GB1040830A - Improvements in means for preventing idle operation of percussion tools - Google Patents

Abstract

1,040,830. Percussion tools. ATLAS COPCO A.B. July 6, 1965 [July 13, 1964], No. 28569/65. Heading B4C. Idle operation of a percussion tool is prevented by the fluid pressure biasing of a valve into a position preventing fluid pressure operation of the hammer piston in response to a release of feed pressure on the handle member. In one embodiment a valve member 19 in a easing on the handle member 9 is biased, by compressed air supplied to a chamber 17, into a position closing a valve head 22 against its seat to cut off the supply to a chamber 18 of the compressed air for operating the hammer piston 3 controlled by a distributing valve member 7. The valve member 19 is actuated to operate the hammer piston 3 by depressing a trigger 30 to displace a spindle 31 carrying an auxiliary valve head 33 to allow compressed air to pass from the chamber 17 and between the spindle 31 and the main valve stem 24 to a chamber 36 at the opposite end of the main valve member 19. Provided that feed pressure is applied to the handle member 8, the trigger 30 will be permitted to be depressed further by the operator to actuate the hammer piston 3. If, however, feed pressure is not applied to the handle 8, the operator will be unable to depress the trigger 30 further, since the compressed air supplied to the chamber 36 will be vented to atmosphere through a tube 40 having vent holes 45 therein which are closed when the handle 8 is moved downwardly relatively to the cylinder housing 1. Two further embodiments are described in which the application of feed pressure to the handle controls operation of the distributing valve instead of the trigger-operated valve.