Abstract: Aqueous emulsions which include polyvinyl butyral are prepared by mixing a nonionic emulsifier with polyvinyl butyral and, if desired, with a plasticizer resin and, if desired, with one or more solvents, and adding water under the action of shear forces.

Abstract: A machine, such as a plough, is driven with a chain back and forth along a guide to strip mineral from a mineral face. The chain is entrained around chain wheels at ends of the guide and the chain wheels are driven by electric motors and gearing assemblies. Each gearing assembly employs an overload protection which generates a signal in the event of an overload. A control unit with a computer responds to the overload signal to provide a stop signal to actuate a clutch to disconnected the drive. Stops are provided at the ends of the guide and spaced from each stop there is a sensor which provides a signal indicative of the presence of the machine. The control unit responds to the detection signal and provides the stop signal at an optimum time calculated by the computer to ensure the machine is halted at or near each end stop.

Abstract: A fluorine-containing powder coating is described, comprisinga) a crosslinkable, fluorine-containing copolymer, composed of a vinyl ester of a highly branched carboxylic acid, whose acyl radical has 9 carbon atoms and is composed of isomers having two quaternary carbon atoms, to which 0 to 80 mol% of isomers which contain one quaternary carbon atom together with at least one tertiary carbon atom in the acyl radical are admixed, of a vinyl monomer containing OH groups, and of a fluoroolefin of the general formulaCF.sub.2 .dbd.CFX,in which X=F, a perfluoroalkyl radical having 1 to 8 carbon atoms or Cl, andb) 20 to 60% by weight of a crosslinking agent suitable for powder coating formulations.Preferably, the latter is a blocked polyisocyanate.

Abstract: A crosslinkable, fluorine-containing copolymer is described which comprisesa) from 10 to 60 mol-% of copolymerized units of a vinyl ester of a highly branched carboxylic acid whose acyl radical has 9 carbon atoms and comprises isomers containing two quaternary carbon atoms to which from 0 to 80 mol-% of isomers containing one quaternary carbon atom together with at least one tertiary carbon atom in the acyl radical are admixed,b) from 20 to 50 mol-% of copolymerized units of a vinyl ester of a short-chain carboxylic acid, where from 50 to 100% of the copolymerized units of this vinyl ester b) are in the OH form obtained by hydrolysis, andc) copolymerized units of a perfluoroolefin of the formulaCF.sub.2 .dbd.CFR.sub.fin which R.sub.f is F or a perfluoroalkyl radical having 1 to 8 carbon atoms, in an amount which makes the sum of components a)+b)+c) up to 100 mol-%, but with the proviso that at least 10 mol-% of the perfluoroolefin are present in the copolymer.

Abstract: A retraction mechanism for drawing a plough drive chain into a chain channel of a coal plough guide built onto the side of a scraper chain conveyor comprises a retraction slide which can be drawn through the chain channel and guided. The plough chain is connected to the slide which, via a chain section and a chain claw can be connected to an external traction drive, preferably to the scraper chain assembly of the scraper chain conveyor, so that the mechanism can draw the plough drive chain through the chain channel. The traction chain incorporates an overload clutch which limits the traction force. The clutch has two complementary parts one of which has a detent ball pressed by a prestressed spring into a detent recess of the other clutch part, so that the clutch is closed. A releasable lock or fixing device secures the detent ball in its released position.

Abstract: A process for automatic ploughing during the winning of coal and the like in a longwall working with a hydraulic advancing lining with individual support units controlled by an electro-hydraulic control means. A plough guide is shifted automatically in stages by the plough cutting depth after passage of the plough by means of rams allocated to the support units and the support units are automatically shifted up as a function of the plough movement. The support units are positioned in support groups of which a plurality in each case are offset relative to one another in the shifting direction by the plough cutting depth and/or a multiple thereof. During the ploughing run only those support units of which the residual stroke of the shifting rams still available for shifting the plough guide is smaller than the plough cutting depth are automatically re-located in each case at a distance behind the passing plough.

Abstract: Apparatus for determining the tension in a chain, for example, has a pair of bearings in a housing mounting a shaft for rotation. The shaft bears a chain wheel. The bearing nearest the chain wheel is fixed in the housing while the opposite bearing is fitted into a floating ring which bears on the ends of a pair of bolts incorporating strain gauges.

Abstract: A coal wining plough in a longwall working employs adjustable floor cutters mounted on curved carriers displaced in guideways on the body of the plough. Wedges abut on the upper ends of the carriers and are moved by hydraulic piston and cylinder units to set the position of the floor cutters and define the cutting level adopted by the plough. The units are operated with the aid of valves which respond to an electronic control device. Command signals from a remote control station are transmitted as by a radio to the plough to set up the electronic control device. Sensors on the plough provide electrical signals representing the position of the interface between the coal face and the floor and these signals are transmitted back to the control station. In a control sequence the plough runs along the seam and the sensor(s) provide signals relayed to the control station which also receives signals representing the distance moved by and/or the position of the plough.

Abstract: A plough drive employs a plough box mounted face to face on a side plate or intermediate plate of a machine frame of a scraper-chain conveyor. A rotatable chain wheel is disposed in the box for driving a chain coupled to the plough. A chain stripper seats in a pocket in the box and is locked therein. The stripper can be withdrawn laterally from the pocket. The stripper is connected to an adjustable annular collar on the casing of a gearing unit which drives the chain wheel and is detachably secured to the side of the box remote from the frame. The gearing unit and stripper can thus be withdrawn together laterally from the box and the chain wheel can likewise be withdrawn laterally via an aperture in the side of the box remote from the frame.

Abstract: A mineral mining installation employs a scraper-chain conveyor constructed from individual pans joined end-to-end and a plough having a drive plate running beneath the conveyor and on a skid bed formed as a sub-frame structure on the floor of the working. The drive plate is connected via guide means to the haulage run of a chain in a lower guide passage at the side of the conveyor opposite to the plough. An upper guide passage accommodates the return run of the chain. The passages are defined by a guide structure fitted to the side walls of the pans and includes detachable covers which can be removed for access purposes. At least some of the covers are linked with the sub-frame structure with the aid of tongue-and-groove connections.

Abstract: Apparatus for monitoring the working stroke of a hydraulic ram 1 includes an indicator 3 having a housing 24 containing a tubular measuring chamber 25 connected to the hydraulic ram by a hydraulic line 2. The tubular measuring chamber is transparent on at least one side for the observation of the level of hydraulic fluid contained therein. The lower end of the tubular measuring chamber is connected to the hydraulic line leading to the hydraulic ram. The upper end of the tubular measuring chamber is closed by an air-permeable but dust-impermeable member 28.

Abstract: A mineral mining machine guide is composed of individual sections joined end-to-end alongside the pans of a scraper-chain conveyor. Each guide section has a side wall component and a web plate component with spacers therebetween dividing upper and lower chain guide passages. An inclined foot plate component projects beneath the web plate component which is itself spaced above the foot plate component to form a slot through which the machine engages with the chain run in the lower passage. A pivotable cover closes the upper passage. Toggle-like coupling pieces fit into pockets in the ends of the web plate components of adjacent sections. Compartments in the web plate components above the pockets and at the level of the upper passage receive extensions of the covers which are hinged in these compartments. The coupling pieces are held in place with detachable locking plates which additionally co-operate with the covers to limit their outward pivotal movement.

Abstract: A coal plough has an elongate plough body which is provided with cutters at each end. The plough body is supported at each of its two ends, by a flat narrow skid on a plate of a plough guide. The skids constitute wear-resistant members and are connected to the plough body in a readily replaceable manner. The skids are so shaped that they guide the plough in the lower zone of the plough guide, and establish connection between the plough and the plough drive chain.

Abstract: Apparatus for controlling the position of a mineral mining machine, such as a coal plough, guided for movement back and forth along a guide employs inclined piston and cylinder units coupled via ball-and-socket joints to brackets on a conveyor supporting the guide and to connectors which are pivotably connected to the conveyor. Assemblies have parallel elongate beams which are guided on roof supports and linked to the connectors. Each connector is of multi-part construction with a main skid resting on the floor of the working and connected to the conveyor and to the associated beams. A further complementary component fits onto the main skid and the parts of the connector have curved recesses which combine to form a socket for receiving a ball of the associated unit.

Abstract: A so-called externally-situated advance mechanism is arranged between the floor sills of adjacent mine roof support units. The advance mechanism includes two laterally-spaced guide rods, and two advance rams positioned above the guide rods. The front ends of the guide rods are connected to a head-piece. A bridge is connected to the two guide rods at a distance behind this head-piece. The piston rods of the two advance rams act on this bridge. The cylinders of the rams are connected, at a distance therebehind, to brackets fixed to the floor sills. Said brackets form guides for the guide rods.

Abstract: A cutter bit assembly comprises a holder and a cutter bit. The holder is formed with a pocket into which the cutter bit can be inserted. The cutter bit is retained within the pocket by means of an arcuate wedge inserted into a tapered gap formed between respective curved support faces formed on the cutter bit and the holder.

Abstract: A guide for mineral mining machines is composed of assemblies each secured to the mineral face side of a conveyor. The assemblies have angle plates secured to the side walls and structures formed with spacers separating upper and lower passages for a drive chain. Covers are detachably and pivotably mounted to the structures. The covers can be secured in a closed position covering the upper passage or swung outwardly to an open position on push-in hinge joints formed at their lower regions by interengaging components of the covers and the structures. The hinge joints have complementary projections and recesses which interengage when the covers are closed.

Abstract: Apparatus for controlling the position of a mineral winning machine, such as a plough, movable along a guide at the mineral face side of a scraper-chain conveyor employs a connector bracket at the goaf side of the conveyor to which a floor-engaging skid plate is pivotably linked. A beam extends from a roof support and is also pivotably connected to the skid plate remote from the conveyor. A pair of piston and cylinder units are pivotably connected at their upper ends to the bracket. One of the units is pivotably connected to the skid plate and the other is pivotably connected to the beam. By operating the units together the skid plate can be held against the floor over part or all of its lower face while the conveyor goaf side is raised or lowered accordingly.

Abstract: A cutter bit assembly comprises a holder and a cutter bit. The holder is formed with a pocket into which the cutter bit can be inserted. The cutter bit is retained within the pocket by means of an arcuate wedge inserted into a tapered gap formed between respective curved support faces formed on the cutter bit and the holder.

Abstract: A mineral mining installation comprises a longwall scraper-chain conveyor, and a mineral winning plough. The plough is drivable to and fro along the face side of the conveyor by means of a plough drive chain and a three-part sword plate. The plough drive chain is housed in a chain guide attached to the goaf side of the conveyor. The sword plate is attached to the plough, and passes underneath the conveyor. Each pair of adjacent sword plate parts is detachable joined together by a pair of detachable pivot joints positioned respectively adjacent to the face and goaf sides of the conveyor.