Image Number 5 for United States Patent #7237983.
A hydraulic shield support is disclosed with at least two adjustable-length hydraulic props supporting a dedicated shield, which are connected through a control bank to a hydraulic fluid supply and borne on base shoes, and to which a pressure in excess of the pressure of the hydraulic fluid may be applied in the set condition of the shield support. In order to provide almost any pressure level at each shield support at a deep face in a simple way, the shield support has at least one pressure intensifier located in a hydraulic pipe system between the hydraulic fluid supply and the hydraulic props, with an oscillating intensifier piston in the form a differential piston effecting the increase in pressure. The low pressure inlet of the pressure intensifier is connected to the setting pressure pipes upstream, and its high-pressure outlet downstream, of a hydraulically-releasable non-return valve.
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