Patents by Inventor William Pierre Liu

William Pierre Liu 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).

  • Hydraulic circuits for tree-harvesting knuckle booms
    Patent number: 6763863
    Abstract: A hydraulic valve is used to judiciously shunt oil from lowering ends of the hoist and stick cylinders that have been plumbed to achieve near horizontal movement. This allows the use of cylinders that have unequal rod/bore ratios or to compensate for certain transient effects that may require the exchange of oil to the reservoir. The action of the hydraulic valve acts without obtrusive operator intervention and is essentially automatic. This allows for greater flexibility in the design of the boom system, allows the boom system to perform various tasks, while not requiring obtrusive intervention from the operator.
    Type: Grant
    Filed: July 19, 2002
    Date of Patent: July 20, 2004
    Assignee: Tigercat Industries Inc.
    Inventor: William Pierre Liu
  • Hydraulic circuits for tree-harvesting knuckle booms
    Publication number: 20040011427
    Abstract: A hydraulic valve is used to judiciously shunt oil from lowering ends of the hoist and stick cylinders that have been plumbed to achieve near horizontal movement. This allows the use of cylinders that have unequal rod/bore ratios or to compensate for certain transient effects that may require the exchange of oil to the reservoir. The action of the hydraulic valve acts without obtrusive operator intervention and is essentially automatic. This allows for greater flexibility in the design of the boom system, allows the boom system to perform various tasks, while not requiring obtrusive intervention from the operator.
    Type: Application
    Filed: July 19, 2002
    Publication date: January 22, 2004
    Inventor: William Pierre Liu