Patent ID: 8516984

Claim:
A hydraulic lost motion system for actuating an internal combustion engine valve comprising: a housing having a housing bore extending through the housing; a housing fluid passage extending through the housing and connecting with the housing bore; a master piston disposed in the housing bore, said master piston having a master piston bore extending into the master piston defined by a master piston side wall; one or more master piston fluid passages extending through the master piston side wall and connecting with the master piston bore, wherein the one or more master piston fluid passages are adapted to selectively register with the housing fluid passage; a slave piston disposed in a lower portion of the master piston bore; a valve catch piston disposed in an upper portion of the master piston bore, said valve catch piston having a hollow interior defined by a valve catch piston wall, a lower end orifice extending from the hollow interior through a lower end of the valve catch piston wall, one or more side passages extending through a side portion of the valve catch piston wall, and one or more seating passages extending through the valve catch piston wall, wherein the lower end orifice is located so as to be selectively occluded by the slave piston, the one or more side passages are located so that hydraulic fluid communication between the one or more side passages and the one or more master piston fluid passages is selectively occluded by the master piston side wall, and the one or more seating passages are located so as to remain in hydraulic communication with the one or more master piston fluid passages; and a valve catch spring disposed in the valve catch piston hollow interior.