Patents Represented by Law Firm Basile and Hanloon
  • Patent number: 5048292
    Abstract: A single rod three chamber fluid motor is driven in a forward stroke which includes a rapid initial advance followed by a relatively short and slow feed stroke under high pressure. The rapid advance is performed by a closed loop system in which a high displacement main pump, pumps fluid to act against a first equal area at the head side of the piston and receives fluid expelled from a second equal area at the rod side of the piston while an accumulator maintains the third chamber exposed to a third area of the head side of the piston filled with fluid. Upon shifting to the feed stroke, the main pump is disconnected and a feed pump applies pressure to both of the first and third areas at the head side of the piston and receives fluid expelled by the second equal area and from a charge pump. The access fluid added to the feed pump circuit by the charge pump is returned via the accumulator to the charge pump sump during the return stroke of the piston.
    Type: Grant
    Filed: August 2, 1990
    Date of Patent: September 17, 1991
    Inventor: Philip A. Kubik