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US 4,306,822 AGranted
Hydraulic control means
AssigneeGewerkschaft Eisenhutte Westfalia
InventorsWalter Weirich, Harry Rosenberg
Life of this patent
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AssigneeGewerkschaft Eisenhutte Westfalia
InventorsWalter Weirich, Harry Rosenberg
Estimating the term…
Hydraulic control means are provided for controlling an auxiliary shield positioned at one side of the roof shield of a mine roof support unit. The auxiliary shield is moved laterally of its roof shield by means of three hydraulic rams and the roof shield is supported by hydraulic props. The hydraulic control means comprises a control valve device and two pilot check valves. One pilot check valve is positioned in a line leading from the control valve device to two hydraulic rams which act in tandem. The other pilot check valve is positioned in a line leading from the control valve device to the other hydraulic ram. The pilot check valves are actuated in dependence upon the pressurization of the hydraulic props whereby the hydraulic rams are depressurised when the props are pressurized and vice versa.
In a mine roof support unit comprising a roof shield supported by hydraulic props, an auxiliary shield positioned at one side of the roof shield, at least one hydraulic ram for moving the auxiliary shield laterally of the roof shield, and hydraulic control means for controlling the movement of the auxiliary shield, the hydraulic control means comprising a control valve device and at least one pilot check valve, the improvements comprising:
A mine roof support unit comprising a main roof shield supported by hydraulic props, an auxiliary shield positioned at one side of the roof shield, at least one hydraulic ram for moving the auxiliary shield laterally of the roof shield, and hydraulic control means for controlling the movement of the auxiliary shield, wherein the hydraulic control means comprises a control valve device and at least one pilot check valve, said at least one pilot check valve being positioned in a respective line connecting the control valve device to a respective hydraulic ram, wherein said at least one pilot check valve is actuated in dependence upon the pressurisation of the hydrauic props to depressurise said at least one hydraulic ram to a floating condition when the hydraulic props are pressurised, and to pressurize said at least one hydraulic ram to a hydraulically locked condition when the hydraulic props are depressurised.
Dependencies are inferred from the claim text.