Image Number 2 for United States Patent #6061901.
To facilitate maintenance, a pneumatic punching machine of this invention includes a poppet portion 44 at the top of a piston 28 of an air cylinder 23 and a piston catch 43 is disposed inside a head cap 24. The piston 28 is fixed as the poppet portion 44 fits into the piston catch 43 under a standby state. A retaining ring 40 is fitted into the head cap 24 to prevent fall-off of a head valve 39. A circumferential groove 41 is formed on the inner peripheral surface of the front part of the head cap 24 and a ring-like seal 42 is fitted into the groove 41. When a driver bit 29 is exchanged, fitting bolts are removed and a housing 22 and the head cap 24 are separated. Then, the head cap 24, the head valve 39, the seal 42, the piston 28 and the driver bit 29 can be removed integrally from the housing 22.