Hammer drill
Patent 4567951 Issued on February 4, 1986. Estimated Expiration Date: 
December 12, 2003. Estimated Expiration Date is calculated based on simple USPTO term provisions. It does not account for terminal disclaimers, term adjustments, failure to pay maintenance fees, or other factors which might affect the term of a patent.
December 12, 2003. Estimated Expiration Date is calculated based on simple USPTO term provisions. It does not account for terminal disclaimers, term adjustments, failure to pay maintenance fees, or other factors which might affect the term of a patent.Patent References 3114421 3720269 Percussion hammer with a one piece striker Power-driven hand tool Patent #: 4456076 InventorsAssigneeApplicationNo. 06/560425 filed on 12/12/1983US Classes:173/201, Pulsation caused by mechanical movement173/117Hammer head driven by electric motorExaminersPrimary: Meister, James M.Assistant: Knoble, John L. Attorney, Agent or FirmInternational ClassesB25D 17/24 (20060101)B25D 17/00 (20060101) B25D 17/06 (20060101) Foreign Application Priority Data1983-02-12 DEAbstractIn a drill hammer a motor driven striking mechanism is provided with two air cushions of changeable volumes, through which impact energy is transmitted from the motor to a reciprocating striker which in turn transmits the energy to a tool of the drill hammer. When the striker moves in the direction towards the tool both air cushions act on the striker whereas when the striker moves away from the tool only one of two air cushions acts on the striker. | |
