This wonderful example of engineering from a bygone age is still working and open to you to visit on regular open days from March to October. The 2008 open days are given in a separate page. On open days the Leawood Pump will normally be in steam!
The site is preserved and operated by the Middleton Top Engine & Leawood Pump Group, volunteers supported by Derbyshire County Council who own the Leawood Pumphouse.
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On the 24th of August 1789 the Cromford Canal Company was formed by an Act of Parliament. £46,000 had been raised to cut the canal and fill it with water. In those days water was a particularly highly valued commodity and it drove the wheels of industry in the Derwent Valley. A committee was appointed and Sir Richard Arkwright, the mill owner was Chairman. Work began on staking out the course of the canal that year.
By 1793 the 14 mile canal was complete and by May had received tolls totaling £1,054. However, a setback occurred in October of that year when the Leawood Aqueduct collapsed, allegedly due to the use of Crich lime in the mortar which did not set. The canal's engineer, Mr. William Jessop, offered to pay for the repairs himself out of his wages. Meanwhile a railway was constructed over the aqueduct to keep the traffic flowing.
The canal operated successfully for a further fiftyone years. 1844 was a dry year and the canal suffered a severe shortage of water. The normal supply from the Cromford and Bonsall soughs (streams) had been supplying less water due to the Merebrook sough removing water from the local lead mines at a level below the canal. By the autumn of that year the situation was so serious that a pump was hired and installed by the end of November to take water from the River Derwent. In January 1845 the Cromford Canal Company decided to have a permanent pump built to prevent a repetition of the events of 1844 and Graham and Company of the Milton Iron Works, Elsecar, were asked to build a 70 horsepower engine costing £1,965 and to be ready for work in July that year. The Pumphouse was to be built on land owned by a Mr. Nightingale on the opposite side of the river to where it stands today. Unfortunately, Mr. Nightingale did not see the light and did not wish to sell his land for such a use, so the present site was chosen instead.
The pump was not installed in July 1845; in fact the manufacturer wrote to the Canal Company in 1848 asking if the engine was to be completed. The reasons for this are not clear. 1844 was a particularly dry year and this was not repeated in subsequent years. The Cromford Canal Company was also considering selling out to the Manchester, Matlock & Midland Joint Railway Company and so did not wish to spend unnecessarily. The Railway Company did not decide that year whether or not to buy the canal but did offer to pay for the engine. In October they were told that the pump would cost £2,700 to be completed and installed with an additional £200 to clean the engine as it had stood outside for some time. The sum was agreed and as the canal had to be diverted for the railway, and the hired pump removed, it appeared a logical solution. In late 1849 the Leawood Pumphouse became operational and pumped water from the River Derwent to the Cromford Canal for the first time since its conception in 1844.
The objective of the pumping engine was to maintain a level of water sufficient to keep the canal traffic flowing. The Cromford Canal has a flight of fourteen locks connecting it to the Erewash Canal at Langley Mill Basin. Each time a boat enters or leaves the Cromford Canal it takes a lock full of water into the Erewash Canal which needs to be replaced. Also, all canals leak and lose water through evaporation. But even these losses do not explain the sheer scale of the engine. If water could be taken out of the River Derwent regularly then why was such a large engine needed and why was it built 13 miles from the nearest lock?
The answer to these questions lies with the significance of the industry on the River Derwent. Water which powered the cotton mills was protected by act of parliament so anyone wishing to extract upstream of the mills had to comply with strict conditions with a heavy financial penalty if they failed to do so. The conditions were that water could only be removed from the Derwent between the hours of 8pm on Saturdays and 8pm on Sundays and no more than one twentieth of the flow of the river in any period of that time, and none at all if the flow was less than 570 tons per minute. The flow was measured at the weir behind Masson Mill, Matlock Bath.
With such restrictions it can be seen that if you wish to maintain a level of water in the canal but can only fill for one 24 hour period each week, then a substantial amount of water will need to be pumped. This explains the size of the engine as it is capable of pumping almost four tons of water per stroke at seven strokes per minute - a total of over 39,000 tons of water per 24 hours. This also helps to explain why the Pumphouse is situated where it is. As water can only be pumped once a week then it needs to be stored in a reservoir. The canal itself acts as the reservoir by, firstly, the time taken for the water to flow down to the locks and, secondly, by being deeper at the Cromford end than at Langley Mill. During the week the level of water would drop as traffic passed onto, along and off the canal. The amount of traffic varied over time but in 1849 in excess of 300,000 tons of freight was transported along the Cromford Canal.
Information for 'A Brief History' and The Pumphouse' was taken from "The Cromford Canal Company 1789-1852", a booklet now out of print but written by Mr. J. W. Walker for the Cromford Canal Society, which no longer exists.
The sheer scale of the pumping engine makes it difficult for the visitor to see the whole operation of the engine working at once. This in part is due to the bob wall, the central dividing wall across the ground floor. This wall supports the beam on an axle twelve inches in diameter. The beam connects the engine to the pump and consists of two single castings 33 feet long, side by side and weighing a total of 27 tons. At one end, the front of the building, it connects to the piston rod. The piston itself is fifty inches in diameter an is located in a cylinder over ten feet deep, giving a stroke of over nine feet.
Steam is produced by two locomotive type boilers in the neighbouring Boiler House. The present boilers were built by the Midland Railway Company in 1900 and can produce steam at a pressure of 40 pounds per square inch (PSI). the original boilers are thought to have been the Lancashire type as some remaining fixtures in the boiler house point to this. The locomotive boilers may be based on those the Midland Railway built for Ireland's railways as they are too wide for the Midlands lines.
The steam passes under pressure from the boilers through the Main Steam Line Valves and into the Main Steam Lines which transport it into the Engine House and the Valve Chest. This is located above the Steam Cylinder and has two valves. The Inlet Valve allows the steam to pass into the Steam Cylinder on the top side of the Piston; the pressure pushes the Piston down for the full length of the stroke. Once the Piston reaches the bottom of its stroke the Inlet Valve is closed and the engine stops in that position. To complete the stroke the Equilibrium Valve is opened. This allows the steam to pass from the high pressure top side of the Piston to the low pressure bottom side of the Piston via the Equilibrium Pipe at the front of the Steam Cylinder. Unlike many engines, the Leawood engine is not double acting. It is not steam that pushes the Piston back to the top of its stroke but gravity. The Pump Plunger weighs 15 tons and it is the weight of this that rocks the beam back and returns the Piston to the top of the Steam Cylinder.
The used steam now occupying the Cylinder below the Piston is exhausted through a Valve which opens at the same time as the Inlet Valve. This removes the steam into a Condenser, a cylindrical chamber in a tank of cold water. a cold water jet is injected into the chamber to condense the steam back into hot water. This has the effect of creating a vacuum which pulls the Piston down while new steam is pushing down for the next stroke.
When the steam pressure is constant and the engine is running well, all the actions of opening and closing Valves are done by two Cams located on either side of the Plugtree. This is a rod fastened to the beam at the top and to an air pump at the bottom so that it moves in unison with the Piston although its stroke is not quite as long. The time taken for each stroke is regulated by a Dashpot, a small twin chambered pot filled with oil. Between the chambers is a wedge which allows oil to pass through at a controlled rate, which is adjustable.
The Dashpot links to the Valves by a complex set of Valve Gear based on the Cornish type of Valve Gear but adapted for this engine. A combination of stroke length and time per stroke adjustments allow the engine to run without manual (human) valve control.
As the Piston strokes up and down and the Beam rock back and forth the Pump Plunger is rising and falling, pumping water from the River Derwent to the Cromford Canal. The Pump works by both suction and pushing of water. as the Plunger is raised an air tight seal is formed by both the gland at the top and by a flow of water which runs around and down the Plunger. This creates a vacuum below the Plunger, a flat bottomed cylinder, and sucks water through a Non-Returnable, One Way Valve into the chamber that the Plunger vacates as it rises. When the Plunger reaches the top of its stroke the pump chamber will contain 3.95 tons, over 800 gallons of water. This weight of water will force the One Way Valve to close, preventing water from flowing back into the sump and, via the tunnel, back to the river. As the Inlet Valve closes and the Equilibrium Valve opens the Plunger falls under its own weight, pushing the water through a second One Way Valve in a connecting chamber and into a five foot diameter pipe, which, as it is below the level of the canal, is always full of water. the River water passes through this pipe and into the canal, causing a small wave to cross the surface.
Today as the canal is no longer a working transport route the need for additional water is considerably less, so the water that we pump flows out of the canal and back into the River Derwent via a small stream on the other side of the canal. The amount of water that leaves the canal in a year is considerably greater than what the Pumphouse puts in.
Very little is known about the building itself. Many visitors comment on the 'Town Hall' like appearance but whose design it is we do not know. The workmanship put in by its constructors is evident to those who visit though. What is known is that the building was erected before the Engine and Pump were installed, hence the size of the doors. All components of the Engine are capable of fitting through them and how this was done we shall credit to Victorian ingenuity and elbow grease!
Steam Piston - fifty inches in diameter with a nine foot six inch stroke, single acting; Cornish cycle with unusual valve gear. The timing is controlled by the Equilibrium valve operated by a Dashpot.
Beam - thirty three feet long on a twelve inch diameter axle, equal on both sides weighing twenty seven tons; Watts parallel motion at either end.
Plunger - fifty six inches in diameter, weighs 15 tons; two double beat Equilibrium valves to stop the water flowing back to the river and pump chamber.
Boilers - two Midland Railway loco type producing 40 PSI; dated 1900 (not the original boilers); installed after Midland Railway ownership.
Boiler water feed pump - inverted vertical banjo feed pump; unusual that for its size it has a flywheel. Supplies canal water to the boilers to make steam.
Coal - takes approximately one ton of coal to produce steam, warm the engine and provide steam for five hours of pumping; cost: over £120.
The Middleton Top Engine & Leawood Pump Group also look after the Middleton Top Engine which stands at the top of Middleton incline on the Cromford & High Peak Railway. This is only a short distance from the Leawood pump and can easily be visited on the same day.
Last updated 03 January, 2008.
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