A hydraulic breaking hammer, comprising: a percussion device comprising a frame and a piston arranged inside the frame and configured to perform a working cycle comprising reciprocating longitudinal movement of the piston in impact direction and return direction due to pressure of hydraulic fluid fed to a first and second working pressure spaces (11, 12) of the percussion device; at least one control device for controlling feeding and discharging of the hydraulic fluid of at least one of the first and second pressure spaces (11, 12) for executing the working cycle; a working collar of the piston which is located between the first and second working pressure spaces (11, 12) and wherein an outer surface of the working collar is sealed to surrounding structures so that the first and second working pressure spaces (11, 12) are hydraulically separated; and a first piston bearing and a second piston bearing which are located at an axial distance from each other; wherein the first and second piston bearings (17, 18) are configured to provide support for the opposite first and second end portions of the piston, whereby the first working pressure space, the working collar and the second working pressure space are all located between the first and second piston bearings (17, 18); at least the second piston bearing is a separate sleeve-like element mountable to the frame in one piece; characterised in that between the outer surface of working collar and the second piston bearing element a radial clearance is arranged and at least one separate collar sealing element is arranged to seal the clearance; and wherein the second piston bearing element comprises at least one first sealing housing for the collar sealing element. a percussion device comprising a frame and a piston arranged inside the frame and configured to perform a working cycle comprising reciprocating longitudinal movement of the piston in impact direction and return direction due to pressure of hydraulic fluid fed to a first and second working pressure spaces (11, 12) of the percussion device; at least one control device for controlling feeding and discharging of the hydraulic fluid of at least one of the first and second pressure spaces (11, 12) for executing the working cycle; a working collar of the piston which is located between the first and second working pressure spaces (11, 12) and wherein an outer surface of the working collar is sealed to surrounding structures so that the first and second working pressure spaces (11, 12) are hydraulically separated; and a first piston bearing and a second piston bearing which are located at an axial distance from each other; wherein the first and second piston bearings (17, 18) are configured to provide support for the opposite first and second end portions of the piston, whereby the first working pressure space, the working collar and the second working pressure space are all located between the first and second piston bearings (17, 18); at least the second piston bearing is a separate sleeve-like element mountable to the frame in one piece; characterised in that between the outer surface of working collar and the second piston bearing element a radial clearance is arranged and at least one separate collar sealing element is arranged to seal the clearance; and wherein the second piston bearing element comprises at least one first sealing housing for the collar sealing element.