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TNA bearings are similar to the TDO, but the inner race narrow faces are extended to abut and eliminate the need for a separate inner race spacer. Supplied with an in-built clearance to give a standard setting range, these bearings provide a solution for many fixed or floating bearing applications where simplicity of assembly is required.

Design Attributes:
  • Double cup and two single cones
  • Internal bearing clearance controlled by extending the front faces of the cones so they contact each other
  • SW variation features chamfers in the bores at the front faces of the two single cones to form a lubrication groove
  • SE variation features a backface rib design to accommodate radial lip seals or stamped closure
Unit of Measure

Key Dimensions

Cone Part Number

 N/A NA78250

Cup Part Number

 N/A 78549D

Design Unit

 N/A Inch

Bore (d)

 N/A 2 1/2 in63.500 mm

O.D. (D)

 N/A 5.5000 in139.700 mm
Dynamic Radial Load Rating - 90M Revs (C90) 1 N/A 11800 lbf52600 N
Dynamic Radial Load Rating 2-Row - 90M Revs (C90-2row)2 N/A 20600 lbf91500 N
K Factor 3 N/A 0.67
e Factor 4 N/A 0.87

Other Dimensions

T - Bearing Width across Cones

 N/A 3.0625 in77.788 mm
Max Shaft Fillet Radius5 N/A 0.09 in2.3 mm
Max Housing Fillet Radius6 N/A 0.06 in1.5 mm

Outer Ring Width (C)

 N/A 2.0395 in51.803 mm

Shaft Backing Shoulder Diameter - Backface (db)

 N/A 3.35 in85 mm

Housing Backing Shoulder Diameter - Frontface (Da)

 N/A 5.19 in131.83 mm

Weight

 N/A 11.28 lb5.11 Kg

Ratings

C1 - Dynamic Radial Rating (1 million revolutions)7 N/A 79300 lbf353000 N
Ca90 - Dynamic Thrust Rating (90 million revolutions)8 N/A 17500 lbf77900 N

Factors

Y1 Factor 9 N/A 0.78
Y2 Factor 10 N/A 1.16
  • 1 Based on 90 x 106 revolutions L10 life, for The Timken Company life calculation method. C90 and Ca90 are radial and thrust values.
  • 2 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.
  • 3 These factors apply for both inch and metric calculations. Consult your Timken representative for instruction on use.
  • 4 These factors apply for both inch and metric calculations. Consult your Timken representative for instruction on use.
  • 5 These maximum fillet radii will be cleared by the bearing corners.
  • 6 These maximum fillet radii will be cleared by the bearing corners.
  • 7 Based on 1 x 106 revolutions L10 life, for the ISO life calculation method.
  • 8 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.
  • 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.