Timken46780-3Tapered Roller Bearing Single Cone, 6-1/4 in Bore x 1-9/16 in Inner Ring Width, Class 3 Precision, 46700 Imperial Series

Product Description

What this part is

A tapered roller bearing splits into two separable halves: the cone (the inner ring, complete with its rollers and cage) and the cup (the outer ring). This listing is the cone. It is a complete, usable cone assembly, but on its own it is not a bearing — it needs a mating cup, and that cup is a separate part number and a separate purchase. For the 46780 the standard mate is the 46720 single cup, or the 46720-B if your housing needs a flanged cup. Complete assemblies are quoted as 46780-46720.

Decoding the designation

This is the part of the number most buyers get wrong, so it is worth being explicit. The -3 is a Timken precision tolerance class. It is not a series, not a revision and not a quantity. Timken’s tapered roller bearing tolerance classes run 4, 2, 3, 0 and 00, in order of increasing precision, with Class 4 the standard commercial grade. A Class 3 cone is therefore held to tighter bore and running-accuracy limits than both the standard Class 4 and the Class 2 grade. You buy it when shaft runout and axial location genuinely matter — gear meshes where tooth contact pattern must hold, rolling mill roll necks, precision indexing drives, machine tool feed screws. In a general conveyor pillow block it is money spent on tolerance you will never see.

A -3 cone shares the 46780’s envelope and load ratings; the tolerance class changes how accurately it is ground, not what it will carry.

Manufacturer figures (from Timken’s own catalogue entry for 46780):

Bore (d): 6.2500 in / 158.750 mm
Inner ring width (B): 1.5625 in / 39.688 mm
Dynamic radial load rating C1, 1 million revolutions: 68,200 lbf / 303,000 N
Dynamic radial load rating C90, 90 million revolutions: 17,700 lbf / 78,600 N
Dynamic axial rating Ca90, 90 million revolutions: 11,600 lbf / 51,600 N
Static radial load rating C0: 143,000 lbf / 635,000 N
K factor: 1.52
Weight: 24.38 lb / 11.059 kg
Effective centre location: 0.1 in / 2.5 mm
Max shaft fillet radius: 0.14 in / 3.600 mm
Shaft backing shoulder diameter, frontface (da): 6.65 in / 169 mm
Shaft backing shoulder diameter, backface (db): 6.93 in / 176 mm
Cage location relative to backface (Aa): 0.13 in / 3.3 mm
Cage location relative to frontface (Ab): 0.12 in / 3 mm
G1 factor 572, G2 factor 133, geometry factor Cg 0.143
Operating temperature range: -65 to 250 F / -54 to 120 C
Material: Timken high-alloy bearing steel, stamped steel cage

What these specs mean in practice

K = 1.52 is the ratio Timken’s own life-calculation method uses to split a combined load into its radial and thrust components. If you are sizing this position rather than just replacing a part, K is the number your calculation hangs on — it is what makes a tapered bearing’s thrust behaviour predictable in a way a straight roller bearing’s is not.

Fitting notes

The two shaft backing shoulder diameters are not interchangeable and this catches people out. The cone needs 6.65 in of shoulder if it seats against its frontface and 6.93 in if it seats against its backface. Undersize the shoulder for the direction you are actually mounting and the ring face is unsupported at exactly the point the thrust load arrives. Keep the shaft fillet radius at or below 0.14 in so the bearing corner clears, and check the cage location dimensions (0.13 in from the backface, 0.12 in from the frontface) against any shoulder or spacer the cage could rub.

Condition of this particular cone

New old stock in an opened box, made in the USA. It has never been fitted or run — it is unused factory stock that has been out of its sealed packaging, so inspect the photographs for the storage preservative and any handling marks before you commit. Storage age is the only thing separating it from current production; the grind and the tolerance class are as they left Timken.

Quantity and configuration

One cone. No cup included.

Carton marking

The carton for this cone carries the marking *3 alongside the part number. It is retained in the title and in the cross-references so the box you receive matches what you searched for.

Interchange guidance

Timken catalogue the 46780 cone into several assemblies, and any of these numbers may be what your equipment manual actually calls out: 46780-46720 (type TS single row), 46780-46720-B (type TSF, flanged cup), 46780-46720CD (type TDO, two row double outer), and 46780-46720 (Y2S-46720) as a 2TS-DM matched direct-mount pair. If your drawing gives one of those assembly numbers, this cone is the inner half of it. The Class 2 equivalent of this cone is 46780-2; the standard commercial grade is plain 46780.