Timken36690-3Tapered Roller Bearing Cone Assembly, 5.750 in Bore x 1.125 in Wide, Class 3 Precision, Cone Only

Product Description

What this part is

This is a tapered roller bearing cone assembly — the inner ring complete with its roller set and cage. It is the 36690 cone from the 36600 inch series, 5.750 in (146.05 mm) bore, cone width 1.1250 in (28.575 mm). It runs in a 36620 cup, which is a separate component and is not included in this listing.

What the “3” means — this is a precision cone:
The markings 36690-3, 36690 #3 and 36690 *3 all denote the same thing: Class 3 precision. This is the single most commercially important fact about the part and it is easy to miss, because to the eye a Class 3 cone is indistinguishable from a standard one.

Timken’s inch tapered roller bearings are supplied in graded precision classes — Class 4 (standard), then Class 3, Class 0, Class 00 and finer — with each step tightening the tolerances on bore, outside diameter, width and, critically, on radial and axial runout. A Class 3 cone therefore runs truer than a standard cone in the same envelope. It costs more, it is stocked less widely, and it is specified where shaft runout translates directly into a quality problem: machine tool spindles, printing and converting rolls, gear grinders, precision index drives, paper machine positions.

The practical consequence for a buyer: a standard 36690 will fit where a 36690-3 is called for, but it will not perform the same, and substituting down a class in a precision position is a common and expensive mistake. Conversely, if your application only ever needed a standard cone, a Class 3 part is a free upgrade. Note that the specific runout limits for Class 3 are set by Timken’s precision tolerance tables and are not reproduced here, because they were not read from the manufacturer’s published table for this part — ask if you need the figures certified.

What is and is not included

Cone assembly only: inner ring, rollers, cage. No cup. Cups and cones are separable by design and are routinely replaced independently, since the cup presses into the housing and the cone onto the shaft. If you need a complete bearing you also require a 36620 cup.

Published dimensions and ratings

Figures below are for the complete 36690 / 36620 single-row assembly. A cone carries no rating on its own, because capacity is a property of the roller set running between both races.

Bore (d): 5.750 in / 146.05 mmCup outside diameter (D): 7.625 in / 193.68 mmAssembly width (T): 1.125 in / 28.58 mmCone width (B): 1.1250 in / 28.575 mmCup width (C): 0.9063 in / 23.02 mmDynamic radial load rating C1: 196,000 NDynamic radial load rating C90: 50,900 NDynamic axial rating Ca90: 32,100 NStatic radial load rating C0: 394,000 N

The e, K and Y calculation factors, the abutment shoulder diameters and the maximum fillet radii for this series were not read from Timken’s own table for this reference and are therefore not stated. Weight is likewise not published for the cone alone.

Quantity and configuration

Eighteen individual cones are on hand. Each piece is one cone, not a set and not a cone-and-cup pair. Eighteen matched-vintage Class 3 cones from one source is an unusual position — if you run a machine with several identical spindle or roll positions, this is the batch that lets you replace them all to the same precision class at once rather than mixing suppliers and classes across the machine.

Fitting notes

The cone presses onto the shaft. Heat-mount it or push on the inner ring face with a proper fitting tool — never strike the cage or the rollers. On a precision cone this matters more than usual: the whole reason you are paying for Class 3 is controlled runout, and a cocked or brinelled cone throws that away instantly.

Tapered roller bearings have no built-in internal clearance; operating endplay or preload is created at assembly by how far the cone is drawn up against the cup. In a precision position that setting is normally specified tightly by the machine builder. Re-set it to specification rather than reusing an old shim stack, because a new cone changes the stack-up.

Interchange guidance

36690 is an industry-standard inch cone designation, so a 36690 from any reputable maker is dimensionally interchangeable — but the precision class is not part of the base number, so a plain 36690 is a Class 4 standard part and is not equivalent to this 36690-3. Cross-references for the base part: 36690, 36-690, 36690-3, 36690 #3, 36690 *3, 36690 CL3.

Same-envelope sibling cone: 36691. Mating cups: 36620, 36620D (double cup), 36620DC, 36620P, 36620-B (flanged cup). Related assemblies: 36690/36620, 36691/36620, 36690/36620D, 36690/36620DC.