The Pre-Trip Inspection for Tractor-Trailer combinations.
Starting with the in-cab inspection:
Windshield not cracked or broken and seal not leaking.
Windshield wipers have good blades.
Side view mirrors secure and adjusted.
Windows roll up and down.
Seat belt works.
Steering wheel has no more than 2” of free play.
Horns, city and air, work.
Turn signals, 4-way hazard flashers and high beam control works.
Oil pressure gauge should read between 45 and 65 psi with engine running.
Coolant temperature should be between 190 and 200 degrees when running.
Voltmeter should read between 12 and 14 volts when running.
The windshield wiper switch and the headlight switch work.
The heater, fan and defroster controls work.
The clutch has no more than 2” of free play travel.
The stick-shift air-line is not leaking, and the range selector switch is working. The boot on the floor around the stick is not leaking.
There is a fire extinguisher rated for the load I’m carrying,
three reflective warning triangles, and spare electrical fuses.
Next you exit the vehicle and begin the exterior inspection.
Standing in front of the vehicle you check the clearance lights, headlights and high-beams, turn signals and 4-way flashers.
There should be no leaks of any fluids under the truck and no hanging wires or hoses visible.
The hood is opened and the inspection starts on the passenger side.
The air intake, which leads to the turbo, which becomes the exhaust line should be free of soot, or carbon, which would indicate a leak.
The air conditioning compressor pump and alternator belt should be tight. The alternator should be secure and wires connected and tight.
The water pump should not be leaking from any connections.
The frame must not have any cracks or welds.
(You will inspect the suspension, tires and brakes, but for the DMV inspection, you will advise the examiner you are going to inspect these systems on the other side in detail, so they may be skipped right now.)
Moving to the driver’s side of the truck, you begin by inspecting the air lines, wires and hoses in general for any signs of leakage or disconnection.
The levels of the engine oil, power steering reservoir, radiator coolant and windshield washer fluid are checked.
The power steering system consists of the reservoir, which has hoses connected to the power steering pump and the steering gearbox. Nothing should be leaking.
The steering gearbox is controlled by the steering shaft which should be secure to the u-joint.
On the side of the steering gearbox is the Pitman arm which connects to the drag link. The drag link connects to the upper steering arm, which connects to lower steering arm that moves the tie-rod. The tie-rod “ties” the steering wheels together.
There is a safety feature, castle nuts and cotter pins to insure the connections cannot vibrate lose and fail.
Next is the Air system, made up of the compressor, which is controlled by the governor. The air line connections are not leaking and the compressor is gear-driven.
Inspect the frame for cracks or welds.
Connected to the frame is the suspension made up of two spring mounts, which have leaf springs between them. The leafs should not be cracked or missing.
The leaf springs are connected to the axle by U-bolts, which should be tight.
There is a shock-absorber which should not be leaking.
The brake system air-line hose to the brake chamber should not be leaking or worn. The ABS electrical line should be connected and secure.
The brake chamber connects with a push rod to the slack-adjuster, which should have no more than 2” inches of free-play.
The slack-adjuster leads to the brake shoes that have pads which must be no thinner than ¼” thick.
The pads contact the brake drums, which must be free of cracks, weld and contamination. (anything greasy or slippery)
The tires are now inspected. (Inflation, Condition and Depth)
The Inflation pressure is found on the sidewall of the tire.
The sidewall Condition should be no abrasions, bulges or cuts visible.
The Tread Depth on a steering axle must be no less than 4/32” and the tire must be new, not a re-tread or used tire.
The tire is inflated through the valve stem which should have a cap.
The ridge along the wheel rim is called the bead, which should not be dented or leaking.
The wheel rim itself must be free of cracks or welds.
The wheel is connected to the drum by lug nuts which must be tight and not missing any.
The wheel turns on a wet-hub. The cap should be tight and the hub full of lubricant.
The doors should open and close correctly.
The fuel tank should not be leaking and have a good cap.
The tank straps should be tight and have rubber pads to prevent vibration damage which causes leakage.
The steps should be secure.
Behind the tractor, the exhaust stack should be secure and not leaking at the connections.
The red air-line is the Emergency supply. The blue air-line is the Service brake supply. At the ends of the lines are “glad-hand” connectors which have seals that should not be leaking.
The electrical line plug should be secure and dry at the connection.
The plate across the frame is called the catwalk. Under the catwalk is the battery box. Check for loose connections or corrosion.
Under the battery box is the drive shaft, which should not be twisted or loose. The shaft connects to the differential which is full of oil and should not be leaking.
On top of the differential is a torque-arm that connects to the frame to keep the differential from twisting.
The rock guards should be secure.
To inspect the drive axle begin with the brake system.
The air-line to the spring-brake chamber is secure, nothing should be leaking. The brake chamber connects with a push rod to the slack-adjuster, which should have no more than 2” inches of free-play.
The slack-adjuster leads to the brake shoes that have pads which must be no thinner than ¼” thick.
The pads contact the brake drums, which must be free of cracks, weld and contamination. (anything greasy or slippery)
The suspension is slightly different from the front axle. The drive axle suspension has one spring mount and one air-bag mount. Between them are the leaf springs which should not be cracked or missing. The air-bag should not be leaking.
The leaf springs are connected to the axle by U-bolts which should be secure. The shock-absorber should not be leaking.
To inspect the dual-tire assembly look between the wheels for debris that could fly loose and that the wheels are touching each other with no space or wobble.
The tires are now inspected. (Inflation, Condition and Depth)
The Inflation pressure is found on the sidewall of the tire.
The sidewall Condition should be no abrasions, bulges or cuts visible.
The Tread Depth on a drive axle tire must be no less than 2/32” and the tires can be recaps.
No mixing of radial and bias-ply tires on an axle is permitted.
The tires are inflated through the valve stems which should have caps.
The ridge along the wheel rim is called the bead, which should not be dented or leaking.
The wheel rim itself must be free of cracks or welds.
The wheel is connected to the drum by lug nuts which must be tight and not missing any.
The drive axle wheels turn on sealed hubs. These hubs have no removable pop-cap to check the fluid level. The lubricant is sealed inside.
The third axle is inspected the same way as the second axle. The only difference is that the third axle often does not have a spring-brake chamber.
To inspect the fifth-wheel assembly begin by checking the apron of the trailer. The king-pin hangs down from the apron.
The king-pin connects to the fifth-wheel by the locking jaws which are operated by the release arm. There should be no space or gap between the fifth-wheel and the apron.
The fifth-wheel connects to the lower or “sliding” fifth-wheel.
The slider is connected to the “glide-path” or track by locking pins which are controlled from the cab. At the ends of the track are stops to prevent the slider from coming off of the track when moved. The track is bolted, not welded to the the frame.
Behind the tractor are turn signals, brake-lights and 4-way flashers which must work.
Mud-flaps must be present if there is no trailer connected.
The front of the trailer is called the bulkhead and must be free of holes. The side of the trailer must be free of damage and should have reflectors or reflective tape showing.
The clearance lights should be intact and working.
The landing gear should work and is made up of the leg, foot, crank and basket. The supports should be secure and undamaged.
Nothing should hang through the floor of the trailer.
The trailer axles are inspected the same way as the other axles, brakes, suspension and tires again, completely.
The rear of the trailer has clearance lights, turn-signals, brake lights and 4-way flashers that should be working and intact.
The license plate should have a working light above it.
The doors are held on by hinges and closed with latches which should be working and secure.
The trailer has a DOT bar or bumper that should be secure to prevent vehicles from going under the trailer.
If the trailer has a pintle-hook, inspect the locking latch. Check the safety-chain hanger and the air and electrical connections for the second trailer.
The mud-flaps should not be higher than 2” to 6” off the ground.
The left side of the truck is inspected the same way as the right side.
