Missouri CDL General Knowledge flashcards

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

Pre-trip inspection areas

Six areas must be checked: engine compartment, cab interior and controls, lights and reflectors, walk-around exterior, coupling devices, and brakes including slack adjusters and air loss.

Static air leak rate

With a fully charged system and engine off, pressure loss must not exceed 3 psi per minute for a single vehicle or 4 psi per minute for a combination vehicle.

Low-air warning threshold

The low-air warning buzzer and light must activate before air pressure drops below 60 psi, alerting the driver before emergency spring brakes apply.

Slack adjuster push rod limit

For a type 30 brake chamber at normal pressure, push rod travel of 1 3/8 inches or more indicates brakes out of adjustment and requires correction.

Progressive shifting

Upshift at lower engine RPM in lower gears and progressively higher RPM in upper gears, staying within the engine's governed range to save fuel and reduce wear.

Double clutching sequence

Press clutch, shift to neutral, release clutch, press clutch again, then shift to the next gear; releasing in neutral lets the input shaft match gear speed.

Off-tracking

Rear wheels of a long vehicle follow a path inside the front wheels' path; longer wheelbases increase off-track, so allow extra room at corners.

Backing a tractor-trailer

Turn the steering wheel opposite the desired trailer direction; the trailer pivots on the drive axles, so small inputs correct large trailer swings.

Four-second following rule

Under 40 mph in ideal conditions, stay at least four seconds behind the vehicle ahead; add one second per 10 feet of vehicle length over 40 feet.

Stopping distance components

Total stopping distance equals perception distance plus reaction distance plus braking distance; at 55 mph a loaded rig needs roughly a football field.

Downgrade gear selection

Choose a gear low enough that engine braking or a retarder holds a steady speed without continuous service brakes, which overheat and fade.

Hydroplaning onset

Hydroplaning can begin at highway speeds with as little as 1/10 inch of water on the road, reducing traction and steering control.

Smith System five keys

Aim high in steering, get the big picture, keep your eyes moving, leave yourself an out, and make sure others see you.

Immediate versus potential hazard

An immediate hazard requires an instant response, such as a car braking suddenly; a potential hazard must be watched until it resolves.

Hazard clue examples

Brake lights ahead, turn signals, drivers looking over their shoulder, children near the road, and unlit vehicles at dusk all signal developing hazards.

Skid recovery steering rule

Steer in the direction you want the front of the vehicle to go, and stop braking or accelerating until the tires regain traction; avoid overcorrecting.

Tire blowout response

Hold the steering wheel firmly, stay off the brakes initially, let the vehicle slow gradually, then pull off the road; sudden braking can cause loss of control.

Brake failure on downgrade

Downshift, pump the pedal, apply the emergency or parking brake gradually, and look for an escape ramp or run-off area to stop safely.

Crash scene procedure

Stop, protect the scene with flashers and triangles, call 911, give first aid if trained, and do not move injured persons unless in immediate danger.

Crossbuck meaning

A crossbuck is a passive railroad crossing warning that means yield to trains; a stop sign at a crossing requires a full stop.

Stalled on railroad tracks

Get everyone out and away immediately, then call 911 and the railroad emergency number posted at the crossing; do not try to restart the vehicle.

Train stopping distance

A freight train traveling 55 mph can take a mile or more to stop, so never try to beat a train at a crossing.

Tiedown aggregate load limit

The combined working load limit of tiedowns must be at least 1.5 times the weight of the cargo, attached to the vehicle's rated anchor points.

Cargo re-inspection intervals

Check the load and tiedowns within the first 50 miles of travel, then every 150 miles or 3 hours, and after any stop or condition change.

Federal axle weight limits

Under the bridge formula, a single axle is typically limited to 20,000 lbs, tandem axles to 34,000 lbs, and gross vehicle weight to 80,000 lbs without permits.

Air tank draining

Drain air tanks daily to remove moisture that can freeze in cold weather and cause brake failure or corrosion inside the system.

Steering free play defect

Steering wheel free play greater than 10 degrees is a defect; excessive play reduces steering control and must be repaired before driving.

CDL alcohol limit

The federal CDL alcohol limit is 0.04% BAC; a driver at or above 0.04 is placed out of service for 24 hours, and refusal to test counts as positive.

Random drug testing

Drivers must submit to random, reasonable-suspicion, post-accident, return-to-duty, and follow-up drug and alcohol testing under FMCSA rules.

Eleven-hour driving limit

A driver may drive a maximum of 11 hours after 10 consecutive hours off duty, and may not drive beyond the 14th hour after coming on duty.

Thirty-minute break rule

A driver must take a 30-minute break after 8 cumulative hours of driving without at least a 30-minute interruption of driving.

Sixty/ seventy-hour limit

A driver may not drive after 60 hours on duty in 7 consecutive days or 70 hours in 8 consecutive days; a 34-hour restart resets the cycle.

Missouri CDL Class A

Class A covers combination vehicles over 26,000 lbs gross with a towed unit over 10,000 lbs, and requires knowledge and skills tests.

Hazardous materials endorsement

The H endorsement is required to drive vehicles carrying hazardous materials; it requires a knowledge test and a security threat assessment.

Out-of-service criteria

Drivers and vehicles placed out of service must remain out of service until the defect is corrected or the driver completes the required rest period.