The beam engines of the early nineteenth were massive in relation to their power output, very slow, and hugely expensive both to buy to install and to run. There was a need for a low cost, lightweight engine that would run at high speeds, that was cheap to install and occupied little space. Marine craft was an obvious example of an application for  an compact engine with high rotational speed for the new-fangled propellers. Even factory owners could be persuaded of the its virtues - no huge foundations, no great engine house, no need for gearing to achieve speeds suitable for machinery. Very many engineers had sought a solution in various designs of rotary engines - only the disc engine had any success albeit it was not actually a rotary engine at all.

                        Davies and Taylor Patent 7072 of 1836
                                                  (click to enlarge)

Superficially quite different, this engine had a fixed shaft at an angle to the casing. The casing rotated as did the web and therefore so did the disc and fixed shaft. Although it may not seem so, this is a Dakeyne engine reconfigured. The drive was from the casing. Its principle advantage is perhaps that that it looked more conventional with no shaft flailing around, just a spinning casing.

In 1840 the partners in the salt works bought out the manufacturing rights for the disc engine and established the Birmingham Patent Disc Engine Co. (BPDE) Davies was appointed superintendent. After 18 months they had sold 26 engines for factories mills and a coal mine.

       Ransomes' portable 5hp disc engine and boiler
                                      (click to enlarge)
Although exhibited at the 1841 Royal Show and retained in the catalogue for several years, it is not certain how many were sold. The addition of a belt driving the main axle the next year ,made this this first ever traction engine.

For several years Davies had been testing disc engine powered canal boats. He was fully vindicated when in 1843 BPDE received their biggest ever order for eight canal tugs designed by Davies and each powered by two 5hp disc engines.

This extraordinary design was used to tow a train of barges. There were two shafts each with four propellers housed in a duct running from stem to stern. The tug and the barges were locked together within troughs, the rounded stems and sterns allowing the craft to swing as they went round bends in the waterway.  These features were designed to reduce wash eroding the banks. Initially very successful, problems soon surfaced. Whilst the manpower required with horse drawn barges was reduced from two per barge to two per train, nobody had thought of the need to get each barge through the locks separately which still required horses and men plus the delay in splitting and reforming the train. When the Shropshire Union merged with another company in 1845, the tugs were abandoned. Competition from the railways was cited.

Virtually coincidentally the BPDE stopped trading. It was suffering cash flow problems nor was it bankrupt. It just sold up including its stock of 29 disc engines. So what could have gone wrong?

It was simple - the engine quickly wore out , clanking and banging and leaking clouds of steam to an even greater extent than when new - and that was bad enough. Moreover it could not be repaired. No one in their right mind would buy it. Davies took our several patents intended to improve the sealing of the engine but it was too little, too late.

George Bishopp, formerly employed as build superintendent at BPDE, patented his "improved"disc engine in 1845. Amongst other things it featured replaceable parts and machined surfaces - the latter apparently in marked contrast to the crude Davies engine. He first achieved prominence when he supplied an engine to drive the printing presses at "The Times" printworks - the world's first mechanised presses.

Bishopp built on this success, supplying engines to paper works, a starch factory, and land drainage. By 1851 about 50 engines were in service. Trials in HMS Minx, a 301 ton ship, were favourable but not sufficiently so to impress the Admiralty. But they did attract the attention of J & G Rennie, a famous London engineering company who produced everything from marine engines to locomotives. Bishopp became a foreman in their works with responsibility for the design and manufacture of disc engines. By 1852 about twenty engines were in service. Rennies re-engined a 752 ton sloop, HMS Cruizer, but no data from the trials survive. Their next venture was to built a few twin screw steam launches for Egypt and India and supplied an engine for a Russian gunboat. Had the Crimean War not intervened, many more would have been supplied.

But by 1856 the writing was on the wall. With the advent of lightweight high speed reciprocating engines, no one was interested in an engine requiring constant maintenance - inevitably the sealing arrangements broke down and this was to prove the Achilles heel of the disc engine. It was fundamentally flawed.

In 1857 Rennies' supplied a disc engine/disc pump fire appliance to Woolwich Dockyard, conceivably the last disc engine they built.

It was not entirely the end of the disc engine - curiously the design is ideal for a mass produced water meter, an idea going back to Henry Davies. Millions have been made, particularly in North America, and are still manufactured to this day.

But it was the end of the use of disc engines to produce power - at least for the next 150 years.