Abstract: An impact mechanism for use with a drive motor comprises a drive engaging member and a tool bit retaining member operatively inter-connected with the drive engaging member. The tool bit retaining member has a main body portion, and an anvil portion and a tool bit retaining portion each securely attached thereto for co-rotation therewith. A hammer is mounted on one of the drive engaging member for guided movement between an anvil contact position whereat force is transmitted from the hammer to the anvil portion so as to create a moment about the longitudinal axis, and a release position whereat the hammer is temporarily removed from the anvil portion. A spring biases the hammer to the anvil contact position. A selectively adjustable spring compression mechanism permits selective compression of the spring.

Abstract: An adjustable amplitude hammer drill mechanism comprises a main shaft having a forward drill chuck end portion and a rearward shank portion, and defining a longitudinal axis. An impact receiving member is mounted in fixed relation on the main shaft for rotation therewith. A selectively operable longitudinal-hammer member is mounted on the main shaft for free rotation of the main shaft with respect to the longitudinal-hammer member and for operative engagement with the impact receiving member. Rotation of the main shaft and impact receiving member about the longitudinal axis when the longitudinal-hammer member is in force transmitting engagement with the impact receiving member, causes the longitudinal-hammer member to move in a reciprocating motion between the forwardly displaced position and the rearwardly displaced position, and transmits impact forces forwardly along the longitudinal axis to the main shaft.

Abstract: An impact mechanism comprises a drive motor engaging member and a tool bit retaining member rotatably inter-connected therewith. The tool bit retaining member has a main body portion, an anvil portion securely attached thereto for co-rotation therewith, and a tool bit retaining portion securely attached thereto for co-rotation with the main body portion. A hammer member is mounted on the drive engaging member for movement between an anvil contact position wherein force is transmitted from the hammer member to the anvil portion, and a release position whereat the hammer member is temporarily removed from the anvil portion. A spring biases the hammer member to the anvil contact position. In use, the hammer member to move from its anvil contact position towards its release position, wherein the hammer member is propelled by the spring and the rotation of the drive engaging member to impact on the anvil portion.

Abstract: “An impact mechanism comprises a drive motor engaging member and a tool bit retaining member rotatably inter-connected therewith. The tool bit retaining member has a main body portion, an anvil portion securely attached thereto for co-rotation therewith, and a tool bit retaining portion securely attached thereto for co-rotation with the main body portion. A hammer member is mounted on the drive engaging member for movement between an anvil contact position whereat force is transmitted from the hammer member to the anvil portion, and a release position whereat the hammer member is temporarily removed from the anvil portion. A spring biases the hammer member to the anvil contact position. In use, the hammer member to move from its anvil contact position towards its release position, whereat the hammer member is propelled by the spring and the rotation of the drive engaging member to impact on the anvil portion.