All Product Types > ENGINEERED BEARINGS > Tapered Roller Bearings > Tapered Roller Bearings - TDI (Tapered Double Inner) > Tapered Roller Bearings - TDI (Tapered Double Inner) Imperial > Part Number 78255D - 78551  

Part Number 78255D - 78551, Tapered Roller Bearings - TDI (Tapered Double Inner) Imperial

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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.




Specifications  · Dimensions  · Abutment and Fillet Dimensions  · Basic Load Ratings  · Factors  · Spacer

Specifications

Series
78000

Cone Part Number
78255D

Cup Part Number
78551

Design Unit
Inch

Cage Material
Stamped Steel

Related Assembly Number(s)
78255D-90077


Dimensions

d - Bore
2.5586 in
64.988 mm

D - Cup Outer Diameter
5.5130 in
140.030 mm

B - Double Cone Width
2.5980 in
65.989 mm

C - Cup Width
0.9260 in
23.520 mm

T - Bearing Width across Cups
2.6020 in
66.091 mm


Abutment and Fillet Dimensions

R - Cone Backface "To Clear" Radius1
0.06 in
1.5 mm

r - Cup Backface "To Clear" Radius2
0.090 in
2.29 mm

da - Cone Frontface Backing Diameter
3.11 in
78.95 mm

Db - Cup Backface Backing Diameter
4.61 in
117.09 mm

Ab - Cage-Cone Frontface Clearance
0.08 in
2 mm
1 These maximum fillet radii will be cleared by the bearing corners.
2 These maximum fillet radii will be cleared by the bearing corners.


Basic Load Ratings

C90 - Dynamic Radial Rating (One-Row, 90 million revolutions)1
9970 lbf
44300 N

C1 - Dynamic Radial Rating (Two-Row, 1 million revolutions)2
66900 lbf
298000 N

C90(2) - Dynamic Radial Rating (Two-Row, 90 million revolutions)3
17400 lbf
77200 N

Ca90 - Dynamic Thrust Rating (90 million revolutions)4
14800 lbf
65700 N
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 1 x 106 revolutions L10 life, for the ISO life calculation method.
3 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.
4 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.


Factors

K - Factor1
0.67

e - ISO Factor2
0.87

Y1 - ISO Factor3
0.78

Y2 - ISO Factor4
1.16

Cg - Geometry Factor5
0.0884
1 These factors apply for both inch and metric calculations. Consult your Timken representative for instruction on use.
2 These factors apply for both inch and metric calculations. Consult your Timken representative for instruction on use.
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 Geometry constant for Lubrication Life Adjustment Factor a3l.


Spacer

Note
Spacer shows standard nominal .01 radii, actual bearing may vary


 MORE IMAGES 

·  Timken_TRB_2ROWASSY_TDI_39585D-90015-A

·  Timken_TRB_2ROWASSY_TDI_39585D-90015-A3

·  Timken_TRB_2ROWASSY_TDI_39585D-90015-T2



 DOWNLOADS 

Bearing Life Calculation Tool

Bearing Dimensional Tolerances

Tools and Guides for Engineers

TRB TDI Line Drawing
(JPG, 14KB)