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August, 1952
Trolley locomotive installation at Beckermet mine
A trolley locomotive installation has recently been completed at Beckermet No. 1 Mine which is owned by the Beckermet Mining Company, a subsidiary of the United Steel Company Limited, and is situated near Egremont, Cumberland ; at Beckermet is produced haematite iron ore for use in the Company's blast furnaces at Workington
By J. G. Gunn*
The trolley locomotive replaces an endless-rope haulage which ran for a distance of approximately 900 yards from No. 1 shaft bottom, Fig. 1, to the top of Sheepfields Dip. As this road will ultimately be extended a further 2,000 yards towards Robert Gate Bridge and also 800 yards to the west of No. 1 shaft, the final distance travelled by the locomotive will exceed 2 miles. It is for this reason that the rectifier station indicated in Fig. 2 is sited at the inbye end of the present length as this position will become the centre of the final layout and the voltage drop in the overhead conductor will be kept to a minimum.
All new drifts are on a rising gradient of 1 in 150 from the pit bottom and although some of the existing roads exceed this, the gradient always favours the load. The track gauge is 2 ft. 6 in. and 35 lb. per yard rails are laid throughout. The track is ballasted with in. limestone chippings.
The installation consists of an 8 ton, 80 h.p. locomotive working on a 250 volt d.c. overhead conductor with the rail used for the negative return. The incoming supply from the pit bottom sub-station is transformed from 3,300 V. a.c. to 250 V. a.c. and converted to d.c. in the rectifier station shown in Fig. 4. It is then fed to the overhead conductor by a single core 0.4 cable.
The possibility of a second locomotive in the future has been considered and for this reason the rectifier, which is a 200 kW pumpless steel-tank rectifier supplied by the British Thomson Houston Co. Ltd., is large enough to take twice the present load.
The overhead conductor is of 4/0 cadmium-copper having a grooved section and is supported by line ears bolted to porcelain insulators which are either clamped to the steel girders or bolted direct to dowels wedged into the rock roof. It is divided into sections not exceeding 500 yards in length and separated by section isolators of the type shown in Fig. 3. Each 500-yard section is fed by an 04 single-core cable from the rectifier. In this way one section can be isolated while other sections remain in use.
All rail points are bonded with a welded copper bond, Fig. 6, the two lines of rails forming a single track being cross bonded every 100 yards. Each girder or dowel holding an insulator is also connected to the rails with a copper bond. The conductor is so fixed that there is a minimum clearance of 6 ft. 6 in. between the rail and the conductor, and 6 in. between the conductor and the roof or any roof supports. The insulators are spaced so that there is a sag of no more than 3 in. at any one point.
Sidings are provided at each end of the system for marshalling the full and empty sets which consists of 20 bogies of 20 cwt. capacity. Double sidings are necessary as the locomotive has to be in front of the train except during shunting operations. Spring-operated points and spring-loaded frogs are provided so that the locomotive automatically keeps to the correct track.
The locomotive, which weighs 8 tons, is shown in Fig. 5 and 7; it was manufactured by the Goodman Company of America and supplied through the Distington Engineering Company. The specification is as follows :—
Gauge 30 in.
Wheelbase 60 in.
Outside Frame.
30 in. diam. wheels with steel tyres.
Roller axle journal bearings.
Two central hung, type 158, 250-V. 40 h.p., motors.
One type LM-141B series or parallel controller line contactor and overload relay.
Automatic transfer switch.
VA-23A cable reel with 600 ft. No. 2 single conductor, all rubber covered cable.
Hand brakes.
Two type Y headlights.
Warning signal — 10-in. gong.
Speedometer.
Link and pin coupling.
Trolley pole and shoe with carbon collector.
"Dead-man" foot switch.
Length: 14 ft. 10 in.
Overhang:
Controller end, 61 in.
Front end, 57 in.
Width : 53½ in.
Height:
Over cab, 63 in.
Over top of reel, 49¼ in.
Over deck, 39 in.
Drawbar pull, starting with sand, about 4,800 lb.
Drawbar running starting with sand, about 4,000 lb.
Speed at running drawbar pull — 1½ to 6 m.p.h.
The drawbar pull is much greater than required for the duty at Beckermet and, in fact, a 4-ton locomotive would have been suitable. The main reason for adopting the 8-ton locomotive was that this size was thought to be the minimum standard likely to be adopted if trolley locomotives are introduced to the coal mines of this country, and it was felt that useful experience would be gained with this installation.
The locomotive is fitted with a "dead man" foot switch so that the power is automatically cut off if anything happens to the driver. In addition a series of switches is installed along the roadway connected by a pull wire, which is so arranged that it can be reached by the driver while sitting in the cab. The pull switches are connected to a low-voltage operating coil which trips the main d.c. circuit breaker when the wire indicated in Fig. 9 is pulled, the low-voltage supply being supplied by a 30 V. Nife battery.
Illuminated panels, Fig. 8, are installed at all road junctions. These are connected to the overhead conductor and are so placed that anyone approaching the locomotive road will see a lighted "Danger" sign when the conductor is live. In addition red lamps are placed along the conductor so that no one can be in the vicinity of the conductor without having visual warning of it being alive.
One feature of this installation which, although common practice in the United States, is thought to be new to this country, is the cable-reel attachment. This consists of a horizontal drum placed on top of the locomotive and holding 600 ft. of single-core rubber-covered cable. One end of this cable has a plug which can be connected into a socket, complete with single-pole switch, on the side of the road. The other end of the cable is connected, through slip rings, to the controller on the locomotive. A switch is incorporated in the base of the trolley pole so that, when the pole is lowered, the current is cut off from the shoe and the supply to the locomotive is taken through the cable.
The cable reel is used to give a greater degree of flexibility to the trolley locomotive as it allows a radius of action up to 600 ft. away from the overhead conductor, provided the rails used are properly bonded. The operation of the cable reel is simple as it is connected to the locomotive by suitable gearing which controls the speed of unwinding and also rotates the drum for reeling in so that there is no possibility of the locomotive running over the cable.
The photographs illustrating this article were taken by the British Insulated Callender's Cables Co. Ltd., who kindly gave permission for their reproduction. This firm supplied the equipment for the overhead conductor and bonding and gave much helpful advice on the installation generally.
With the exception of connecting up the rectifier, the whole of the underground work was carried out by the staff at the mines, with assistance from the electrical engineers of the Workington Iron & Steel Company and the Distington Engineering Company.
* Agent, The Beckermet Mining Co. Ltd.
Drawings and Photographs accompanying the article
Article reproduced from a copy of the magazine held at National Mining Museum Scotland, Newtongrange, Midlothian.
Contains public sector information licensed under the 
