As a bearing application engineer with years of experience working in heavy-duty vehicle systems, I often get asked by truck owners and mechanics: “What bearings are actually used on trucks, and where exactly are they installed?” This is a crucial question because the right bearing selection directly affects a truck’s performance, fuel efficiency, and long-term durability. In this article, I’ll walk you through the common types of bearings used in trucks, including their specific models and the functional areas where they are installed.

1. Wheel Bearings

Type: Tapered Roller Bearings

Installation Location: Front and Rear Axles

Wheel bearings are among the most critical components on any truck. In trucks, especially heavy-duty and commercial vehicles, we primarily use tapered roller bearings for the wheels. These bearings can handle both radial and axial loads, which is essential when trucks are cornering or carrying heavy cargo.

For example, on a typical Class 8 truck, the front wheel hub assembly usually includes a matched set of inner and outer tapered roller bearings such as:

• Model: Timken SET-403 (for steer axle applications)
• Model: SKF SET-401 or SET-404 (commonly used in rear drive axles)

Proper installation and preload are essential here — too much preload and the bearing will overheat; too little and it will wobble and wear prematurely.

2. Transmission Bearings

Types: Cylindrical Roller Bearings, Needle Roller Bearings, and Ball Bearings

Installation Location: Main and Countershafts of the Transmission

Inside the transmission, you’ll find a mix of cylindrical roller bearings for high radial loads, needle roller bearings for compact axial support, and sometimes deep groove ball bearings for general load management.

For example, many gearboxes use:

• Model: NSK NU2206 (cylindrical roller bearing)
• Model: INA NK series (needle bearings for gear idlers)
• Model: SKF 6306 (ball bearing for input/output shafts)

These bearings must withstand constant meshing forces, temperature variations, and contaminants like transmission oil and metallic particles.

3. Differential Bearings

Type: Tapered Roller Bearings

Installation Location: Pinion Shaft and Differential Carrier

The differential, which allows your truck’s wheels to rotate at different speeds, relies heavily on tapered roller bearings due to the high torque loads transmitted through the pinion and ring gears.

Common setups include:

• Model: Timken HM88542/HM88510 (pinion head)
• Model: Timken 387A/382A (carrier side)

In this area, bearing failure can lead to noisy operation, gear misalignment, and even catastrophic drivetrain failure.

4. Driveshaft Bearings

Type: Center Support Bearings (Ball Bearing inside Rubber Housing)

Installation Location: Driveshaft Midpoint

Longer trucks often have multi-piece driveshafts supported in the middle by center support bearings. These are typically deep groove ball bearings housed in rubber mounts, designed to absorb vibrations and maintain alignment.

Commonly used models:

• Model: SKF HB88107A or HB88512
• Usually installed in a rubber cushion assembly to allow for shaft flexibility.

Failure here often results in excessive vibration and whining during acceleration.

5. Clutch Release Bearings

Type: Thrust Ball Bearings

Installation Location: Clutch Assembly (between clutch fork and pressure plate)

These bearings help disengage the clutch when you press the pedal. Since they operate under both axial load and high-speed rotation, thrust ball bearings are used. They must also resist heat from the engine and friction from frequent engagement.

Typical models:

• Model: NSK 60TKZ3501
• Or OEM-specific integrated clutch release bearing assemblies.

A faulty release bearing often manifests as a grinding noise or resistance when shifting gears.

6. Alternator and Fan Bearings

Type: Deep Groove Ball Bearings

Installation Location: Engine Accessories (Alternator, Water Pump, Cooling Fan)

These bearings may seem small, but they run at very high speeds. Deep groove ball bearings, like 6203 or 6204 series, are commonly used in these areas. Their key feature is their ability to handle high RPM with minimal maintenance.

Failure signs include squealing noises or seized pulleys.

7. Air Compressor and Steering Pump Bearings

Types: Ball Bearings and Needle Bearings

Installation Location: Engine-Mounted Auxiliary Systems

In modern air-brake trucks, the air compressor and power steering pump both contain precision bearings. These are subject to high load and pressure cycles.

Common models:

• Model: FAG 6305 or SKF 6206 for compressor shafts
• INA drawn-cup needle bearings in compact power steering pumps

Conclusion: Precision Matters

As you can see, trucks use a wide variety of bearing types across different assemblies — each chosen based on its load-bearing capacity, speed rating, and durability requirements. Whether you’re a fleet owner looking to minimize downtime or a mechanic diagnosing issues, understanding where and how these bearings are used is essential to keeping trucks on the road safely and efficiently.

If you’re performing routine maintenance or replacing OEM parts, always ensure you select the right type and size of bearing, preferably from a reputable manufacturer with certified specifications. And don’t overlook lubrication and proper installation — even the best bearing can fail prematurely if not handled correctly.

Need help identifying or sourcing the right bearing for your truck application? Feel free to reach out — I’m happy to offer expert guidance or help you match cross-reference models.