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TDI bearings have a one-piece double inner race and two single outer races and are typically supplied complete with an outer race spacer as a pre-set assembly. The bearing can be used at fixed positions on rotation shaft applications. For rotating housing application it can be used to float on the stationary shaft.
Unit of Measure

Specifications

Series

 N/A 78000

Cone Part Number

 N/A 78251D

Design Units

 N/A Imperial

Cage Type

 N/A Stamped Steel
C1 - Dynamic Radial Rating (1 million revolutions)1 N/A 38400 lbf171000 N

C0 - Static Radial Rating

 N/A 43400 lbf193000 N

Dimensions

d - Cone Bore

 N/A 2 1/2 in63.500 mm

B - Double Cone Width

 N/A 2.5980 in65.989 mm

Abutment and Fillet Dimensions

R - Cone Backface "To Clear" Radius2 N/A 0.09 in2.300 mm

da - Cone Frontface Backing Diameter

 N/A 3.11 in79 mm

Ab - Cage-Cone Frontface Clearance

 N/A 0.08 in2 mm

Basic Load Ratings

C90 - Dynamic Radial Rating (90 million revolutions)3 N/A 9970 lbf44300 N
C1 - Dynamic Radial Rating (Two-Row, 1 million revolutions)4 N/A 66900 lbf298000 N
C90(2) - Dynamic Radial Rating (Two-Row, 90 million revolutions)5 N/A 17400 lbf77200 N
Ca90 - Dynamic Thrust Rating (90 million revolutions)6 N/A 14800 lbf65700 N

Factors

K - Factor7 N/A 0.67

G1 - Heat Generation Factor (Roller-Raceway)

 N/A 62.6

G2 - Heat Generation Factor (Rib-Roller End)

 N/A 19.1
Cg - Geometry Factor8 N/A 0.0884
  • 1 Based on 1 x 106 revolutions L10 life, for the ISO life calculation method.
  • 2 These maximum fillet radii will be cleared by the bearing corners.
  • 3 Based on 90 x 106 revolutions L10 life, for The Timken Company life calculation method. C90 and Ca90 are radial and thrust values.
  • 4 Based on 1 x 106 revolutions L10 life, for the ISO life calculation method.
  • 5 Based on 90 x 106 revolutions L10 life, for The Timken Company life calculation method. C90 and Ca90 are radial and thrust values for a single-row, C90(2) is the two-row radial value.
  • 6 Based on 90 x 106 revolutions L10 life, for The Timken Company life calculation method. C90 and Ca90 are radial and thrust values for a single-row, C90(2) is the two-row radial value.
  • 7 These factors apply for both inch and metric calculations. Consult your Timken representative for instruction on use.
  • 8 Geometry constant for Lubrication Life Adjustment Factor a3l.
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