SKF780Tapered Roller Bearing Cone Only, 4 in / 101.6 mm Bore, 1.89 in Wide, Mates 772 Cup

Product Description

What this part is:

The cone of a single-row inch-series tapered roller bearing on the 780 numbering — the inner ring complete with its tapered roller set and cage, on a 4.0000 in (101.6 mm) bore. Paired with its 772 cup it forms the 780/772 bearing, a 7.1250 in outside diameter assembly with a static radial capacity of 111,000 lbf. That is heavy-industrial territory: mill and crusher shafts, large gearbox and reducer output shafts, kiln and dryer support rolls, marine and rail journals.

Quantity and configuration:

This listing is the cone only. No cup is included. Cones and cups are ordered separately as service parts precisely because a cup often survives when the cone and rollers are worn — but if you need a complete bearing you also need a 772 cup, or one of the alternatives below.

Decoding the designation:

• 780 – the cone number, in the AFBMA inch scheme used by SKF, Timken and every other maker of this envelope.
• 772 – the standard mating cup.
• 780/772 – the complete two-piece bearing. A number without a slash always denotes a single ring.

What these specs mean in practice:

Because the cup is a separate ring, a tapered roller bearing has no internal clearance of its own — it is created at assembly. Two bearings mounted in opposition on the same shaft are adjusted against each other, with shims, a spacer or a lock nut, until the assembly reads the specified end play or preload. On a bearing carrying loads of this order, the setting is what determines whether the assembly runs cool for years or overheats in weeks, and no part number protects you from getting it wrong.

The K factor of 1.51 describes the cup angle and therefore how the bearing divides a combined load: with e 0.39 and Y 1.56, those are the figures for the equivalent-load calculation whenever the applied load has an axial component.

Watch the width dimensions on this size. The cone alone is 1.8900 in wide, while the assembled 780/772 bearing measures 1.8750 in across — the cone backface rib stands proud of the cup, so a caliper reads more on the bore side than the catalogue T dimension. Use T (1.8750 in) for shaft and housing stack-up calculations, and 1.8900 in when checking physical clearance against an adjacent shoulder or seal.

Published ratings and mounting data:

• Cone bore d: 4.0000 in (101.600 mm)
• Cone width B: 1.8900 in (48.006 mm)
• Mating cup: 772 — 7.1250 in (180.975 mm) outside diameter, 1.5000 in (38.100 mm) wide
• Assembled bearing width T with the 772 cup: 1.8750 in (47.625 mm)
• Rows: 1, tapered rollers
• Dynamic radial rating C90: 20,200 lbf — C1 77,800 lbf
• Dynamic thrust rating Ca90: 13,300 lbf
• Static radial rating C0: 111,000 lbf (495 kN)
• K factor: 1.51 — e 0.39, Y 1.56
• Cage: stamped steel
• Closure: open

Interchange guidance:

780 is a standard AFBMA inch cone number, so SKF 780, Timken 780, NTN 4T-780 and Koyo 780 describe the same ring; the complete bearing is 780/772 in every catalogue. Single cups that mate the 780 cone: 772 (standard), 772A, 773, and the flanged 772-B. For two-row TDO arrangements the double cups are 774D, 774DC and 774CD — note that 774 does not exist as a single cup, so a request for “780/774” needs clarifying before it is filled. There is no metric BT1B equivalent assigned at this size, so the inch numbering is the only designation in use.