Publication Account
Date 1986
Event ID 1017662
Category Descriptive Accounts
Type Publication Account
Permalink http://canmore.org.uk/event/1017662
Situated at the N end of the old lead-mining village of Wanlockhead, this engine stands above a disused mineshaft on what was part of the Straitsteps Mine. It probably dates from about the last quarter of the 19th century and is believed to have served as an auxiliary pump for draining water from abandoned workings to the S. Technically defined as a water-bucket pumping-engine, its motive power was supplied by the weight of water fed into a box-like bucket at one end of the beam, which worked on a centre and carried the pumping-apparatus at the other; at the bottom of each stroke the water was discharged from the bucket through a sluice or flap-valve, thereby transmitting the primary load to the far end of the beam and causing it to move up and down alternately. An earlier engine, evidently conforming to the same working principles, was recorded in operation in the parish of Canonbie, Dumfriesshire, during the 1790s, and by that time similar engines were being used extensively on coal and metal-mines in various parts of Britain.' Today, however, the engine at Wanlockhead is believed to be the only example of its type in Britain to remain virtually intact.
The beam, which measures 27 ft 9 in (8.46m) in length and 25 in (0.63m) by 11 1/2 in (292mm) in section, is made of two baulks of pitch-pine, strengthened by moulded wooden pad-plates at the ends and centre, and bound together by a combination of iron straps and tie-rods. Mounted on a 13ft-high (3.96m) dressed stone pillar, the beam is pivoted on a forged gudgeon-block set in cast-iron plummer-blocks and split-brass bearings. The plummer-blocks are secured to their mountings by long anchor-bolts extending through the masonry to the base of the pillar; the beam itself is locked on to the gudgeon-block by means of a lower clamp-plate whose soffit is shaped and recessed to fit round the seating. At the power end the bucket-rod is attached to a crosshead-slide which moved up and down on guide-rails held in a wooden steeple-frame; the slide in its turn is connected to the beam by two link-rods and a cross headcoupling. In general, the various iron forgings and castings are made to a high standard, and all the critical moving parts are held in brass bearings.
No trace of the bucket remains, but the stone-lined pit into which it descended, measuring 5 ft (1.52m) in depth and 4ft (1.22m) by 2ft 3in (0.69m) in area, preserves its drainage outlet at the bottom, and also the iron-clad wooden rails for steadying the bucket when in motion. An 8 in-diameter (203mm) iron plate with raised rim, held loosely on the end of the bucket-rod by a large iron wedge, may have been part of the water-release valve mechanism attached to the bucket. Depending on the position of the bucket on the rod, the related lengths of the bucket-rod and steeple slide-rods (respectively 11 ft 2 in (3.40m) and 10 ft (3.05m) between centres) would allow an engine-stroke of approximately 7ft (2.13m). The other end of the beam overhangs the mine-shaft and carries the remains of a Sin-square (127mm) wooden pump-spear, which is connected to the beam by a shackle and crosshead-coupling.
Water for working the engine was collected in a cistern situated on the hillside above and then piped into the bucket at a level coinciding with the head of the stroke. On the evidence of a photograph taken c.1900, the engine was then in a state of disuse, but at that time it still retained a sheer-leg structure over the mine-shaft, used apparently in association with a nearby horse-gin for the handling of materials and pumping-apparatus.
Information from ‘Monuments of Industry: An Illustrated Historical Record’, (1986).
