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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.
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Unit of Measure

Specifications

Series

 N/A 78000

Cone Part Number

 N/A 78251D

Cup Part Number

 N/A 78537

Design Unit

 N/A Inch

Cage Material

 N/A Stamped Steel

Related Assembly Number(s)

 N/A 78251D-90050

Dimensions

d - Bore

 N/A 2 1/2 in63.500 mm

D - Cup Outer Diameter

 N/A 5.3750 in136.525 mm

B - Double Cone Width

 N/A 2.5980 in65.989 mm

C - Cup Width

 N/A 0.9260 in23.520 mm

T - Bearing Width across Cups

 N/A 2.6020 in66.091 mm

Abutment and Fillet Dimensions

R - Cone Backface "To Clear" Radius1 N/A 0.09 in2.300 mm
r - Cup Backface "To Clear" Radius2 N/A 0.130 in3.30 mm

da - Cone Frontface Backing Diameter

 N/A 3.11 in79 mm

Db - Cup Backface Backing Diameter

 N/A 4.53 in115.06 mm

Ab - Cage-Cone Frontface Clearance

 N/A 0.08 in2 mm

Basic Load Ratings

C90 - Dynamic Radial Rating (One-Row, 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
e - ISO Factor8 N/A 0.87
Y1 - ISO Factor9 N/A 0.78
Y2 - ISO Factor10 N/A 1.16

G1 - Heat Generation Factor (Roller-Raceway)

 N/A 62.6

G2 - Heat Generation Factor (Rib-Roller End)

 N/A 19.1
Cg - Geometry Factor11 N/A 0.0884

Spacer

Note

 N/A Spacer shows standard nominal .01 radii, actual bearing may vary
  • 1 These maximum fillet radii will be cleared by the bearing corners.
  • 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 These factors apply for both inch and metric calculations. Consult your Timken representative for instruction on use.
  • 9 These factors apply for both inch and metric calculations. Consult your Timken representative for instruction on use.
  • 10 These factors apply for both inch and metric calculations. Consult your Timken representative for instruction on use.
  • 11 Geometry constant for Lubrication Life Adjustment Factor a3l.