Vertical shafts, 700ft. / 116 fathoms to Dunnet Shale
Serving Westwood Crude Oil Works (from c.1942)
One of the largest, deepest and longest-lived of shale workings, and the last shale pit to remain in operation. Westwood was Scottish Oils Ltd's showcase pit during the 1920's and 30's, featured in their promotional films, and received many important visitors. See foot of page for a full technical description.
Shale-field: West Calder shale field.
Mapped by the Ordnance Survey of c.1955, showing the pit in production.
These pits were sunk to the Dunnet Shale by the Oakbank Oil Company Ltd in the year 1915 and command and area of about 500 acres of oil shale, comprising the Broxburn and Dunnet seams. The pits are circular in shape, the downcast or winding shaft being 16' in diameter, the upcast being 14' in diameter. Both pits are 700 feet deep and are brick-lined from top to bottom. At present only the downcast shaft is used for winding shale and this pit is fitted with eight wire rope guides suspended in the shaft and kept taut by large balance weights at the bottom. The two cages are of the single deck type, holding two hutches each, and are raised and lowered in the shaft by steel wire ropes 1.25" in diameter.
There are two seams of shale presently being worked; Broxburn and Dunnet. The distance between the seams is 380 feet. The Broxburn Shale is about 5' thick and the Dunnet Shale from 12' to 14' thick. The method of working is stoop and room. In the first working of the Dunnet, a thickness of only 9' is taken the remainder being recovered in the second working or stooping operation. The shale to the the dip is brought from the working faces to the pit bottom by means of mechanical haulage of either the endless rope type or single rope dook haulage. Shale to the rise is lowered by gravity haulages which are self-acting. Water is pumped from the mine by three motor driven turbine pumps consisting of two 500 gallons per minute pumps, and one 450 gallons per minute. The present output is 650 tons per day, but the plant is capable of dealing with 800 tons in eight hours.
Steam is raised to a pressure of 160 lbs. per sq. inch by means of three Lancashire boilers 9'10" diameter and 24'0" long. There boilers are fitted with underfeed stokers and forced draught is supplied by means of a fan. Steam passes through Cooper and Greig superheaters placed at the back of the boilers. Steam is supplied to the winding engines and the power station.
The winding engines for No.1 pit are of the coupled non-condensing type with cylinders 20" diameter and 3'6" stroke. The drum is 10' diameter and carries a 1.25" diameter winding rope for the downcast pit. The engine is fitted with a Barclay controller, which is a device for the prevention of overwinding. Should the winding engineman fail to reduce the speed of his engine when the ascending cage nears the top of the pit, the controller, by means of a system of levers and governors, automatically cuts off the supply of steam to the engineman and applies a powerful brake, thus bringing the engine to rest. The winding engine for No.2 pit have 18" cylinders and 4'0" stroke. This engine is mainly used at present for raising and lowering the cages for the purpose of inspecting the shaft which contains the water pipes and electric cables leading underground.
There are two generating sets in the power station, each with an output of 625 K.V.A., 820 Amps. 440 volts, 25 cycles, at a speed of 250 r.p.m. The alternators are coupled direct to Bellis and Morcom triple-crank compound condensing engines. A single Korting jet condenser deals with the exhaust steam from both engines, and is working in conjunction with an open cooling pond.
The generators supply current for lighting on the surface, power on the surface and underground and power to No. 26 mine Polbeth. Coupled to each generator shaft is a direct current exciter of 21 K.W. 250 r.p.m. 190 amps. 110 volts. While supplying the exciting current for the field magnets each alternator, this machine has surplus energy which is used for lighting lamps on the surface. The generators supply power at 440 volts for driving motors on the surface and also for lighting underground after passing through the step down transformer. There is also in the power station and oil-cooled transformer, which raises the voltage from 440 to 3300 for transmission by overhead line to No .26 mine, Polbeth.
The air passes into the mine through the downcast shaft and after travelling round the workings is drawn out through the upcast shaft by means of a Sirocco fan, 105 inches in diameter, belt driven at a speed of 140 r.p.m. The ventilating pressure, or the difference in pressure of the air in the two shafts is registered continuously on a recording water gauge placed in the fan-house, and is about 1.5" W.G.
Dated 8/6/27, the original source of this transcription is not known.
Above left: View towards pit, showing offices, c.1920's.