Rodless pneumatic cylinders usually don't work in temperatures greater than 150F because the plastic and rubber parts in the cylinder melt and fail. To solve that problem, designers at Hoerbiger-Origa Corp., Glendale Heights, Ill., incorporate an integral cooling system in its Thermocylinder line of pneumatic cylinders. This makes them suitable for use in glass and steel foundries and bakeries to open and close oven or furnace doors.

The cylinder uses special endcaps to distribute coolant flow into five lines that pass through the entire length of the cylinder. As it does so, the coolant absorbs heat of forced convection, letting the barrel of the cylinder act as a water jacket to keep heat away from the cylinder bore where plastic and rubber parts are used. High-temperature gaskets between the endcaps and cylinder barrel prevent coolant from leaking.

In tests, the cylinder operated at temperatures to 500F, and about 9,200 Btu/hr were removed from a 40-mm bore cylinder with a 65-in. stroke. Although the company used a blower/heat exchanger system to reduce the outflowing coolant's temperature, there are several other methods available, including a chiller. Heat removed from the cylinder could also be put to use.