Timken27881-3/27820-3Tapered Roller Bearing Cone & Cup Set – 1-1/2 in Bore, 3.1510 in Cup Outer Diameter, 0.9688 in Assembled Width, Class 3, Case-Carburized Steel

Product Description

What this part is

Timken 27881-3/27820-3 single-row tapered roller bearing, supplied as a matched cone and cup set. The 27881 is the cone, comprising the inner ring with its roller and cage assembly; the 27820 is the cup, the outer race. Bore 1-1/2 in (38.1 mm), cup outside diameter 3.1510 in (80.035 mm), assembled width 0.9688 in (24.608 mm).

Decoding the designation

Timken writes a single-row tapered roller assembly as cone number over cup number, so 27881/27820 names the two halves. The –3 suffix carried by both halves, marked on the carton as 27881 *3 and 27820 *3, is Timken precision Class 3. Cage is stamped steel and both rings are case-carburized steel.

What these specs mean in practice

The K factor of 1.04 is the ratio of radial to thrust capability, and at that value this is a steep-angle taper with thrust capacity close to its radial capacity: dynamic axial rating is 4,370 lbf against a dynamic radial rating of 4,550 lbf on the Timken ninety-million-revolution basis. The e factor is 0.56 and the Y factor 1.07. Dynamic radial rating on the ISO one-million-revolution basis is 17,500 lbf and static radial rating is 20,500 lbf. Effective centre location is –0.1 in, inside the cone backface.

Quantity and configuration

Two pieces, one cone and one cup, forming one complete single-row bearing. Assembled weight 1.2 lb.

Mounting dimensions

Shaft backing shoulder diameter is 1.85 in at the frontface and 2.09 in at the backface. Housing backing shoulder diameter is 2.99 in at the frontface and 2.68 in at the backface. Maximum shaft fillet radius that the bearing corners clear is 0.14 in, and maximum housing fillet radius 0.06 in. Cone inner ring width is 0.9330 in and cup outer ring width 0.7288 in. Cage location relative to the backface is 0.1 in and relative to the frontface 0.09 in.

Fitting notes

Tapered roller bearings mount in opposing pairs, and the setting is established at assembly by adjusting the axial position of one row against the other. Class 3 holds tighter bore, outside diameter and running accuracy tolerances than standard Class 4 product. The lubrication life adjustment geometry factor Cg is 0.0839, with G1 of 24.6 and G2 of 12.6.

Interchange guidance

The 27881 cone runs against the 27820 cup in this pairing. The 27880/27820 is a related size sharing the 27820 cup with a different cone.