A U engine is a piston engine made up of two separate straight engines (complete with separate crankshafts) placed side-by-side and coupled to a shared output shaft. When viewed from the front, the engine block resembles the letter "U".
Although much less common than the similar V engine design, several U engines were produced from 1915 to 1987 for use in airplanes, racing cars, racing and road motorcycles, locomotives, and tanks.
The main benefit of a U engine layout is the ability to share common parts with a straight engine upon which is it based. Additionally, if the two crankshafts rotate in opposite directions, the gyroscopic effect of the rotating components in each cylinder bank cancel each other out.
A V engine is typically more compact and lighter than a U engine, in part due to the lack of a second crankshaft, making V engines far more common than U engines. However, the V engine does not cancel the gyroscopic effect.
The H engine layout uses a similar concept to U engines, whereby two flat engines are stacked vertically.
The first U engine known to have been built was the 1915–1916 Bugatti U-16 aircraft engine, which had 16 cylinders and a displacement of 24.3 L (1,483 cu in). [1] Approximately 40 engines were built at the Duesenberg factory in the United States during World War I. [2] A small number of engines based on the Bugatti U engine were also produced after the war by Breguet Aviation in France. [3]
The Fiat 806 was a 1927 Grand Prix racing car that was powered by a 1.5 L (92 cu in) twelve-cylinder U engine. [4] This engine, designated the 'Type 406', used a supercharger and had a single centrally-mounted intake camshaft which operated the intake valves located on the inside of each cylinder bank. [5] Two separate camshafts operated the exhaust valves (one per bank). On test the unit delivered 187 bhp at 8,500 rpm at maximum boost. [4] The Fiat 806 car competed in only one race, the 50 km (31 mi) Milan Grand Prix on 4 September 1927 (not to be confused with the 500 km 1927 Italian Grand Prix held on the same day). The race was won by the Fiat 806; however, Fiat then retired from Grand Prix racing and the Type 806 did not race again. [6] [7]
The 1931–1959 Ariel Square Four motorcycle used a four-cylinder engine (also called a 'square four' engine). The engine was compact and had as narrow a frontal area as a 500 cc, parallel twin. The rear pair of cylinders on this air-cooled engine were prone to overheating.[ citation needed ]
The 1985–1987 Suzuki RG500 motorcycle, and several related racing motorcycles, used a water-cooled four-cylinder U engine. Although some racing success was achieved, the road bikes did not sell well and the design was phased out in favour of a conventional inline-four engine.[ citation needed ]
In the 1930s Sulzer Brothers Ltd. began production of an 'LD series' twelve-cylinder U engine for use in rail locomotives. The LD series was replaced by the LDA series, for a combined production period of over 50 years. The Sulzer 12LDA twin-bank engine formed the mainstay of British locomotives built in the 1960s, with over 700 used in the Peak and Class 47 locomotives. [8] The Sulzer LDA engine used a smaller gear for the central output shaft than the two gears attached to the crankshaft. This resulted in the output shaft rotating at approximately 1000 rpm while the crankshafts rotated at approximately 750 rpm. The purpose of this gearing was to allow the use of a smaller, and lighter, electrical generator when the engine was used in a diesel-electric locomotive.
The General Motors 6046 is a twin-engine setup that was used by Sherman tanks during World War II. The 6046 was built using two straight-six engines that were separately clutched to a single output shaft, which was itself clutched to the transmission unit. A total of 10,968 6046D-powered M4A2 Shermans were produced. [9] After World War II, several Soviet Union tanks powered by 16-cylinder and 18-cylinder engines that were reverse-engineered from the General Motors 6046 engine. These Soviet engines were designated Russkiy Dizel (Diesel Energo) DPN23/2H30 and the DRPN23/2H30. [10] [11]
A tandem twin engine, occasionally used in motorcycles and go-karts, is a two-cylinder engine which uses a similar design to U engines. The motor has two crankshafts, [12] [13] one for each cylinder [14] [15] which are joined and kept in co-ordination by load carrying, crank-phasing gears connecting the two cylinders. [16]
The tandem twin layout is used only with two-stroke engines since these must have a discrete crankcase chamber per cylinder. The prime advantage of a tandem-twin two-stroke is that the engine can be very narrow while allowing chain final drive without a power-wasting 90° turn.
Between 1975 and 1982, Kawasaki used the design to win four 250 cc and four 350 cc world championships before they retired from Grand Prix racing. [17] The engine design was also used for a road legal production motorcycle inspired by the racer. [18] [19] The Kawasaki KR models were instrumental in establishing the company as a manufacturer of high-performance motorcycles. [20]
Rotax developed a similar tandem twin design, the model 256, which it sold to independent constructors. The CCM Armstrong 250 cc, Waddon, EMC, Hejira, Decorite, and Cotton racers used this engine. CCM Armstrong developed a 350 cc version of the engine. [21] Aprilia's 1985 GP racing bikes also used the Rotax model 256. [22]
An unusual variation on the U engine is the use of a single crankshaft which is linked to the pistons in both cylinder banks by rocking beams. This system was used in an eight-cylinder petrol engine produced by the All-British Car Company between 1906 and 1908.[ citation needed ]
A V-twin engine, also called a V2 engine, is a two-cylinder piston engine where the cylinders are arranged in a V configuration and share a common crankshaft.
A straight-twin engine, also known as an inline-twin, vertical-twin, or parallel-twin, is a two-cylinder piston engine whose cylinders are arranged in a line along a common crankshaft.
A straight-four engine is a four-cylinder piston engine where cylinders are arranged in a line along a common crankshaft.
An H engine is a piston engine comprising two separate flat engines, most often geared to a common output shaft. The name "H engine" is due to the engine blocks resembling a letter "H" when viewed from the front. The most successful "H" engine in this form was the Napier Dagger and its derivatives. The name was also applied to engines of the same basic layout, but rotated through 90 degrees—most famously the Napier Sabre series. A variation on the "H" theme were the Fairey Prince (H-16) & Fairey P.24 Monarch, where the two engines retained separate drives, driving Contra-rotating propellers through separate concentric shafts. Although successful, they only existed in prototype form.
Motorenwerke Zschopau GmbH is a German motorcycle manufacturer located in Zschopau, Saxony. The acronym MZ since 1956 stands for Motorenwerke Zschopau GmbH. From 1992 to 1999 the company was called MuZ, an acronym for Motorrad und Zweiradwerk.
A straight-three engine is a three-cylinder piston engine where cylinders are arranged in a line along a common crankshaft.
An overhead camshaft (OHC) engine is a piston engine in which the camshaft is located in the cylinder head above the combustion chamber. This contrasts with earlier overhead valve engines (OHV), where the camshaft is located below the combustion chamber in the engine block.
The Honda NSR500 is a road racing motorcycle created by HRC and debuted in 1984 for the Grand Prix motorcycle racing's 500 cc class. Honda won ten 500cc World Championships with the NSR500 from 1984 to 2002, with six in a row from 1994 to 1999. With more than 100 wins to its credit, the NSR500 is the most dominant force in modern Grand Prix motorcycle racing. The 1989 NSR500 that won Honda's third 500 World Championship with Eddie Lawson exemplifies the overwhelming power, acceleration and raw speed that has always been synonymous with Honda's 500 cc two-stroke V4.
The Ducati singles were single cylinder motorcycles, made by Ducati from 1950 to 1974. Chief Engineer Fabio Taglioni developed a desmodromic valve system in these years, a system that opens and closes the valves using the camshaft, without the need for valve springs. This valve system has become a trademark feature of Ducati motorcycles.
The BSA Gold Star is a motorcycle made by BSA from 1938 to 1963. They were 350 cc and 500 cc single-cylinder four-stroke production motorcycles known for being among the fastest bikes of the 1950s. Being hand built and with many optional performance modifications available, each motorcycle came from the factory with documented dynamometer test results, allowing the new owner to see the horsepower (bhp) produced.
Dave Simmonds was a British professional Grand Prix motorcycle road racer. He competed in the Grand Prix world championships from 1963 to 1972. Simmonds is notable for winning the 1969 125 cc FIM road racing world championship.
NR500 was a racing motorcycle developed by Honda HRC in 1979 to compete in Grand Prix motorcycle racing. "NR" stands for "New Racing".
The Yamaha RD500LC is a high-performance, two-stroke sports motorcycle, also known as the RZ500 in Canada and Australia. A lightened but detuned version known as the RZV500R was developed for the Japanese home market. Strict United States Environmental Protection Agency regulations meant that the RZ500 was not available for sale in that country. Produced for a short period between 1984 and 1986 it has become a sought after collector's machine.
In internal combustion engines, a split-single design is a type of two-stroke where two cylinders share a single combustion chamber.
The Kawasaki KR250 was a racing motorcycle built by Kawasaki from 1975 to 1982 for the 250 cc class of Grand Prix motorcycle racing. It was powered by a two-stroke "tandem twin" engine The motorcycle won four world championships, in 1978 and 1979 with Kork Ballington and in 1980 and 1981 with Anton Mang.
Meguro motorcycles were built by Meguro Manufacturing Co motorcycle works (目黒製作所), founded by Nobuji Murata and a high-ranking naval officer, Takaji Suzuki, in 1937. One of the first Japanese motorcycle companies, it became a partner of Kawasaki Heavy Industries Ltd, and was eventually absorbed. Named after a district of Tokyo, Meguro had its roots in Murato Iron Works, which was established in 1924. Meguro Seisakusho, which had once developed a copy of a Harley-Davidson V-twin, was established to design and build gearboxes for the nascent Japanese motorcycle industry. Abe Industries, which had once produced its own motorcycle, merged with Meguro in 1931. The brand is being revived by Kawasaki with a new K3 model to be introduced in Japan on February 1, 2021.
The MV Agusta 600, also called the MV Agusta 600 4C and the MV Agusta 600 Turismo, was a motorcycle built by the MV Agusta company from 1966 to 1970. For the first time, a four-cylinder engine was fitted transversely to the direction of travel on a standard motorbike and cable-operated disc brakes were used. A total of 135 of this model were manufactured.
The MV Agusta 350 6 cilindri was a prototype racing motorcycle built by the Varese company MV Agusta in 1957, for the 350 cc class of the FIM Motorcycle World Championship. The project was resurrected in 1968. Neither version was ever used in a race. The only surviving model is now in the MV Agusta factory museum.
Piero Remor was an Italian engineer and motorcycle constructor, best known for his work for the Gilera and MV Agusta brands.
Bridgestone motorcycles were a division of the Bridgestone Tire Co. of Kyōbashi, Tokyo, Japan that produced mopeds and motorcycles from 1952 to 1970. Initially producing power assisted bicycles, the division moved on to producing mopeds and then motorcycles. The motorcycles were technologically advanced and powered by two-stroke engines. The high technical specification resulted in the machines being more expensive compared to other manufacturers models. Production was stopped in 1970 to protect the supply of tyres to other manufacturers.
Both have at their heart a twin-cylinder two-stroke engine that is, in effect, two 125cc Singles mounted one behind the other in a common crankcase, their cranks connected by large gears.
Sato, like Kaaden, realised that the convention twin-cylinder two-stroke, with its cylinders across the frame, coupled to the outward facing carburettors of a disc-valve twin had a major drawback, because of excessive width.
These hopes were due to the introduction of the Model 256 inline twin...