| 摘要 |
PCT No. PCT/SE95/00209 Sec. 371 Date Feb. 10, 1997 Sec. 102(e) Date Feb. 10, 1997 PCT Filed Feb. 28, 1995 PCT Pub. No. WO95/23051 PCT Pub. Date Aug. 31, 1995A pneumatic impact breaker comprises a housing (11) with a cylinder bore (20), a hammer piston (28) with a piston head (63) and an impact delivering stem portion (64), an anvil (14) displaceably supported in a cylinder bore extension (50) and normally abutting against the shank (15) of a working implement (16), an annular energy absorbing air cushion chamber (59) is formed between the hammer piston (28), the cylinder bore (20) and an annular shoulder (49) in the cylinder bore (20), wherein the piston head (63) is formed with two axially spaced end portions (65, 66) for guiding and sealing cooperation with the cylinder bore (20). The length of the piston head (63) is considerably larger than the length of the stem portion (64), and the radial play between each one of the end portions (65, 66) and the cylinder bore (20) is smaller than the play between the stem portion (64) and the cylinder bore extension (50),whereby is guaranteed a non-metallic yet effective sealing cooperation between the stem portion (64) and the cylinder bore extension (50) and an improved tightness of the energy absorbing air cushion chamber (59). |
