Timken18200Class 00 Precision Tapered Roller Bearing Cone Only, 2.0000 in Bore x 0.7190 in Inner Ring Width, Inch Series – Mating Cup Not Included

Product Description

What this part is

This is the cone half of a single-row tapered roller bearing — the inner ring with its ground tapered raceway, the tapered rollers, and the cage that holds them, supplied as one non-separable assembly. It is the Timken 18200 cone, 2.0000 in (50.8 mm) bore by 0.7190 in (18.263 mm) inner ring width, in Class 00 precision. The cone is the half that presses onto the shaft.

What is and is not included

This listing is the cone only. No cup is included. A tapered roller bearing is two separately numbered halves: the cup (outer ring) presses into the housing, the cone (inner ring plus rollers plus cage) presses onto the shaft. Without a mating cup you do not have a working bearing. Cups and cones are sold apart as standard practice because they mount in different members and wear at different rates — but if you are building a complete bearing you need to buy the cup separately. This is the most frequent and most costly ordering mistake in this product family.

Which cup does the 18200 cone need

The 18200 cone runs against cups in Timken’s 18300 series. Timken’s own catalogue entry for the 18200 lists 18335E and 18335X among its related cups, with further options in the series; the widely quoted complete assembly for this cone is 18200 / 18337. Because more than one cup is valid, the safe approach is to match the number stamped on the cup already in your machine rather than assume. If you are starting from scratch, specify the assembly (for example 18200/18337) so the supplier ships a matched pair — and note that a precision-class cone should be paired with a cup of matching class if the position is a precision one.

What Class 00 precision actually buys you

The “#00” / “*00” marking carried on this cone is a Timken precision class designation, not a variant part number. Timken’s inch tapered roller classes run from standard through Class 3 to Class 0 and Class 00, with each step tightening the tolerances. Class 00 is tighter than Class 3, which makes it the top of the commercially available inch precision ladder.

What tightens is closer control on the bore and on the raceway geometry, and tighter running accuracy — less radial and axial runout as the bearing turns. That matters where the bearing sets the position of something, not merely supports it: machine-tool spindles, precision gearboxes and index heads, grinding and boring positions, measuring and test equipment. In those positions bearing runout is transferred straight into the workpiece or the gear mesh, so a tenth of a thousandth of an inch at the bearing becomes a visible error at the tool.

It is also a genuine price differentiator rather than a marketing suffix. A Class 00 cone costs materially more than a standard-class 18200 because it takes extra grinding and gauging to produce, and a buyer who needs it cannot substitute the standard version. Equally, if your position is an ordinary industrial one, a standard 18200 will do the job and there is no reason to pay for Class 00 — but if the drawing calls for Class 00, this is the part.

Published ratings and mounting data

Load ratings below are Timken’s own published figures for the 18200 cone reference. They describe the complete single-row assembly — cone plus its mating cup — not the cone in isolation. A bare cone has no load rating of its own, because capacity is a property of the roller set running between both raceways. Bore, inner ring width, weight and shaft abutment figures are cone-specific.

Cone bore (d): 2.0000 in / 50.8 mmInner ring width (B): 0.7190 in / 18.263 mmPrecision class: Class 00Dynamic radial load rating C1 (1 million revolutions, ISO method): 13,700 lbf / 61,100 NDynamic radial load rating C90 (90 million revolutions, Timken method): 3,560 lbf / 15,800 NDynamic axial rating Ca90: 3,470 lbf / 15,400 NStatic radial load rating C0: 14,400 lbf / 63,900 NK factor: 1.03Effective centre location (a): 0.08 in / 2 mmMaximum shaft fillet radius cleared: 0.06 in / 1.5 mmShaft backing shoulder diameter, frontface (da): 2.2 in / 56 mmShaft backing shoulder diameter, backface (db): 2.32 in / 59 mmCage location relative to backface (Aa): 0.07 in / 1.8 mmCage location relative to frontface (Ab): 0.09 in / 2.3 mmG1 factor 26.1, G2 factor 20.3, geometry factor Cg 0.0852Cone weight: 2.8 lb / 1.3 kg

What these specs mean in practice

The K factor of 1.03 is unusually low for a tapered roller bearing and it tells you a lot. K is the ratio of radial to thrust capability, set by the cup angle: the lower the K, the steeper the angle and the more thrust the bearing takes for a given radial load. At 1.03 this bearing is close to balanced — its published Ca90 of 3,470 lbf is nearly equal to its C90 of 3,560 lbf. That is a steep-angle bearing intended for positions where axial load is a serious part of the duty, which is exactly the profile of a machine-tool spindle or a bevel/helical gearbox shaft. Pair that with Class 00 accuracy and the intended application becomes clear.

C1 and C90 are the same bearing described at two different life bases — C1 (13,700 lbf) at one million revolutions on the ISO method, C90 (3,560 lbf) at ninety million revolutions on Timken’s method. They are not competing claims. Compare like with like across catalogues or you will draw a nonsense conclusion.

Quantity and configuration

Priced and sold per single cone; two are in stock. Single-row tapered roller bearings normally work in opposed pairs, because one row can only resist thrust in one direction — so a typical shaft needs two cones and two cups. Two cones is exactly one shaft’s worth for a back-to-back or face-to-face pair, which for a precision-class part in short supply is worth knowing before someone else buys one of them.

Fitting notes

The cone is an interference fit on the shaft. Press it on square, loading the cone backface only — never through the rollers or the cage. A hammer blow that passes through the roller set will brinell the raceway and destroy the running accuracy you paid for, which on a Class 00 part means throwing away the entire reason for buying it. Respect the 0.06 in maximum shaft fillet radius and keep the backing shoulder within the published da / db window.

A tapered roller bearing has no built-in internal clearance. Operating clearance or preload is created at assembly by how far the cone is drawn up against the cup, and that setting is the single largest determinant of both bearing life and spindle accuracy. On a precision position, set it to the machine builder’s figure with a dial indicator or a torque-and-rotation check rather than by feel, and do not reuse an old shim stack against a new cone — an unworn raceway changes the stack-up.

Interchange guidance

18200 is an industry-standard inch cone designation rather than a Timken-proprietary code, and cones to this number are produced by several manufacturers, so a same-number cone from another maker is dimensionally interchangeable in the standard class. The precision class does not interchange — a standard-class 18200 will fit the same envelope but will not deliver Class 00 running accuracy, so if the drawing specifies the class, match the class.

Searchable forms: 18200, 18200-00, 18200 #00, 18200 *00, 18-200, 18 200, K-18200, and the unsuffixed standard-class 18200. Cups and assemblies: 18337, 18335E, 18335X, 18200/18337, 18200-18337, 18200/18335E. Central Surplus also stocks other Timken inch-series cups and cones, including Class 3 precision cones and large-bore cup references, so a matched-class pair may be available from stock.