Timken14125A/14276DDouble Row TDO Tapered Roller Bearing Assembly, 1-1/4 in Bore x 2.717 in Outside Diameter, Two Cones and One Double Cup, 1.5 in Cup Width, K Factor 1.53

Product Description

What this part is

This is a complete TDO (Tapered Double Outer) two-row tapered roller bearing assembly, made up of two 14125A cone assemblies and one 14276D double cup. A TDO is a two-row unit built around a single double-wide outer ring with two internal raceways, so both rows share one cup and the whole stack drops into a plain straight-bored housing. Bore is 1.25 in / 31.750 mm, cup outside diameter is 2.7170 in / 69.012 mm, and the double cup is 1.5 in / 38.1 mm wide.

Decoding the designation

14125A — the cone, meaning the tapered inner ring complete with its roller and cage assembly. Bore 1.25 in, inner ring width 0.7710 in / 19.583 mm.14276D — the cup. The trailing D marks it as a double cup, one outer ring machined with two opposed raceways rather than the single-race 14276 that pairs with one cone.Cone and cup carry separate part numbers because they are separate rings. A tapered roller bearing is only a bearing once you have both, which is why this lot deliberately contains three pieces rather than one.

Quantity and configuration

One assembly, three physical pieces: two cones and one double cup. That is the full complement for a 14276D — nothing further is needed to make the bearing itself. Photographs show the two cones stamped X-TIMKEN 14125-A MADE IN USA and the double cup stamped 14276D MADE IN USA, along with the assembled two-row stack. No spacer, retaining ring, seal or housing is included.

What these specs mean in practice

The K factor of 1.53 is the ratio of dynamic radial rating to dynamic thrust rating, and it is what you use to work out how much of a combined load a given row will actually carry. A K near 1.5 puts this design in the general-purpose steep-enough-to-take-real-thrust band rather than the shallow, radial-only band. The e value of 0.38 with Y1 1.77 and Y2 2.63 is the pair you feed into an equivalent-load calculation: below an axial-to-radial ratio of 0.38 you use one thrust factor, above it you use the other, because the load zone in the raceway changes shape.

The effective centre location on the 14125A cone is −0.17 in / −4.3 mm, and the minus sign matters. It says the point where the bearing’s reaction load actually acts sits inside the cone backface, not outside it. If you are laying out shaft spans or calculating bearing spacing, using the physical face instead of the effective centre puts your reaction loads in the wrong place and understates the real bending on the shaft.

Why a TDO is worth having

A TDO ships preset. The internal clearance between the two rows is established at the factory by the geometry of the double cup, so you do not have to set endplay by trial-and-error shimming on assembly. With two independent single-row tapered bearings you must set a specified endplay or preload by adjusting a nut or shim pack; too much endplay and the rollers skid and beat out the raceway, too much preload and you cook the bearing from friction heat within hours. A preset two-row unit removes that whole failure mode, which is why TDO designs are common on wheel ends, gearbox pinions and roll necks where nobody wants a technician guessing.

Published ratings and mounting data

Bore (cone) d: 1.25 in / 31.750 mmCup outside diameter D: 2.7170 in / 69.012 mmCone inner ring width B: 0.7710 in / 19.583 mmDouble cup outer ring width C: 1.5 in / 38.1 mmDynamic radial rating C1 (1 million revolutions), per row: 12,300 lbf / 54,600 NDynamic radial rating C90 (90 million revolutions), per row: 3,180 lbf / 14,200 NDynamic axial rating Ca90, per row: 2,080 lbf / 9,260 NStatic radial rating C0, per row: 13,900 lbf / 61,700 NK factor 1.53; e 0.38; Y1 1.77; Y2 2.63; Cg 0.0668Maximum shaft fillet radius: 0.14 in / 3.600 mmShaft backing shoulder diameter, frontface da: 1.54 in / 39 mm; backface db: 1.77 in / 45 mmMaximum housing fillet radius: 0.03 in / 0.8 mm; housing shoulder frontface Da: 2.52 in / 64 mmGeometry factors G1 18, G2 13.3Weight: cone 1.63 lb / 0.738 kg each, double cup 1.86 lb / 0.843 kg

Fitting notes

Cones and cups are lapped as matched families, not as individually interchangeable rings. Mixing a 14125A cone against a cup of a different part number, or forcing a nominally similar cup from another maker, changes the contact angle relationship and gives you edge loading on the roller ends. Keep the set together.

Press only on the ring that is being fitted. Drive the cup by its own face into the housing bore and the cone by its own face onto the shaft — never transmit installation force through the rollers, because a single hammer blow passed through a roller leaves a brinell mark in the raceway that becomes a vibration source and then a spall. Respect the fillet radius limits above: a shaft or housing corner radius larger than the figure quoted will hold the ring off its shoulder and tilt it.

Interchange guidance

The 14125A cone’s standard single-cup mate is the 14276. This lot uses the 14276D double cup instead, which is the correct two-row form. The cone series is written variously as 14125A, 14125-A and 14125 A; the cup as 14276D, 14276-D and 14276 D. Set nomenclature for the pair is commonly quoted as 14125A/14276D or SET-style references in distributor catalogues. Cross-reference by dimension when comparing against other makers: 31.750 mm bore, 69.012 mm cup outside diameter, 38.1 mm double cup width.