The patent badge is an abbreviated version of the USPTO patent document. The patent badge does contain a link to the full patent document.
The patent badge is an abbreviated version of the USPTO patent document. The patent badge covers the following: Patent number, Date patent was issued, Date patent was filed, Title of the patent, Applicant, Inventor, Assignee, Attorney firm, Primary examiner, Assistant examiner, CPCs, and Abstract. The patent badge does contain a link to the full patent document (in Adobe Acrobat format, aka pdf). To download or print any patent click here.
Patent No.:
Date of Patent:
Mar. 24, 1998
Filed:
May. 31, 1996
Hitachi Koki Co., Ltd., Tokyo, JP;
Abstract
A pneumatically operated screw driver having a moving unit rotatable about its axis by rotation of a rotor and movable axially by a pneumatic pressure. The moving unit includes a spline shaft supported by the rotor through a ball spline, and a drive bit aligned with the spline shaft and engageable with a head of a screw. The spline shaft has an annular flange portion. A movable piston is disposed concentrically over the spline shaft and movable in an axial direction thereof with respect to the spline shaft. A spring is disposed over the spline shaft and is interposed between the movable piston and the flange portion. A stop member is provided to a rotor or a frame body. If pneumatic pressure is applied to the movable piston, the latter is axially moved downwardly and is brought into abutment with the stop member. The spline shaft is also moved axially slightly after the movement of the movable piston. The shrinkage of the spring will generate shape-restoration force thereof to further move the spline shaft after the stop of the movable piston.