Pressure cushion for underground construction work

摘要

The cushion comprises a ductile shell (25) connected to a low pressure supply and take-off (10,12). The shell sits in a housing (27) formed from several rigid parts (1,2) which can move relative to each other. The housings has the supply and take-off at at least one end. The rigid parts are preferably nested pipes. The ends of the pipes and shell (24) may be sealed by covers. The covers may have sealing rings (21) which match with pads (20) on the pipes. The sealing rings may be made from silicone.