DRUCKGASBETAETIGTES GESTEINSBEARBEITUNGSGERAET MIT FLUESSIGKEITSSPUELUNG

摘要

A pneumatically operated stone-working tool has a tool drive, a spraying device for spraying the work area with a liquid and a control assembly for opening and closing the pneumatic line. The control assembly includes a valve plunger rotatably and linearly displaceably received in a chamber which is in the path of a pneumatic line feeding the tool drive and a liquid line feeding the spraying device. The plunger has a first linear position in which it maintains the pneumatic line closed regardless of the angular position of the plunger and a second linear position in which it maintains the pneumatic line open solely when the plunger is manually rotated into an "open" angular position. A force-exerting arrangement continuously urges the plunger towards its first linear position. The plunger has a work face so oriented that it is continuously exposed to a pressure of the liquid in that part of the chamber which is in communication with the liquid line. This pressure displaces the plunger into its second linear position against the effect of the force-exerting arrangement when the pressure reaches a predetermined level indicative of a safe pressure for operating the spraying device.