A Hollow-Shaft Encoder for Places With No Room for One

Industrial Encoder Corporation, part of Global Encoder Systems, announced the IH810 series from St. Catharines, Ontario on 1 September. It is an incremental hollow-shaft encoder built for the constraint that decides most feedback retrofits: there is no axial room left behind the shaft.

The housing is 81 millimetres in diameter with a deliberately low axial profile, flange mounted, with a hollow bore that slides straight onto the shaft. Bore diameters run from 15 to 30 millimetres, covering 5/8 inch to 1 inch. Resolution goes up to 5,000 pulses per revolution, outputs are push-pull HTL or RS422 TTL, and supply options cover 5 VDC, 4.75 to 30 VDC and 8 to 30 VDC.

The specification most likely to matter in service is the galvanic isolation. An encoder cable running alongside motor leads in a compact drive assembly sits in one of the noisiest electrical environments a low-voltage signal can occupy, and isolation between the encoder's supply and its output stage is what stops drive switching transients from arriving as counts. A machine that gains phantom pulses under acceleration is usually not suffering a mechanical fault.

The named applications describe the gap precisely: small automation cells, AGVs and AMRs, compact conveyor drives, compact packaging machines, and small motors and drive systems. Mobile robot drive wheels are the clearest case — the gearmotor, the wheel and the suspension consume the available depth, and a conventional shaft-mounted encoder with its own bearing set simply does not fit.

There is nothing novel in the underlying technology, and that is rather the point. Incremental hollow-shaft encoders have existed for decades; what changes a design is one that fits the envelope, tolerates the noise and can be specified from a catalogue rather than negotiated as a custom part.