Initially presented early in 1933, the Audi Front UW 220 was Europe’s first car to combine front-wheel drive with a six-cylinder engine. It remained in production for slightly under two years before being replaced by the Audi Front UW 225 featuring a larger 2.25-litre engine. The larger-engined car introduced in 1935 was built till April 1938 and continued to be listed into 1939. Between 1933 and 1938, the Front was the only Audi in volume production.
24-651: At launch the Front UW 220 featured a straight-six-cylinder ohv engine of 1,950 cc. Claimed maximum power output was 40 PS (29 kW; 39 hp) at 3,500 rpm. The two-litre engine was shared with the Auto Union group’s Wanderer W22 introduced at the same time. The letters "UW" in the car's name stood for "Umgekehrter Wanderer" and referred to the fact that it featured a Wanderer engine that had been "umgekehrt" (turned around) through 180 degrees in order to drive wheels which, on this application, were actually ahead of
48-459: A camshaft , pushrods and rocker arms , therefore becoming the first OHV engines. In 1896, U.S. patent 563,140 was taken out by William F. Davis for an OHV engine with liquid coolant used to cool the cylinder head, but no working model was built. In 1898, bicycle manufacturer Walter Lorenzo Marr in the United States built a motorised tricycle powered by a single-cylinder OHV engine. Marr
72-407: A hybrid design combining elements of both side-valves and overhead valves. The first internal combustion engines were based on steam engines and therefore used slide valves . This was the case for the first Otto engine , which was first successfully run in 1876. As internal combustion engines began to develop separately to steam engines, poppet valves became increasingly common. Beginning with
96-500: A loophole in the rules, the pushrod engine was allowed to use a larger displacement and higher boost pressure, significantly increasing its power output compared to the OHC engines used by other teams. Team Penske qualified in pole position and won the race by a large margin. In the early 21st century, several pushrod V8 engines from General Motors and Chrysler used cylinder deactivation to reduce fuel consumption and exhaust emissions. In 2008,
120-401: The crankshaft and, in the case of a four-stroke engine, rotates at half the speed of the crankshaft. Motion is transferred from the crankshaft to the camshaft most commonly by a rubber timing belt , a metallic timing chain or a set of gears. Pushrods are long, slender metal rods that are used in overhead valve engines to transfer motion from the camshaft (located in the engine block) to
144-424: The cylinder head above the combustion chamber . This contrasts with flathead (or "sidevalve") engines , where the valves were located below the combustion chamber in the engine block . Although an overhead camshaft (OHC) engine also has overhead valves, the common usage of the term "overhead valve engine" is limited to engines where the camshaft is located in the engine block. In these traditional OHV engines,
168-418: The 1885 Daimler Reitwagen , several cars and motorcycles used inlet valve(s) located in the cylinder head, however these valves were vacuum-actuated ("atmospheric") rather than driven by a camshaft as with typical OHV engines. The exhaust valve(s) were driven by a camshaft, but were located in the engine block as with side-valve engines. The 1894 prototype Diesel engine used overhead poppet valves actuated by
192-445: The 1906–1912 Wright Brothers Vertical 4-Cylinder Engine . In 1911, Chevrolet joined Buick in almost exclusive use of OHV engines. However, flathead "side-valve" engines remained commonplace in the U.S. until the mid-to-late 1950s, when they began to be phased out for OHV engines. The first overhead camshaft (OHC) engine dates back to 1902, in the Marr ; however, use of this design
216-680: The Audi shared its engine featured an advertised turning circle of 12 meters. Jørgen Skafte Rasmussen who till 1932 owned and controlled the companies that comprised the Auto Union had acquired Audi in 1928, and as part of the deal had acquired their manufacturing plant at Zwickau . However, since 1931 the Audi Zwickau plant had been producing the DKW F1 , replaced in 1932 with the DKW F2 . The small front-wheel drive DKWs proved popular, and completely utilised
240-491: The claimed top speed to 105 km/h (65 mph). The ohv engine came, again, from fellow Auto Union group member Wanderer, being shared with the Wanderer W245 and its successors. Despite the relative novelty of the front-wheel-drive configuration, the manufacturer quoted the car's turning circle as 12.5 metres (41 ft) which was not greatly above the norm for cars of this size. The rear-wheel-drive Wanderer with which
264-405: The components responsible for transferring the rotational movement of the camshaft into the opening and closing of the intake and exhaust valves. Typical components are listed below in order from the crankshaft to the valves. The timing and lift profile of the valve opening events are controlled by the camshafts , through use of a carefully shaped lobe on a rotating shaft. The camshaft is driven by
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#1732851093225288-481: The description of the rear wheel drive 920 as a replacement for the front wheel drive Audi Front UW 225 is not unchallenged. Oswald, Werner (2001). Deutsche Autos 1920-1945, Band (vol) 2 (in German). Motorbuch Verlag. ISBN 3-613-02170-6 . Overhead valve engine An overhead valve engine , abbreviated ( OHV ) and sometimes called a pushrod engine , is a piston engine whose valves are located in
312-405: The engine. In common with many performance cars of the period, the Front UW 220 provided a claimed top speed of 100 km/h (62 mph): presumably actual performance data would have varied according to the weight and wind-cheating qualities of each individual car body. Various body styles were offered, including four-door sports limousines and two-door cabriolets / roadsters. The car was one of
336-457: The few at its time to have a sloping grille, a feature first popularized by the 1932 Packard Light Eight and later the 1933 Ford . For the UW 225 produced from 1935, engine size was increased to 2,257 cc, and reported maximum power rose to 50 PS (37 kW; 49 hp) or 55 PS (40 kW; 54 hp), respectively at 3,300 or 3,800 rpm: increased power was reflected by a modest increase in
360-501: The first production pushrod engine to use variable valve timing was introduced in the Dodge Viper (fourth generation) . OHV engines have several advantages compared with OHC engines: Compared with OHC engines, OHV engines have the following disadvantages: Pushrod A valvetrain is a mechanical system that controls the operation of the intake and exhaust valves in an internal combustion engine . The intake valves control
384-431: The flow of air/fuel mixture (or air alone for direct-injected engines) into the combustion chamber, while the exhaust valves control the flow of spent exhaust gases out of the combustion chamber once combustion is completed. The valvetrain layout is largely dependent on the location of the camshaft. The common valvetrain configurations for piston engines, in order from oldest to newest, are: The valvetrain consists of all
408-474: The motion of the camshaft is transferred using pushrods (hence the term "pushrod engine") and rocker arms to operate the valves at the top of the engine. However, some designs have the camshaft in the cylinder head but still sit below or alongside the valves (the Ford CVH and Opel CIH are good examples), so they can essentially be considered overhead valve designs. Some early intake-over-exhaust engines used
432-470: The production capacity at what had hitherto been the Audi plant. The Audi Front was therefore assembled at the nearby plant of Horch , another automaker purchased by Rasmussen in 1928, and one which, after Rasmussen's bank enforced a restructuring in 1932, became another of the four Auto Union group companies. Approximately 4,500 Audi Fronts were produced, including 1,817 of the earlier UW 220 model built between April 1933 and November 1934. By 1938 2,591 of
456-437: The pushrods) by the cam lobes . Overhead camshaft engines use fingers or bucket tappets, which are actuated from above directly by the cam lobes. Most modern engines use poppet valves , although sleeve valves , slide valves and rotary valves have also been used at times. Poppet valves are typically opened by the camshaft lobe or rocker arm, and closed by a coiled spring called a valve spring . Valve float occurs when
480-560: The same year that Buick received a patent for an overhead valve engine design. In 1904, the world's first production OHV engine was released in the Buick Model B . The engine was a flat-twin design with two valves per cylinder. The engine was very successful for Buick, with the company selling 750 such cars in 1905, and the OHV engine has powered almost all Buick automobiles since then. Several other manufacturers began to produce OHV engines, such as
504-624: The successor UW 225 model had been produced. Production of the successor model, the Audi 920 , began in November 1938. The Audi 920 was designed to be built and branded as a Horch, and the last minute decision to badge it instead as an Audi was led by marketing considerations. The 920 neatly slotted into the Auto Union range between the larger and more costly Horch models and the slightly smaller cheaper cars produced by Wanderer . Under these circumstances,
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#1732851093225528-476: The valves (located in the cylinder head). The bottom end of a pushrod is fitted with a lifter , upon which the camshaft makes contact. The camshaft lobe moves the lifter upwards, which moves the pushrod. The top end of the pushrod pushes on the rocker arm, which opens the valve. Depending on the design used, the valves are actuated by a rocker arm , finger , or bucket tappet . Overhead valve engines use rocker arms, which are actuated from below indirectly (through
552-470: Was hired by Buick (then named Buick Auto-Vim and Power Company ) from 1899–1902, where the overhead valve engine design was further refined. This engine employed pushrod-actuated rocker arms, which in turn opened poppet valves parallel to the pistons. Marr returned to Buick in 1904 (having built a small quantity of the Marr Auto-Car , with one of the first known engines to use an overhead camshaft design),
576-409: Was mostly limited to high-performance cars for many decades. OHC engines slowly became more common from the 1950s to the 1990s, and by the start of the 21st century, the majority of automotive engines (except for some North American V8 engines) used an OHC design. At the 1994 Indianapolis 500 motor race, Team Penske entered a car powered by the custom-built Mercedes-Benz 500I pushrod engine. Due to
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