🚛 Stuff Every CDL Driver Should Know: Training Guide

Vehicle classes

Federal rules group commercial vehicles into three classes: A, B and C. Class A covers a combination with a gross combination weight rating of 26,001 pounds or more, and a towed unit over 10,000 pounds. A tractor-trailer is a common example.

Class B covers a single vehicle rated 26,001 pounds or more. If it tows a trailer, that trailer must be rated 10,000 pounds or less. Dump trucks, large box trucks and city buses are typical Class B vehicles.

Class C covers smaller vehicles when they are designed to carry 16 or more people including the driver, or when they haul hazardous materials that require placards. The driver is counted in that 16.

A Class A CDL also lets you drive Class B and C vehicles, if you have any required endorsement. A Class B holder may drive Class C vehicles but not Class A. Endorsements add vehicle types.

Endorsements and restrictions

T is the endorsement for double and triple trailers. You get it by passing a knowledge test only, with no extra road skills test.

N is the tank vehicle endorsement. Liquid sloshing in a partly full tank is called surge, and that is why tankers have their own knowledge test.

X is a combined endorsement meaning tank vehicle and hazardous materials. Fuel tanker drivers usually carry it.

P, the passenger endorsement, requires both a knowledge test and a road skills test. Hazmat and tank endorsements need only a knowledge test, and hazmat also needs a TSA background check with fingerprints.

If you fail the air brake knowledge test, or take your skills test in a truck without air brakes, your CDL gets an L restriction. Air over hydraulic brakes count as air brakes for this rule.

Taking the CDL skills test in an automatic transmission truck gives an E restriction, meaning no manual transmission commercial vehicles. Any transmission that is not a true manual counts as automatic for this rule.

Learner's permit rules

A commercial learner's permit holder must be at least 18 years old. Driving a CMV across state lines generally takes age 21, so many younger drivers stay within their own state. You must already hold a regular driver's license from the same state.

Only P, S and N endorsements are allowed on a CLP, and each requires passing its knowledge test first. H, T and X are not allowed on a permit. A CLP holder with P or S may not carry real passengers. The only people allowed to ride are the supervising CDL holder, test examiners, other trainees, and federal or state auditors and inspectors.

The supervising CDL holder must sit in the front seat next to the driver. On a bus they sit directly behind the driver or in the first row. The supervisor must be allowed to drive that same vehicle on that trip.

After your CLP is first issued, wait at least 14 days before taking the CDL skills test. The CLP is valid at most one year, and it must be a separate document from your regular license.

Training and medical basics

First-time Class A and Class B applicants must complete entry-level driver training with a provider on the federal Training Provider Registry. The same training applies the first time you seek the P, S or H endorsement.

Most drivers need a DOT medical examiner's certificate at least every 24 months. As of June 23, 2025, medical examiners send results electronically to FMCSA, and the state posts the driver as certified.

A driver whose diabetes is treated with insulin may qualify under a special standard, but must be re-examined at least every 12 months. Drivers certified under the vision exception also need a yearly exam.

Alcohol rules

Driving a commercial motor vehicle with a blood alcohol concentration of 0.04 or higher is illegal. A first conviction brings a CDL disqualification of at least one year. Driving a CMV counts as consent to an alcohol test.

Any detected alcohol while on duty, even a level under 0.04, is a federal violation. The driver is placed out of service for 24 hours and must tell the employer within 24 hours.

A CMV driver may not use alcohol, or be under its influence, for 4 hours before going on duty or driving. The truck may not carry alcohol unless it is listed on a shipping manifest or belongs to bus passengers.

If you refuse an alcohol test that the law requires, it is treated like a major offense. A first refusal brings a CDL disqualification of at least one year, whether you were in a CMV or your personal car.

Major and serious offenses

Leaving the scene of an accident and driving at 0.04 or higher are major offenses. A first major offense while driving a placarded hazmat vehicle brings at least 3 years instead of 1.

A second major offense of any mix brings a lifetime disqualification. Some drivers can be reinstated after 10 years if they complete an approved rehabilitation program. Using a CMV in a drug-dealing felony brings life with no reinstatement.

Speeding 15 mph or more over the limit is a serious traffic violation. Reckless driving, erratic lane changes, following too closely, and texting while driving a CMV also count.

Two serious traffic violations in a CMV within 3 years bring at least 60 days disqualification. Three within 3 years bring at least 120 days. Violations in your personal car can count if they cost your regular license.

Railroad crossings and out-of-service orders

A first railroad crossing violation in a CMV brings at least 60 days disqualification. A second within 3 years brings 120 days, and a third within 3 years brings 1 year. Crossing violations stay on a California CDL record for 4 years.

Starting across a railroad crossing without room to clear it is an offense for all drivers. Getting stuck because the trailer hangs up on a raised humped crossing also counts.

Violating an out-of-service order while hauling non-hazardous freight brings at least 180 days for a first offense. A second within 10 years brings at least 2 years. Out-of-service violations stay on a California CDL record for 15 years.

Property-carrying limits

After 10 consecutive hours off duty, a freight driver may drive up to 11 hours total. Those 11 driving hours must fit inside a 14-hour window.

The 14-hour window starts when the driver comes on duty. It keeps running during lunch breaks and other stops. Once 14 consecutive hours pass, no more driving until another 10 hours off. You may still do non-driving work after the window.

Once you have driven 8 hours without at least a 30-minute continuous break, you cannot drive again until you take that break. The break can be off duty, sleeper berth, or on duty but not driving, like fueling. Short-haul drivers with certain exceptions do not need the break.

A driver may not drive after 60 on-duty hours in 7 days, or 70 hours in 8 days if the carrier operates every day. These are rolling totals, not calendar weeks.

A 34-hour restart of at least 34 consecutive hours off duty begins a new 7 or 8 day period. After it, the 60 or 70 hour count starts fresh. Taking the restart is optional, not required.

Passenger rules, weather and fatigue

Passenger-carrying drivers may drive up to 10 hours after 8 consecutive hours off duty. They may not drive after 15 on-duty hours.

In adverse driving conditions, bus and truck drivers may drive up to 2 extra hours to finish the run or reach safety.

Nothing removes driver fatigue except sleep. Coffee and cold air may give a short feeling of alertness, but they cannot replace rest. If you are drowsy, stop and sleep before you drive again.

Inspection steps and brake tests

Step 1 is the vehicle overview: look at general condition, leaks and hazards, and review the last vehicle inspection report. Step 2 is the engine compartment. Doing the steps in the same order every time helps you remember.

To test hydraulic brakes for leaks, pump the brake pedal 3 times, then hold firm pressure for 5 seconds. If the pedal moves down, there may be a leak. Get it fixed before driving.

To test the parking brake, set it, put the vehicle in a low gear, and gently pull forward. If the parking brake does not hold, it is faulty.

Even outside a formal pre-trip, use your senses on the road. When you stop, check tires, wheels, rims, brakes, lights, trailer connections, couplings and cargo securement.

Tires, steering and emergency gear

Front steering tires need at least 4/32 inch of tread in every major groove. Other tires need at least 2/32 inch. No fabric should show through the tread or sidewall. Recapped or regrooved tires are banned on the front wheels of a bus.

Steering wheel free play of more than 10 degrees can make the truck hard to steer. On a 20-inch wheel, that is about 2 inches of movement at the rim.

Emergency equipment includes a fire extinguisher, spare fuses unless the truck has circuit breakers, and warning devices. The warning devices can be 3 red reflective triangles, 6 fuses, or 3 liquid burning flares.

Carry tire chains in winter because snow and ice may make it impossible to drive without them. Carry the right number plus extra cross-links, and make sure they fit your drive tires. Some states require chains when signs are posted.

Reports, hot weather and ABS lamps

At the end of each day's work, prepare a written vehicle inspection report covering brakes, steering, lights, tires and more. If no defect is found, no report is needed. Carriers keep these reports for three months.

Before driving, review the previous driver's inspection report. You sign it only if defects were noted and the carrier certified the repairs were done or not needed.

In very hot weather, inspect tires every 2 hours or 100 miles. Do not let air out of hot tires. If a tire is too hot to touch, stay stopped until it cools.

Vehicles with ABS have yellow malfunction lamps. On trailers the lamp is on the left side, front or rear corner. If the ABS lamp warns of a fault, you still have regular brakes, but get it serviced soon.

Space and stopping

Scan the road 12 to 15 seconds ahead. At highway speeds that is about one quarter of a mile. This gives you time to spot hazards and avoid sudden stops or lane changes.

Check your mirrors regularly, not just before a lane change. Traffic beside and behind you keeps changing. Every truck has blind spots that mirrors cannot show.

Total stopping distance has three parts: perception, reaction and braking. Perception is how far you travel while your brain sees the hazard. Reaction is how far you go before your foot hits the brake. Braking is how far you roll while braking.

Braking distance grows much faster than speed. Doubling speed from 20 to 40 mph makes braking distance four times longer. Tripling speed to 60 mph makes it nine times longer.

Use the one-second-per-10-feet rule for speeds under 40 mph. Above 40 mph, add one second. A 40-foot vehicle at 55 mph needs 5 seconds of following distance.

Weather and light

In snow, ice, fog or smoke, reduce speed enough to stop safely. If conditions get dangerous enough, stop driving until it is safe.

On a wet road, reduce speed by about one third. Wet roads can double stopping distance. On packed snow, reduce speed by half or more.

Dim high beams within 500 feet of an oncoming vehicle, and also when following another vehicle within 500 feet. Low beams let you see about 250 feet, high beams about 350 to 500 feet.

Avoid overdriving your headlights: always be able to stop in the distance you can see. Dirty headlights may give only half the light they should.

Use low beams in fog, even in daytime. Slow down before entering fog, turn on four-way flashers and use fog lights if you have them. If possible, wait out fog at a rest area.

On ice, slow to a crawl and stop as soon as you can safely do so. Shady parts of the road stay icy long after open areas have melted.

Signals, flashers and distractions

Signal early when you plan to turn or change lanes. Keep the signal on through the turn, then cancel it. If it does not cancel by itself, turn it off manually.

Use four-way flashers when parked at the side of the road. This warns other drivers that your truck is not moving, especially at night.

Federal rules ban texting while driving a CMV, even when stopped in traffic or at a red light. Pull off the road and stop first. Contacting police or emergency services is the only exception.

Using a hand-held mobile phone is also banned while driving a CMV. The same emergency exception applies. If you must take a call, pull off the road and stop first.

Physical distractions take your hands or eyes away. Mental distractions take your mind away. Texting does both, so it is the most dangerous kind of distraction.

Hazard moves and emergency actions

When making a quick turn to avoid a hazard, do not apply the brake while turning. Braking while turning can lock wheels and cause a skid. Steer only as much as needed and be ready to countersteer.

If your drive wheels start to spin from too much power, take your foot off the accelerator. On very slippery roads, push in the clutch too. Speed up very gradually when traction is poor.

The space ahead is the most important space around a truck. A smaller vehicle ahead can stop faster than your truck, so leave plenty of room. A hazard is any road condition or road user that could be dangerous, such as curves, potholes, cyclists and pedestrians.

After a turn, if the turn signal does not cancel, turn it off yourself. Leaving it on confuses other drivers.

If the trailer starts to swing out in a jackknife, release the brakes. Locked trailer wheels make the trailer swing. Releasing lets the wheels roll and grip again. Do not use the trailer hand brake to straighten out.

With an engine fire, turn off the engine as soon as you can. Do not open the hood if you can avoid it, because opening feeds the fire. Shoot the extinguisher through the louvers, the radiator or from underneath. Pull off in an open area away from buildings, never into a service station.

Air brake system basics

Air brakes are really three systems in one: the service brake for normal driving, the parking brake, and the emergency brake. The emergency system uses parts of the service and parking brake systems.

The governor controls when the compressor pumps air into the tanks. At cut-out, around 125 psi, it stops the compressor. At cut-in, about 100 psi, the compressor starts pumping again.

A safety relief valve is usually set to open at 150 psi. It protects the first tank the compressor fills from too much pressure. If it releases air, something is wrong and a mechanic should fix it.

Compressed air carries some water and compressor oil. These collect at the bottom of the tanks. Drain the tanks to remove them, because the water can freeze in cold weather and cause brake failure. Manual drain tanks need draining at the end of each day of driving.

An alcohol evaporator adds alcohol to the air to reduce ice in brake valves in cold weather. You still need to drain the tanks daily unless they have automatic drains.

Most heavy trucks use a dual air brake system with two separate air systems, each with its own tanks and lines. One usually works the rear brakes and the other the front brakes.

Warnings and pressure tests

A low air pressure warning must come on before tank pressure drops below 55 psi. On large buses the warning often sounds at 80 to 85 psi.

Tractor spring brakes typically come fully on when pressure drops to the 20 to 45 psi range. Do not wait for that: stop when the low air warning comes on.

If the low air pressure warning comes on while driving, stop and safely park as soon as possible. You can brake under control only while there is enough air in the tanks.

In the applied leakage test, build air to cut-out, shut off the engine, release the parking brake and hold the foot brake for one minute. A single vehicle may lose 3 psi; a combination may lose 4 psi.

With the engine at operating rpm, pressure should build from 85 to 100 psi within 45 seconds. If it builds too slowly, pressure could drop too low while driving.

Parking and emergency braking

On newer trucks, pull the yellow diamond-shaped parking brake knob out to set the spring brakes, and push it in to release them. Use the parking brakes whenever you park.

Never push the brake pedal down when the spring brakes are on. The combined spring and air force can damage the brakes.

Air brakes have a delay called brake lag. It takes half a second or more for air to flow through the lines to the brakes. At 55 mph on dry pavement, brake lag adds about 32 feet.

With ABS, brake the same way you always would. With working ABS on all axles, you may fully apply the brakes in an emergency. ABS may not stop you faster, but it helps steering control.

Stab braking can be used only in vehicles without ABS. Apply the brakes all the way and release when the wheels lock. As soon as the wheels roll again, apply fully again.

Downgrades and brake adjustment

Before starting down a long mountain grade, shift into a lower gear. A lower gear lets the engine help hold back speed. Do not try to downshift after speed has built up.

Brake fade happens when brakes overheat on a long downgrade and stop working well. Brakes out of adjustment stop doing their share first, so the other brakes overheat and fade.

An escape ramp uses a long bed of loose, soft material, sometimes with an uphill grade, to stop runaway vehicles. Learn where the escape ramps are on your route.

On a long downgrade, use the manual's braking method. Brake just hard enough to feel a definite slowdown. Release about 5 mph below your safe speed, then repeat when you are back at the safe speed. Each application should last about 3 seconds.

Do not set the parking brakes when the brakes are very hot, such as after a steep grade. Chock the wheels on a level surface and let the brakes cool first. Also skip the parking brakes when the brakes are wet in freezing weather.

To check a slack adjuster, park on level ground, chock the wheels and release the parking brakes. If the slack adjuster moves more than about an inch where the push rod attaches, it likely needs adjusting. Out-of-adjustment brakes are a common roadside inspection problem.

Cargo securement and weight

Cargo must be firmly immobilized or secured by structures, dunnage, shoring, tiedowns or a combination. It must not leak, spill, blow or fall from the vehicle.

Under federal rules, tiedowns must have total working load limits of at least half the weight of the cargo they secure. Heavier or awkward loads may need more securement.

After starting a trip, inspect cargo securement within the first 50 miles. Then recheck every 3 hours or 150 miles, whichever comes first. Also recheck whenever you change duty status.

Keep the heaviest cargo low and under the lighter cargo. A low center of gravity keeps the vehicle stable. A high center of gravity makes tipping more likely in curves or sudden swerves.

GVWR means gross vehicle weight rating, the maximum loaded weight set by the manufacturer for a single vehicle. Exceeding it is unsafe and illegal. For a tractor and trailers, the matching rating is GCWR, gross combination weight rating.

Liquid tank surge

Baffles are bulkheads with holes that let liquid flow through. They slow forward and backward surge in a liquid tank.

Even with baffles, side-to-side surge can still cause a rollover. Drivers must be especially smooth in curves and turns.

Smooth bore tanks have no baffles. They are often used for food products like milk because baffles are hard to clean. Without baffles, surge can be stronger.

Railroad crossings

When a CDL vehicle must stop at a railroad crossing, stop within 50 feet of the tracks and no closer than 15 feet. The rule covers every bus carrying passengers and many hazmat trucks.

Shift gears before crossing railroad tracks, not while on the tracks. Shifting while crossing can cause the vehicle to stall on the tracks.

A typical tractor-trailer needs at least 14 seconds to clear a single track, and more than 15 seconds for a double track. Never race a train to a crossing because train speed is hard to judge.

After a train passes at a crossing with multiple tracks, check whether a second train is coming before you cross. Look for a sign below the crossbuck that shows the number of tracks.

Hazard classes and placards

Hazardous materials are sorted into nine classes. Class 7 is radioactive material and Class 8 is corrosives. Class 1 is explosives and Class 9 is miscellaneous hazmat.

Class 2 is gases. It has Division 2.1 flammable gases, 2.2 non-flammable gases and 2.3 poisonous or toxic gases.

Table 1 materials, such as Division 1.1 to 1.3 explosives and Division 2.3 poison gas, need placards whenever any amount is hauled.

For Table 2 materials, except bulk packaging, placards are required only when the total amount reaches 1,001 pounds or more. Add the amounts from all shipping papers for Table 2 products on board. Package weight counts.

A placarded vehicle needs at least four identical placards on the front, rear and both sides. Placards are at least 9.84 inches square and set on point like a diamond.

Hazmat ID numbers are four-digit codes used by first responders. The letters UN or NA come before the number. Cargo tanks may show the ID on placards, orange panels or white diamonds.

Shipping papers, ERG and loading

While driving, keep hazmat shipping papers within reach with your seat belt on, or in a pouch on the driver's door. When you leave the truck, place them on the driver's seat or in the door pouch.

Shipping papers must list an emergency response phone number so responders can get expert help. Providing that number is the shipper's job.

The Emergency Response Guidebook, or ERG, is indexed by proper shipping name and ID number. Responders use it to learn how to protect themselves and the public.

The Segregation Table lists hazardous materials that must not be loaded together because they may react. Never load a package labeled POISON in the cab or sleeper, or with food.

Compressed gas cylinders must ride upright on a flat floor when there are no cylinder racks, or be held in boxes that prevent them from turning over. They may lie down only if the relief valve is designed to stay in the vapor space.

Before loading, check that packages are labeled and placards are ready. The shipper labels packages, but the driver still checks the shipment and placards the vehicle when required.

Routing, parking and loading hazards

For certain explosives, Division 1.1, 1.2 or 1.3, parking is banned within 300 feet of a bridge, tunnel, building, crowd or open fire, except for a short stop for needs like fueling. Also keep at least 5 feet from the traveled part of the road.

When your truck is placarded, avoid crowds, tunnels, narrow streets and alleys. Take other routes even if they are less convenient. For certain explosives, the carrier gives a written route plan.

To attend a placarded vehicle, stay awake in it, or be within 100 feet with it in clear view. Know the hazards and be able to move the vehicle. Someone must attend a placarded vehicle parked on a public roadway or shoulder.

Do not smoke or carry a lit cigarette, cigar or pipe within 25 feet of a vehicle with explosives, flammable liquids, flammable solids or oxidizers. Never use flares near Class 3 or Division 2.1 tanks or Division 1.1 to 1.3 explosives; use reflective triangles.

Leaks, fires, training and shipper duties

If you suspect cargo fire, feel the trailer doors before opening them. If they are hot, do not open them; opening feeds the fire. Call for help and keep the shipping papers with you. Do not fight hazmat fires unless you are trained and equipped.

Identify a leaking hazardous material from shipping papers, labels or package location. Never touch a leaking material, and never sniff to find the leak. Toxic gases can hurt you even if they have no smell. Do not keep driving with a leak. Park, secure the area, stay there and call for help.

Hazmat employees must be trained and tested at least once every 3 years, including security risks. Employers keep training records while the employee works with hazmat plus 90 days.

The shipper packages, marks and labels hazmat, prepares shipping papers, gives emergency response information and supplies placards. The driver still checks the shipment and placards the vehicle when loading if required.