Timken478WTapered Roller Bearing Cone – 2.5591 in Bore, 1.1420 in Inner Ring Width, Straight Bore, Pressed Steel Cage, Mates With 472, 472A And 474 Cups

Product Description

What this part is

Timken 478W inch tapered roller bearing cone. Cone only. Manufacturer: Timken. Manufacturer Part Number: 478W. Cone Part Number: 478W. Base Number: 478. Series: 475. Bearing Type: Tapered Roller Bearing Cone. Number of Rows: 1. Rolling Elements: Tapered Rollers. Design Units: Inch. Bore: 2.5591 in (65.001 mm). Inner Ring Width: 1.1420 in (29.007 mm). Bore Type: Straight. Closure Type: Open. Cage Type: Pressed steel. Cage Material: Steel. Bearing Material: Case-Carburized Steel. Precision Class: Not specified. Item Weight: 8.05 lb (3.652 kg). Unit Quantity: 1 Pc. The matching single cups are the Timken 472, 472A and 474.

Decoding the designation

478 is the cone number in Timken’s 475 inch series. The W is a Timken design-variant letter on the cone, so the 478W is a distinct part from the plain 478 and carries its own published dimensions and ratings. Searchable forms of the number are 478W, 478-W, 478 W and 478.

What these specs mean in practice

Dynamic Radial Load Rating C1, per row, ISO method at 1 million revolutions: 30,500 lbf (135,000 N). Dynamic Radial Load Rating C90, per row, Timken method at 90 million revolutions: 7,890 lbf (35,100 N). Dynamic Axial Rating Ca90, per row: 5,200 lbf (23,100 N). Static Radial Load Rating C0: 41,900 lbf (186,000 N). K Factor: 1.52. G1 Factor: 77.2. G2 Factor: 23. Geometry Factor Cg: 0.108. Every rating above is a single-row value for this cone. A tapered roller bearing carries combined radial and thrust load through one row of rollers running on matched cone and cup raceways, and the K factor of 1.52 is a comparatively steep raceway angle, which weights a larger share of the capacity toward thrust. C1 and C90 are two different life bases for the same bearing, so they are not interchangeable in a calculation. Maximum Temperature: 120°C. Minimum Temperature: −54°C. Harmonization Code: 8482.20.00.

Mounting dimensions

Effective Center Location: −0.16 in (−4.1 mm), which places the effective centre inside the cone backface. Maximum Shaft Fillet Radius: 0.09 in (2.3 mm). Shaft Backing Shoulder Diameter, frontface (da): 2.87 in (73 mm). Shaft Backing Shoulder Diameter, backface (db): 3.03 in (77 mm). Cage Location relative to the backface (Aa): 0.04 in (1 mm). Cage Location relative to the frontface (Ab): 0.12 in (3 mm). These figures decide whether a given shaft step and fillet will clear the bearing corners and the cage.

Quantity and configuration

Unit Quantity: 1 Pc. Cone only: the inner ring with its tapered roller set and pressed steel cage, as one non-separable assembly.

Cone and cup mating

The matching single cups are the Timken 472, 472A and 474, giving the TS single-row assemblies 478W/472, 478W/472A and 478W/474. The cup carries no bore, no cage and no roller set: it is the outer race alone, and its raceway angle is cut to match the cone.

Interchange guidance

Cross-Reference 1: SKF 478. Cross-Reference 2: NTN 4T-478. Cross-Reference 3: Bower 478. The NTN 4T prefix denotes the cone half in that maker’s scheme. The plain 478 shares the series and bore but is a separate Timken part number with its own published figures, so it is a related part rather than a direct substitute for the W variant.