ATRA-FLEX Catalog 2025

QUICK SELECTION GUIDE

Coupling Selection Formula

INFORMATION NEEDED TO SIZE A COUPLING:

\ Driver HP \ Operating RPM \ Service Factor \ DBSE (Distance Between Shaft Ends) \ Shaft Diameters

DRIVER F1

SF

DRIVER F2

SF

ELECTRIC MOTOR

GENERATORS, GEAR BOXES, LIGHT DUTY AGITATORS & CONVEYORS, STOKERS

1.0

1.0

GAS OR STEAM TURBINE

CENTRIFUGAL PUMPS, COMPRESSORS, BLOWERS, FANS, ETC.

1.0

1.0

GEAR BOX INCREASER/REDUCER

RECIPROCATING PUMPS, COMPRESSORS, FEEDERS, FREQUENT STOPS/STARTS, ETC.

1.0

2.0

GAS OR DIESEL ENGINE 4+ CYL

PULP & PAPER MILL EQUIPMENT (REFER TO MILL STANDARD COUPLING SF GUIDE)

3.0

1-3

GAS OR DIESEL ENGINE 1-3 CYL

STEEL MILL EQUIPMENT (REFER TO MILL STANDARD COUPLING SF GUIDE)

4.0

1-3

For a complete list of service factors, reference page 41 of the catalog.

HP/100 RPM Method:

Transmitted Torque Method:

1. Obtain Service Factor

1. Obtain Service Factor

(SF) SF = F1 X F2 (Not to Exceed 4)

(SF) SF = F1 X F2 (Not to Exceed 4)

2. Determine HP/100 RPM as Follows:

2. Determine Torque as Follows:

HP/100 RPM = HP Transmitted X 100 X SF RPM

Torque (in lbs) = HP Transmitted X 63025 X SF RPM

3. Reference the appropriate insert table depending on coupling type and choose coupling size that has a higher HP/100 RPM than what was calculated.

3. Reference the appropriate insert table depending on coupling type and choose coupling size that has a higher torque rating than what was calculated.

4. Check maximum coupling speed rating and compare to the coupling application speed.

4. Check maximum coupling speed rating and compare to the coupling application speed.

5. Compare the shaft sizes of the driver and driven equipment with the maximum bore of the selected coupling series and size.

5. Compare the shaft sizes of the driver and driven equipment with the maximum bore of the selected coupling series and size.

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