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July, 1939

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The firm of Hugh Wood & Co. Ltd. has familiar associations with all mining engineers as the sponsor of many successful innovations for attacking the colliery cost sheet. Since its inception in 1908 the firm may be said to have had its pioneering hand in every major mechanical development that has effected that vast conversion from hand-working to machine-mining methods, and furnished the British coal industry with the best equipment in the world. As a further progressive step in its history the firm has now launched a new enterprise, having formed a subsidiary, under the title "Huwood" Machinery Limited, to operate a new factory in the Team Valley Trading Estate at Gateshead-on-Tyne. By way of introducing the new factory to his customers Mr. Wood took the opportunity of inviting the members of the Colliery Managers' Association to lunch and a visit of inspection, on the occasion of their Annual Meeting at Whitley Bay last month.

Various interior views of the factory are reproduced herewith. It is built in accordance with best modern practice as regards spaciousness, lighting, heating and ventilating, and contains a handsome block of offices separated from the works proper by a strip of open yard, which serves the double purpose of a sound insulator and lighting well. A road-vehicle loading dock occupies the whole of the east end of the factory, while the west is traversed by a railway siding. The factory is constructed of 9 in. concrete brick walls built into a steel framework, the floor consisting of reinforced concrete, 5 in. thick and overlaid with 1½ in. of granolithic surfacing. The roof, which is flat, has a steel deck, Tentest lining and a double layer of composition roof covering.

The excellence of the natural lighting may be judged from the illustrations, and the arrangements made for the artificial lighting likewise afford an equally good example of what can be done by modem methods. In the latter scheme B.T.H. "Mercra" gas-discharge lamps are employed, thus enabling few points to be employed, while the quality of the light emitted has special advantages for examining metals. To eliminate disconcerting stroboscopic effects through the current periodicity synchronising with multiples of the speeds of the machine tools, adjacent lighting units are connected to different phases of the supply, so that the light at any one point is received from overlapping phases. In the main bay, which is chiefly used for erection purposes, the lighting equipment consists of twenty eight 400W lamps mounted at a height of 26 ft. in Mazdalux dispersive fittings and placed 25 x 30 ft. apart to give an average illumination at floor level of 8 ft. candles. Both the side bays are furnished with 125 W lamps 13 ft. apart and at a height of 11 ft. to give a lighting intensity of 15 ft. candles at 2 ft. 6 in. above floor level.

Heating is provided by a low-pressure hot-water system, the boiler being fired by a mechanical stoker. Coal is delivered directly into the feed hopper, which is situated below ground level. Radiators are used in the offices and unit heaters in the works, thus keeping the factory floor clear of pipework. In summer electric fans attached to the unit heaters stimulate general ventilation.

To give a word to the exhibits, the major part of the display consisted of a range of conveyors, interconnected to show the juxtaposition of face and gate units. Of these the simultaneous loading conveyor can claim to be the latest development, although it is in no sense so new that it has not been thoroughly tried out in actual practice. In this conveyor the return belt is suspended above, instead of below, what is normally the conveying belt, so that the conveyor can be arranged along the whole length of a double-unit face, the coal from one unit being filled on the bottom belt and that from the other on the top belt. At the mothergate the coal from both belts is delivered into the trunk conveyor by ploughs, which remove everything but the finest dust. No undue wear is caused by the ploughs, and it is claimed that their sliding action, as opposed to the tumbling action induced by the normal conveyor discharge, minimises the dust nuisance. Furthermore the coal is delivered in the direction of travel of the gate conveyor, and no abrupt change of direction is involved. As a further advantage the driving ends of the face units are removed from the mothergate, thus relieving congestion at this point. The plough frame is quite light and can easily be removed when the ripping is being taken. The conveyor is fitted with the firm's SL/1 driving head, which incorporates a short auxiliary belt, an idler drum and a spring-loaded jockey drum. By passing round the idler, and being tensioned by the jockey, the auxiliary belt forms a large arc of contact with the driving drum; the main belt is, of course, driven by the auxiliary belt, with which it has a very large contact area indeed, so that it can be operated successfully with a minimum of tension.

Also on view was a light-duty bottom-belt gate conveyor of the "FGS" semi-troughed type. In this type the whole structure is rigid instead of the trestles for the top and bottom belts being separate. Each section is 14 ft. long and is built up from 4 by 2 in. R.S. channel sections connected by stay bracings to support the carrying rollers. The sections are light enough to be carried by two men, but to facilitate handling in awkward places they can readily be dismantled into smaller components when necessary. Bottom rollers are placed 7 ft. apart and the top rollers 14 ft. apart. An SL type head provides the drive, this being somewhat heavier than the SL/1, as it can accommodate a 25-h.p. motor as compared with the 15 h.p. for the SL/1.

Lying parallel with this unit was a 24-in, top-belt conveyor fitted with a tail-end drive. This conveyor is built up in 6-ft. sections and the return belt is totally enclosed by cover plates. It is of the semi-troughed type and is normally supplied without spill plates, though these can be provided if required. The overall height is 12 in. The trestles are made in two parts, this feature enabling quick and easy inspection of the bottom rollers and facilitating threading the belt after "bumping up." An interesting point in this conveyor is that the top carrying rollers have a slight forward inclination at the outside to keep the belt centralised when running.

Other conveyor exhibits consisted of a 30-in, fully troughed top-belt conveyor, Type GB, and a 20-in, low-seam top-belt face unit. The former represents a completely new design, although the driving head incorporates many standard parts used in SL heads, e.g. gearbox, drum housings, bearings, &c. — a feature of some importance when the maintenance of stocks is considered. The sections are stoutly constructed and are 9 ft. long, the conveyor being of the fully troughed type and fitted with cover pans for the bottom belt.

This conveyor is provided with a long receiving hopper, and the return drum, which is oil-filled, is housed in a compact box-like structure. The driving head of the low-seam face unit is 14 in. in height, and the intermediate sections are of standard flat top-belt construction. In this conveyor the tail end is of the totally enclosed type, and is fitted with an oil-filled return drum mounted on ball bearings.

All these conveyors are provided with oil-filled idler rollers, perhaps one of the most striking innovations of Hugh Wood & Co. Ltd.

Oil-filled rollers

Belt conveying, in spite of its many advantages, has hitherto involved the bugbear of idler-roller maintenance. Some of the earlier designs were reduced to a deplorable condition at a comparatively early stage, and even with the more satisfactory designs there was the constant need to apply suitable lubrication at frequent intervals — a formidable task when the hundreds of individual points, none too accessible, on a belt conveyor system are considered. To meet the need for an idler that would minimise maintenance costs and eliminate the necessity for intermittent lubricating services, Hugh Wood & Co. Ltd. have introduced an oil-filled roller which, it is claimed, is provided with a really effective seal against oil leakage and ingress of dirt into the bearings.- A part-sectional sketch of the roller is given in the accompanying illustration. The seal, which is the crux of the success of the roller, is composed of a new synthetic product; not only is this material quite unaffected by oil and acid but is capable of being accurately moulded to any shape, and moreover has a coefficient of friction of about of that of the best chrome leather. The seal is provided with two tapering lips which splay on the spindle to prevent the escape of oil on the one side and the ingress of dirt on the other. The diagram illustrates the juxtaposition of the seal, the inner oil-filled tube, the ball bearings, the die-cast end discs and the roller tube, all these components being manufactured with extreme accuracy to ensure interchangeability in all circumstances. A department of the works has now been laid out to produce the rollers on mass-production lines, such is the demand that is being experienced.

Protective equipment

A further exhibit consisted of a selection of protective equipment such as safety helmets, boots and goggles. One of the most interesting items of this display was the variety of helmets that have recently been redesigned to afford greater comfort. The linings have been made to be easily renewable, the peak is in one piece with the shell, and alternative positions are now available for the lamp bracket.

"Everite" asbestos pipes

A selection of Everite asbestos pipes was also on view. It will be recalled that an installation of these pipes at Ladyshore colliery was described in this journal in December last (page 417), and it will be sufficient here to mention that the pipes, which are composed of a mixture of agglutinated cement and asbestos, are entirely unaffected by corrosive waters and are available for pressures up to 400 ft. — or in exceptional cases 800 ft. head. Longitudinal and cross sections were shown to demonstrate the homogeneous nature of the asbestos-cement material and to give some idea of the range of sizes manufactured. Sections of the joints were also exhibited to show the simplicity of assemblage.

Ingersoll-Rand compressors

The extent to which electricity is now used underground has created an increasing demand for small electrically driven air-compressing units to supply pneumatic drills and picks in relatively limited areas inbye. A range of these compressors was shown at the exhibition, giving deliveries from 60 to 360 cu. ft. per min. at 100 lb. per sq. in. All these were Ingersoll-Rand two-stage machines and designed for air cooling. The latter feature not only eliminates the necessity to provide a supply of suitable cooling water but also reduces the installation costs. Compared with a single-stage compressor the two-stage machine delivers 20% more air for the same piston displacement and, furthermore, effects a considerable reduction, 200° F., in the temperature of the discharged air. An automatic stop-and-start control can be fitted if desired, and the compressors are arranged for either direct or veerope drive.

Drills and picks

Examples of each of the extensive range of drills and picks now marketed by Hugh Wood & Co. Ltd. were also displayed. Among these was a rotary coal drill weighing 28 lb. and driven by a high-speed motor working on 150 cycle current. This is essentially a single-operator machine — a claim that can also be made for a rotary stone drill that was being shown. With the stone drill a ratchet-operated screw-feed device is provided, the whole being arranged for attachment to a prop so that no stand of any kind is necessary. In conjunction with this machine was a Type MV 10 gate-end box for the conversion of 40/50 cycle current to a frequency of 120/150, and a selection of "Cutanit" drilling bits. A number of different types were to be seen designed to suit the various cutting needs of the pit, from normal coal to hard stone; and for drilling the somewhat larger holes for Cardox shells.

The range of hammer drills included the "XC," "XSM," "XSH" and RV18 units, the first being suitable for high-speed cutting in coal while the remaining three, which are fitted with a blowing device for use in conjunction with a hollow drill, are intended for hard coal and stone of all types.

Drawings and Photographs accompanying the article