Portable percussive power tool - uses rotating spiral ramp engaging radial rib to oscillate recoil sprung hammer shaft

摘要

The portable power tool imparts a non-rotary reciprocating hammer action to a bit. The transmission system includes a rotating cylinder with a spiral ramped stepped surface (4) which engages a circumferential rib (17) on a recoil sprung (18) hammer shaft (14). A secondary tool holding shaft (6), also recoil sprung (13), forms an axial extension of the hammer shaft, and receives hammer blows as the latter oscillates axially. A radial flange (21) and a sliding shell bearing (16) may retain the hammer shaft spring. A threaded sleeve (19) is rotated to adjust the spring strength by displacing the bearing. Also rotation of the hammer shaft due to friction when the ramp contacts the rib is permitted, for even wear.