Abstract: The invention relates to an arrangement for indicating a need for maintaining a hydraulic breaking apparatus, the arrangement comprising means for measuring at least one parameter describing the loading of the apparatus. The invention also comprises an indicator which is specific for each breaking apparatus and which is arranged to indicate visually, for example by means of LED lamps, that the parameter measured has exceeded the limit value determined in advance for maintenance.

Abstract: An impact breaker has a sleeve which slidably receives an end portion of a tool. The tool is formed over its end portion with a groove extending completely around the end portion of the tool for receiving lubricant for lubricating movement of the tool in the sleeve.

Abstract: The invention relates to a hydraulic percussion hammer comprising a piston (1), a pressure accumulator (7) in the high pressure circuit, a main valve (8) alternately conducing a high and low pressure to at least one of the pressure surfaces (2,4) of the piston (1) for making the piston (1) move reciprocally, and a tool (3) which the piston (1) strikes, and, for the purpose of controlling the main valve (8), a control pressure valve (9) which opens when the pressure exceeds a set value. According to the invention, the control pressure valve (9) is placed in such a way that the spindle (27) of the control pressure valve (9) is connected from one end to the high pressure circuit of the hydraulic percussion hammer.