Technical Selection of Flexible Shaft Couplings

 
Selection of Flexible Shaft Couplings

Information required to select the correct size coupling:
  • Actual power to be transmitted in kW
  • The type of drive to driving conditions so a service factor can be determined.
  • The speed (RPM) of the drive.
  • The shaft dimensions and type of connection (key or taper lock).
Selection formula:
Actual power (kW) x service factor (SF) x 100(RPM) = kW per 100 RPM
     Coupling Speed

Service Factor (SF)
(Prime mover to machinery load classifications)
Load Classification Electric motor, (normal torque), steady input,turbine,hydraulic drive Electric motor,(high torque),frequent starts, multi-running conditions Single cylinder IC engines or uneven drive/medium duty
Smooth Running 1 1.5 2.5
Moderate shock 1.5 2.0 3.0
Heavy shock 2.5 3.0 3.5

For operating periods of over 8 hours per day add .25(SF) over 16 hours .5 (SF)

Machinery load classification
smooth running Agitators and mixers (constant density). Fans & blowers (centrifugal & light duty). Pumps (centrifugal & uniform loading). Conveyors & elevators (uniform feed and load). Generators (uniform loading). All machinery operating at a steady load.
Moderate Shock Agitators and mixers (variable density). Fans ( forced draught, cooling towers, rotor type, vane type). Cranes & hoists (medium duty). Pumps (plunger & multi-cylinder type, geared and centrifugal). Conveyors & elevators (non uniform loading). Compressors (multi-cylinder & lobe). Winches. Timber & textile industry.
Heavy ShockCompressors (single cylinder). Conveyors (reciprocating, vibratory, live roll stacking). Crushing and quarrying plant. Pumps (one or two cylinder, plunger type). Timber industry (log hauling, live rollers). Drum drives.

Sometimes it is not easyto define a service factor from the above tables. Below are general guidelines related to the subject of flexible couplings for consultation.

A general guide for load/service factor classifications

 RunningService Factor
1.Continuous running with light loads with little load variation1.5
2. Variations in torque load and speed when equipment is operating 1.5
3. Variations in torque load and speed with frequent stop/start cycles 2.0
4. shock/impact loading and high torque variations are encountered 2.5
5. For heavy shock/impact loading or for light reverse drives 3.0
6. Frequent reversing torque loads or reverse cycles with heavy load Consult I-trans
For a reciprocating power source or load add the following to the selected service factor: Single cylinder IC Engine or equipment = 1, Multi-cylinder IC Engine or equipment = 0.5
 
 
Elastomeric Failure Selection based on Torque

ring gears




   
     
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