Patents by Inventor Bob H. Ha

Bob H. Ha has filed for patents to protect the following inventions. This listing includes patent applications that are pending as well as patents that have already been granted by the United States Patent and Trademark Office (USPTO).

  • Rolling hammer drill
    Patent number: 7191848
    Abstract: A hammer drill with rolling contact at the contact surfaces for transmission of axial force between a drive shaft and wave race. By using roller bearings, line contact is obtained. The area of contact is thus close to zero as opposed to a relatively large area in engagement systems using toothed surfaces. Use of point or line contact reduces heat generation and reduces energy loss due to friction.
    Type: Grant
    Filed: July 9, 2004
    Date of Patent: March 20, 2007
    Inventor: Bob H. Ha