COMBUSTION ENGINE DRIVEN HAMMER MACHINES

1383720 Percussive tools ATLAS COPCO AB 2 July 1973 [30 June 1972] 31369/73 Heading B4C [Also in Divisions F2 and B3] A hammer device comprises a crankshaft 2 having a combustion engine piston 25 and a compressor piston 3 for driving a hammer piston 28 against a tool 8, rotation of the crankshaft being transferred to the tool through a clutch 10. Rotation of the tool is by way of a worm wheel on the crankshaft 2, a shaft 58 and intermeshing gears 17, 18 and is not operable when the engine is idling. When a throttle 4 on the handles 20 is depressed a vent 22 is closed to permit the airflow along a pipe 11 from the compressor to depress a diaphragm 14, rod 13 and a second coupling part 57 against the action of a spring 16. When the part 57 is depressed, jaws 71 engage jaws 70 on a driven first coupling part 56 so that rotation is transmitted to the shaft 58 via splines 72. The first coupling part 56 is driven from a continuously rotatable part 51 via a slip clutch arrangement consisting of rollers 53 retained in recesses in the part 51 and between flats on the part 56 and an annular spring 54. A selector disc 32 having an operating knob 31 may be provided so that a hammering action can be obtained without rotation when the selector disc is turned into the position to release a dog 35 into engagement with projections 19 and to cause a slide valve 36 to cut off the airflow through the pipe 11. Flushing air may be conducted through channels 40, 41 and chamber 42 to a central duct in the tool 8.