Fluid powered striking mechanism with automatic stroke switching

摘要

The hammer mechanism (1) has a striking piston (3) moving alternately through working strokes and return strokes under the influence of a control valve (5). The control unit is itself influenced by a servo valve (14) with a returning device (17, 17a) which can be in locked position or open position, depending on the setting of the striking piston. When the piston limit setting in the direction of the working stroke (3e) is exceeded, the control valve is changed to the return stroke setting. During the return stroke immediately following, a short stroke line (18) pressurises the control valve in advance into the working stroke position so that the piston only makes a short stroke.