We had an enquiry from a customer running heavy equipment – the kind of application with drawworks, hoists, or conveyor drives where the encoder takes a real beating from shock and vibration. Their existing encoder kept failing at the shaft coupling, and they wanted something more rugged that didn’t need a separate flexible coupling to survive.
This looks simple, but a standard shaft-mount encoder relies on that coupling to protect it from misalignment and shock. In heavy mill or oilfield-type equipment, that coupling becomes a wear part and a failure point. A hollow-shaft design solves this differently – the encoder mounts directly over the driven shaft, with a tether or torque arm to react torque, so there’s no separate coupling to fail.
In actual application, the Hengstler HS35R is a ruggedized hollow-shaft optical encoder built for exactly this kind of heavy-duty use – drawworks drums, mud pumps, catwalks, hoists, winches and similar vector-motor duty. It uses a phased array sensor for reliable signal output, is rated to withstand 400g shock and 20g vibration, and carries an IP67 protection option (IP52 also available) across a wide -40°C to +100°C temperature range. Hollow bore sizes run from 6mm up to 1-1/4″, mounting is direct over the shaft with a choice of three tether/torque arm options (including an optional grounding strap), and resolution goes up to 20,000 PPR – a fair bit higher than what we had on file previously, so we’ve corrected that going forward. Supply voltage is 5-26V or 5-15VDC depending on output type, with Open Collector, Open Collector with Pull-Up, Push-Pull, DLD 7272, DLD 4469, or High Power MOSFET Line Driver outputs available.
From our experience, before we quote this, we would normally check the exact bore size, torque arm/tether configuration, resolution (PPR), output type, and IP rating needed for the application. Hope this helps.
