Montage of Timken Bearing Products
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This is the most basic and most widely used type of tapered roller bearing. It consists of two main separable parts: the cone (inner ring) assembly and the cup (outer ring). It is typically mounted in opposing pairs on a shaft.
Unit of Measure

Specifications

Series

 N/A 315

Cone Part Number

 N/A 321

Cup Part Number

 N/A 312

Design Unit

 N/A Inch

Cage Material

 N/A Stamped Steel

Dimensions

d - Bore

 N/A 1.0148 in25.776 mm

D - Cup Outer Diameter

 N/A 2.8593 in72.626 mm

B - Cone Width

 N/A 0.8730 in22.174 mm

C - Cup Width

 N/A 0.9375 in23.813 mm

T - Bearing Width

 N/A 1.0627 in26.993 mm

Abutment and Fillet Dimensions

R - Cone Backface "To Clear" Radius1 N/A 0.03 in0.760 mm
r - Cup Backface "To Clear" Radius2 N/A 0.130 in3.30 mm

da - Cone Frontface Backing Diameter

 N/A 1.3 in33 mm

db - Cone Backface Backing Diameter

 N/A 1.34 in34 mm

Da - Cup Frontface Backing Diameter

 N/A 2.68 in67.10 mm

Db - Cup Backface Backing Diameter

 N/A 2.48 in62.99 mm

Ab - Cage-Cone Frontface Clearance

 N/A 0.04 in1 mm

Aa - Cage-Cone Backface Clearance

 N/A 0.01 in0.3 mm
a - Effective Center Location3 N/A -0.27 in-6.9 mm

Basic Load Ratings

C90 - Dynamic Radial Rating (90 million revolutions)4 N/A 4370 lbf19400 N
C1 - Dynamic Radial Rating (1 million revolutions)5 N/A 16800 lbf74900 N

C0 - Static Radial Rating

 N/A 16800 lbf74800 N
Ca90 - Dynamic Thrust Rating (90 million revolutions)6 N/A 1880 lbf8370 N

Factors

K - Factor7 N/A 2.32
e - ISO Factor8 N/A 0.25
Y - ISO Factor9 N/A 2.38

G1 - Heat Generation Factor (Roller-Raceway)

 N/A 20.3

G2 - Heat Generation Factor (Rib-Roller End)

 N/A 7.9
Cg - Geometry Factor10 N/A 0.0602
  • 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 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 Geometry constant for Lubrication Life Adjustment Factor a3l.