Percussion mechanism

A percussion mechanism of the type having a relatively long piston stroke and limited consumption of working fluid actuated by a pressurized working fluid supplied from a source of pressurized fluid, comprising a housing (52) with an internal cylindrical space and exhaust ports (59, 60) and having at least one longitudinal side passage (61) connected to an idle stroke chamber;

• a fluid actuated piston (54) positioned for axial reciprocation in said internal cylindrical space of said housing and dividing said internal cylindrical space into a working stroke chamber (55) of a variable volume and said idle stroke chamber (56) of a variable volume, and each of said chambers communicating with one of said exhaust ports;
• fluid distributing means (53) having radial passages (71) and cooperatively associated with pressure responsive surfaces of a resilient annular valve element (73, 74) adapted to create inlet passages (75,76) for distributing the fluid into said working stroke chamber (55) of the mechanism;
• a closure (67) having inlet means for said housing (52) defining with said fluid distributing means (53) a supply space (63) for receiving said pressurized fluid from said source;
• at least one inlet passageway (78) formed between said fluid distributing means and said housing connecting said supply space (63) with said idle stroke chamber (56) via said at least one side passage (61);
• a work performing member (58) accommodated in said housing (52) to receive impacts from said piston (54) reciprocated by the action of the fluid;
• valve seats provided in a surface of said fluid distributing means, their number equalling that of the radial passages (71) in said fluid distributing means (53) connecting said working stroke chamber (55) with said inlet passages (75, 76);
• said resilient annular valve element (73,74) being stretched tight about an outer surface of said fluid distributing means (53) in opposition to said radial passages (71) in said fluid distributing means and encircling said fluid distributing means about its periphery, an internal surface of said resilient valve element (73,74) with the valve seats defining at least one of said inlet passages (75,76) for controlling fluid flow about said fluid distributing means (53) and for controlling fluid flow into said working stroke chamber, whereby said piston is repeatedly driven up and down in said housing by the action of said fluid flowing into and out of said chambers and said exhaust ports via said distribution means and said inlet passages (75, 76), said radial passages 71, said at least one inlet passageway (78) and said at least one side passage;
• and whereby a portion of said resilient valve element located opposite said at least one longitudinal side passage (61) controls fluid flow into both said working stroke chamber (55) and said idle stroke chamber (56).