U engine
Encyclopedia
A U engine is a piston engine made up of two separate straight engine
s (complete with separate crankshafts) joined by gear
s or chain
s. It is similar to the H engine
which couples two flat engine
s. The design is also sometimes described as a "twin bank" or "double bank" engine, although these terms are sometimes used also to describe V engine
s.
This configuration is uncommon as it is heavier than a V design. The main interest in this design is its ability to share common parts with straight engines. However, V engines with offset banks can also share straight engine parts (except for the crankshaft), and this is therefore a far more common design today when both engine forms are produced from the same basic design.
proposed in April 1916 was intended to be powered by a doubled version of the 105 hp Daimler
'Silent Knight' engine, with two banks of cylinders side by side sharing a common crankcase. However this was not a true 'U' engine as the cylinder banks were to have been independent, each separately driving its own crankshaft and four-speed gearbox. Neither the tank nor the engine were ever made.
The first U engine known to have been built was the 16 cylinder 24.3 litre displacement Bugatti u-16
aero engine designed and patent
ed by Ettore Bugatti
in 1915-1916. Bugatti licensed the design to Duesenberg
in America, who produced about 40, and Breguet of France, who built a few in the years after the end of World War 1. Bugatti later used the same engine layout in the Bugatti
Type 45 of 1928, but only two were produced.
Matra
developed a high-end Bagheera
prototype powered by a 2.6 L U8 engine made of two Simca 1000 Rallye 2 Straight-4
s connected by chains around 1974. However because of the petroleum crisis
this car was never put in production.
Sulzer Brothers developed a diesel engine for rail traction of this type, the LD series, in the 1930s, that was in production for more than fifty years. Several cylinder sizes were produced, including the 19 (bore 190 mm), 22 (bore 220 mm), 25 (bore 250 mm), 28 (bore 280 mm) and 31 (bore 310 mm). The engines of the LD and later, the LDA series, were commonly found in 6 and 8 cylinders inline and 12 cylinders U form. The U form engines were installed in railway locomotives operating in several countries, including Britain, Bulgaria, China, France, Poland and Romania. For further information on the British Railways locomotives (classes 44, 45, 46, 47) see List of British Rail modern traction locomotive classes.
Sulzer Brothers later discontinued the rail traction engine business.
In the Sulzer LDA engine, a gear wheel on each crankshaft meshed with a slightly smaller gear wheel on the central output shaft. The crankshafts ran at around 750 rpm but the output shaft ran at about 1,000 rpm. This allowed the use of a smaller, and lighter, electrical generator
when the engine was used in a diesel-electric locomotive.
This configuration was used on the Ariel Square Four
motorcycle from 1931 to 1959.
This design was revived as a two-stroke version on some racing Suzuki
s, and their subsequent road-going version the Suzuki RG500
. Although some racing success was achieved, the road bikes didn't sell in great numbers, and the design was phased out in favour of in-line, four-stroke designs, as at the time engineering and marketing resources were being applied to more common four-stroke designs.
Straight engine
Usually found in four- and six-cylinder configurations, the straight engine, or inline engine is an internal-combustion engine with all cylinders aligned in one row, with no offset...
s (complete with separate crankshafts) joined by gear
Gear
A gear is a rotating machine part having cut teeth, or cogs, which mesh with another toothed part in order to transmit torque. Two or more gears working in tandem are called a transmission and can produce a mechanical advantage through a gear ratio and thus may be considered a simple machine....
s or chain
Roller chain
Roller chain or bush roller chain is the type of chain drive most commonly used for transmission of mechanical power on many kinds of domestic, industrial and agricultural machinery, including conveyors, wire and tube drawing machines, printing presses, cars, motorcycles, and simple machines like...
s. It is similar to the H engine
H engine
An H engine is an engine configuration in which the cylinders are aligned so that if viewed from the front, they appear to be in a vertical or horizontal letter H....
which couples two flat engine
Flat engine
A flat engine is an internal combustion engine with multiple pistons that move in a horizontal plane. Typically, the layout has cylinders arranged in two banks on either side of a single crankshaft and is sometimes known as the boxer, or horizontally opposed engine. The concept was patented in 1896...
s. The design is also sometimes described as a "twin bank" or "double bank" engine, although these terms are sometimes used also to describe V engine
V engine
A V engine, or Vee engine is a common configuration for an internal combustion engine. The cylinders and pistons are aligned, in two separate planes or 'banks', so that they appear to be in a "V" when viewed along the axis of the crankshaft...
s.
This configuration is uncommon as it is heavier than a V design. The main interest in this design is its ability to share common parts with straight engines. However, V engines with offset banks can also share straight engine parts (except for the crankshaft), and this is therefore a far more common design today when both engine forms are produced from the same basic design.
Petrol
A prototype British heavy tankTank
A tank is a tracked, armoured fighting vehicle designed for front-line combat which combines operational mobility, tactical offensive, and defensive capabilities...
proposed in April 1916 was intended to be powered by a doubled version of the 105 hp Daimler
Daimler Motor Company
The Daimler Motor Company Limited was an independent British motor vehicle manufacturer founded in London by H J Lawson in 1896, which set up its manufacturing base in Coventry. The right to the use of the name Daimler had been purchased simultaneously from Gottlieb Daimler and Daimler Motoren...
'Silent Knight' engine, with two banks of cylinders side by side sharing a common crankcase. However this was not a true 'U' engine as the cylinder banks were to have been independent, each separately driving its own crankshaft and four-speed gearbox. Neither the tank nor the engine were ever made.
The first U engine known to have been built was the 16 cylinder 24.3 litre displacement Bugatti u-16
Bugatti U-16
|-See also:- References :...
aero engine designed and patent
Patent
A patent is a form of intellectual property. It consists of a set of exclusive rights granted by a sovereign state to an inventor or their assignee for a limited period of time in exchange for the public disclosure of an invention....
ed by Ettore Bugatti
Ettore Bugatti
right|thumb|Ettore Bugatti in 1932Ettore Arco Isidoro Bugatti was an Italian-born and French naturalized citizen automobile designer and manufacturer....
in 1915-1916. Bugatti licensed the design to Duesenberg
Duesenberg
Duesenberg was an Auburn, Indiana based American luxury automobile company active in various forms from 1913 to 1937, most famous for its high-quality passenger cars and record-breaking racing cars.-History:...
in America, who produced about 40, and Breguet of France, who built a few in the years after the end of World War 1. Bugatti later used the same engine layout in the Bugatti
Bugatti
Automobiles E. Bugatti was a French car manufacturer founded in 1909 in Molsheim, Alsace, as a manufacturer of high-performance automobiles by Italian-born Ettore Bugatti....
Type 45 of 1928, but only two were produced.
Matra
Matra
Mécanique Aviation Traction or Matra was a French company covering a wide range of activities mainly related to automobile, bicycles, aeronautics and weaponry. In 1994, it became a subsidiary of the Lagardère Group and now operates under that name.Matra was owned by the Floirat family...
developed a high-end Bagheera
Matra Bagheera
The Matra Bagheera is a sports car created by the French engineering group Matra in cooperation with the automaker Simca and design by Greek designer Antonis Volanis...
prototype powered by a 2.6 L U8 engine made of two Simca 1000 Rallye 2 Straight-4
Straight-4
The inline-four engine or straight-four engine is an internal combustion engine with all four cylinders mounted in a straight line, or plane along the crankcase. The single bank of cylinders may be oriented in either a vertical or an inclined plane with all the pistons driving a common crankshaft....
s connected by chains around 1974. However because of the petroleum crisis
1973 oil crisis
The 1973 oil crisis started in October 1973, when the members of Organization of Arab Petroleum Exporting Countries or the OAPEC proclaimed an oil embargo. This was "in response to the U.S. decision to re-supply the Israeli military" during the Yom Kippur war. It lasted until March 1974. With the...
this car was never put in production.
Diesel
Several types of U-form diesel engine have been historically produced, by companies such as Lister Blackstone and Sulzer Brothers Ltd. A twin bank diesel engine for marine use is described in US Patent 4167857. However, no further documentation has been found for any ship or marine application of such an engine.Sulzer Brothers developed a diesel engine for rail traction of this type, the LD series, in the 1930s, that was in production for more than fifty years. Several cylinder sizes were produced, including the 19 (bore 190 mm), 22 (bore 220 mm), 25 (bore 250 mm), 28 (bore 280 mm) and 31 (bore 310 mm). The engines of the LD and later, the LDA series, were commonly found in 6 and 8 cylinders inline and 12 cylinders U form. The U form engines were installed in railway locomotives operating in several countries, including Britain, Bulgaria, China, France, Poland and Romania. For further information on the British Railways locomotives (classes 44, 45, 46, 47) see List of British Rail modern traction locomotive classes.
Sulzer Brothers later discontinued the rail traction engine business.
Variations
If the crankshaft on one bank of cylinders is made to rotate in the opposite direction of the crankshaft on the other bank, then the gyroscopic effects of the rotating components would be canceled. However, counter-rotating crankshafts would make the joining of the power outputs very difficult.In the Sulzer LDA engine, a gear wheel on each crankshaft meshed with a slightly smaller gear wheel on the central output shaft. The crankshafts ran at around 750 rpm but the output shaft ran at about 1,000 rpm. This allowed the use of a smaller, and lighter, electrical generator
Electrical generator
In electricity generation, an electric generator is a device that converts mechanical energy to electrical energy. A generator forces electric charge to flow through an external electrical circuit. It is analogous to a water pump, which causes water to flow...
when the engine was used in a diesel-electric locomotive.
Square four engine
A square four is a U engine with two cylinders on each side.This configuration was used on the Ariel Square Four
Ariel Square Four
The Square Four was an Ariel motorcycle designed by Edward Turner, who devised the Square Four engine in 1928. At this time he was looking for work, showing drawings of his engine design to motorcycle manufacturers. The engine was essentially a pair of 'across frame' OHC parallel twins joined by...
motorcycle from 1931 to 1959.
This design was revived as a two-stroke version on some racing Suzuki
Suzuki
is a Japanese multinational corporation headquartered in Hamamatsu, Japan that specializes in manufacturing compact automobiles and 4x4 vehicles, a full range of motorcycles, all-terrain vehicles , outboard marine engines, wheelchairs and a variety of other small internal combustion engines...
s, and their subsequent road-going version the Suzuki RG500
Suzuki RG500
The Suzuki RG500 "Gamma" was a motorcycle built by Suzuki between 1985 and 1987 and inspired by the 1984 Suzuki RG500 "Gamma" Grand Prix motorcycle, capitalizing on Suzuki's seven consecutive constructors title wins in the 500 cc-class. The Gamma was powered by a two stroke, rotary valve, twin...
. Although some racing success was achieved, the road bikes didn't sell in great numbers, and the design was phased out in favour of in-line, four-stroke designs, as at the time engineering and marketing resources were being applied to more common four-stroke designs.