The sleeve valve is a type of valve mechanism for piston engines, distinct from the usual poppet valve. Sleeve valve engines saw use in a number of pre-World War II luxury cars and in the United States in the Willys-Knight car and light truck. They subsequently fell from use due to advances in poppet-valve technology, including sodium cooling, and the Knight system double sleeve engine's tendency to burn a lot of lubricating oil or to seize due to lack of it. The Scottish Argyll company used its own, much simpler and more efficient, single sleeve system (Burt-McCollum) in its cars, a system which, after extensive development, saw substantial use in British aircraft engines of the 1940s, such as the Napier Sabre, Bristol Hercules, Centaurus, and the promising but never mass-produced Rolls-Royce Crecy, only to be supplanted by the jet engines.
A sleeve valve takes the form of one or more machined sleeves. It fits between the piston and the cylinder wall in the cylinder of an internal combustion engine, where it rotates and/or slides. The cylinder wall has inlet and exhaust ports, identical to a two-stroke motor. Ports (holes) in the side of the sleeves come into alignment with the cylinder's inlet and exhaust ports at the appropriate stages in the engine's cycle.
The first successful sleeve valve was patented by Charles Yale Knight, and used twin alternating sliding sleeves. It was used in some luxury automobiles, notably Willys, Daimler, Mercedes-Benz, Minerva, Panhard, Peugeot and Avions Voisin. Mors adopted double sleeve-valve engines made by Minerva. The higher oil consumption was heavily outweighed by the quietness of running and the very high mileages without servicing. Early poppet-valve systems required decarbonization at very low mileages.
The Burt-McCollum sleeve valve was named for the two inventors who applied for similar patents within a few weeks of each other. The Burt system was an open sleeve type, driven from the crankshaft side, while the McCollum design had a sleeve in the head and upper part of the cylinder, and a more complex port arrangement (Source: 'Torque Meter' Magazine, AEHS). The design that entered production was more 'Burt' than 'McCollum.' It was used by the Scottish company Argyll for its cars, and was later adopted by Bristol for its radial aircraft engines. It used a single sleeve driven by an eccentric from a timing axle set at 90 degrees to the cylinder axis. Mechanically simpler and more rugged, the Burt-McCollum valve had the additional advantage of reducing oil consumption (compared to other sleeve valve designs), while retaining the combustion chambers and big, uncluttered, porting area possible in the Knight system.
A small number of designs used a "cuff" sleeve in the cylinder head instead of the cylinder proper, providing a more "classic" layout compared to traditional poppet valve engines. This design also had the advantage of not having the piston within the sleeve, although in practice this appears to have had little practical value. On the downside, this arrangement limited the size of the ports to that of the cylinder head, whereas in-cylinder sleeves could have much larger ports.
The main advantages of the sleeve-valve engine are:
Most of these advantages were evaluated and established during the 1920s by Roy Fedden and Harry Ricardo, possibly the sleeve valve engine's greatest advocate. He conceded that some of these advantages were significantly eroded as fuels improved up to and during World War II and as sodium-cooled exhaust valves were introduced in high-output aircraft engines.
A number of disadvantages plagued the single sleeve valve:
In 1901 Knight bought an air-cooled, single-cylinder three-wheeler whose noisy valves annoyed him. He believed that he could design a better engine and did so, inventing his double sleeve principle in 1904. Backed by Chicago entrepreneur L.B. Kilbourne, a number of engines were constructed, followed by the "Silent Knight" touring car, which was shown at the 1906 Chicago Auto Show.
Knight's design had two cast-iron sleeves per cylinder, one sliding inside the other with the piston inside the inner sleeve. The sleeves were operated by small connected rods actuated by an eccentric shaft. They had ports cut out at their upper ends. The design was remarkably quiet, and the sleeve valves needed little attention. It was, however, more expensive to manufacture due to the precision grinding required on the sleeves' surfaces. It also used more oil at high speeds and was harder to start in cold weather.
Although he was initially unable to sell his Knight Engine in the United States, a long sojourn in England, involving extensive further development and refinement by Daimler supervised by their consultant Dr Frederick Lanchester, eventually secured Daimler and several luxury car firms as customers willing to pay his expensive premiums. He first patented the design in England in 1908. The patent for the US was granted in 1910. As part of the licensing agreement, "Knight" was to be included in the car's name.
Six-cylinder Daimler sleeve valve engines were used in the first British tanks in WW1, up to and including the Mark IV. As a result of the tendency of the engines to smoke and hence give away the tank positions, Harry Ricardo was brought in, and devised a new engine which replaced the sleeve valve starting with the Mark V tank.
Among the companies using Knight's technology were Avions Voisin, Daimler (1909–1930s) including their V12 Double Six, Panhard (1911–39), Mercedes (1909–24), Willys (as the Willys-Knight, plus the associated Falcon-Knight), Stearns, Mors, Peugeot, and Belgium's Minerva company that was forced to stop their sleeve-valve line of engines as a result of the limitations imposed on them by the winners of WWII, some thirty companies in all. Itala also experimented with rotary and sleeve valves in their 'Avalve' cars.
Upon Knight's return to America he was able to get some firms to use his design; here his brand name was "Silent Knight" (1905–1907) — the selling point was that his engines were quieter than those with standard poppet valves. The best known of these were the F.B. Stearns Company of Cleveland, which sold a car named the Stearns-Knight, and the Willys firm which offered a car called the Willys-Knight, which was produced in far greater numbers than any other sleeve-valve car.
The Burt-McCollum sleeve valve, having its name from the surnames of the two engineers that patented the same concept with weeks of difference, Peter Burt and James Harry Keighly McCollum, patent applications are of August 6 and June 22, 1909, respectively, both engineers hired by the Scottish car maker Argyll, consisted of a single sleeve, which was given a combination of up-and-down and partial rotary motion. It was developed in about 1909 and was first used in the 1911 Argyll car. The initial 1900 investment in Argyll was £15,000 and building the magnificent Scotland plant cost £500,000 in 1920. It is reported that litigation by the owners of the Knight patents cost Argyll £50,000, perhaps one of the reasons for the temporary shutdown of their plant. Another car maker that used the Argyll SSV patents, and others of their own (patent GB118407), was Piccard-Pictet (Pic-Pic); Louis Chevrolet and others founded Frontenac Motors in 1923 with the aim of producing an 8-L SSV engined luxury car, but this never reached production for reasons connected to the time limits to the Argyll patents in the USA. The greatest success for single sleeve valves (SSV) was in Bristol's large aircraft engines, it was also used in the Napier Sabre and Rolls-Royce Eagle engines. The SSV system also reduced the high oil consumption associated with the Knight double sleeve valve.
Barr and Stroud Ltd of Anniesland, Glasgow, also licensed the SSV design, and made small versions of the engines that they marketed to motorcycle companies. In an advertisement in Motor Cycle magazine in 1922 Barr & Stroud promoted their 350cc sleeve valve engine and listed Beardmore-Precision, Diamond, Edmund, and Royal Scot as motorcycle manufacturers offering it. This engine had been described in the March edition as the 'Burt' engine. Grindlay-Peerless started producing a SSV Barr & Stroud engined 999cc V-twin in 1923.  and later added a 499cc single SSV as well as the 350cc. Vard Wallace, known for his aftermarket forks for motorcycles, presented in 1947 drawings of a Single Cylinder, Air-Cooled, 250 cc SSV engine. Some small SSV auxiliary boat engines and electric generators were built in the UK, prepared for burning 'paraffin' from start, or after a bit of heat-up with more complex fuels. (Petter Brotherhood, Wallace. 'The Engineer', Dec 9, 1921, pg 618)
A number of sleeve valve aircraft engines were developed following a seminal 1927 research paper from the RAE by Harry Ricardo. This paper outlined the advantages of the sleeve valve and suggested that poppet valve engines would not be able to offer power outputs much beyond 1500 hp (1,100 kW). Napier and Bristol began the development of sleeve-valve engines that would eventually result in limited production of two of the most powerful piston engines in the world: the Napier Sabre and Bristol Centaurus. The Continental Motors Company, around the years of the Great Depression, developed prototypes of single sleeve-valve engines for a range of applications, from cars to trains to airplanes, and thought that production would be easier, and costs would be lower, than its counterpart poppet valve engines. Due to the financial problems of Continental, this line of engines never entered production. ('Continental! Its motors and its people', William Wagner, Armed Forces Journal International and Aero Publishers, 1983, ISBN 0-8168-4506-9)
Potentially the most powerful of all sleeve-valve engines (though it never reached production) was the Rolls-Royce Crecy V-12 (oddly, using a 90-degree V-angle), two-stroke, direct-injected, turbocharged (force-scavenged) aero-engine of 26.1 litres capacity. It achieved a very high specific output, and surprisingly good specific fuel consumption (SFC). In 1945 the single-cylinder test-engine (Ricardo E65) produced the equivalent of 5,000 HP (192 BHP/Litre) when water injected, although the full V12 would probably have been initially type rated at circa 2,500 hp (1,900 kW). Sir Harry Ricardo, who specified the layout and design goals, felt that a reliable 4,000 HP military rating would be possible. Ricardo was constantly frustrated during the war with Rolls-Royce's (RR) efforts. Hives & RR were very much focused on their Merlin, Griffon then Eagle and finally Whittle's jets, which all had a clearly defined production purpose. Ricardo and Tizard eventually realized that the Crecy would never get the development attention it deserved unless it was specified for installation in a particular aircraft but by 1945, their "Spitfire on steroids" concept of a rapidly climbing interceptor powered by the lightweight Crecy engine had become an aircraft without a purpose.
Following World War II, the sleeve valve became utilised less, Roy Fedden, very early involved in the S-V research, built some flat-six single sleeve-valve engines intended for general aviation around 1947; after this, just the French SNECMA produced some SSV engines under Bristol license that were installed in the Noratlas transport airplane, also another transport aircraft, the Azor built by the Spanish CASA installed SSV Bristol engines post-WWII. Bristol sleeve valve engines were used however during the post-war air transport boom, in the Vickers Viking and related military Varsity and Valetta, Airspeed Ambassador, used on BEA's European routes, and Handley Page Hermes (and related military Hastings), and Short Solent airliners and the Bristol Freighter and Superfreighter. The Centaurus was also used in the military Hawker Sea Fury, Blackburn Firebrand, Bristol Brigand, Blackburn Beverly and the Fairey Spearfish. The poppet valve's previous problems with sealing and wear had been remedied by the use of better materials and the inertia problems with the use of large valves were reduced by using several smaller valves instead, giving increased flow area and reduced mass, and the exhaust valve hot spot by Sodium-cooled valves. Up to that point, the single sleeve valve had won every contest against the poppet valve in comparison of power to displacement. The difficulty of Nitride hardening, then finish-grinding the sleeve valve for truing the circularity, may have been a factor in its lack of more commercial applications.
When the Argyll car was launched in 1911, the Knight and Kilbourne Company immediately brought a case against Argyll for infringement of their original 1905 patent. This patent described an engine with a single moving sleeve, whereas the Daimler engines being built at the time were based on the 1908 Knight patent which had engines with two moving sleeves. As part of the litigation an engine was built according to the 1905 specification and developed no more than a fraction of the rated RAC horsepower. This fact coupled with other legal and technical arguments led the judge to rule, at the end of July 1912, that the holders of the original Knight patent could not be supported in their claim that it gave them master rights encompassing the Argyll design. Costs of litigation against claims by Knight patent holders seem having substantially contributed to bankrupt of Argyll in Scotland.
The sleeve valve has begun to make something of a comeback, thanks to modern materials, dramatically better engineering tolerances and modern construction techniques, which produce a sleeve valve that leaks very little oil. However, most advanced engine research is concentrated on improving other internal combustion engine designs, such as the Wankel.
Mike Hewland with his assistant John Logan, and also independently Keith Duckworth, experimented with a single-cylinder sleeve-valve test engine when looking at Cosworth DFV replacements. Hewland claimed to have obtained 72 hp (54 kW) from a 500 cc single-cylinder engine, with a specific fuel consumption of 177-205 g/HP/hr (0.39 - 0.45 lb/HP/hr), the engine being able to work on creosote, and with no specific lubrication supply for the sleeve.
An unusual form of four-stroke model engine that uses what is essentially a sleeve-valve format, is the British RCV series of "SP" model engines, which use a rotating cylinder liner driven through a bevel gear at the cylinder liner's "bottom", which is actually at the aft end of the cylinder; and, even more unusually, have the propeller shaft — as an integrally machined part of the rotating cylinder liner — emerging from what would normally be the cylinder head, which in this design is placed at the extreme front of the engine, achieving a 2:1 gear reduction ratio compared to the vertically oriented crankshaft's rotational speed. The same firm's "CD" series of model engines use a conventional upright single cylinder with the crankshaft used to spin the propeller directly and also use the rotating cylinder valve. As a parallel with the earlier Charles Knight-designed sleeve-valved automotive powerplants, any RCV sleeve-valved model engine that is run on model glow engine fuel using castor oil (about 2% to 4% content) of the maximum 15%-content lubricant in the fuel allows the "varnish" created through engine operation to provide a better pneumatic seal between the rotating cylinder valve and the unitized engine cylinder/head castings, initially formed while the engine is being broken in.
Another concept, the Rotating Liner Engine has been developed, where the wear and friction benefit of the sleeve valve is exploited in a conventional engine layout. A friction reduction of the order of 40% has been reported for a Heavy Duty diesel.
The same company can also supply somewhat larger engines for use in military drones, portable generators and equipment such as lawn mowers. These are "multi fuel" insofar as they can be configured to run on gasoline, kerosene, including aircraft fuels, and diesel oil.
Owing to the impossibility to use conventional poppet valves in opposed-piston engines, American company Pinnacle Engines also promotes a sleeve-valve layout in its 4-stroke opposed-piston engine developments. Variable valve timing was also proposed in a 3-cylinder 1.5L development from Pinnacle Engines, but as of December 2016 there are not so many details available for the general public.
Sleeve valves have occasionally, but unsuccessfully, been used on steam engines, for example the SR Leader class.
During World War II, my original enthusiasm for the sleeve-valve engine simplicity proved to be based on dubious premises. My inspection of a captured Bristol two-row radial engine revealed a bucket full of gear wheels for the sleeve drive. I believe there were over 100 gears!
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