A percussive machine comprises a housing (10) with a cylinder (11) therein, in which a reciprocating drive piston (40) via a gas cushion in a working chamber (44) repeatedly drives a hammer piston (15) to impact on the neck (17) of a tool (20) carried by the housing (10). At empty blows with the neck (17) out of reach, the hammer piston (15) is thrown forwardly and caught pneumatically in a braking chamber (47) at the bottom end (12) of the cylinder (11). The braking is combined with an elastic yielding of the bottom end (12) against the action of a recoil spring (23) in the housing (10). The pressure in the braking chamber (47) during such yielding is controlled by throttling apertures (48) in the cylinder (11) uncovered by the bottom end (12). The hammer piston (15) is thus checked to halt pneumatically by throttling avoiding to collide with the bottom end (12) and takes inactive position below ports (46) in the cylinder wall through which the working chamber (44) is relieved and ventilated. The bottom end (12) is returned upon yielding by the recoil spring (23) and closes the throttling apertures (48) by check valve action.
申请公布号
DE69011469(D1)
申请公布日期
1994.09.15
申请号
DE1990611469
申请日期
1990.10.22
申请人
ATLAS COPCO BEREMA AB, NACKA, SE
发明人
GUSTAFSSON, KLAS RUNE LENNART, S-393 51 KALMAR, SE