Patent ID: 7237983

Claim:
A hydraulic shield support system adapted for underground mining, the shield support system comprising: at least one base shoe; a shield; at least two adjustable length hydraulic props disposed on the base shoes, the props adapted to support the shield; a hydraulic fluid supply; a control bank in fluid communication with the hydraulic fluid supply and the hydraulic props, the control bank including at least one control valve; a hydraulic pipe system providing fluid communication between the hydraulic fluid supply and the hydraulic props; at least one pressure intensifier in fluid communication with the hydraulic pipe system, the pressure intensifier including an oscillating intensifier piston in the form of a differential piston for effecting an increase in pressure and a pilot pipe providing fluid communication between a directional control valve and the intensifier piston, whereby at the end of downward movement of the intensifier piston, hydraulic fluid in the pilot pipe, moves the directional control valve into a position that imparts upward movement of the intensifier piston.