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July, 1927

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There are comparatively few collieries which are in the fortunate position of being equipped with entirely modern plant, and it is one of the most delicate problems the mining engineer is required to solve to decide when the existing equipment — the best, no doubt, that could be purchased in its day — has to be scrapped or otherwise brought into line with modern economic needs. Entirely to replace equipment which possesses many years of useful life frequently an economic, if drastic, necessity, but if portions of it can be adapted to work in harmony with modern additions the saving that is thus effected is all to the good. In the instance under review it was found to be possible to utilise a considerable amount of the old plant in this way and we trust, for this reason, that our account will be of particular interest and offer valuable suggestions in regard to haulage con versions of this kind.

Before proceeding we should like to express our thanks to Mr. T. E. Parrington, the Agent and General Manager of the Wearmouth Coal Co. Ltd., for the facilities so kindly granted us to visit the collieries and to publish this article. We are also indebted to Messrs. W. C. Mountain, Son & Wood, Consulting Electrical and Mechanical Engineers, of Newcastle-upon-Tyne, Birmingham and London (in accordance with whose specifications and under whose supervision the work has been carried out for the loan of drawings and for supplying us with much of the data presented. In the actual carrying out of the work Mr. W. B. H. Lockerbie, the Assistant Agent, Mr. W. R. Bell, the Manager of Wearmouth Colliery, Mr. Rankin, the Hylton Colliery Manager, and Mr. C. Paris, the Chief Mechanical Engineer to the company, have of course, taken active parts and have rendered valuable assistance in their respective spheres.

Outline of Scheme.

The scheme entails the electrification of the whole of the main underground haulages situated near the pit bottom at both the collieries mentioned in the sub-title and the conversion of a small staple winder, all of which were formerly driven by steam or compressed air. It was decided to take current for the Hylton Colliery from the County of Durham Electric Supply Co. Ltd., which is associated with the Newcastle-upon-Tyne Electric Power Supply Company, for Wearmouth Colliery the current is being taken n from the Sunderland Corporation Supply.

On closely investigating the power necessary for operating the main and tail haulages underground, it was found that it would be possible to utilise one standard size of motor for each haulage, but due to the periodicity of the County of Durham supply being 40 and the Sunderland Corporation being 50, it was necessary in order to have the motors duplicates of each other, that the voltage at Hylton Colliery should be 2,200 at 40 cycles and at Wearmouth 2,750 at 50 cycles. Under these circumstances the motors at Hylton Colliery give 200 effective horse-power on continuous rating (with 2½ times full load torque equivalent to 500 hp. before breaking out of step) at a Speed of 400 r.p.m synchronous, or about 385 r.p.m. actual. At Wearmouth Colliery the motors give 250 h.p. each on continuous rating (or, say, 625 hp, each before breaking out of step) at a speed of 500 r.p.m. synchronous or, say, 485 r.p.m. actual. This enables any motor in either pit to be transferred from one pit to the other and only makes it necessary to hold one spare motor under ordinary circumstances.

In addition to the haulages which will he described later, it is proposed to add an additional haulage in the Harvey Seam at Hylton Colliery and a main shaft pump in the bottom of the shaft at Wearmouth Colliery.

At Hylton Colliery two transformers, each having a capacity of 800 k.v.a., will be eventually installed in the sub-station to reduce the voltage from 20,000 to 2,200 volts. The high-tension switchgear and the 2,200-volt low-tension switchgear at which pressure the three-phase 40-cycle current is supplied to the main haulages, are also housed in this building . At present only one transformer is installed, this being the of the Wearmouth Coal Co. Ltd. it was supplied by Ferranti Limited.

The high-tension switchgear and also the whole of the remaining switchgear, both on the surface and underground, is by Reyrolle & Co. Ltd. This is all of their well-known mining draw-out type and of their latest design.

Shaft Cables.

The main shaft cables run in duplicate from the substation to the surface distribution board (which is equipped with five panels) and thence to the shaft bottom, a total distance of approximately 887 yards. They are of the three-core type, paper insulated, and protected by a lead covering and double-wire armouring. The cores are 0.15 in. in area throughout, and in case of emergency one cable is capable of carrying the normal load of the colliery, so that a breakdown due to cables is guarded against as far as possible. They are carried down by heavy wood cleats secured to the shaft sides, these being spaced at approximately 20-yard intervals throughout the entire depth of the shaft.

The cables were installed in lengths of not more than 240 yards, which enabled them to be got into the pit without difficulty. They were led into the insets with suitable link boxes, so that it will he an easy matter to disconnect them at any time for testing purposes. It may be mentioned that the entire cable work in connection with the scheme was supplied by Callender's Cable & Construction Co. Ltd., who also supplied the junction boxes and supervised the installation both in the shaft and underground.

Fig. 3 shows the type of sub-station at Hylton Colliery, and a duplicate of the same is also built at Wearmouth Colliery. This design has been standardised by the County of Durham Electric Supply Co. Ltd., to whom we are indebted for permission to reproduce the drawings.

Haulage for the West Pit, Maudlin Seam.

In this instance it was found that the existing compressed air haulage was incapable of conversion into electrical haulage as it was too light for the heavier duty which would be required of it in the future, it being intended to extend the haulage distance and increase the number of tubs in the train. An entirely new main and tail and haulage gear, by M. B. Wild & Co. Ltd., was therefore installed to the following general particulars :—

Diameter of each drum	5 ft.
Width of drums	2.5 ft.
Diameter over drum sides	7 ft.
Revs. of drum per minute	47
Length of present run	1,700 yards.
Weight of coal drawn per hour	75 tons.

Three roads are served, the maximum average gradient being 1 in 52. The drums are capable of accommodating 3,000 yards of the 2½-in. circumference rope which will be used. At present 54 of the 10-cwt. capacity tubs comprise the train, but this number will shortly be increased to 60.

The general design of this haulage and the arrangements in the haulage room, together with the switchgear and controller, and water-cooling tank, are shown on drawing, Fig. 1. The drums are in halves and are constructed entirely of steel with steel centres. Brake paths are fitted on each side of each drum, together with brake gear of exceptionally substantial design.

The drum shaft is supported in four bearings, that is, with a central support between the drums and with bearings on each side of the spur gearing. Clutches of the friction type are fitted to enable the haulages to be started up, if desired, with the motor running at full speed, without subjecting the gear to undue shock. They are operated by means of a weigh-bar with screw and hand-wheel.

The pinion and main spur wheel, which is in halves, are of steel of the double-helical type, and run in an oil bath which is provided with suitable means for filling and emptying. The bedplate is of very substantial design, consisting of longitudinal channels plated top and bottom and tied together by cross channels with gusset plate, thus enabling the girders to be readily got down the pit and placed in position on the foundations.

A suitable indicator is provided to show the position of the tubs on the road. This is of the horizontal type which enables a diagram showing the contour of the road to be placed upon it, indicating clearly to the driver any variation in the gradient. The various new haulage gears in both the collieries were supplied by M. B. Wild & Co. Ltd., of Birmingham to specification and designs supplied by the consulting engineers.

The motor, which is from the works of the General Electric Co. Ltd., is in every way similar to the other motors installed, and is of the three-phase slip-ring type of the following capacity :—

Effective horse-power on continuous rating	200
Maximum horse-power before breaking out of step	500
Revs. per minute	385
Volts	2,200
Cycles	40

A flexible coupling is fitted which attaches to the pinion shaft of the haulage gear. This arrangement enables the motors to be removed or interchanged if required, without disturbing the gearing in any way. The controller is of the Allen West liquid type with independent stator and reversing switch, and is operated by a suitable quadrant placed in a convenient position on the haulage platform.

Distribution switchgear for this seam is arranged in the haulage room and embodies the control switch for the haulage and a remote tripping switch placed on the haulage platform. together with an ammeter and voltmeter mounted upon an independent column, the instruments being provided with 12-in. dials. The flexible coupling-up cables in the haulage room are of the three-core vulcanised India-rubber type, suitably cleated and carried in trenches under the floor.

Conversion of East Pit Haulages.

The haulage gear which has been converted from compressed air to electric drive was made by Barclay & Co. Ltd., Kilmarnock. It is of the main and tail type, and is fitted with two drums each 5 ft. diameter by 2 ft. 6 in. wide each drum has a friction clutch and an all-round band brake. Upon the drum shaft, which is carried by two bearings, one at each end, is mounted a spur wheel which was originally driven from the air engine through a steel pinion. Unfortunately it was impossible to include a drawing showing this conversion, but a new countershaft is provided, supported by three self-oiling bearings, one being placed in a wall box, and the other two supported by the engine bed and an extension to the foundations with special sole plate. A new pinion has been placed on this shaft gearing into the spur wheel on the drum shaft, and also a rope pulley, in halves 12 ft. in diameter. Five roads are served, the average gradients ranging from 1 in 26 to 1 in 400 the maximum gradient, on a 20-yard length, is 1 in 8, but in estimating the power required the figure worked upon was 1 in 11, this being the effective gradient so far as the whole set was concerned.

The motor is arranged for a rope drive and is, of course, similar in every respect to the one already described. It is mounted upon a cast-iron combination bedplate planed on the underside and carried on three cast-iron slide rails, which enables the slack of the rope to be taken when required. The engine which it has displaced had two cylinders 16 in. in diameter by a 36-in. stroke, the working pressure being 95 lb. per sq. in A cast-iron coupling of the solid type is keyed upon the motor shaft and connected to an independent pulley shaft, running in two self-oiling bearings.

The controller is of the Allen West liquid type with an independent stator and reversing switch, and a quadrant suitably placed to afford the attendant a good of the machinery whilst operating An instrument column is provided carrying a 12-in. ammeter and voltmeter, also a remote tripping switch for operating the main oil switch, which forms part of the distribution board, amid which is installed in the haulage room All the necessary coupling up cables (of the vulcanised india-rubber three-core type) are carried either by cleats or in trenches between the main switch and the controller, &c.

The conversion of this haulage from compressed air to electric drive shows how satisfactorily a conversion of this kind can be made and existing haulages utilised. Also the method of driving by ropes from the motor to the haulage is specially recommended where sufficient space is available. There is a great deal of advantage in having the elasticity of a rope drive, and it enables the conversion to be made without stopping the haulages for more than the week-end, if the arrangement is suitably designed and good staff work is exercised.

Drawings and Photographs accompanying the article