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Inertia Dynamics SO Series Clutch Couplings for Elevator Smoke Curtains

A leading U.S. smoke and fire curtain manufacturer, needed a small, reliable electric clutch solution for use on its elevator smoke curtains. The roll-up transparent screens are connected to a smoke detector near the elevators. When smoke (or a power outage) is detected, the curtains are automatically deployed from recessed system housings located above the front of the elevator doors. The curtains roll down to completely cover the entire elevator door opening from top to bottom. The side edges of the curtains feature flexible magnetic strips that adhere to the metal elevator frame, creating a tight seal.

Inertia Dynamics (IDI) supplied modified Model SO clutch couplings to meet the customer’s small footprint application requirements. The power-on clutch couplings provide 50 of static torque and are mounted on the driven shaft between a small gear motor and a cable pulley. When the curtain is deployed, the clutch allows the curtain to freely roll down to the floor. Rewind switches are located on both sides of the screen. When one of the switches is activated, the clutch engages the cable drive pulley to roll the curtain back up into the ceiling housing.

Series SO bearing-mounted clutch couplings are specifically designed for in-line shaft applications. These stationary field clutches feature precision-centered sleeve and ball bearings, a zero-backlash armature assembly.

Inertia SO Series Clutch Couplings


  • Modified SO Series stationary field clutches
  • Power-on function
  • Compact footprint
  • Zero backlash
  • Supplied models provide 50 of torque
  • 9 sizes available, from .90 in. to 4.2 in. diameter

Contact Information

Inertia Dynamics
31 Industrial Park Rd.
New Hartford, CT 06057 - USA
Toll Free: 1-800-800-6445
Phone: 860-379-1252
Fax: 860-379-1137