Patent ID: 9334857
Filing Date: 2016-05-10
CPC Classification: B21J,F04B,F15B

Claim Text:
1. A pump comprising: a cylinder body having a first end opposed from a second end along a longitudinal axis, wherein the cylinder body includes a cylinder bore; a plug shaft positioned in the cylinder bore, the plug shaft including a first end, a second end, and a plug shaft bore, wherein the first end of the plug shaft is fixed relative to the cylinder body, and wherein the second end of the plug shaft includes a stop; a first piston sealingly and slideably received within the cylinder bore to partially bound a first gas chamber and a hydraulic fluid chamber, the first piston being sealingly and coaxially received over the plug shaft and axially moveable relative to the plug shaft into engagement with the stop; a socket shaft positioned in the cylinder bore and axially aligned with the plug shaft, the socket shaft including a first end, a second end, and a socket shaft bore, the socket shaft bore being sized and shaped to sealingly receive the plug shaft; a second piston sealingly and slideably received within the cylinder bore to partially bound a second gas chamber and partially bound the hydraulic fluid chamber, the second piston being connected to and moveable with the socket shaft; a third piston sealingly and slideably received within the cylinder bore to partially bound a third gas chamber and a vent chamber, the third piston being connected to and moveable with the socket shaft; and a baffle sealingly received within and connected to the cylinder bore to partially bound the second gas chamber and the vent chamber, the baffle being sealingly and coaxially received over the socket shaft such that the socket shaft is axially moveable relative to the baffle; wherein, during a first stage of operation, the plug shaft is spaced from the socket shaft and the plug shaft bore and the socket shaft bore are in fluid communication with the hydraulic fluid chamber to define a first volume of hydraulic fluid at a first pressure, wherein, during a second stage of operation, the socket shaft is urged axially toward the plug shaft and the plug shaft bore and the socket shaft bore are in fluid communication with the hydraulic fluid chamber to define a second volume of hydraulic fluid at a second pressure, wherein, during a third stage of operation, the plug shaft is sealingly received in the socket shaft bore and the plug shaft bore and the socket shaft bore are fluidly coupled and fluidly isolated from the hydraulic fluid chamber to define a third volume of hydraulic fluid at a third pressure, and wherein the second volume is less than the first volume, the third volume is less than the second volume, the second pressure is greater than the first pressure, and the third pressure is greater than the second pressure.