Timken98788B-3Flanged Tapered Roller Bearing Single Cup (TSF) – 7.8740 in Cup Outside Diameter, 1.3750 in Cup Width, 8.2500 in Flange Diameter, 0.3750 in Flange Thickness, Class 3, Case-Hardened Alloy Steel

Product Description

What this part is

Timken 98788B-3 flanged tapered roller bearing cup — the outer race, 7.8740 in cup outside diameter, 1.3750 in cup width, with an integral mounting flange of 8.2500 in outside diameter and 0.3750 in thickness. 98000 imperial series, Class 3 precision. Cup only. The matching cone is the Timken 98350.

Decoding the designation

98788 is the Timken cup number. The B identifies the flanged execution of that cup, which Timken assembles with the 98350 cone as the TSF configuration — tapered single, flanged cup — designated 98350/98788B. The trailing –3, marked on the carton as *3 or #3, is Timken precision Class 3.

What these specs mean in practice

A flanged cup locates itself axially against the face of the housing instead of relying on a bored shoulder or a retaining ring, so the housing can be a through bore and the bearing position is set by the flange face. That simplifies machining and makes the setting repeatable on reassembly. Class 3 tolerances tighten outside diameter, width and running accuracy over standard inch tolerance, which matters on a 7.8740 in cup where a small runout translates into a large shaft deflection at the roller path.

Quantity and configuration

One flanged cup. Single raceway, taking one cone. Case-hardened alloy steel with a hardened raceway and a tough core.

Fitting notes

The cup body is a light interference or transition fit in the housing bore, and the flange face bears on the machined housing face, drawn up square. Assembled against a 98350 cone the complete bearing measures 3.5000 in bore by 7.8740 in outside diameter by 2.0772 in total width. Bearing setting to end play or preload is established at the shaft after the cup is clamped.

Interchange guidance

The 98788B cup number is published to the same ABMA inch designation across tapered roller makers, and the NTN equivalent is the 4T-98788. A plain 98788 without the B is the unflanged cup of the same raceway geometry and is a related item, since it needs a shouldered housing bore rather than a flange face. A 98788-2 or 98788B-20000 is the same cup at a different precision class.