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The configuration of the TDO provides a wide effective bearing spread, making it ideal for applications in which overturning moments are a significant load component. TDO bearings can be used in fixed positions or allowed to float in the housing bore.
Unit of Measure

Specifications

Series

 N/A 78000

Cone Part Number

 N/A 78255X

Cup Part Number

 N/A 78551DF

Design Unit

 N/A Inch

Cage Material

 N/A Stamped Steel

Dimensions

d - Bore

 N/A 2.5586 in64.988 mm

D - Cup Outer Diameter

 N/A 5.5100 in139.954 mm

B - Cone Width

 N/A 1.2962 in32.923 mm

C - Double Cup Width

 N/A 2.0395 in51.803 mm

T - Bearing Width across Cones

 N/A 3.0625 in77.788 mm

Abutment and Fillet Dimensions

R - Cone Backface "To Clear" Radius1 N/A 0.14 in3.600 mm
r - Cup Backface "To Clear" Radius2 N/A 0.06 in1.5 mm

db - Cone Backface Backing Diameter

 N/A 3.5 in89 mm

Da - Cup Frontface Backing Diameter

 N/A 5.19 in131.83 mm

Aa - Cage-Cone Backface Clearance

 N/A 0.24 in6.1 mm
a - Effective Center Location3 N/A 0.31 in7.9 mm

Basic Load Ratings

C90 - Dynamic Radial Rating (One-Row, 90 million revolutions)4 N/A 11800 lbf52600 N
C1 - Dynamic Radial Rating (Two-Row, 1 million revolutions)5 N/A 79300 lbf353000 N
C90(2) - Dynamic Radial Rating (Two-Row, 90 million revolutions)6 N/A 20600 lbf91500 N
Ca90 - Dynamic Thrust Rating (90 million revolutions)7 N/A 17500 lbf77900 N

Factors

K - Factor8 N/A 0.67
e - ISO Factor9 N/A 0.87
Y1 - ISO Factor10 N/A 0.78
Y2 - ISO Factor11 N/A 1.16
Cg - Geometry Factor12 N/A 0.0884
  • 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 Negative value indicates effective center inside cone backface.
  • 4 Based on 90 x 106 revolutions L10 life, for The Timken Company life calculation method. C90 and Ca90 are radial and thrust values.
  • 5 Based on 1 x 106 revolutions L10 life, for the ISO life calculation method.
  • 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 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.
  • 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 These factors apply for both inch and metric calculations. Consult your Timken representative for instruction on use.
  • 12 Geometry constant for Lubrication Life Adjustment Factor a3l.
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