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MINIMUM SHEAVE DIAMETERS

    For other than v-belt drives, multiply the minimum v-belt sheave pitch diameter by the following factors:

    Chain drive. . . . . . . . . . . . . . . .(0.67)
    Gear or gear belt drive . . . . . . . .(0.83)
    Flat belt drive . . . . . . . . . . . . . .(1.33)

    For sheaves centered at positions other than the keyway midpoint, multiply the minimum v-belt sheave pitch diameter at the keyway midpoint (given in the High Speed Shaft Minimum V-Belt Sheave Pitch Diameter table) by the overhung load position factor (given in the High Speed Shaft Overhung Load Position Factors table).
    For example, on a flat belt drive on a 207TR40 (Class 1 Service, 5 HP, 14 RPM) centered 2 1/2 inches from the seal face, the minimum sheave pitch diameter allowable is 2.75 inches
(2.2 x 1.33 x 0.94).
    Keep the sheave as close as possible to the seal face and the gear drive housing.
    High speed shaft overhung loads may be limited by shaft strength, shaft deflection or the life of the tapered roller bearings used throughout these units.  For those limited by bearings, these calculations are based on a minimum of 25,000 hour average life with AGMA #4 oil at 150o F bearing temperature.  Cooler temperatures and/or thicker oil will increase the bearing life.  If smaller sheaves are required, contact Dorris Company.

High Speed Shaft Minimum V-Belt Sheave Pitch Diameter (Inches)*

MODEL

SHAFT DIA. (INCHES)

DISTANCE FROM SEAL FACE TO KEYWAY MIDPOINT (INCHES)

NOMINAL GEAR DRIVE RATIO

5

10

15

20

25

30

35

40

60-250**

107TR

7/8

2 1/8

3.9

4.1

2.7

2.2

2.2

2.2

2.2

2.2

----

115TR

1 1/8

2

3.6

3.0

2.2

2.2

2.2

2.2

2.2

2.2

----

203TR

1 1/4

2 5/16

5.2

4.2

2.8

2.2

2.2

2.2

2.2

2.2

----

207TR

1 1/4

2 3/4

10.5

7.1

4.8

3.9

3.0

2.5

2.2

2.2

----

215TR

1 1/2

3

7.4

8.5

6.0

4.3

3.4

2.8

3.3

3.0

----

307TR

1 3/4

3 3/16

8.2

9.8

6.8

5.6

4.3

3.5

3.1

2.7

----

315TR

2

3 9/16

9.0

9.5

6.6

5.2

4.4

7.0

5.9

5.3

----

407TR

2 1/4

3 15/16

9.0

14.2

9.2

6.7

5.4

4.4

4.0

4.7

----

415TR

2 7/16

4 9/16

----

----

11.6

8.1

6.8

----

----

4.7

4.7

507TR

2 3/4

4 15/16

----

----

14.6

----

8.6

----

----

5.7

5.2

* When centered at keyway midpoint.

** 250:1 for 415TR; 200:1 for 507TR

 

High Speed Shaft Overhung Load Position Factors

MODEL

DISTANCE FROM SEAL FACE TO CENTER OF OVERHUNG LOAD (INCHES)

1/2

1

1 1/2

2

2 1/2

3

3 1/2

4

4 1/2

5

5 1/2

6

6 1/2

107TR

0.60

0.67

0.82

0.97

1.11

1.26

----

----

----

----

----

----

----

115TR

0.86

0.86

0.92

1.00

1.14

1.28

----

----

----

----

----

----

----

203TR

0.85

0.85

0.88

0.95

1.05

1.18

1.30

----

----

----

----

----

----

207TR

0.67

0.67

0.72

0.83

0.94

1.05

1.16

1.28

----

----

----

----

----

215TR

0.69

0.69

0.69

0.79

0.90

1.00

1.11

1.22

1.33

----

----

----

----

307TR

0.71

0.71

0.71

0.76

0.86

0.96

1.06

1.16

1.26

1.36

----

----

----

315TR

0.85

0.85

0.85

0.85

0.90

0.95

0.99

1.08

1.17

1.27

----

----

----

407TR

0.75

0.78

0.83

0.86

0.90

0.94

0.97

1.01

1.05

1.08

1.13

----

----

415TR

0.73

0.77

0.80

0.83

0.86

0.90

0.93

0.96

1.00

1.03

1.08

1.12

1.16

507TR

0.73

0.77

0.80

0.83

0.86

0.90

0.93

0.96

1.00

1.03

1.08

1.12

1.16
--Identical for TL (Screw Conveyor) Gear Drives
 

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