SURE-FLEX COUPLING SIZE SELECTION
2. Determine Service Factor using Load Symbol and driver.
|Standard AC Motor
DC Shunt Motor
*Engine, 8 or more cylinders
|High Torque AC Motor
DC Series & Comp.
*Engine, 4-6 cylinders
|*Engine, 3 cylinders or less
*On applications involving varying torque loads, design around the maximum load. Then determine the resulting service factor at minimum load. If this value is greater than 4.0, special coupling alignment will be required (see page F1-18).
Caution: Applications involving reciprocating engines and reciprocating driven devices are subject to rotational vibrational critical speeds which may destroy the coupling. The factory can determine these speeds when the rotational inertia (WR2) of the driveR and driveN units is known.
3. Locate the correct chart & columns for your sleeve material. motor speed and service factor; you can read the coupling size across from the motor horsepower.
Example: For 150 HP @ 1750 RPM and 1.5 Service Factor - Use #13 EPDM or Neoprene or #10 Hytrel or Urethane.
4. For other speeds. use the following formula to calculate the required coupling horsepower rating @ 100 rpm.
HP @ 100 rpm = HP x Service Factor x 100/ coupling RPM
5. Use the chart below to find a coupling with a HP @ 100 RPM rating which is greater than calculated above.
Example: For 5 HP @ 55 RPM and 1.25 Service Factor:
HP @ 100 = 5 x 1.25 x 100/55 = 11.36
Use #12 EPDM or Neoprene or #9 Hytrel with rating of 11.4 HP.