Timken3577XImperial Tapered Roller Bearing Cone, 1.6250 in / 41.275 mm Bore, Mates Cup 3520 – 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. The design is open, with no snap ring.

Decoding the designation

The base number is 3577, a standard imperial cone in the 35xx family; its matching cup is 3520 (3525 is also listed), so a complete single-row bearing is a 3577 cone plus a 3520 cup. The X in 3577X is a variant suffix carried on the ring or carton for which Timken publishes no decode, so it is treated here as an alternate form of the number rather than a claimed specification. The published 3577 dimensions and ratings below are what govern fit.

Correcting the source data

Earlier copy on this listing gave a dynamic rating of 51.5 kN, a static rating of 66.5 kN, a width of 22.225 mm, a −40 to 120°C temperature range and a weight of about 0.8 lb. The published figures are a dynamic rating (C1) of 113,000 N, a static rating (C0) of 134,000 N, an inner ring width of 30.886 mm / 1.2160 in and a weight of 1.3 lb. No temperature range is published for a standalone cone, because operating temperature depends on the lubricant, cup, housing and setting rather than the ring. The 22.225 mm width quoted previously belongs to a different family entirely — if you were calculating a spacer stack from it, work again from 1.2160 in.

Published dimensions

Cone bore (d): 1.6250 in / 41.275 mm
Inner ring width (B): 1.2160 in / 30.886 mm
Mating cup 3520 outside diameter (D): 3.3125 in / 84.138 mm
Mating cup 3520 width (C): 0.9375 in / 23.813 mm
Cone weight: 1.3 lb / 0.6 kg

Published ratings and mounting data

The ratings below are catalogue values for the complete 3577/3520 single-row assembly, not for the cone alone.

Dynamic radial rating C1 (1 million rev basis): 25,500 lbf / 113,000 N
Dynamic radial rating C90 (90 million rev basis): 6,610 lbf / 29,400 N
Dynamic axial rating Ca90: 3,460 lbf / 15,400 N
Static radial rating C0: 30,100 lbf / 134,000 N
K factor: 1.91 · e: 0.31 · Y: 1.96 · geometry factor Cg: 0.0808
Effective load centre: −0.40 in / −10.2 mm (inside the cone backface)
Maximum shaft fillet radius cleared: 0.14 in / 3.600 mm
Shaft backing shoulder diameter, frontface (da): 1.89 in / 48 mm
Shaft backing shoulder diameter, backface (db): 2.13 in / 54 mm

What these specs mean in practice

The shallow 1.91 K factor makes this a radially biased taper that hands very little induced thrust to the opposing bearing, and the static rating exceeding the dynamic C1 marks it as a shock and overload design rather than a high-speed one. The generous 0.14 in permissible shaft fillet radius is worth noting — it is more than double what the closely related 3585 allows, which makes 3577 the easier of the two to fit on a shaft that was not machined to bearing-seat standards. Carburised bearing steel gives a tough core under a hard case, which is what resists spalling under shock. Lubricate with oil or grease to suit the housing.

Quantity and configuration

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

Fitting notes

Press the cone on square with the driver bearing on the backface only, never on the rollers or cage. Keep the shaft shoulder within the da/db range. A tapered roller bearing has no internal clearance until it is mounted, so the end play or preload is set after the cup is fully home in its housing.

Interchange guidance

3577 is dimensionally standardised, so 3577 cones from Timken, Koyo, NTN, Bower/BCA and Federal-Mogul interchange with one another and with any maker’s 3520 cup. Inside the family, 3576 and 3585 share this bore, inner ring width and every published rating, and run in the same 3520 cup, but differ in permissible shaft fillet radius and backface shoulder diameter — close relatives rather than blind substitutes. A 3577X ring marking should be read as a 3577 for fitting purposes.