An exiting new series of Magnetic Clutches & Magnetic Couplings rounds out the growing products from Sterling Instrument (an ISO 9001 manufacturer) and features no friction or wearing parts, uses no electricity and no magnetic particles to leak.

These units, identified as the S90MCC Series, are stocked in 3 different Hollow bore sizes: .625", .750", and .875". Their torque range is from 3-70 lb. in. and they weigh 14.2 lb. Their applications include: material handling such as for conveyor belts, film transport, capping of syringes or bottles, shrink wrapping, constant wire tension, coil winding, film tensioning, and torque limiting.

http://www.sdp-si.com/estore/CoverPg/Clutches.htm