The Backbone of Automotive Differentials
The Timken 387A-382A tapered roller bearing set is one of the most widely utilized components in the automotive drivetrain industry. Belonging to the 385 series, this bearing is ubiquitous in rear differential pinion applications for light-to-medium trucks and SUVs. Its dimensions (2.25" ID x 3.8125" OD) make it the ideal candidate for managing the severe axial thrust loads generated by hypoid gears.
Understanding the "A" Suffix
Precision in nomenclature is critical. The "A" in 387A signifies a modification from the original 387 design, typically involving a specific chamfer radius on the bore to accommodate the filet radius of the pinion shaft. Using a non-A variant (if one exists) could lead to interference fit issues, preventing the cone from seating fully against the shaft shoulder. This detail is crucial for mechanics and engineers to verify during assembly.
Load Distribution and K-Factor
A key metric for this bearing is its K-Factor of 1.54. This value represents the ratio of basic rated radial load to axial load. A lower K-factor indicates a steeper cup angle, which is better for thrust loads. The 387A/382A strikes a balance, allowing it to handle the complex vector forces found in transmission outputs. Compare this to the heavier Timken 462 series, which is often used when radial loads predominate over thrust loads.
Material Science: Case Carburized Steel
Like its metric counterparts in the LM300800 series, the 387A/382A is manufactured using case-carburized steel. This heat treatment allows the bearing to survive "shock loading"—sudden spikes in force that occur when a vehicle accelerates rapidly or tows a heavy load. Through-hardened bearings often crack under these specific conditions, whereas the tough core of the Timken 387A yields slightly to absorb the energy.
For industrial applications outside of automotive, this bearing is frequently found in conveyor drives and agricultural gearbox outputs. Our factory supply chain ensures that you receive genuine, batch-traceable units capable of meeting these rigorous demands.