Percussive tool

摘要

PCT No. PCT/SU85/00101 Sec. 371 Date Aug. 21, 1987 Sec. 102(e) Date Aug. 21, 1987 PCT Filed Dec. 23, 1985 PCT Pub. No. WO87/03925 PCT Pub. Date Jul. 2, 1987.A percussive tool comprising a housing (1) accommodating a movable striker (2) and connected with a power cylinder (6) in which is arranged a striker shank (4) with a gripping mechanism (14) and a drive in the form of a hydraulic cylinder (8). The percussive tool is provided with a control unit having a spool valve means (18) to control a distribution means (19). The spool valve means (18) has a casing (22) and a spool (23) taking two positions in the casing and defining two chambers (25, 26) interconnected through a throttling means (24). One chamber (25) constantly communicates with a discharge line (21), and the other chamber (26) is periodically put in communication with the space of the hydraulic cylinder (8). The spool (23) is spring-loaded with respect to the casing (22) on the side of one chamber (25) and takes in this case its first position.