The Ultimate Guide to Every Truck Parts Name You Need to Know
January 29, 2026 - 8:17:01 am

In the commercial trucking industry, your rig is more than just a vehicle; it is a complex machine made up of thousands of individual components working in unison. Whether you are an owner-operator performing your own maintenance, a fleet manager ordering inventory, or a driver trying to describe a breakdown to a technician over the phone, knowing the correct truck parts name is the first step to a solution.

Using the right terminology saves time, prevents costly ordering mistakes, and ensures that you get back on the road faster.

At Wallwork Truck Center, we understand that the sheer number of parts in a modern heavy-duty truck can be overwhelming. To help you navigate the complexity, we have compiled this ultimate, alphabetized guide to the most essential truck parts you need to know.

A

ABS (Anti-lock Braking System)

An electronic safety system that prevents the wheels from locking up during braking. By automatically modulating brake pressure, the ABS allows the driver to maintain steering control while stopping on slippery surfaces like ice or wet pavement.

Air Compressor

The heart of the air brake system. Engine-driven and typically gear-operated, the air compressor pumps air into the storage tanks, which is then used to power the brakes, air suspension, and air horn.

Air Dryer

Located between the compressor and the reservoirs, the air dryer removes moisture and oil contaminants from the compressed air. This is critical in cold climates to prevent brake lines from freezing.

Alternator

The electrical generator that recharges the batteries and powers the truck's electrical systems (lights, radio, ECM) while the engine is running. Heavy-duty trucks require high-output alternators to handle the increased electrical load.

Axle (Steer, Drive, Tag, Pusher)

• Steer Axle: The front axle that controls direction.
• Drive Axle: The rear axle(s) that receive power from the driveshaft to move the truck.
• Tag Axle: A non-powered axle located behind the drive axles to support more weight.
• Pusher Axle: A non-powered axle located in front of the drive axles.

B

Battery Box

The secure enclosure, usually mounted to the frame rail or under the steps, that houses the truck's batteries. It protects them from road debris and vibration.

Brake Chamber

The metal canister located at each wheel position. It converts compressed air pressure into mechanical force to apply the brake shoes or pads.

Bumper

The front-most structure of the truck designed to absorb minor impacts. In modern trucks, the bumper is often aerodynamic to improve fuel efficiency and contains sensors for collision mitigation systems.

C

Camshaft

A rotating shaft within the engine that opens and closes the intake and exhaust valves. In the context of brakes, the "S-Cam" is a shaft that turns to push brake shoes against the drum.

Chassis

The structural framework of the truck. It includes the frame rails, cross-members, and suspension mounting points. It is the skeleton upon which the cab, engine, and body are built.

Clutch

In manual and automated manual transmissions, the clutch engages and disengages the power flow from the engine to the transmission, allowing the driver to change gears.

Coolant Reservoir (Surge Tank)

A plastic or metal tank that holds excess engine coolant. It allows for the expansion of hot fluid and provides a location for the driver to check coolant levels and add fluid.

D

DEF Tank (Diesel Exhaust Fluid)

A separate tank holding DEF, a solution of urea and deionized water. This fluid is injected into the exhaust stream to break down dangerous NOx emissions into harmless nitrogen and water.

Differential

Located inside the axle housing, the differential is a gear train that allows the outer drive wheel to rotate faster than the inner drive wheel during a turn, while still transmitting power to both.

DPF (Diesel Particulate Filter)

A ceramic filter in the exhaust system that traps soot and particulate matter. It requires periodic "regeneration" (burning off the soot) to stay clean.

Drive Shaft

The heavy-duty steel or aluminum tube that transmits rotational power from the transmission to the rear differentials.

E

ECM (Electronic Control Module)

The computer "brain" of the engine. It receives data from sensors and controls fuel timing, turbo boost, and other parameters to optimize performance and emissions.

EGR Valve (Exhaust Gas Recirculation)

An emissions control device that recirculates a portion of the exhaust gas back into the engine intake. This lowers combustion temperatures and reduces Nitrogen Oxide (NOx) emissions.

Fifth Wheel

The horseshoe-shaped coupling device mounted on the rear of the tractor. It locks onto the trailer's kingpin to tow the load.

F

Fan Clutch

A mechanism that engages or disengages the engine cooling fan. It runs the fan only when the engine reaches a certain temperature, saving horsepower and fuel when cooling isn't needed.

Frame Rail

The long, heavy steel beams that run the length of the truck. They are the primary structural component of the chassis.

Fuel Injector

A precision component that sprays atomized fuel directly into the engine's combustion chamber at extremely high pressures.

G

Glad Hands

The coupling devices attached to the air hoses on the back of the tractor. They connect the tractor's air supply to the trailer's brake system. They are color-coded (Red for Emergency, Blue for Service).

Governor

A valve that controls the air compressor. It stops the compressor from pumping air once the system reaches its maximum pressure (typically 120-130 psi) and starts it again when pressure drops.

H

Headlamp Assembly

More than just a bulb, the modern assembly includes the lens, reflector, and housing. It is critical for night visibility.

Heater Core

A small radiator-like device located under the dashboard. Hot engine coolant passes through it, and a blower fan pushes air through the fins to warm the cab.

Hub Seal

A rubber and metal seal that prevents wheel bearing lubricant (oil or grease) from leaking out onto the brakes or tires.

I

Intercooler (Charge Air Cooler)

A heat exchanger located in front of the radiator. It cools the hot, compressed air coming from the turbocharger before it enters the engine, increasing oxygen density for better power and efficiency.

K

Kingpin

• Trailer Kingpin: The steel pin on the trailer that locks into the fifth wheel.
• Steering Kingpin: The pivot pin that connects the steering knuckle to the axle beam, allowing the front wheels to turn.

L

Landing Gear

The retractable legs on a semi-trailer that support the front of the trailer when it is disconnected from the tractor.

M

Mud Flap

Rubber or plastic guards hanging behind the wheels to prevent road debris, water, and rocks from being thrown at following vehicles.

O

Oil Cooler

A device that removes excess heat from the engine oil by transferring it to the engine coolant. This ensures the oil maintains the correct viscosity to lubricate the engine.

P

Pitman Arm

A steering component that links the steering box to the drag link, converting the rotary motion of the steering wheel into the linear motion needed to turn the wheels.

PTO (Power Take-Off)

A mechanism usually attached to the transmission. It diverts engine power to drive auxiliary equipment like hydraulic pumps for dump trucks, blowers, or wet kits.

R

Radiator

The primary component of the cooling system. It dissipates heat from the engine coolant into the atmosphere as air passes through its fins.

Receiver Drier

A part of the A/C system that acts as a storage tank for refrigerant and contains a desiccant to absorb moisture from the system.

S

Shock Absorber

Hydraulic devices that dampen the impact of road bumps and control the rebound of the suspension springs, ensuring a smooth ride and keeping tires in contact with the road.

Slack Adjuster

A mechanical link between the brake chamber pushrod and the S-cam. It automatically (or manually) adjusts the slack in the brakes as the brake linings wear down.

Starter Motor

A powerful electric motor that cranks the engine to start the combustion cycle.

Suspension Air Bag

Heavy-duty rubber bellows used in air-ride suspensions. They are inflated with compressed air to support the truck's load and provide a cushioned ride.

T

Tie Rod

A rod connecting the left and right steering knuckles. It ensures that both front wheels turn together and maintain proper alignment.

Torque Rod

A suspension link that prevents the axle from twisting during acceleration or braking. It maintains the proper axle angle.

Turbocharger

A turbine driven by exhaust gas that forces more air into the engine cylinders. This allows a smaller engine to produce the massive horsepower and torque required for heavy hauling.

U

U-Bolt

A U-shaped bolt with threads on both ends, primarily used to secure leaf springs to the axle.

U-Joint (Universal Joint)

A flexible coupling in the driveshaft that allows power to be transmitted even when the driveshaft is at an angle due to suspension movement.

W

Water Pump

A centrifugal pump that circulates coolant through the engine block, cylinder head, and radiator to prevent overheating.

Wheel Bearing

Steel balls or rollers held in a race that allow the wheel to rotate smoothly on the axle spindle with minimal friction.

Need a Part? Call Wallwork Truck Center.

Knowing the truck parts name is only half the battle; finding a high-quality replacement is the other. Whether you need a simple filter or a complex turbocharger assembly, Wallwork Truck Center has the inventory and expertise you need.

Our parts department is staffed by specialists who speak your language. Stop by one of our locations or give us a call today to get the right part, the first time.