FAG36620B-3Tapered Roller Bearing Cup 7-5/8 in OD x 0.9063 in Wide Class 3 Precision 36600 Series — Cup Only, No Cone

Product Description

What this part is

This is a tapered roller bearing cup: the outer ring on its own, with the tapered raceway ground into its bore. It is the 36620-B cup from Timken’s 36600 inch series, 7.6250 in (193.675 mm) outside diameter by 0.9063 in (23.020 mm) wide, supplied to Class 3 precision. A cup is one half of a tapered roller bearing. The other half is the cone assembly, inner ring, tapered rollers and cage, which is separately numbered and is not part of this listing.

What is and is not included

This listing is the cup alone. A complete bearing also takes a 36690 cone (5.750 in bore), or one of its siblings such as 36691. Cup and cone are separately numbered halves of one bearing.

Cups and cones are separable by design, and replacing one without the other is normal practice. The cup presses into the housing and the cone onto the shaft, so the two wear at different rates and in different failure modes. A cup-only replacement against a sound cone is a routine and cheaper repair.

Decoding the designation

36620 is the Timken inch-series cup number in the 36600 series. Within an inch series the cup and the cone are numbered separately: 36620 is a cup, 36690 and 36691 are cones. B is a Timken design-revision letter on the cup; Timken catalogues the 36620-B under Single Flanged Cups, Imperial, and publishes an outer ring flange outside diameter (D1) of 7.7772 in / 197.541 mm and a flange width (C2) of 0.1563 in / 3.97 mm. A flanged cup locates axially against the face of the housing instead of a machined shoulder inside the bore, which gives a repeatable seat in a through-bored or thin-walled housing.

−3 denotes Timken precision Class 3, and the notations 36620B-3, 36620B #3 and 36620B *3 all mean the same thing. K-36620-B and K36620B are Timken component-order forms of the same cup number, used when a cup is ordered as a loose component. The cone number, not the cup number, selects the bore: a 36620-B cup fixes the 7.6250 in housing fit and the 36690 cone fixes the 5.750 in shaft fit.

What Class 3 precision buys you

Timken supplies inch tapered roller bearings in graded precision classes: Class 4 is the standard commercial grade, then Class 3, Class 0, Class 00 and finer. Each step up tightens the tolerances on outside diameter and width, and on radial and axial runout of the ground raceway.

A Class 3 cup runs truer in the housing than a standard cup of the same nominal size, and it is specified where housing-bore runout translates directly into a product-quality problem: machine tool spindles, precision gearboxes and index drives, printing and converting rolls, gear grinders, paper machine positions. It costs more than a standard cup and it is stocked far less widely.

A standard 36620B fits where a 36620B-3 is called for, and it does not run the same. The specific Class 3 runout limits are set by Timken’s precision tolerance tables.

Published dimensions and factors

Timken publishes the following against the 36620-B cup itself.

Cup Part Number: 36620-B. Series: 36600 inch series. Outside Diameter (D): 7.6250 in / 193.675 mm. Outer Ring Width (C): 0.9063 in / 23.020 mm. Outer Ring Flange Outside Diameter (D1): 7.7772 in / 197.541 mm. Outer Ring Flange Width (C2): 0.1563 in / 3.97 mm. Mass: 5.4 lb / 2.5 kg. e Factor: 0.37. K Factor: 1.59. Y Factor: 1.63. G1 Factor: 91.7. G2 Factor: 24.3. Geometry Factor Cg: 0.177. Precision Class: Class 3. Number Of Rows: 1.

Envelope of the mating half, for a stack-up: 36690 cone bore 5.7500 in / 146.050 mm, cone inner ring width (B) 1.1250 in / 28.575 mm.

What these specs mean in practice

The K Factor of 1.59 is the ratio of radial to thrust capability set by the cup angle: a higher K means a shallower cup angle and a bearing that is radially strong and comparatively thrust-weak. At 1.59 the 36600 series sits in the middle of the tapered roller range, carrying a useful axial component alongside its radial load. That is the mix a gear-driven shaft produces, which is why the series turns up in gearbox and roll positions rather than in pure thrust duty.

The e Factor of 0.37 is the threshold in the equivalent-load equation: below an axial-to-radial load ratio of 0.37 the thrust component drops out of the calculation, above it the equation changes. With e = 0.37, K = 1.59 and Y = 1.63 the geometry side of a bearing life calculation on this position can be run from this page.

Quantity and configuration

Each piece is one cup, not a set and not a cone-and-cup pair. A complete bearing also takes a 36690 cone.

Mounting data

Maximum Housing Fillet Radius: 0.06 in / 1.5 mm. Housing Backing Shoulder Diameter, frontface (Da): 7.50 in / 190.5 mm.

The cup presses into the housing bore. Tapered roller bearings have no built-in internal clearance: the operating endplay or preload is created at assembly by how far the cone is drawn up against the cup, and that setting governs bearing life more than any other single variable. In a precision position the machine builder specifies it tightly.

Interchange guidance

36620 is an industry-standard inch cup designation rather than a proprietary Timken code, so it is manufactured by several bearing makers and a 36620B from any source is dimensionally interchangeable. The precision class is not part of the base number, so a plain 36620B from any maker is a standard-class part and is not equivalent to this 36620B-3.

Cross-references: 36620B, 36620-B, 36620 B, 36620B-3, 36620B #3, 36620B *3, 36620B CL3, K-36620-B, K36620B, K-36620B. Base cup without the B revision: 36620. Related cup forms: 36620D and 36620DC double cups, 36620P. Mating cones: 36690 (5.750 in bore), 36691. Related assemblies: 36690/36620-B, 36690/36620, 36691/36620, 36690/36620D.

Central Surplus also stocks the matching Timken 36690 Class 3 cone under SKU B-BS3#LAQ8WA, and the complete 36690-3 / 36620B-3 Class 3 cone-and-cup set under SKU CF4#JTOIVS.