NTN3386Imperial Tapered Roller Bearing Cone, 1.5625 in / 39.688 mm Bore, Mates Cup 3320 – 1 Pc

Product Description

What this part is

This is an imperial single-row tapered roller bearing cone — the inner ring with its tapered rollers and cage. It is one half of a tapered roller bearing. The mating cup (outer race) is a separate part number and is not included in this listing.

Decoding the designation

3386 is the industry-standard imperial cone number; NTN catalogues it as 4T-3386, where 4T is NTN’s case-carburised steel designation for shock-resistant tapered rollers. Its matching cup is 3320 (3321 is also listed), so a complete single-row bearing is a 3386 cone plus a 3320 cup.

Published dimensions

Cone bore (d): 1.5625 in / 39.688 mm
Inner ring width (B): 1.1965 in / 30.391 mm
Mating cup 3320 outside diameter (D): 3.1562 in / 80.167 mm
Mating cup 3320 width (C): 0.9375 in / 23.813 mm
Cone weight: 2.1 lb / 0.9 kg

Published ratings and mounting data

The ratings below are catalogue values for the complete 3386/3320 single-row assembly, not for the cone alone.

Dynamic radial rating C1 (1 million rev basis): 25,800 lbf / 115,000 N
Dynamic radial rating C90 (90 million rev basis): 6,700 lbf / 29,800 N
Dynamic axial rating Ca90: 3,130 lbf / 13,900 N
Static radial rating C0: 29,100 lbf / 129,000 N
K factor: 2.14 · e: 0.27 · Y: 2.20 · geometry factor Cg: 0.0744
Effective load centre: −0.43 in / −10.9 mm (inside the cone backface)
Maximum shaft fillet radius cleared: 0.03 in / 0.80 mm
Shaft backing shoulder diameter, frontface (da): 1.79 in / 45.5 mm
Shaft backing shoulder diameter, backface (db): 1.83 in / 46.5 mm

What these specs mean in practice

A K factor of 2.14 is at the shallow, radially biased end of the tapered roller range, and the low e value of 0.27 with a high Y of 2.20 says the same thing from the other direction: this bearing is at its best carrying radial load, and thrust starts to dominate the calculation early. The payoff is that it passes very little induced thrust to the opposing bearing, which is what you want on a long shaft with a light second bearing. Two constraints deserve attention: the 0.03 in maximum shaft fillet radius is tight, and the effective load centre sits 0.43 in inside the cone backface, which is a long way in — use it rather than the physical face when calculating bearing spread.

Quantity and configuration

This listing ships 1 Pc — one 3386 cone. No cup, no spacer, no seal.

Fitting notes

Press the cone on square with the driver on the backface only, never through the rollers or cage. Keep the shaft shoulder within the da/db range and the fillet under 0.03 in — a generous machined radius will hold the cone off its seat. A tapered roller bearing has no internal clearance until it is mounted, so the setting is established after the cup is fully home.

Interchange guidance

3386 is a dimensionally standardised imperial cone, so NTN 4T-3386, Timken 3386, Koyo 3386, Bower/BCA 3386 and Federal-Mogul 3386 interchange with one another and with any maker’s 3320 cup. 3387 and 3385 are related sizes, not equivalents, and cup 3321 differs from 3320 in width — match the number to your housing rather than assuming the family is interchangeable.