Rodless cylinders cope with temperature extremes

Rodless cylinders have proven to be one of the most popular and reliable ways of providing linear motion and, as such, there are many engineers wishing to use them in somewhat unusual circumstances. One such application is bus, tram and train doors, which can be exposed to wide variations in temperature.

The new units are based on the proven Origa OSPP range, and are available in the standard sizes of 25, 32, 40 and 80mm bore. They incorporate a sliding seal arrangement so that the air-driven piston can be connected directly to the load. Automatic temperature compensation is provided to the inner band of the seal so that it adjusts for thermal expansion and contraction, while maintaining an airtight seal.

As with all Hoerbiger-Origa actuators, the external dimensions are absolutely standardised, so that they can be exchanged simply by undoing the mounting bolts; they are also maintenance-free and can be used as structural elements within their application.

Temperature range

The temperature compensating actuators have a total range of -40 to +120degC, although special seals are required for duties below -10degC or above +80degC. Significantly, the highest performing seals Hoerbiger-Origa is able to offer work across a temperature differential of 160 Kelvin, although in such cases the effective stroke length may have to be limited.

Origa invented the rodless cylinder in the 1970s and the company has since developed a substantial number of variants, so the company is able to address an ever-expanding range of applications. It has also developed electrically driven actuators that share the same casing, end caps, mountings, etc as the pneumatic versions so that they are completely interchangeable.

Initially applications were found in mainstream industry, but the user base is constantly expanding and now includes cryogenic installations, animatronics and large-scale outdoor displays, furnace and oven feed systems and many applications in extreme weather climates.