Timken46790A-3Single Row Tapered Roller Bearing Cone Only, 6-1/2 in / 165.1 mm Bore, 1.5625 in Inner Ring Width, Precision Class 3, K Factor 1.52 — Cup Not Included

Product Description

Cone without cup — read this first

This listing is a cone only. In tapered roller bearing language the cone is the inner ring complete with its tapered rollers and cage; the cup is the separate outer ring the rollers run against. A tapered roller bearing does not become a bearing until you have both. Nothing here will run on its own, and it will not fit a housing bore — it fits a shaft.

Buy this if your cup is already installed and sound (still in the housing, in the wheel hub, pressed into a gearbox wall) and you need the rotating half replaced. If you need a complete bearing, you need this cone plus a 46720 cup. Central Surplus can supply the mate; ask before ordering rather than after.

What this part is

A large inch-series single-row tapered roller cone, 6.5 in / 165.1 mm bore, inner ring width 1.5625 in / 39.688 mm, weight 21.63 lb / 9.812 kg. Photographs show the ring stamped 46790A with a *3 class mark, and the original Timken carton is marked PRECISION. Made in USA.

Decoding the designation

46790A — the cone base number in Timken’s inch tapered roller series. The trailing A is a design revision, not a size change.*3 / -3 — a precision class suffix. Timken applies a numeric class mark to cones held to tighter running and bore tolerances than the standard class, which matches the PRECISION marking on this carton. Treat the exact class as read from the ring and box, not as a catalogue-published figure.46720 — the mating cup. Not part of this listing.

Correcting the source data

The legacy listing implied a complete bearing and, in places, referenced 46792 as the mate. That is wrong. The correct mating cup for a 46790A cone is the 46720, which is also offered as a 46720CD double cup for two-row TDO builds. The 6-1/2 in bore figure in the original title is correct and has been retained. We have also made the cone-only scope explicit in the title and copy, because a buyer expecting a set and receiving a single ring is a guaranteed dispute.

What these specs mean in practice

The K factor of 1.52 is the ratio between the bearing’s dynamic radial and dynamic thrust ratings, set by the raceway contact angle. You use it to convert a real-world combined radial-plus-thrust load into an equivalent radial load so a life calculation means something. It also tells you the design is steep enough to carry meaningful thrust rather than being a radial-only bearing.

The effective centre location is 0.1 in / 2.5 mm, positive, which puts the point where the bearing’s reaction actually acts just outside the cone backface. On a two-bearing shaft that offset is what you should use as your support point when you calculate bearing spacing and shaft bending. Substituting the physical ring face instead moves both reaction points and gives you the wrong bending moment, which on a shaft this size is not a rounding error.

The two dynamic ratings are quoted on different bases and are not alternatives. C1 of 68,200 lbf is the load for one million revolutions; C90 of 17,700 lbf is the load for ninety million revolutions. Timken’s inch catalogue quotes C90 because ninety million revolutions is 3,000 hours at 500 rpm, a working-life figure rather than a headline number. Compare C90 with C90, or you will badly misjudge two candidate bearings.

Published ratings and mounting data

Bore d: 6.5 in / 165.1 mmInner ring width B: 1.5625 in / 39.688 mmDynamic radial rating C1 (1 million revolutions): 68,200 lbf / 303,000 NDynamic radial rating C90 (90 million revolutions): 17,700 lbf / 78,600 NDynamic axial rating Ca90: 11,600 lbf / 51,600 NStatic radial rating C0: 143,000 lbf / 635,000 NK factor: 1.52Effective centre location: 0.1 in / 2.5 mmMaximum shaft fillet radius: 0.310 in / 7.900 mmShaft backing shoulder diameter, frontface da: 6.85 in / 174 mm; backface db: 7.44 in / 189 mmCage location Aa 0.13 in / 3.3 mm, Ab 0.12 in / 3 mmGeometry factors G1 572, G2 154; Cg 0.143Weight: 21.63 lb / 9.812 kg

Fitting notes

Cone and cup are lapped as a matched design family. Running a 46790A cone against a cup of a different base number, or mixing makers on nominally similar dimensions, shifts the contact pattern to the roller ends and gives you edge loading and early spalling. If the installed cup is worn, scored or has any raceway distress, replace both rings, not just this one.

Press the cone on by its own inner ring face and never through the rollers. Force passed through a roller brinells the raceway, and at 21 lb this ring takes real force to seat — a mechanical press or controlled induction heating, not a hammer and drift. Check that your shaft corner radius does not exceed 0.310 in, and that the backing shoulder falls between the da and db figures above, or the ring will sit tilted on the shoulder and never load evenly.

Single-row tapered roller bearings are not preset. Once assembled against its cup, the bearing must be adjusted to a specified endplay or preload. Left too loose the rollers skid instead of rolling and beat the raceway out; set too tight it generates heat faster than the lubricant can carry it away and fails in hours. Get the OEM setting figure before final assembly.

Interchange guidance

Written variously as 46790A, 46790-A, 46790 A, 46790A-3, 46790A*3 and 46790A/3. Mating cup 46720 (also 46720-B in some listings); double cup form 46720CD for TDO arrangements. Complete single-row bearing is commonly quoted as 46790A/46720. Cross-reference by dimension against other makers: 165.1 mm bore, 39.688 mm inner ring width.