Power driven hammer drill
Patent 5320177 Issued on June 14, 1994. Estimated Expiration Date: 
March 26, 2013. 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.
March 26, 2013. 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 3876014 Rotary hammer driving mechanism Rotary hammer Hand tool with a shifting gear unit Rotary hammer with variable hammering stroke Apparatus for driving a drilling or percussion tool Patent #: 5052497 InventorsAssigneeApplicationNo. 037936 filed on 03/26/1993US Classes:173/48, Adjustable to impacting device173/109, Rotated by hammer head or drive for hammer head173/201Pulsation caused by mechanical movementExaminersPrimary: Rada, Rinaldi I.Attorney, Agent or FirmForeign Patent References
International ClassB25D 011/10Foreign Application Priority Data1992-03-30 JPAbstractThe invention provides an improved intermediate housing incorporated in a power driven hammer drill, which is light in weight, easily and safely handled, and uncostly manufactured. The intermediate housing of the invention includes a bearing member and a cylindrical piston housing member which are integrally composed of a synthetic resin having high tenacity and excellent heat resistance and wear resistance. The intermediate housing further includes a plurality of ribs radially extending from the piston housing member to give a sufficient strength durable to a stress applied onto the piston housing member. In the intermediate housing thus constructed, the bearing member has at least one opening for feeding an air flow generated by a fan while the piston housing member includes at least one air conduit for circulating the air flow. This structure efficiently prevents overheat and thermal deformation of the piston housing member and the bearing member in continuous operation of the hammer drill. | |
