Gewerkschaft Eisenhutte Westfalia, Gmbh

Uwe Trox

Willy Kussel

Walter Weirich

Michael Dettmers

Martin Reuter

Johannes Konig

An electro-hydraulic control system for a mineral mining installation has a series of valve blocks, each contain a number of valves which are operated in dependence on electrical signals to cause hydraulic appliances of roof supports to operate. To allow emergency operation, when there is a power failure or when the control system fails or is otherwise inoperative, further manually operable valves are connected by a flexible, multi-core connecting cable to the valve block of the associated support. The emergency control valves can operate hydraulically controllable direction control valves of the control system and by-pass the electrical controls. The support can then be controlled purely hydraulically, at least in its main functions, using the emergency device.

Arrangement for emergency operation of hydraulic appliance in an

The operation of an electromagnetic valve is monitored by connecting the coil of the valve to a d.c. source for a period of time sufficient to permit the current in the coil to reach its maximum steady state value then disconnecting the coil to permit the current to fall and re-connecting the coil to the source again and measuring the current which is established in the coil.

Method of, and apparatus for, monitoring the operation of

As is known mineral, e.g. coal, is won from a mineral face with the aid of a winning machine guided for movement along a conveyor composed of individual pans joined end-to-end. The conveyor is advanced towards the face behind the machine by shifting rams linked to the pans. In accordance with the invention, the rams are connected to and disconnected from a supply of pressure fluid in a controlled manner to form a group composed of a predetermined number of rams which are simultaneously charged with pressure fluid and this group progresses along the working behind the machine step-by-step in a sliding fashion within and over larger bank-push groups of rams.

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Ottmarsbocholt, Germany

Uwe Trox