Patents by Inventor Brian K. Hierholzer

Brian K. Hierholzer 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).

  • Patent number: 5299658
    Abstract: An improved hydraulic circuit for a two-post lift having a master cylinder hydraulically connected to a slave cylinder. The master cylinder and slave cylinder are sized so fluid volume displaced at the rod end of the master cylinder is equal to the volume displaced at the piston side of the slave cylinder. The hydraulic circuit employs an automatic leveling valve assembly disposed to open when the lift reaches a fully lowered position to automatically equalize the displaced fluid volume of the master and slave cylinders so as to relevel the lift each time the lift is fully lowered. A sequence valve is positioned to pre-pressurize the slave cylinder before raising to compensate for any air in the circuit and fluid compressibility. A pilot operated check valve is designed to close and stop the descent of the lift in a level position if an obstruction is encountered under a side of the lift.
    Type: Grant
    Filed: June 17, 1993
    Date of Patent: April 5, 1994
    Assignee: Hunter Engineering Company
    Inventors: Joseph H. Cox, Richard A. Killeen, Brian K. Hierholzer, Paul W. Roloff, Michael A. Olsen