The Hallite 744 is a robust double acting rod seal specifically developed for longwall mining roof support applications. It is of similar construction to the well established Hallite 730 and comprises a tough wear resistant thermoplastic polyester elastomer (TPE) face, which is loaded by a profiled nitrile energiser.
Most designs have rectangular polyacetal anti-extrusion rings. This seal has been developed as a double acting rod seal, which is required for a constant setting mining roof support leg cylinder. The operating conditions given are for HFA (water based) fluids.