Patents Assigned to Oildrive Pty. Ltd.
  • Heavy equipment jack
    Patent number: 5406880
    Abstract: A double acting hydraulic jack comprising a housing from which at least two pistons extend, each of the pistons being telescopic with respect to one another and with respect to the housing, and a counterbalance valve between adjacent pistons. The counterbalance valve allows hydraulic fluid to flow from an outer piston to an inner piston during piston extension and prevents back flow of hydraulic fluid, thus eliminating piston retraction during extension under load.
    Type: Grant
    Filed: December 3, 1993
    Date of Patent: April 18, 1995
    Assignee: Oildrive Pty. Ltd.
    Inventor: Graeme F. Haller