| 摘要 |
<p>A pneumatic percussion tool (1) for demolition and/or breaking work in for example concrete and connectable to an insert tool (2). The percussion tool has a percussion cylinder (4), a piston (5), arranged to travel in the bore of the cylinder (4), a buffer (8), and a valve unit (6), designed to act on the piston (5) during operation and produce a repetitive reciprocating travel in the bore of the cylinder (4) by alternately applying pressure to the upper or lower end of the cylinder (4) while the insert tool (2) is subject to influence by the stroke of the piston (5) when this is at its dead centre at the lower end of the cylinder (4). The percussion tool comprises a means (11) of preventing the piston's reciprocating motion when the buffer (8) reaches a predetermined degree of wear and the tool is not pressed against any object being worked.</p> |
