Bower48120Tapered Roller Bearing Cup, 6.375 in / 161.925 mm Outside Diameter, 1-1/16 in Wide, Mates 48190 Cone, 1 Pc

Product Description

What this part is

Bower 48120 tapered roller bearing cup — the outer race of the 48190/48120 single-row imperial tapered roller bearing. Brand: Bower. Manufacturer Part Number: 48120. Base Number: 48120. Bearing Type: single-row tapered roller bearing cup. Series: 481. Outside Diameter: 6.375 in / 161.925 mm. Overall Width: 1.0625 in / 26.988 mm. Number of Rows: 1. Material: through-hardened bearing steel with a ground raceway. Design Units: Imperial. Unit Quantity: 1 Pc.

Quantity and configuration

Cup only. The matching cone is the 48190, which carries a 4.25 in / 107.95 mm bore. Assembled, the 48190/48120 bearing measures 4.25 x 6.375 x 1.375 in / 107.95 x 161.925 x 34.925 mm. Unit Quantity: 1 Pc.

Decoding the designation

48120: the industry-standard cup number for this size, shared across makers, so a 48120 from any of them is the same race. 48190: the mating cone number. Cone and cup numbers pair by roller and raceway geometry and are quoted together, which is why the bearing is written 48190/48120 or 48190-48120. Bower and BCA are the legacy US brand names carried on this line of imperial taper bearings, so both appear on cartons and rings for the same numbers.

What these specs mean in practice

A tapered roller bearing is a two-piece bearing by design. The cup presses into the housing, the cone presses onto the shaft, and running clearance is set at assembly with an adjusting nut rather than being built into the bearing. That makes the cup a spare part in its own right: a housing that has spalled or spun its race is restored with a new cup while the shaft stays untouched.

At 6.375 in outside diameter on a 4.25 in shaft, this is a heavy-duty size — truck and trailer wheel ends, agricultural and construction axles, industrial rolls and gearbox output shafts. Bearings this size run in opposed pairs, so the two cups take thrust in opposite directions and jointly locate the shaft.

Interchange guidance

48120 is an industry-standard cup number, so Timken 48120, Bower 48120, BCA 48120, Koyo 48120 and NTN 4T-48120 are the same race on the same envelope and all mate with a 48190 cone. Class-suffixed versions such as 48120-2 are the same race held to a tighter Timken tolerance class and are dimensionally interchangeable, a related build on the same envelope. The cone number governs the contact geometry, so the pairing is 48190 to 48120. Searchable variants of this number are 48120, 48 120, 48-120, 48190/48120, 48190-48120 and 48120-2.