Patent ID: 9222489
Filing Date: 2015-12-29
Classification: F04B,F15B,Y10T

Abstract:
1. An apparatus, comprising: a valve for switching a direction of travel of a piston in a hydraulic cylinder; a main spool movable in the valve for directing a hydraulic fluid to either a first side or a second side of the piston wherein the main spool comprises an axial bore having an axis that defines axial directions of travel of the main spool; and a pilot spool that comprises an axial bore having an axis that defines axial directions of travel of the pilot spool wherein the pilot spool is movable at least in part in the axial bore of the main spool to direct the hydraulic fluid for hydraulic switching that comprises moving the main spool under positive hydraulic pressure in one of the axial directions of travel of the main spool simultaneous with and opposite to moving of the pilot spool in one of the axial directions of travel of the pilot spool during at least part of a reciprocating cycle of the valve.