Formsprag FHB High Speed External Backstop for Inclined Mining Conveyor
A large mine in Minnesota needed a backstop delivered quickly to replace a popular competitor model that failed on an inclined conveyor used to move taconite pellets. The customer was familiar with Formsprag Clutch and had very good experiences with previously installed products.
A Formsprag Model FHB backstop was selected since it was developed as a dimensional drop-in replacement for the competitive unit and was available with a much shorter lead time. FHB backstops are specifically designed for use on inclined conveyors, bucket elevators and other applications where a rotating shaft must be absolutely prevented from rotating in a reverse direction. The unit is externally-mounted on a through-shaft with its inner race driven by a key, and its integral outer race torque arm prevented from rotating through a clearance fit interface with a fixed reaction pin. All FHB units feature inner race centrifugal throw-out sprags and grease-packed bearings with a B-10 life of more than 100 years.
The FHB-20 model supplied has a torque rating of 1,734 lb.ft. (2350 Nm) and a speed rating up to 2,000 RPM which are both significantly higher than the same sized competitor unit. For this application, Formsprag engineers had to accommodate fittings to allow for possible grease replenishment during quarterly scheduled maintenance. No mounting modifications were required.