Formspag Clutch Backstops HSB Backstopping ClutchIntended for use as backstops on the high-speed shaft or intermediate shaft of reducers and as holdbacks on the head shaft of conveyors. HFB & VFB SeriesModels HFB and VFB are backstopping clutching designed to prevent reverse rotation of shafts. LCB Series Fan BackstopsModels LCB-200 and 400 are economical, low-torque clutches designed to prevent problems associated with windmilling in fan applications. LLH HoldbacksFormsprag Long Life Holdbacks (LLH) are designed for use on conveyor heads hafts, bucket elevators, pumps. RSBW BackstopModel RSBW is a specialized backstop based on a DC sprag type dual cage retainer assembly. Backstop Shaft Mount GearboxesFormsprag Clutch has been designing and manufacturing backstops for use in shaft mount gearboxes for over 50 years. View Parts Catalogue FHB Backstopping ClutchModel FHB is a high speed, centrifugal throw-out (C/T) Sprag type backstop with internal sealed ball bearings that is maintenance free.