Timken397W-3/394DC-3Tapered Roller Bearing Cone and Double Cup – 2.3622 in Bore, 4.3307 in Cup OD, 1.8125 in Cup Width, 0.8660 in Cone Width, Class 3, Case-Hardened Steel

Product Description

What this part is

Timken 397W-3 tapered roller bearing cone together with a 394DC-3 double cup. The cone is the inner ring with its roller and cage assembly, bore 2.3622 in (60 mm). The 394DC is a double cup: one outer ring carrying two opposed tapered raceways, outside diameter 4.3307 in (110 mm) and width 1.8125 in. Both pieces are Class 3 precision, denoted by the -3 suffix.

Quantity and configuration

One cone and one double cup. A double cup carries two raceways and is designed to seat two cones in a TDO arrangement, so the pair here forms one of the two rows.

Decoding the designation

The DC on 394DC marks a double cup in Timken’s tapered double outer family. The -3 on both pieces is Timken precision Class 3, a tighter tolerance grade than standard Class 4 or Class 2. The 397 cone and the 394 cup family share the 2.3622 in bore and 4.3307 in outside diameter, so the 394DC sits on the same envelope as the single 394 cup.

Ratings and factors

Single-row cone ratings for the 397: dynamic radial 22,200 lbf (98,900 N) at 1 million revolutions, 5,760 lbf (25,600 N) at 90 million revolutions, dynamic axial 3,970 lbf (17,600 N) at 90 million revolutions, and static radial 28,100 lbf (125,000 N). The K factor is 1.45 and the e factor 0.40. The 394DC carries Y1 1.68 and Y2 2.50, and the geometry factor Cg is 0.0984 on both pieces.

What these specs mean in practice

A tapered roller bearing carries combined radial and thrust load in one direction per row, and the ratio between the two is set by the cup angle. A K factor of 1.45 and an e factor of 0.40 mean thrust becomes the governing load once the axial-to-radial ratio passes 0.40, at which point the Y2 factor of 2.50 applies in the equivalent load calculation. The TDO double cup geometry places the two effective load centres outboard, which gives a wide effective bearing spread and makes the arrangement well suited to overturning moments — wheel ends, pinion mountings and gearbox output shafts.

Fitting notes

Cone side: shaft backing shoulder diameter is 2.68 in at the frontface and 2.72 in at the backface, and the maximum shaft fillet radius cleared by the bearing corner is 0.03 in. Cage clearance is 0.05 in relative to the backface and 0.11 in relative to the frontface. Effective centre location is -0.03 in, inside the cone backface. Cup side: housing backing shoulder diameter is 4.12 in and the maximum housing fillet radius is 0.03 in. Cone weight is 4.33 lb and cup weight 3.98 lb.

Interchange guidance

Timken pairs the 394DC double cup with 395A, 395X and 399AS cones as well as the 397, and the 397 cone also runs against the single 394, 394A and 394D cups. Those combinations change the effective spread and the ratings, so the cone and cup numbers are matched as a pair rather than substituted independently.