TimkenTapered Roller Bearing Cone – 2.1880 in Bore, 0.8640 in Width, Class 3, K Factor 1.65

Product Description

What this part is

Timken 389-3 tapered roller bearing cone. This is the inner ring with its tapered roller set and cage, the rotating half of a Timken TS single-row inch tapered roller bearing, built to Class 3 precision. Bore Diameter: 2.1880 in (55.575 mm). Overall Width: 0.8640 in (21.946 mm) inner ring width. Item Weight: 2.56 kg (5.64 lb). Dynamic Load Rating: 108,000 N (24,200 lbf) at C1. Static Load Rating: 107,000 N (24,100 lbf). Precision Class: Class 3. Rolling Elements: Tapered Roller. Number Of Rows: 1. Bore Type: Straight. Cage Type: Pressed. Bearing Material: case-carburized alloy steel. Design Units: Imperial. Series: 380. Base Number: 389.

Decoding the designation

389 — a cone number in Timken’s inch 380 tapered roller series, fixing the 2.1880 in bore and the 0.8640 in inner ring width.

-3 — Precision Class 3, also written *3 and #3. A tighter tolerance than standard, giving lower running vibration and closer location of the shaft. The class changes tolerance only; bore, width, raceway angle and load ratings are those of the 389.

What these specs mean in practice

K Factor: 1.65. A K factor of 1.65 is a moderate taper: radial load dominates, with a useful thrust reserve. That is the general-purpose profile for a shaft carried on an opposed pair.

Dynamic Load Rating: 108,000 N (C1, at 1 million revolutions, ISO method). Static Load Rating: 107,000 N. Dynamic Radial Load Rating at 90 million revolutions (C90): 28,000 N. Dynamic Axial Rating at 90 million revolutions (Ca90): 16,900 N. On this cone the static and dynamic radial figures sit within one per cent of each other, so a duty that is limited by shock load is limited at essentially the same number as one limited by fatigue life.

G1 Factor: 42. G2 Factor: 15.7. Geometry Factor (Cg): 0.0859, the geometry constant for the lubrication life adjustment factor a3l.

Mounting data

Maximum Shaft Fillet Radius: 0.09 in (2.3 mm) — the largest fillet the shaft shoulder may carry and still be cleared by the cone corner. Shaft Backing Shoulder Diameter, frontface (da): 2.40 in (61 mm). Shaft Backing Shoulder Diameter, backface (db): 2.56 in (65 mm). Effective Centre Location: -0.12 in (-3 mm); the negative value places the effective load centre inside the cone backface. Cage Location relative to backface (Aa): 0.03 in. Cage Location relative to frontface (Ab): 0.11 in.

Quantity and configuration

Unit Quantity: 1 Pc. Cone only — inner ring, rollers and cage. The matching cups are the Timken 382 and 382A.

Interchange guidance

389 is an inch tapered roller cone number on the common industry dimensional standard, so a 389 from another inch-series maker carries the same bore, width and raceway angle. The Class 3 tolerance is a Timken execution, so a standard-tolerance 389 matches the envelope but not the running accuracy. Cross-references: Koyo 389, NTN 4T-389, NSK 389, Bower / BCA 389, Fersa 389.