Abstract: A pressure medium operated reciprocating impact mechanism has at least one working member (7) and at least one stop member (15), which are axially movable with respect to each other, and a working chamber (22) for pressure medium is arranged in at least one of them and is opened towards the other member. One of the members has an opening (39) emerging into the working chamber for feeding pressure medium to the working chamber. The impact mechanism comprises an arrangement (21) for sealing the working chamber in the position in which the members are brought most together and allow pressure medium to escape out of the working chamber when a predetermined relative position of the members is reached during their movement apart.

Abstract: An impact element having the effect of elongating the pulse of force in impact tools and devices for chipping, hammering and similar operations, consisting of an element (8) which, for generating the striking motion, is axially moveable as a whole and comprises a driving mass (16) intended to be actuated by a propelling force, and a striking mass (17) located in front thereof relative to the direction of striking, which masses possess a limited freedom of axial movement with respect to each other in that they are coupled together by a stiff spring arrangement, e.g. cup washers (15), extremely hard plastics or gas cushions.

Abstract: A vibration attenuating device to be used in conjunction with reciprocating-motion type impact mechanisms having working and stop members that are axially movable relative towards or away from one another. The members define a pressure chamber therebetween, which is in communication with a source of pressure medium and is sealed by a flexible sealing material such as an O ring. Each member is acted upon by a compression spring exerting a force on the individual member in a direction towards the other member. The introduction of the pressure medium into the pressure chamber results in a cycle comprising the (1) members being forced away from each other, (2) the pressure medium escaping from the pressure chamber and (3) the members being returned to their original positions by the action of the springs. The invention provides a completely balanced two mass system which is particularly useful in conjunction with impact mechanisms used for hand tools.

Abstract: A fluid pressure operated impact mechanism of the type having a reciprocating working member guided for movement along an axis toward and away from a stop member, a pressure chamber between the working and stop members to receive a fluid pressure medium to exert forces separating the two members, and pressure sealing means for maintaining the pressure chamber sealed as the working member and stop member separate. The mechanism is characterized by a sealing arrangement which requires few precision parts yet is applicable to a variety of different devices. In the sealing arrangement, the pressure chamber is formed in the surface of at least one of the members, so that the two members meet along a separating line at the periphery of the pressure chamber. One of the members forms a support wall or flange extending in an axial direction along the separating line, and a flexible sealing means extends from the support wall of the one member to the other member, thereby effecting a seal therebetween.