device that activates before pressure drops below 60 psi; a low-air warning buzzer and light are required.

The spring brakes (emergency/parking brakes) apply automatically when air pressure drops to between 20 and 45 psi.

The safety valve releases air at about 150 psi to protect the system from overpressure.

Compressor builds air pressure; the governor cuts the compressor in at about 100 psi and out at about 125 psi on most systems.

To test for air leaks: build pressure to 120 psi, shut off the engine, and watch the gauge; loss should be less than 3 psi per minute for a single vehicle and less than 4 psi per minute for a combination.

To test the low-air warning: reduce pressure by pumping the brake; the warning must come on before 60 psi.

To test spring brakes: release the parking brake when pressure is above 100 psi, then fan the brakes to reduce pressure; spring brakes should apply between 20 and 45 psi.

Fanning the brakes means applying and releasing the brake repeatedly to reduce air pressure; use it only for testing, not for stopping on a downgrade.

Trailer air lines: the emergency (supply) line is typically blue and the service line is red; the tractor's glad hands connect to the trailer's matching lines.

Check that the trailer is locked to the fifth wheel by tugging on the trailer with the tractor after coupling; also check the kingpin is fully seated.

The trailer hand valve (trolley valve) operates only the trailer brakes and is used only for testing; it must not be used for normal stopping.

The tractor protection valve closes and prevents air loss from the tractor if the trailer breaks away or air pressure drops.

Off-tracking: the rear wheels of a combination follow a shorter path than the front wheels; a tractor-trailer can off-track 2 to 3 feet or more in a tight turn.

When backing a tractor-trailer, steer the tractor in the opposite direction of the desired trailer movement; use a helper if possible.

Before driving, check that the trailer landing gear is fully raised and the crank handle is secured.

The trailer's spring brakes apply automatically if the emergency air line is disconnected or air pressure drops.

Doubles and triples require a converter dolly (also called a dolly) between the first and second trailer; the dolly has its own air lines and brakes.

Before coupling a dolly, check that its pintle hook is open, that the dolly is at the correct height, and that the safety chains and air lines are properly connected.

Converter dollies have a pintle hook at the rear and a drawbar at the front; make sure the pintle hook is latched and the safety pin is in place.

The shut-off valves on the dolly must be open to supply air to the trailer brakes, and closed only when the dolly is disconnected.

Doubles and triples require more stopping distance and have more off-tracking than a single trailer; allow extra room in turns and lane changes.

When backing doubles or triples, back only the rear trailer if possible; backing more than one trailer at a time is difficult and usually avoided.

Check that the rear trailer's emergency line is connected to the dolly and that the dolly's brakes work before driving.

Doubles and triples have a higher center of gravity and are more likely to roll over in sharp turns at speed.

Tank vehicles have a high center of gravity and a liquid load that shifts; the shifting load can cause rollover, especially in curves or evasive maneuvers.

Baffles inside the tank reduce the movement of liquid but do not eliminate it; a partially filled tank is more dangerous than a full or empty one.

On a tank with baffles, the load shifts less; on an unbaffled tank, the surge can be strong enough to push the vehicle into a rollover.

When driving a tanker, reduce speed on curves and ramps; make turns smoothly and avoid sudden steering or braking.

Tank vehicles have a lower speed limit on some roads and must obey posted tanker limits; check the vehicle's gross weight and axle limits.

Before loading or unloading, check that the tank valves are closed and that the vehicle is properly grounded to prevent static electricity ignition.

Check the tank for leaks, damaged hoses, and proper venting; never smoke or use open flames near a tank vehicle.

A tank vehicle's braking distance is longer when the load is shifting; increase following distance and brake earlier.

A hazardous materials endorsement (H) is required to drive a vehicle carrying hazardous materials that require placards.

Placards are required for 1,001 pounds or more aggregate gross weight of a hazardous material in one vehicle, and for any amount of certain materials (e.g., poison gas, explosives).

The hazardous materials table (49 CFR 172.101) lists the proper shipping name, hazard class, and placard for each material.

Shipping papers must be within reach of the driver while driving; they must include the proper shipping name, hazard class, UN number, and quantity.

Emergency response information must accompany the shipping papers; the Emergency Response Guidebook (ERG) is a common reference.

Never smoke or use open flames near a vehicle carrying hazardous materials; keep the engine off during loading and unloading unless required.

Park a vehicle carrying hazardous materials away from people, tunnels, and bridges; do not park within 5 feet of the traveled portion of a road.

A vehicle carrying hazardous materials must stop at railroad crossings and may not be left unattended unless the vehicle is secured and the materials are not likely to be disturbed.

A school bus driver must have a school bus (S) endorsement and a passenger (P) endorsement; the CDL must show both.

School buses must stop at all railroad crossings, whether loaded or empty, and open the door to listen before proceeding.

The school bus stop arm and red flashing lights are used when loading or unloading students; drivers must stop for them in both directions unless separated by a median.

Before loading, check that the bus is in park or neutral with the parking brake set, and that the students are accounted for.

Students must cross in front of the bus, never behind it, and the driver must watch them until they are clear of the bus.

The bus must be inspected before each trip, including brakes, lights, stop arm, mirrors, and emergency exits.

Do not allow students to stand or move around while the bus is moving; keep aisles clear.

After unloading, walk to the rear of the bus and check for sleeping or left-behind students.

Pre-trip inspection includes checking the engine compartment, lights, tires, brakes, steering, mirrors, and emergency equipment.

Check tire tread depth: at least 4/32 inch on the front steer tires and 2/32 inch on all other tires.

Check that the brake lights, turn signals, headlights, and clearance lights work; have a helper or use a wall to check them.

Check the engine oil, coolant, and power steering fluid levels; check for leaks under the vehicle.

Check the air brake system for leaks, low-air warning, and spring brake operation as part of the pre-trip inspection.

Check that the fire extinguisher is charged and secured, and that the emergency triangles or reflectors are present.

Check the mirrors and adjust them before driving; make sure the view is clear and the mirrors are not cracked.

During the trip, check cargo securement and the vehicle's condition after the first 50 miles and every 150 miles or 3 hours.

Use the accelerator, steering, and brakes smoothly; avoid sudden movements that can cause skids or rollovers.

When starting from a stop, release the parking brake only after the engine is running and the transmission is in gear.

To stop, press the brake pedal firmly but smoothly; for a vehicle with air brakes, do not pump the brakes.

Use the mirrors to check blind spots before changing lanes; signal and check mirrors and blind spots before moving.

When turning, slow down before the turn and accelerate gently through it; do not brake hard in a turn.

Backing: use a helper and get out to check the area behind the vehicle if possible; back slowly and use mirrors.

On slippery roads, reduce speed and increase following distance; avoid sudden braking and steering.

Use the engine brake or retarder on downgrades to help control speed; do not rely on the service brakes alone.

Shift up or down at the correct speed for the gear; do not lug the engine or over-rev it.

Use the tachometer to know when to shift; shift before the engine reaches the governed speed.

When shifting a manual transmission, use the clutch properly and do not coast in neutral; coasting reduces control.

On a downgrade, shift to a lower gear before starting down to use engine braking and avoid brake fade.

Seeing hazards: scan ahead 12 to 15 seconds, check mirrors regularly, and look for brake lights, road signs, and changing traffic patterns.

Hazardous conditions include curves, intersections, railroad crossings, bridges, and work zones; slow down before reaching them.

Use the 4-second following distance rule and increase it in bad weather or heavy traffic.

When approaching a hazard, decide whether to stop, slow down, or change lanes; communicate your intentions with signals and brake lights.