| 摘要 |
A pneumatic percussion tool for rock breaking and other purposes has, removably enclosed within an outer casing (10) a pneumatic engine (11) including a cylinder (16) with a work head (29, 12) extending slidably from its lower end, a piston (26) slidable in the cylinder (16) impacting the work head (29, 12) on its downstroke. The piston (26) serves also as a sliding valve into which compressed air is admitted through an air inlet tube (23) fixed coaxially in the cylinder (16) and on which the piston (26) is slidable. The piston (26) and cylinder (16) are formed with such air ports and passages (36, 37, 38, 39, 40, 41) that the engine remains at rest until the work head (29, 12) applied with pressure to a work-piece (44) is retracted into the cylinder (16) displacing the piston valve (26) which thereupon is reciprocated, causing the work head (29, 12) to deliver percussive blows while applied to the work-piece (44). At the final part of its upstroke the piston (26) enters a compression chamber or energy cell (22) which thus decelerates the piston (26) and commences its downstroke. |
