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In addition to being a legal necessity, thorough vehicle inspections may significantly increase the safety and effectiveness of your car.


1. A dangerous situation may be found before it results in an accident.


2. Mechanical issues may be identified before they result in roadside breakdowns.


3. Inexpensive on-the-road repair services may be avoided by preventing

breakdowns avoided.


4. Your business will have fewer delivery delays as a result of preventing failures, which will improve customer service.service.


5. Enforcement officers won't disable the car, which would cause delays.


6. Your company's maintenance staff will be able to keep expenditures under control if mechanical issues are identified early.


Types of Inspections


Three types of inspections are mandated by the Federal Motor Carrier Safety Regulations (FMCSRs).


1. Pretrip inspection (Sec. 396.13). This inspection is performed before taking your vehicle on the road. Doing a pre-trip inspection allows you to identify problems that could cause a breakdown or accident.


2. On-the-road (en-route) inspection (Sec. 392.9). Look for any warning indicators on your vehicle's instruments. Every time you stop, check all important components, including the trailer's electrical and air connections, tires, wheels and rims, brakes, lights, trailer coupling systems, and cargo securement mechanisms.


3. Post-trip inspection (Sec. 396.11). A post-trip inspection is conducted at the end of your day’s work on the vehicle you are operating. This inspection includes filling out a driver vehicle inspection report (DVIR), listing any problems you may have discovered. This report helps a motor carrier make necessary repairs before the vehicle returns to the road.road.


What to Look at When Conducting an Inspection


Regular car inspections are not only required by law, but they may also avoid expensive and time-consuming breakdowns and potential accidents caused by faulty vehicles. The following are important topics and matters that need to be routinely addressed.


Fluid leaks – Any fluid leakage—oil, gasoline, coolant, etc.—can badly damage an engine. It's a good idea to routinely check the fluid levels (pre-trip, post-trip, while driving, and sometimes even while you're driving) if your car's gauges display unusual readings. Additionally, keep an eye out for fluid leaks (drips, puddles, etc.) below the car.



Bad tires – A blowout from a tire issue may lead to handling issues, a loss of control, or even an accident. Additionally, a flat tire may cause downtime, which is expensive for both you and your business. Defects in the wheel and rim might result in a tire losing air pressure or coming off, which would slow down traffic and perhaps result in an accident. Beware of:

  1. Rust around lug nuts;
  2. Tightness of lug nuts;
  3. Mismatched, bent, or cracked lock rings;
  4. Unsafe or illegal welding repairs;
  5. Absence of clamps, spacers, or lugs
  6. Dented rims;
  7. Loose rims.


Braking system defects — Brake system air pressure checks are critical. You should not be able to hear any air leaks or observe a loss of air pressure on the air pressure gauge.


When the engine is off and the brakes are released, the air pressure shouldn't leak more than 3 pounds per minute, and it shouldn't leak more than 4 pounds per minute when the engine is off and the brakes are completely engaged (after the initial application).


Check for broken gauges and low-air alert systems. Following Section 393.51 of the FMCSRs, all trucks and truck tractors must be fitted with functional warning devices.


Cracks in the brake drums should be inspected. It is necessary to check shoes or pads for wear, adequate thickness, and evidence of oil or grease. Chambers for the brakes should be placed firmly. Slack adjusters need to be checked for any loose or missing pieces and adjusted properly.


Brake lines (hoses) must be properly secured. They shouldn’t show signs of hardening, swelling, or excessive wear or damage. They shouldn’t be bent or folded over, causing possible air flow restriction. The air reservoir should be properly attached to the vehicle and shouldn’t contain excessive water. It should be bled daily to check for moisture.


There shouldn't be any twisted, congested, or broken air lines leading to the trailer. They need to be properly supported and fastened. They shouldn't scuff up the catwalk or framing.

Suspension system defects — The suspension system stabilizes the axles and supports the vehicle and its load. Among other things, a damaged or malfunctioning suspension might enable unexpected changes in the load or the steering, which can result in an accident.

Inspect for:


• loose Spring hangers, cracked, or damaged;


• Torque rods that are broken, loose, or cracked;


• U-bolts that are damaged, loose, or cracked;


• Leaf springs with missing, crooked, or damaged leaves;


• Airbags with damage;


• Defective or lose airbag mounts;


• Leaking shock absorbers; and


• Missing, fractured, or loose frame components.


Defects in the steering system — Defects in the steering system include missing parts, such as nuts, bolts, and cotter pins, as well as twisted, loose, or damaged steering system components, such as the steering column, steering gear box, tie rods, drag link, pitman arm, and steering arm.


Check the hoses, pumps, and fluid level, and keep an eye out for leaks if your car has power steering.


Check the power steering fluid.


Frame — The frame is the vehicle’s base. It is linked to every component of the vehicle, either directly or indirectly. Sec. 393.201 of the FMCSRs mandates that it be in excellent condition. Check to see whether the frame is not drooping, loose, cracked, or damaged. The fasteners holding the vehicle's cab or body to the frame must not be damaged, loose, or missing.


Coupling system defects — A coupling system issue may result in a major accident or cargo damage.


Check the fifth wheel system for excessive slack or damage. Look for security issues, breaks, and fractures in the fifth wheel assembly. Make sure the fifth wheel is properly lubricated as well.


Check for wear or cracks in the vicinity of the pivot pin. Make that the safety latch and release arm are in good condition and not bent.


The fifth wheel sliding mechanism pins must be completely undamaged and firmly fastened in place.

Check the kingpin for any unusual wear, bending, or cracking.

Fifth-wheel mounting devices should be fixed or replaced if they have missing U-bolts, cracked or broken welds, or other flaws.


Cargo problems — Check the cargo for overloading, proper balance, and securement.


Exhaust system defects — Defects in the exhaust system might cause toxic fumes to enter the cab or sleeper berth.


Check for missing, damaged, leaky, loose, or loose parts:​ Exhaust pipes;​​ Mufflers;​​ Exhaust stacks;​ ​Mounting brackets;

​​Clamps; and​ ​Nuts and bolts.


Parts of the fuel system, the tires, or any other vehicle components shouldn't rumble against the exhaust system. Additionally, check the exhaust system for leaks. A leak is indicated by soot around the clamps.


Pretrip Inspection


Before every travel, a pre-trip check is done to find any issues that might result in a breakdown or accident. According to Section 396.13 of the FMCSRs, before operating a motor vehicle:


  • Assure yourself that the car is in a safe operating   condition;                    

  • Review the last vehicle inspection report (see post-trip inspection); and

  • Sign the report, only if defects or deficiencies were noted by the driver who prepared the report, to acknowledge that the report has been reviewed and that there is certification that the repairs have been performed.


The Seven-Step Pretrip Inspection


Every time you do a pre-trip checkup, you are less likely to overlook checking a crucial vehicle component. It is advised to use the following seven-step process.


  • Vehicle overview — Walk around the vehicle and note its overall condition. Look for body damage or any fluids leaking from the vehicle.


Look for tilting, door security, cargo security, license plates, stickers, or other paperwork from yearly inspections.


Additionally, scan the area around the car for any dangers (pedestrians- and, overhead wires, other vehicles, etc.)


Analyze the most recent car inspection report. Verify that any damage or flaws mentioned in the report have been remedied or corrected.


  • Engine compartment — Make sure the parking brakes are on and the wheels are chocked. Open the vehicle hood, tilt the cab, or open the engine compartment hood and check the following:



- All fluid levels, including those for the power steering, gearbox (if applicable), power coolant, and windshield washer

- Checking each hose for leaks, wear, or slackness;

- All belts for wear or loose- ness;

- The alternator, water pump, and air compressor;

- Check for leaks in the engine compartment;

The electrical wiring insu- lation for cracks or wear.


Also check the wheels and tires, brakes, steering system, suspension, exhaust, and frame at this point. Although these items are not part of the engine compartment check, this is where these parts are most accessible.


  • Inside the cab — Make sure the parking brake is on and the vehicle is in neutral or (if an automatic with “park”) in park. Depress the clutch and start the vehicle. Listen for unusual noises and check all gauges for normal readings including the following:


    • Steering wheel;


    • Clutch;


    • Accelerator;


    • Brakes;


    • Transmission control;


    • Horn;


    • Windshield wipers; and


    • Lights


    • Oil pressure (read within 15 seconds; 30-45 seconds in cold weather);


    • Ammeter (should register positive);


    • Voltmeter (should register positive);


    • Coolant temperature (will rise); and


    • Air pressure (85-100 psi within 45 seconds).


Check for cracks, debris, and other obstructions in the mirrors and windshield. Mirrors should be cleaned and adjusted as needed.


Ensure that the car's safety equipment is present and in working order. This consists of a fire extinguisher that is fully charged, extra fuses, if applicable, and three emergency triangles.


Lights —After locking the parking brake, put on the headlights and emergency flashers. Step outside the car, go to the front and check all of the lights. Make that the high beam and low beam settings on the headlights are in working order. Turn off the emergency flashers and headlights. Parking, clearance, side marker, and identifying lights should be turned on. Start the walkaround examination on the driver's side (left front side) of the car after turning on the right turn signal.


Left front side — Check that all door latches and locks operate correctly and that the window and mirror on the driver's door are both clean. Examine the left front wheel for the following details:


  • Wheel and rim — Check for evidence of misalignment as well as missing, crooked, or damaged studs, clamps, or lugs. Look for damaged wheels.

  • Tires — Check the condition of the valve and stem, the tire inflation pressure, and the presence of all valve covers on the tires. Look for any bulges or wounds. Pay attention to unusual tread wear.

  • Hub Oil Seal — No leaks

  • Lug nuts — Take extra care with rusty lug nuts.


Check the springs, spring hangers, shackles, U-bolts, and shock absorbers in the left front suspension for damage.


Check the push rod, slack adjuster, brake chamber, hoses, and brake drum for damage while examining the left front brake.


Front – Examine the steering system and front axle for damage. Watch out for any loose, damaged, twisted, worn, or missing components while inspecting the steering system. Check for any looseness in the steering mechanism as well.


Verify the windshield's condition. Look for damage, and if it's unclean, clean it. Also, check the wipers on the windshield. Examine the wiper blades for damage and the wiper arms for correct spring tension.

Verify that all reflectors are clean, functional, and the appropriate color, as well as the parking, clearing, and identification lights.


Make that the right front turn signal light is clean, functional, and the appropriate color by doing a similar inspection.


Right side — Repeat the examination of all the elements you looked at on the left front of the car on the right side (windows, door, wheels, tires, suspension, brake, etc.).


Make that the main and safety cab locks are in the on position if the vehicle has a cab-over-engine arrangement.


Check the gasoline tank on the right, checking sure it is installed properly and is not damaged or leaking. The gasoline crossover line has to be tight and leak-free. There should be adequate gasoline in the tanks, and the cap(s) should be tight.


Check the condition of visible parts including the:


  • Rear of the engine for leaks;
  • Header board;
  • Transmission for leaks;
  • ​​Exhaust system, making sure it’s secure, not leaking, and not touch- ing wires, fuel, or air lines;​​
  • Frame and cross members for bends or cracks;

  • Check the spare tire or wheel to make sure it is the right size, inflated correctly, and firmly fastened to its rack

  • Drive shaft;

  • Air lines and electrical wiring, making sure they’re secured against snagging, rubbing, or wearing;

  • Spare tire carrier or rack for damage;


Coupling system area — Verify the lower fifth wheel's attachment to the frame and the tightness of all the mounting bolts. Look for any missing or damaged components. Make sure there isn't any apparent gap between the upper and lower fifth wheels and that there is adequate oil on it. Instead of the kingpin's head, the locking jaws should be positioned around the shank. Make that the safety latch/lock is engaged and the release arm is correctly placed as well, if applicable. Make that the gliding plate is properly fastened to the trailer frame and the kingpin is not damaged while checking- ing the fifth wheel (upper) (upper). Examine the trailer's electrical and airlines. Examine the front and back of the trailer as well as the back of the tractor. The electrical and air cables shouldn't snag or chafe along the catwalk. The electrical line has to be firmly connected and fastened. The airlines should be prop- early linked to joyful hands. No air leaks should exist, and there ought to be enough slack for turning.Check the sliding fift wheel. The slide shouldn’t be dam- aged or have any parts miss- ing. It should be properly greased and all locking pins must be present and locked in place. If the sliding fift wheel is air powered, there shouldn’t be any air leaks. Also make sure the fift wheel isn’t so far forward that the tractor frame will hit the landing gear, or that the trailer will hit the cab when turning.


Right rear — Examine the rims and wheels for damage. Verify that there are no spacers, studs, clamps, or lugs that are missing, twisted, or damaged. Verify the tires' condition. Make that the valves and stems are in excellent shape, that they are inflated correctly, and that all of the valve caps are on. Look for any bulges or wounds. Pay attention to unusual tread wear. Nothing should be wedged in between them, and they shouldn't rub against one another. The tires have to be the same brand and size (evenly matched).


Inspect the wheel bearings and seals for leaks as well.

Check the suspension's springs, spring hangers, shackles, and U-bolts for damage. The powered axles shouldn't leak, and the axle should be solid. Examine the torque rod, arms, bushings, and shock absorbers for damage.


Check the lift mechanism's condition if the vehicle is equipped with retractable axles, and if the lift is driven by air, look for leaks.


Check the brakes for the following:,

  • Brake drums, shoes, and pads;

  • Hoses;

  • Slack adjusters; and

  • Brake chambers.



Check every light and reflector, including the side marker lights. They must be spotless, functionally sound, and have the appropriate shade of color. This includes:

  • Rear clearance and identification lights;

  • Reflectors Tail lights;

  • Rear turn signals.


Verify each door hinge. Check to see that the splash guards are in excellent shape, that the license plate is clean, that it is affixed, and that it is not dangling.


There should be no missing or broken pieces, and the landing gear should be completely extended. The crank handle has to be set up and fastened. Check for air or hydraulic leaks if it is powered.


Left side — Check the battery (if it isn't affixed to the engine compartment) to make sure it is securely fastened and isn't cracked or leaking, in addition to the components you examined on the right side (the fuel tank, engine, gearbox, exhaust, frame, airlines, etc.).


Signal Lights — As you enter the car, switch off all of the lights before turning on the stop lights (apply the trailer hand brake or have a helper put on the brake pedal). Activate the left turn signal lights as well. Look at the left front turn signal light after exiting the car. It must be functional, clean, and the right shade of color. After that, pay attention to the left rear turn signal and both stop lights. Ensure that they are functional, clean, and in the right shade of color.


Brake System — It is important to test each brake system to ensure that it is functioning correctly.


Parking brake — Release the parking brake to stop the trailer. Turn on the tractor parking brake and test its stability by gently pulling on it while in low gear.


Service brakes — Wait for normal air pressure, remove the parking brake, pull the car forward gently, and then firmly apply the brakes to service the brakes (brake pedal). Keep an eye out for the car veering to one side or any delayed stopping movement.


Trailer service brakes — After making sure the tire pressure is normal, releasing the parking brake, and moving the car forward very gently, engage the trailer brakes. The brakes ought to be audible to you. Not all trucks have a method for doing this.


Trailer emergency brakes — Charge the trailer air brake system before using the emergency brakes. Use the emergency brakes on the trailer. To check the brakes, gently pull the trailer with the tractor.


Air leakage rate — chock the car, switch off the engine, let all of the brakes go, and time how quickly the air pressure drops after the first drop. For a single vehicle, the loss rate should be under two pounds per square inch (psi) per minute, and for combination vehicles, it should be under three psi per minute. Put the brakes on harshly. The air loss is too significant if, after the first pressure drop, the air pressure drops more than three psi in a minute for single cars and more than four psi for combination vehicles. Be sure there are no leaks before starting the car.


Low pressure warning signal — Once the car has adequate air pressure, turn off the engine and let off the brakes when the low-pressure warning indicator appears. To lower the pressure in the air tank, turn on the electrical power and step on and off the brake pedal. Before the pressure in the air tank falls below 60 psi, the low air pressure warning indicator needs to turn on. The signal may be visible or heard. Without realizing it, you might lose air pressure if the signal isn't functioning properly.


Tractor protection valve — Increase the air brake system's normal air pressure and turn the air supply knob in. Turn off the engine. To lower the air pressure in the tanks, repeatedly pump the brake pedal. When the air pressure drops within the pressure range specified by the manufacturer, the tractor protection valve control, also known as the trailer air supply control, shall move from the normal position to the emergency position (pop out). When the air pressure reaches between 30 and 45 psi, this should happen. A trailer brake leak or faulty tractor protection valve might empty the tractor's tank of air. The emergency brakes would activate as a result, perhaps leading to loss of control.


Rate of air pressure buildup — In dual air systems, the pressure should rise from 85 to 100 psi in 45 seconds while the engine is running at operating rpm. (This might vary; see the manufacturer's specs. The vehicle's pressure might drop too low if air pressure doesn't rise quickly enough, necessitating an emergency stop or engaging the spring brakes.


Air compressor governor cut-in and cut-out pressures — The air compressor's pumping should begin at around 90 to 100 psi and end at about 125 psi. (For specifics, see the manufacturer's specification.) Keep the engine idling quickly. At the manufacturer's specified pressure, the air governor should shut off the air compressor. The air pressure gauge's measurement should cease increasing. Step on and off the brake to lower the air tank pressure while the engine is running. The governor ought to engage, and the compressor ought to begin increasing air pressure. The governor will cut off when the tank pressure hits 125 psi, and the procedure will then begin again. It could be necessary to repair the air governor if it doesn't function as mentioned above. A governor that isn't functioning properly can not keep the system's air pressure high enough to allow for safe driving.


En Route Inspection


There are several items you should be checking regularly while on the road including: Vehicle gauges; Air pressure gauges; Engine-temperature gauges; Pressure gauges; Ammeter; Voltmeter; Mirrors; Tires; and Cargo including covers and restraints.


By inspecting these things, you may find issues before they cause a breakdown or accident.


From Sec. 392.9 of the FMCSRs stipulates that the driver must adhere to certain inspection criteria when operating a vehicle. Within the first 50 miles of a journey, the cargo and load-securing mechanisms of the vehicle must be inspected. At this stage, any modifications that are required must be made. The vehicle's cargo and load-securing equipment have to be reevaluated after the first 50 miles of the trip:


  • When the driver changes his or her position on duty;

  • Depending on which comes first:

  • After 150 miles. If the trailer is sealed and you have been told not to remove the seal, it may not be feasible to check the cargo while it is being transported. If at all feasible, you should still do an in-transit examination of your automobile as well as a check of your cargo's security.


Post-Trip Inspection


You must submit a written report (driver vehicle inspection report (DVIR)) after each day's work on each vehicle driven that covers at least the following components and accessories.

  • Service brakes including trailer brake connections;

  • Parking brake;

  • Steering mechanism;

  • Lamps and reflective surfaces;

  • Tires;

  • Horn;

  • Windshield wipers;

  • Rear vision mirrors;

  • Coupling devices;

  • Wheels and rims;

  • Emergency equipment.


Any elements indicated as damaged or deficient that may affect the safety of the vehicle must be rectified before the vehicle may be used once more. The following requirements must be fulfilled:

• The motor carrier must attest (on the report) that the flaw or deficiency has been fixed or that it is not required to be fixed to drive the vehicle safely; and


• For at least three months after the date the repairs were finished, the motor carrier must keep the original copy of each vehicle inspection report and certification of repairs.


Intermodal equipment — If the intermodal equipment you are transporting has a flaw or defect, you must fill out a DVIR and submit it to the supplier of the intermodal equipment. The report must at least include the following components and add-ons:


      • Brakes;


      • Lighting equipment, lights, markers, and materials for conspicuous marking;


      • Wheels, rims, lugs, tires;


      • Air line connections, hoses, and couplers;


      • King pin upper coupling device;


      • Rails or support frames;


      • Tie down bolsters;


      • Locking pins, clevises, clamps, or hooks; and


      • Sliders or sliding frame lock.


The report must contain your signature, the USDOT numbers of the motor carrier and the supplier of the intermodal equipment, the name of the motor carrier responsible at the time the defect or deficiency was discovered, a unique identification number for the intermodal equipment, the date and time the report was submitted, a list of the defects or deficiencies, and the motor carrier's name.


Any flaw or deficit that compromises the equipment's ability to operate safely must be fixed before it may be transported using intermodal methods once again. The supplier of intermodal equipment must attest that any flaws or deficiencies were fixed or that further action is not required.


The original copy of each vehicle inspection report and certification of repairs must be kept on file by the intermodal equipment supplier for at least three months.


Special Rigs


Additionally, in certain situations, special inspection procedures are needed for special rigs. Following is a list of the extra steps for three different kinds of vehicles (tankers, refrigerated units, and numerous trailers).


Multiple trailers — Special attention should be given to:


  • Glad hands, air hoses, and valves connecting the two trailers;

  • Valve positions;

  • Brake operation;

  • Hook up of emergency lines and glad hands;

  • Pintle hook latches and safety chains.


Tankers — Special attention should be given to:


    • Dome covers to tank compartments;


    • Hoses and pumps (fastened and secured);


    • Emergency shut off valves;


    • Condition of the tank; and


    • Correctly displaying signs for hazardous materials (if applicable).


Refrigerator Units (Reefers) — The trailer's condition should get special care, and this includes searching for:


    • Holes in the walls, ceiling, or floor;


    • Cleanliness;


    • Damaged cold air circulation ducts;


    • Proper locks and seals on the doors; and


    • Proper securement of rails or racks on the ceiling.


The thermostat should be adjusted to the proper temperature and the water, oil, and coolant levels in the refrigerator unit should be checked. Before loading, the refrigeration unit should be turned on (the amount of time varies).





You have learned about the procedure for inspecting vehicles in this chapter. This entails executing precise and effective pre-trip, en-route, and post-trip inspections as well as checking important vehicle components.

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