Henry Davies lived at Stoke Prior, a village near Droitwich Spa. In 1836 he and Taylor granted manufacturing rights for the disc engine to Fardon and Gossage, joint owners of a salt works exploiting the recently discovered brine springs in the area. At that time Davies was working on a canal tug with a disc engine driving a paddle wheel at the stern - perhaps not entirely a coincidence because the salt was shipped by canal.
By 1838 a 5hp engine was operating in the salt works quite possibly pumping brine. It was said in one account to have been invented by a "labouring mechanic".
In 1839 the patentees together with the owners of the salt works conveyed the disc engine manufacturing rights to the Birmingham Patent Disc Engine company (BPDE). As Superintendent of the Company, Henry Davies would be responsible for all design and manufacture. Gossage was one of the directors. In February 1841 the Board were able to report that 26 engines had been completed , further engines totalling 260 horsepower were in progress and yet a further total of 500 horsepower were on order. They could make engines ranging from 5 to 30 horsepower and were currently making engines for a railway carriage.
An article in a French journal reported in 1841 that a 12hp engine had been in use for six months as a winding engine at Corbyn's Hall Mine, Dudley apparently quite satisfactorily. It could lift a load of 1 ton 180ft in 1min. The disc engines cost from £96 for a 8hp machine up to £300 for a 30hp model. The winding gear,boiler and installation costs added a further 80%.
Ransomes of Ipswich (who were later to become the well known agricultural engineers, Ransomes and Sims) exhibited a portable steam engine at the Royal Liverpool Show in 1841. Powered by a 5 horsepower BPDE disc engine, it had a threshing drum carried on the same frame which was lifted off and anchored to the ground when in use.
At the Bristol Show the following year a chain drive to the main axle was featured. This, the first traction engine, was capable of 5 to 6 mph. It was judged of equivalent output to a three horse threshing machine and won a £30 prize. Ransomes continued to poffer the machoine for some years but sales are not recorded.
By 1840 a canal boat "The Experiment" powered by a Davis engine was being used for propellor testing. Two years later Davis installed an engine and disc pump in a barge which he demonstrated by draining 1/2 mile of the Stourbridge canal. It was capable of pumping 6500 gal/min.
In 1842 a 5 horsepower engine was fitted in a pinnace from Captain Carpenter's ship HMS Geyser primarily to demonstrate the efficacy of the propellors designed by him. Trials on the Thames and later before the Directors of the Grand Junction canal failed to convince either the Admiralty or the canal owners (although Carpenter's propellors were to become the standard type used by the Royal Navy)
Nevertheless there was a growing interest in using steam power on the canals. The damage to the canal banks from the wash created by paddle wheels was a problem but the alternative might be the new-fangled propellors. The small size of canal boats very much favoured disc engines. Davies saw his opportunity.
He built an iron hulled tug with a 16 horsepower BPDE engine in 1843. To minimise wash he fitted four propellors spaced along a shaft the length of the boat and enclosed in a tube below the waterline. There were two of these propulsion units side by side so a total of 8 propellors.
The tug was tightly coupled to a barge so that the latter followed the tug fairly precisely and the stern and bow respectively were enclosed in a trough designed to reduce wash and aid steering. The concept envisaged one tug pulling a train of barges with a crew of just three men.
It worked well enough to convince the Directors of the Birmingham and Liverpool Junction (later Shropshire Union) canal to order six tugs. As many as sixteen barges could be towed at a reasonable speed. In practice each day a train of six to eight barges left from Ellesmere Port and from Wolverhampton, 69 miles apart carrying an average of 100 tons. It was calculated that one ton could be moved 1 mile for 1lb of coal. A total of 2000 to 3000 tons could be transported each week.
But there was a problem that had not been forseen. Nobody had thought about the transit of the barge train through the locks and the various shallows on the canal. The train had to be uncoupled and each barge manhandled or towed by horse through each obstruction before reassembling the train at the other side. This totally negated any benefit of the tug and train method. In 1845 the Directors gave up and took the tugs out of service. Most were scrapped.
It was not just the canal company that was in trouble - in 1844 the BPDE collapsed. The workshop equipment, 28 completed engines and large quantities of work in progress was offered for sale. Sales had stopped.
So what had gone wrong? Clearly the engine worked or it would never have attracted investors and gone into relatively large scale production. But in 1849 "Iron, an Illustrated Weekly Journal for Iron and Steel Manufacturers" referred to the "utter failure" of the Davies and Taylor engine in the hands of the company "formed for working the invention". In legal proceedings in 1851, following the bankruptcy of two of the principal BPDE investors, the engine was said not to have made a profit and to have relied on it as a realisable asset "was absurd".
There is no direct evidence of what went wrong but it is reasonable to deduce that while it worked it did not do so for very long. Why?
The disc engine must maintain very tight clearances to minimise leakage of the working fluid. As can be seen in the patent drawing, the sphere/disc is mounted on the end of the rotating shaft. All shafts will bend when a radial load is applied. Therefore locating the disc within the casing in addition was essential. The only way of doing this was introduce plain bearings around the internal rims of the casing. But allowing for the fitting of seals as well. the bearing on the rotating shaft end of the casing was very narrow .At the other side, although well able to withstand axial loads, it has a limited surface area constraining radial loads.
In operation the disc is subject to complex radial and axial loads and these in turn load the bearing surfaces. Although there was no rotational wear (since the disc and casing rotate together) the disc still tilted within the casing. This constant movement (perhaps 300 times per minute) combined with heavy loading on narrow bearings may have resulted in very heavy wear. Once the bearings deteriorated, seals would be damaged and pass steam significantly reducing efficiency. Unless rectified, the disc might rub on the casing causing real damage eventually stopping the engine.
There is no contempary evidence but this seems the most plausible reason why an engine which ran perfectly well initially soon failed in service. The design was flawed.
It was not surprising that Bishopp's engine met with considerable scepticism from the technical press when he launched it on the market 5 years later. But the reversion to the Dakeynes' original design with a yoke taking the most of the dynamic forces in operation must have significantly reduced the load on the bearings and seals around the inner rim of the casing. If there were to be any leakage, the seals were adjustable.
Furthermore Bishopp used companies with superb engineering capabilities rather than making his own. Donkins had built at least one prototype. Some of the first engines he sold were built by Joseph Whitworth & Co of Manchester, a world class engineering company owned by one of the great engineers of the day. Another company with an excellent reputation was G Rennie and Son of London. They were so convinced of the potential that in 1849 they employed Bishopp for five years as their foreman of works with specific responsibility for the disc engine.
In contrast Davies had chosen to make his own engines. BPDE was a new company set up by investors with no track record in making anything - perhaps a critical difference when making a product which required manufacturing capabilities of the highest order.
By 1849 a number of Bishopp engines had been sold. A Whitworth built engine was supplied in 1849 to drain an estate at Partington near Hull. This was a 21in diameter machine developing 8hp which drove a 57in pump. Like most modern stationary engines it was a condensing engine employing expansive working. There were no less than four engines driving a paper mill - one 30hp, two 16hp, and one 8hp. At a starch works in Battersea there was another 30hp engine and in a paper works in Dover one of 16hp.
Somewhat later Donkon & Co experimented with a Bishopp engine driving a disc pump. It ejected a 40ft high column of water from a 2in pipe but whether it was put into service is not known.
Bishopp demonstrated a Whitworth-built engine at the Great Exhibition of 1851. It ran smoothly and quietly impressing all those who saw it. This was in a marked contrast to the Davies engine which had earlier been described as "noisy and leaky". After the Exhibition the engine was installed in the printing office of the Times newspaper - a surprising but prestigious application. Visitors were invited to see it at work.
The 16hp engine for The Times Print Works
With Bishopp now working for Rennies, all subsequent engines were marketed and built by them. That such a company would risk their reputation demonstrates their belief that the sceptics would be confounded. By 1853 they had built 20 engines. The Times engine was still operating very satisfactorily although later designs had included numerous improvements. They built a 33 ft long shallow draught steamer for the Governor of Egypt which was a great success. A second order for an iron steamer followed. With two 13in diameter disc engines driving 2ft diameter propellors, it was 60 ft long, 6ft beam and drew a mere 21in. With a steam pressure of 60psi in its 5ft diameter 6ft 8in long boiler it attained 12 knots at a shaft speed of 320rpm, a significantly higher speed than that attained by the Nile paddle boats. It frequently did the 172 mls from Cairo to Alexandria in 10h. People were amazed by its ability to stop quickly by reversing its engines and to turn in its own length.
The Russian Admiralty were delighted with a similar engine supplied by Rennies and fitted in a 55ft long gunboat which achieved 7 knots. It had a 3in gun. The outbreak of the Crimean War in 1853 prevented the supply of more engines
Another 33ft long steamer with a single disc engine of 10in diameter was built for private use in 1853. Given a beam of only 4ft, it must have been an intrepid captain who sailed it from Folkestone to Boulogne in six hours!
The following year a 70ft long twin 13in engine steamer was built for use as a Passage Boat on the Cochrane Canal near Madras. It displaced just over 6 tons. Driven by 2ft 2in diameter screws running at 260rpm, in trials on the Thames it attained 10 knots..
Rennies also built ten twin screw gunboats for the India Government in 1857. With 70 ft iron hulls, they were of 20hp.
One of the Rennie steamers for India powered by two disc engines
In that same year the Lords of the Admiralty invited Rennies to build a disc engine powered fire pump. Running at 300rpm, the 6hp engine was of 13in diameter. Mounted with the pump in a 6ft long carriage and with an overall height of 6ft, it weighed 2 tons complete with the boiler. Intended for primariy for pumping the caissons at Woolwich Dockyard it also served as a fire engine capable of sending a jet of water to a height of 120ft at a delivery rate of 30 tons/hour. This was probably one of the last disc engines built - at least no records of later engines have been traced.
So what went wrong? The Bishopp engine seems to have worked reasonably well. However one commentator writing in 1844 said " There are competent men who declare them to be inferior - - - - and allege that the construction of the disc engine is attended with great difficulty and its operation with considerable escapes of steam which it is nearly impossible to prevent." So it seems even the engine built by Rennies was not
problem-free. This view is supported by Bishopp's later patents which were directed not only to improved sealing but also to simplifying part replacement - for example by making the sphere in two halves it was possible to reface or replace it without replacing the disc.
Undoubtedly the competition from the modern high speed steam engines by then available was the major factor leading to the demise of the disc engine. They were small, light and could offer advanced features such as compounding. They did not require the "nicety of manufacture" demanded by the disc engine and steam leakage was not a problem! The overwhelming superiority of the conventional engine is well illustrated by the fact that by 1857 a company in Lincoln was producing 500 portable engines a year for agricultural use and there were at least 20 manufacturers in that field. The first such machine, that built by Ransomes, had an engine now regarded as a complete failure!