Timken344AImperial Tapered Roller Bearing Cone, 1.5748 in / 40 mm Bore, Mates Cup 332A – 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

344A is a Timken imperial cone in the 33x/34x family. Its published mating cups are 332A and 332US, so a complete single-row bearing is a 344A cone plus a 332A cup. The 1.5748 in bore is the inch equivalent of a 40 mm shaft, which is why this cone appears in metric-shafted machinery as well as inch drivetrains.

Published dimensions

Cone bore (d): 1.5748 in / 40 mm
Inner ring width (B): 0.8820 in / 22.403 mm
Mating cup 332A outside diameter (D): 3.1496 in / 80 mm
Mating cup 332A width (C): 0.8268 in / 21.001 mm
Cone weight: 1.1 lb / 0.5 kg

Published ratings and mounting data

The ratings below are catalogue values for the complete 344A/332A single-row assembly, not for the cone alone.

Dynamic radial rating C1 (1 million rev basis): 21,200 lbf / 94,300 N
Dynamic radial rating C90 (90 million rev basis): 5,490 lbf / 24,400 N
Dynamic axial rating Ca90: 2,570 lbf / 11,400 N
Static radial rating C0: 18,700 lbf / 83,400 N
K factor: 2.14 · e: 0.27 · Y: 2.20 · geometry factor Cg: 0.0676
Maximum shaft fillet radius cleared: 0.03 in / 0.8 mm
Shaft backing shoulder diameter, frontface (da): 1.79 in / 45.5 mm
Shaft backing shoulder diameter, backface (db): 1.81 in / 46 mm

What these specs mean in practice

A K factor of 2.14 with an e of 0.27 and a Y of 2.20 describes a shallow, radially biased taper: excellent radial capacity for the envelope, modest thrust capacity, and very little induced thrust handed to the opposing bearing. That is the right choice for a mainly radial position — a countershaft, an idler, a conveyor head shaft — and the wrong one where axial load dominates. The tight 0.03 in shaft fillet allowance is the one thing to check before fitting; anything more generous on the shaft shoulder will hold the cone off its seat.

Quantity and configuration

This listing ships 1 Pc — one 344A cone. No cup, no spacer, no seal.

Fitting notes

Press the cone on square, driving on the backface only and never through the rollers or cage. Keep the shaft shoulder within the da/db figures above. A tapered roller bearing has no internal clearance until it is mounted, so the end play or preload is set after the cup is seated in its housing.

Interchange guidance

344A is dimensionally standardised, so 344A cones from Timken, Koyo, NTN, Bower/BCA and Federal-Mogul interchange with one another and with any maker’s 332A cup. Note the important distinction inside the family: plain 344 shares this bore, width and every published rating but takes the 332/333 cup family rather than 332A/332US, and it permits a much larger shaft fillet radius (0.14 in against 0.03 in here). Treat 344 as a related part, not a drop-in equivalent, unless you are also matching the cup.