The STM R Series worm gearbox range from HMA Flow & Industrial is based on three innovative principles, namely two technical and one commercial. All aluminium components are die cast (from size 28 to size 70) to increase torsional resistance and structural flexibility. ZI Gear tooth profiles (section and involute) increase efficiency and result in quiet operation. Finally, a modular attachable output flange (FL) has been adopted to increase flexibility. STM was the first to patent a torque limiter built inside a standard gearbox in 1987.