Timken397W-3Tapered Roller Bearing Cone Only, 2.3622 in / 60 mm Bore, Class 3 Precision, Slotted, Mates 394A Cup

Product Description

What this part is

The cone of a single-row inch-series tapered roller bearing on the 397 numbering — that is, the inner ring complete with its tapered roller set and cage. The bore is 2.3622 in, which is exactly 60.000 mm: this is one of the inch-series bearings Timken produces on a metric bore so it drops onto metric shafting. The mating cup is the 394A, which has a 4.3307 in (110.000 mm) outside diameter.

Quantity and configuration

This listing is the cone only. No cup is included. That is the normal way tapered roller bearings are sold as service parts, because the cup is often still good when the cone and rollers are worn — but if you need a complete bearing you will also need a 394A cup, or one of the other cups listed below.

Decoding the designation

397 – the cone number. The complete bearing is 397/394A.
W – a slot feature on the cone, a Type 12 slot in Timken’s suffix scheme. It is a geometry feature for lubricant flow or anti-rotation, not a change to the bore, the outside diameter or the load rating. Related suffixes WA, WB, WE and WD denote other slot forms.
*3 or Class 3 – the precision class.

What these specs mean in practice

Class 3 is the reason to want this particular cone, and the numbering is genuinely counterintuitive. For inch-series tapered roller bearings the precision ladder runs, loosest to tightest: Class 4 (standard commercial) → Class 2 → Class 3 → Class 0 → Class 00 → Class 000. So Class 3 is the first true precision grade above commercial, broadly equivalent to ABEC 5, ISO P5, or Timken’s metric Class C. It is not a downgrade from Class 0 — it is two steps below it, and two steps above ordinary Class 4. Anyone reading the number as a simple “lower is looser” scale will get it backwards, which is exactly why it is worth stating.

Tighter class means tighter control of bore and raceway runout and of the assembled bearing’s width variation, so a Class 3 cone belongs in machine tool spindles, precision gearboxes, printing and converting equipment and anywhere shaft position or repeatability matters. Fitting one into a commercial position does no harm; fitting a Class 4 cone into a Class 3 position gives away the accuracy the machine was designed around.

Remember that a tapered roller bearing has no internal clearance until it is assembled. Two of these mounted in opposition on a shaft are set against each other with shims, a spacer or a nut to a specified end play or preload, and that setting governs how the assembly runs.

Published ratings and mounting data

Cone bore d: 2.3622 in (60.000 mm)
Cone width B: 0.8660 in (21.996 mm)
Mating cup: 394A — 4.3307 in (110.000 mm) outside diameter, 0.7411 in (18.824 mm) wide
Assembled bearing width T with the 394A cup: 0.8661 in (21.999 mm)
Rows: 1, tapered rollers
Dynamic radial rating C90: 5,760 lbf — C1 22,200 lbf
Dynamic thrust rating Ca90: 3,970 lbf
Static radial rating C0: 28,100 lbf (125 kN)
K factor: 1.45 — e 0.40, Y 1.49
Precision class: 3 (approximately ABEC 5 / ISO P5)
Cage: stamped steel

Interchange guidance

397 is a standard AFBMA inch cone number, so Timken 397, SKF 397, NTN 4T-397 and Koyo 397 describe the same ring. Cups that mate the 397 cone: 393, 393A, 393AS, 393C, 393WE, 394, 394A, 394ARB, 394AS, 394CS and 394XS as single cups, 394AB as a flanged cup, and 394D, 394DC and 394YD as double cups for two-row TDO builds. Be careful of one common mix-up: cup 3920 is not a mate for the 397 — it belongs to the 3979/3980/3982/3984 cone family on a 2.500 in bore with a 4.4375 in outside diameter, and it will not fit. Standard-class cones 397 and 397A cover the same envelope without the Class 3 precision or the W slot, and are carried here as cross-references for buyers who do not need the tighter class.