| 摘要 |
<p>A pneumatic drive unit (50) including a cylinder (52) provided with a plurality of coupled pistons (14, 18) moveable within the cylinder (52), wherein the plurality of pistons defines at least a reaward chamber (22) and a forward chamber (24), and in use said plurality of pistons (14, 18) is moveable beteween a rearward position and a forward position, the cylinder (52) is adapted to admit a first gas supply (56) in excess of ambient pressure at a location rearward of the rearward chamber (22) when said plurality of pistons (14, 18) is in the reaward position, the cylinder is adapted to admit a second gas supply (58) at a pressure greater than the first gas supply (56) at a location coincident with the forward chamber (24) when the plurality of pistons (14, 18) is in the rearward position, and coincident with the rearward chamber (22) when the pistions are in the forward position, the cylinder (52) is adapted to provide fluid communication between the forward chamber (24) and a region forward of the forward chamber (24) when the pistons (14, 18) are in said forward position, and the rearward chamber has a rearward end wall (30) and a forward end wall (32) wherein the rearwall end wall (30) corresponds to a greater bore than the forward end wall (32). Also disclosed are paint ball gun and other mechanical devices incorporating such a pneumatic drive unit (50).</p> |
