Crank 1 rotates about a fixed axis. Connecting rod 8 is connected by turning pairs B and C to crank 1 and to piston 2 which reciprocates in pneumatic cylinder 3. When crank 1 rotates, motion is transmitted to piston 2 of cylinder 3 from which compressed air is delivered through valve 4 and passages 5 and 6 to power cylinder 7. Depending upon the position of valve 4, controlled by a special mechanism (not shown), air passes either through passage 5, in which case ram 9 is driven downward to strike a blow, or through passage 6 in which case the ram is lifted for the next blow.
$3970$LHP,HP$