Dbt Gmbh

Hermann Hemscheidt Maschinenfabrik Gmbh & Co.

Dbt Deutsche Bergbau-technik Gmbh

Dbt Automation Gmbh

Hermann Henscheidt Maschinenfabrik Gmbh & Co.

Hemscheidt Fahrwerktechnik Gmbh & Co. Kg

Wolfgang Kobow

Werner Reinelt

Michael Dettmers

Karl Krieger, Deceased

An electromagnet switching device for hydraulic or electrohydraulic directional control valves, especially applied in advancing supports of underground mining equipment with controllable electromagnets ( A, B) accommodated in a case ( ) and comprising armature ( ), coil bodies ( ), magnetisable core ( ) and switching plunger ( ), whose switching plunger ( ) has a switching end which can be coupled to the closing element of a hydraulic valve ( A, B) and an actuating end ( ) for manual operation, whereby the effective switching lift of the switching plunger ( ) is adjustable. The switching plunger ( ) is joined to the armature ( ) by means of a screwed connection and adjustment of the switching lift is facilitated by a relative rotation between the armature ( ) and the switching plunger ( ).

Electromagnet switching device

In the directional control valve ( ) for support mechanisms in underground mining, the valve piston ( ) is guided seal free in the valve seat carrier ( ) between the high pressure connection (P) and a sealing ring ( ) and thus permits an overflow of high pressure fluid from the high pressure connection (P) to the return flow connection (T) on opening the valve ( ). The valve ( ) thus achieves an opening and closing characteristic with negative overlapping and so provides gentle switching processes, so that switching impacts with high pressure peaks do not arise.

Hydraulically operated directional control valve

A valve arrangement ( ) for hydraulically actuated machinery installations, especially for powered support assemblies in underground mining, with hydraulically actuated working valves ( ) to control hydraulic cylinders ( ) or other hydraulically actuated machinery units of the machinery installation and with pilot valves ( ) controlling the working valves. In order to avoid the pilot valves ( ) and working valves ( ) entering an unstable operating condition in the event of a falling off of pressure in the hydraulic fluid supply to the valves, and opening and closing in an uncontrollable and undesired manner, the pilot valves ( ) are attached to their own pressure medium supply ( ), separate or separable from the hydraulic fluid supply ( ) to the working valves ( ), so that pressure variations in the hydraulic fluid supply circuit do not affect the pressure medium for the switching of the working valves ( ), but the pressure in them is maintained largely constant.

Valve arrangement

Electrohydraulic control valve

The body (1) of the hydraulically trippable check valve for mine support hydraulics according to the invention contains: a valve poppet (13) biased in the closing direction by a spring (22); a control piston (17) which can be acted on by a hydraulic control pressure, causing the poppet (13) to be lifted off its seat (11); and an initial relief valve (20, 21) which can be tripped by the control piston (17) against its spring closing force. Matters are arranged so that the control piston (17) which can be acted on by the hydraulic control pressure is dimensioned in terms of piston surface area (17') so that the poppet (13) of the check valve cannot be lifted off its seat (11) until the opening of the initial relief valve has caused a predetermined initial relief of operating pressure on the high-pressure side. The result is a hydraulically pilot-controlled check valve which has high operational reliability and in which harmful oscillation or chatter of the valve poppet (13) of the check valve and/or control piston (17) cannot occur.

Hydraulically trippable check valve for underground mine support

The control device is adapted to be inserted between the control valves of a pilot device and the pressure-medium consumers (hydraulic prop and hydraulic working cylinder) in an hydraulic self-advancing mine-roof support and is connected to a pressure-medium line and to a return line. The control device comprises a valve block with continuous longitudinal bores for connection to a multiple tubing line leading to the pilot device, the valve block having bores for receiving piloted 3/2-way valves and bores for connection to the directly-controlled working cylinders of the mine-roof support.

Control device for mine-roof support

A 2-port, 2-directional hydraulic valve is disposed alongside a pulse generator in a casing, the actuating force of the pulse generator being transmitted to a push rod of the valve for actuating the latter via a two-armed lever mounted like the beam of a balance. A threaded bore in one lever arm receives a bush which is adjustable in the direction of actuation and contains a spring-loaded pressure member. A set screw can be used to pre-stress the spring and thus exactly adjust the transmitted actuating force, while the adjustable bush is used for pre-setting the actuating travel.

Hydraulic valve actuating device

A change-over valve for hydraulic walking mine-roof supports comprises a valve housing containing a sealed-off operating piston in which a valve member supported on a helical spring is displaceably arranged, the piston being responsive to the supply of small quantities of hydraulic fluid through an end connection in the housing and having a sealing cone adapted to close a connection of large throughflow cross-section at the opposite end of the housing which also has a side connection for the supply of pressurized fluid to a working cylinder of a mine-roof support, the large throughflow cross-section at the connection thereby guaranteeing brisk pushing-in of a piston rod of a piston in the cylinder.

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Wuppertal, Germany

Wolfgang Kobow