Misplaced Pages

#998001

75-468: The Liberty L-12 is an American water-cooled 45° V-12 aircraft engine displacing 1,649 cubic inches (27 L) and making 400  hp (300  kW ) designed for a high power-to-weight ratio and ease of mass production. It saw wide use in aero applications, and saw marine use both in racing and runabout boats once it was marinized . A single bank 6-cylinder version, the Liberty L-6 , and V-8,

150-411: A pushrod which transfers the motion to the top of the engine, where a rocker opens the intake/exhaust valve. Although largely replaced by SOHC and DOHC layouts in modern automobile engines, the older overhead valve layout is still used in many industrial engines, due to its smaller size and lower cost. As engine speeds increased through the 20th century, single overhead camshaft (SOHC) engines— where

225-561: A slide valve . Camshafts more like those seen later in internal combustion engines were used in some steam engines, most commonly where high pressure steam (such as that generated from a flash steam boiler ), required the use of poppet valves, or piston valves. For examples see the Uniflow steam engine , and the Gardner-Serpollet steam cars, which also included axially sliding the camshaft to achieve variable valve timing. Among

300-403: A two-stroke engine that uses a camshaft, each valve is opened once for every rotation of the crankshaft; in these engines, the camshaft rotates at the same speed as the crankshaft. In a four-stroke engine , the valves are opened only half as often, therefore the camshaft is geared to rotate at half the speed of the crankshaft. The camshaft's duration determines how long the intake/exhaust valve

375-415: A ' brewery horse ' could produce 32,400 foot-pounds [43,929 J] per minute." James Watt and Matthew Boulton standardized that figure at 33,000 foot-pounds (44,742 J) per minute the next year. A common legend states that the unit was created when one of Watt's first customers, a brewer, specifically demanded an engine that would match a horse, and chose the strongest horse he had and driving it to

450-409: A camshaft are usually either: Many early internal combustion engines used a cam-in-block layout (such flathead , IOE or T-head layouts), whereby the camshaft is located within the engine block near the bottom of the engine. Early flathead engines locate the valves in the block and the cam acts directly on those valves. In an overhead valve engine, which came later, the cam follower presses on

525-402: A different RPM range. Advancing the camshaft (shifting it to ahead of the crankshaft timing) increases low RPM torque, while retarding the camshaft (shifting it to after the crankshaft) increases high RPM power. The required changes are relatively small, often in the order of 5 degrees. Modern engines which have variable valve timing are often able to adjust the timing of the camshaft to suit

600-429: A group of engineers modified a dynometer to be able to measure how much horsepower a horse can produce. This horse was measured to 5.7 hp (4.3 kW). When torque T is in pound-foot units, rotational speed N is in rpm , the resulting power in horsepower is The constant 5252 is the rounded value of (33,000 ft⋅lbf/min)/(2π rad/rev). When torque T is in inch-pounds, The constant 63,025

675-503: A hammer used in forging or to pound grain. Evidence for these exists back to the Han dynasty in China, and they were widespread by the medieval period. Once the rotative version of the steam engine was developed in the late 18th century, the operation of the valve gear was usually by an eccentric , which turned the rotation of the crankshaft into reciprocating motion of the valve gear, normally

750-530: A healthy human can produce about 1.2 hp (0.89 kW) briefly (see orders of magnitude ) and sustain about 0.1 hp (0.075 kW) indefinitely; trained athletes can manage up to about 2.5 hp (1.9 kW) briefly and 0.35 hp (0.26 kW) for a period of several hours. The Jamaican sprinter Usain Bolt produced a maximum of 3.5 hp (2.6 kW) 0.89 seconds into his 9.58 second 100-metre (109.4 yd) sprint world record in 2009. In 2023

825-620: A lower displacement of 1,411 in (23.12 L). A 6-cylinder version of the Liberty L-12, nicknamed the "Liberty Six" , consisted of a single bank of cylinders, with the resulting engine bearing a strong external resemblance to both the Mercedes D.III and BMW III straight-six German aviation engines of World War I. 825 cubic inches (13.5 L) An 8-cylinder V engine using Liberty cylinders in banks of four at 45°. 1,099.6 cubic inches (18.0 L) The Nuffield Liberty tank engine

SECTION 10

#1732773068999

900-483: A number of cams (discs with protruding cam lobes ) along its length, one for each valve. As the cam rotates, the lobe presses on the valve (or an intermediate mechanism), thus pushing it open. Typically, a valve spring is used to push the valve in the opposite direction, thus closing the valve once the cam rotates past the highest point of its lobe. Camshafts are made from metal and are usually solid, although hollow camshafts are sometimes used. The materials used for

975-703: A rapid and highly mobile tank. Using Christie's concept, Russian forces selected and copied the Liberty in the BT-2 & BT-5 Soviet interwar tank (at least one reconditioned Liberty was installed in a BT-5). Demonstration of this tank was witnessed by the British, and Christie's design characteristics were licensed and incorporated into the British A13 design specification . As World War II loomed, Nuffield, producing British cruiser tanks , licensed and re-engineered

1050-574: A set of basic drawings. After just five days, Vincent and Hall left the Willard with a completed design for the new engine, which had adopted, almost unchanged, the single overhead camshaft and rocker arm valvetrain design of the later Mercedes D.IIIa engines of 1917–18. In July 1917, an eight-cylinder prototype assembled by Packard's Detroit plant arrived in Washington for testing, and in August,

1125-420: A steeper camshaft profile is required, which increases the forces needed to open the valve. A related issue is valve float at high RPM, where the spring tension does not provide sufficient force to either keep the valve following the cam at its apex or prevent the valve from bouncing when it returns to the valve seat. This could be a result of a very steep rise of the lobe, where the cam follower separates from

1200-414: A wider LSA to compensate for excessive duration can reduce power and torque outputs. In general, the optimal LSA for a given engine is related to the ratio of the cylinder volume to intake valve area. Camshafts are integral components of internal combustion engines, responsible for controlling the opening and closing of the engine's intake and exhaust valves. As the camshaft rotates, its lobes push against

1275-464: Is a coefficient of theoretical brake horsepower and cylinder pressures during combustion. Nominal horsepower (nhp) is an early 19th-century rule of thumb used to estimate the power of steam engines. It assumed a steam pressure of 7 psi (48 kPa). Camshaft A camshaft is a shaft that contains a row of pointed cams in order to convert rotational motion to reciprocating motion . Camshafts are used in piston engines (to operate

1350-420: Is also used in many places to symbolize brake horsepower. Drawbar power (dbp) is the power a railway locomotive has available to haul a train or an agricultural tractor to pull an implement. This is a measured figure rather than a calculated one. A special railway car called a dynamometer car coupled behind the locomotive keeps a continuous record of the drawbar pull exerted, and the speed. From these,

1425-463: Is equivalent to a boiler heat output of 33,469 Btu/h (9.809 kW). Present industrial practice is to define "boiler horsepower" as a boiler thermal output equal to 33,475 Btu/h (9.811 kW), which is very close to the original and revised definitions. Boiler horsepower is still used to measure boiler output in industrial boiler engineering in the US. Boiler horsepower is abbreviated BHP, which

1500-454: Is equivalent to a boiler heat output of 33,485 Btu/h (9.813 kW). A few years later in 1884, the ASME re-defined the boiler horsepower as the thermal output equal to the evaporation of 34.5 pounds per hour of water "from and at" 212 °F (100 °C). This considerably simplified boiler testing, and provided more accurate comparisons of the boilers at that time. This revised definition

1575-484: Is in psi, and flow rate is in US gallons per minute. Drilling rigs are powered mechanically by rotating the drill pipe from above. Hydraulic power is still needed though, as 1 500 to 5 000 W are required to push mud through the drill bit to clear waste rock. Additional hydraulic power may also be used to drive a down-hole mud motor to power directional drilling . When using SI units, the equation becomes coherent and there

SECTION 20

#1732773068999

1650-465: Is needed to pull a drawbar load of 2,025 pounds-force at 5 miles per hour? { P } h p = 2025 × 5 375 = 27. {\displaystyle \{P\}_{\mathrm {hp} }={\frac {2025\times 5}{375}}=27.} The constant 375 is because 1 hp = 375 lbf⋅mph. If other units are used, the constant is different. When using coherent SI units (watts, newtons, and metres per second), no constant

1725-507: Is needed, and the formula becomes P = Fv . This formula may also be used to calculate the power of a jet engine, using the speed of the jet and the thrust required to maintain that speed. Example: how much power is generated with a thrust of 4000 pounds at 400 miles per hour? { P } h p = 4000 × 400 375 = 4266.7. {\displaystyle \{P\}_{\mathrm {hp} }={\frac {4000\times 400}{375}}=4266.7.} This measure

1800-434: Is no dividing constant. where pressure is in pascals (Pa), and flow rate is in cubic metres per second (m ). Boiler horsepower is a boiler 's capacity to deliver steam to a steam engine and is not the same unit of power as the 550 ft lb/s definition. One boiler horsepower is equal to the thermal energy rate required to evaporate 34.5 pounds (15.6 kg) of fresh water at 212 °F (100 °C) in one hour. In

1875-582: Is often used as a standard measurement procedure, since this is considered most representative of the lift range that defines the RPM range in which the engine produces peak power. The power and idle characteristics of a camshaft with the same duration rating that has been determined using different lift points (for example 0.006 or 0.002 inches) could be much different to a camshaft with a duration rated using lift points of 0.05 inches. A secondary effect of increased duration can be increased overlap , which determines

1950-430: Is open for, therefore it is a key factor in the amount of power that an engine produces. A longer duration can increase power at high engine speeds (RPM), however this can come with the trade-off of less torque being produced at low RPM. The duration measurement for a camshaft is affected by the amount of lift that is chosen as the start and finish point of the measurement. A lift value of 0.050 in (1.3 mm)

2025-513: Is ordinarily stated in watts or kilowatts. In the United States, the power output is stated in horsepower which, for this purpose, is defined as exactly 746 W. Hydraulic horsepower can represent the power available within hydraulic machinery , power through the down-hole nozzle of a drilling rig , or can be used to estimate the mechanical power needed to generate a known hydraulic flow rate. It may be calculated as where pressure

2100-743: Is the approximation of Assuming the third CGPM (1901, CR 70) definition of standard gravity , g n = 9.80665 m/s , is used to define the pound-force as well as the kilogram force, and the international avoirdupois pound (1959), one imperial horsepower is: Or given that 1 hp = 550 ft⋅lbf/s, 1 ft = 0.3048 m, 1 lbf ≈ 4.448 N, 1 J = 1 N⋅m, 1 W = 1 J/s: 1 hp ≈ 745.7 W The various units used to indicate this definition ( PS , KM , cv , hk , pk , k , ks and ch ) all translate to horse power in English. British manufacturers often intermix metric horsepower and mechanical horsepower depending on

2175-440: Is usually referred to as a double overhead camshaft engine (although colloquially they are sometimes referred to as "quad-cam" engines). Accurate control of the position and speed of the camshaft is critically important in allowing the engine to operate correctly. The camshaft is usually driven either directly, via a toothed rubber "timing belt"' or via a steel roller "timing chain". Gears have also occasionally been used to drive

2250-762: The Liberty L-8 , were derived from the Liberty L-12. It was succeeded by the Packard 1A-2500 . In May 1917, a month after the United States had declared war on Germany, a federal task force known as the Aircraft Production Board summoned two top engine designers, Jesse G. Vincent (of the Packard Motor Car Company) and Elbert J. Hall (of the Hall-Scott Motor Company), to Washington . They were given

2325-781: The kilowatt as the official power-measuring unit in EEC directives. Other names for the metric horsepower are the Italian cavallo vapore (cv) , Dutch paardenkracht (pk) , the French cheval-vapeur (ch) , the Spanish caballo de vapor and Portuguese cavalo-vapor (cv) , the Russian лошадиная сила (л. с.) , the Swedish hästkraft (hk) , the Finnish hevosvoima (hv) ,

Liberty L-12 - Misplaced Pages Continue

2400-556: The 12-cylinder version was tested and approved. In the fall of 1917, the War Department placed an order for 22,500 Liberty engines, dividing the contract among the automobile and engine manufacturers Buick , Ford , Cadillac , Lincoln , Marmon , and Packard . Hall-Scott in California was considered too small to receive a production order. Manufacturing by multiple factories was facilitated by its modular design. Ford

2475-501: The 1926 Iowa State Fair , they reported that the peak power over a few seconds has been measured to be as high as 14.88 hp (11.10 kW) and also observed that for sustained activity, a work rate of about 1 hp (0.75 kW) per horse is consistent with agricultural advice from both the 19th and 20th centuries and also consistent with a work rate of about four times the basal rate expended by other vertebrates for sustained activity. When considering human-powered equipment ,

2550-861: The Estonian hobujõud (hj) , the Norwegian and Danish hestekraft (hk) , the Hungarian lóerő (LE) , the Czech koňská síla and Slovak konská sila (k or ks ), the Serbo-Croatian konjska snaga (KS) , the Bulgarian конска сила , the Macedonian коњска сила (KC) , the Polish koń mechaniczny (KM) ( lit.   ' mechanical horse ' ), Slovenian konjska moč (KM) ,

2625-767: The Liberty for use in the A13 (produced as the Cruiser Mk III ) and later cruiser tanks, with an output of 340 hp (410 hp from the Mark IV version). In later British tanks it was replaced by the Rolls-Royce Meteor , an engine based on the Rolls-Royce Merlin aero engine, which offered greater engine power (600 hp). Nuffield Liberty engines were used in British tanks of immediate pre-war and Second World War: HD-4 or Hydrodome number 4

2700-747: The Liberty showed good potential for use in tanks as well as aircraft. The Anglo-American, or "Liberty", Mark VIII tank was designed in 1917–18. The American version used an adaptation of the Liberty V-12 engine of 300 hp (220 kW), designed to use cast iron cylinders rather than drawn steel ones. One hundred tanks were manufactured at the Rock Island Arsenal in 1919–20, too late for World War I . They were eventually sold to Canada for training in 1940, except for two that have been preserved. Inter-war, J. Walter Christie combined aircraft engines with new suspension design, producing

2775-477: The Liberty was in aircraft. The engine was also used in the RN-1 (Zodiac) blimp. Based on aircraft use the engine provided a good power-to-weight ratio. This made it ideal for use in land speed attempt vehicles. It was selected for two land speed record attempts. Both attempts set new records. Both crashed during further attempts, resulting in the deaths of the drivers and a newsreel cameraman. As early as 1917

2850-487: The Lobe Separation Angle is increased to compensate. A lay person can readily spot a long duration camshaft by observing the broad surface of the lobe where the cam pushes the valve open for a large number of degrees of crankshaft rotation. This will be visibly greater than the more pointed camshaft lobe bump that is observed on lower duration camshafts. The camshaft's lift determines the distance between

2925-639: The Mercedes and BMW straight-six powerplants. Delco Electronics provided the ignition system and Zenith the carburetor . Dry weight was 844 lb (383 kg). Fifty-two examples of a six-cylinder version, the Liberty L-6 , which very closely resembled the Mercedes and BMW powerplants in overall appearance, were produced but not procured by the Army. A pair of the 52 engines produced were destroyed by William Christmas testing his so-called " Christmas Bullet " fighter. An inverted Liberty 12-A referred to as

3000-412: The RPM of the engine at any given time. This avoids the above compromise required when choosing a fixed cam timing for use at both high and low RPM. The lobe separation angle (LSA, also called lobe centreline angle ) is the angle between the centreline of the intake lobes and the centreline of the exhaust lobes. A higher LSA reduces overlap, which improves idle quality and intake vacuum, however using

3075-667: The Ukrainian кінська сила (к. с.) , the Romanian cal-putere (CP) , and the German Pferdestärke (PS) . In the 19th century, revolutionary-era France had its own unit used to replace the cheval vapeur (horsepower); based on a 100 kgf ⋅m/s standard, it was called the poncelet and was abbreviated p . Tax or fiscal horsepower is a non-linear rating of a motor vehicle for tax purposes. Tax horsepower ratings were originally more or less directly related to

Liberty L-12 - Misplaced Pages Continue

3150-592: The United States entered World War I , the Cadillac division of General Motors was asked to produce the new Liberty aircraft engine, but William C. Durant was a pacifist who did not want General Motors or Cadillac facilities to be used for producing war material. This led to Henry Leland leaving Cadillac to form the Lincoln Motor Company to make Liberty engines. He quickly gained a $ 10,000,000 government contract to build 6,000 engines. Subsequently,

3225-654: The V-1650 was produced up to 1926 by Packard. The same designation was later applied to the Packard V-1650 Merlin , an engine with nearly identical engine displacement . This was a World War II Packard produced version of the Rolls-Royce Merlin , and is not to be confused with the earlier Liberty-based version. The Allison VG-1410 was an air-cooled inverted Liberty L-12, with a geared super-charger, Allison epicyclic propeller reduction gear, and bore reduced to 4 + 5 ⁄ 8  in (120 mm), giving

3300-407: The cam lobe (due to the valvetrain inertia being greater than the closing force of the valve spring), leaving the valve open for longer than intended. Valve float causes a loss of power at high RPM and in extreme situations can result in a bent valve if it gets struck by the piston. The timing (phase angle) of the camshaft relative to the crankshaft can be adjusted to shift an engine's power band to

3375-458: The camshaft is located within the cylinder head near the top of the engine— became increasingly common, followed by double overhead camshaft (DOHC) engines in more recent years. For OHC and DOHC engines, the camshaft operates the valve directly or via a short rocker arm. The valvetrain layout is defined according to the number of camshafts per cylinder bank. Therefore, a V6 engine with a total of four camshafts - two camshafts per cylinder bank -

3450-540: The camshaft. In some designs the camshaft also drives the distributor , oil pump , fuel pump and occasionally the power steering pump. Alternative drive systems used in the past include a vertical shaft with bevel gears at each end (e.g. pre-World War I Peugeot and Mercedes Grand Prix Cars and the Kawasaki W800 motorcycle) or a triple eccentric with connecting rods (e.g. the Leyland Eight car). In

3525-444: The cylinders were separately formed from forged steel tubes with thin metal jackets surrounding them to provide cooling water flow. A single overhead camshaft for each cylinder bank operated two valves per cylinder, in an almost identical manner to the inline six-cylinder German Mercedes D.III and BMW III engines. Each camshaft was driven by a vertical driveshaft that was placed at the back of each cylinder bank, again identical to

3600-436: The distance that the valve opens (the valve lift ) is greater than the distance from the peak of the camshaft's lobe to the base circle (the camshaft lift ). There are several factors which limit the maximum amount of lift possible for a given engine. Firstly, increasing lift brings the valves closer to the piston, so excessive lift could cause the valves to get struck and damaged by the piston. Secondly, increased lift means

3675-666: The early days of steam use, the boiler horsepower was roughly comparable to the horsepower of engines fed by the boiler. The term "boiler horsepower" was originally developed at the Philadelphia Centennial Exhibition in 1876, where the best steam engines of that period were tested. The average steam consumption of those engines (per output horsepower) was determined to be the evaporation of 30 pounds (14 kg) of water per hour, based on feed water at 100 °F (38 °C), and saturated steam generated at 70 psi (480 kPa). This original definition

3750-521: The engine itself include: Data from Janes's All the World's Aircraft 1919 Comparable engines Related lists Horsepower The term was adopted in the late 18th century by Scottish engineer James Watt to compare the output of steam engines with the power of draft horses . It was later expanded to include the output power of other power-generating machinery such as piston engines , turbines , and electric motors . The definition of

3825-530: The engine's bore size, number of cylinders, and a (now archaic) presumption of engine efficiency. As new engines were designed with ever-increasing efficiency, it was no longer a useful measure, but was kept in use by UK regulations, which used the rating for tax purposes . The United Kingdom was not the only country that used the RAC rating; many states in Australia used RAC hp to determine taxation. The RAC formula

SECTION 50

#1732773068999

3900-499: The engine. The situation persisted for several generations of four- and six-cylinder British engines: For example, Jaguar's 3.4-litre XK engine of the 1950s had six cylinders with a bore of 83 mm (3.27 in) and a stroke of 106 mm (4.17 in), where most American automakers had long since moved to oversquare (large bore, short stroke) V8 engines . See, for example, the early Chrysler Hemi engine . The power of an engine may be measured or estimated at several points in

3975-522: The first cars to utilize engines with single overhead camshafts were the Maudslay, designed by Alexander Craig and introduced in 1902 and the Marr Auto Car designed by Michigan native Walter Lorenzo Marr in 1903. In piston engines , the camshaft is used to operate the intake and exhaust valves . The camshaft consists of a cylindrical rod running the length of the cylinder bank with

4050-567: The following twelve years, Wood built nine more Packard V-12 driven Miss Americas and broke the record five times, raising it to 124.860 miles per hour (200.943 km/h). He also won five straight powerboat Gold Cup races between 1917 and 1921, and the prestigious Harmsworth Trophy nine times between 1920 and 1933, at the helm of his Miss Americas . Many gentlemen's runabouts , Gold Cup, and other race-winners were built with Liberty L-12 engines. A number of Liberty engines survive in restored operational and static display vehicles. Displays of

4125-411: The intake and exhaust valves), mechanically controlled ignition systems and early electric motor speed controllers . Camshafts in piston engines are usually made from steel or cast iron, and the shape of the cams greatly affects the engine's characteristics. Trip hammers are one of the early uses of a form of cam to convert rotating motion, e.g. from a waterwheel, into the reciprocating motion of

4200-400: The length of time that both the intake and exhaust valves are open. It is overlap which most affects idle quality, in as much as the "blow-through" of the intake charge immediately back out through the exhaust valve which occurs during overlap reduces engine efficiency, and is greatest during low RPM operation. In general, increasing a camshaft's duration typically increases the overlap, unless

4275-454: The limit. In that legend, Watt accepted the challenge and built a machine that was actually even stronger than the figure achieved by the brewer, and the output of that machine became the horsepower. In 1993, R. D. Stevenson and R. J. Wassersug published correspondence in Nature summarizing measurements and calculations of peak and sustained work rates of a horse. Citing measurements made at

4350-542: The order was increased to 9,000 units, with an option for 8,000 more if the government needed them. (Durant later changed his mind and both Cadillac and Buick produced the engines.) More than 16,000 Liberty engines were produced during the calendar year 1918. To November 11, 1918, more than 14,000 Liberty engines were produced. Lincoln had delivered 6,500 of the 400 hp (300 kW) V-12 overhead camshaft engines when production ceased in January 1919. The Liberty engine

4425-512: The origin of the engine in question. DIN 66036 defines one metric horsepower as the power to raise a mass of 75 kilograms against the Earth's gravitational force over a distance of one metre in one second: 75 kg × 9.80665 m/s × 1 m / 1 s = 75  kgf ⋅m/s = 1 PS. This is equivalent to 735.49875 W, or 98.6% of an imperial horsepower. In 1972, the PS was replaced by

4500-670: The power generated can be calculated. To determine the maximum power available, a controllable load is required; it is normally a second locomotive with its brakes applied, in addition to a static load. If the drawbar force ( F ) is measured in pounds-force (lbf) and speed ( v ) is measured in miles per hour (mph), then the drawbar power ( P ) in horsepower (hp) is { P } h p = { F } l b f { v } m p h 375 . {\displaystyle \{P\}_{\mathrm {hp} }={\frac {\{F\}_{\mathrm {lbf} }\{v\}_{\mathrm {mph} }}{375}}.} Example: How much power

4575-423: The size of the engine; but as of 2000, many countries changed over to systems based on CO 2 emissions, so are not directly comparable to older ratings. The Citroën 2CV is named for its French fiscal horsepower rating, "deux chevaux" (2CV). Nameplates on electrical motors show their power output, not the power input (the power delivered at the shaft, not the power consumed to drive the motor). This power output

SECTION 60

#1732773068999

4650-467: The task of designing as rapidly as possible an aircraft engine that would rival if not surpass those of Great Britain, France, and Germany. The Board specified that the engine would have a high power-to-weight ratio and be adaptable to mass production. The Board brought Vincent and Hall together on 29 May 1917 at the Willard Hotel in Washington, where the two were asked to stay until they produced

4725-647: The time of the Armistice with Germany , the various companies had produced 13,574 Liberty engines, attaining a production rate of 150 engines per day. Production continued after the war, for a total of 20,478 engines built between July 4, 1917, and 1919. Although it is widely reported otherwise, a few Liberty engines did see action in France as power for the American version of the British Airco DH.4 . As

4800-502: The transmission of the power from its generation to its application. A number of names are used for the power developed at various stages in this process, but none is a clear indicator of either the measurement system or definition used. In general: All the above assumes that no power inflation factors have been applied to any of the readings. Engine designers use expressions other than horsepower to denote objective targets or performance, such as brake mean effective pressure (BMEP). This

4875-685: The unit varied among geographical regions. Most countries now use the SI unit watt for measurement of power. With the implementation of the EU Directive 80/181/EEC on 1 January 2010, the use of horsepower in the EU is permitted only as a supplementary unit. The development of the steam engine provided a reason to compare the output of horses with that of the engines that could replace them. In 1702, Thomas Savery wrote in The Miner's Friend : The idea

4950-404: The valve and the valve seat (i.e. how far open the valve is). The farther the valve rises from its seat the more airflow can be provided, thus increasing the power produced. Higher valve lift can have the same effect of increasing peak power as increased duration, without the downsides caused by increased valve overlap. Most overhead valve engines have a rocker ratio of greater than one, therefore

5025-483: The valves, allowing the intake of air and fuel and the expulsion of exhaust gases. This synchronized process is crucial for optimizing engine performance, fuel efficiency, and emissions control. Without precisely engineered camshafts, the smooth and efficient operation of an engine would be compromised. The most common methods of valve actuation involve camshafts and valve springs, however alternate systems have occasionally been used on internal combustion engines: Before

5100-609: Was 12 feet (3.7 m) in radius; therefore, the horse travelled 2.4 × 2π × 12 feet in one minute. Watt judged that the horse could pull with a force of 180 pounds-force (800 N). So: Engineering in History recounts that John Smeaton initially estimated that a horse could produce 22,916 foot-pounds (31,070 J) per minute. John Desaguliers had previously suggested 44,000 foot-pounds (59,656 J) per minute, and Thomas Tredgold suggested 27,500 foot-pounds (37,285 J) per minute. "Watt found by experiment in 1782 that

5175-453: Was a modular design where four or six cylinders could be used in one or two banks, allowing for inline fours, V-8s, inline sixes, or the V-12. The design was held together by a two-part cast aluminium crankcase . The two pieces formed the upper and lower halves of the completed assembly and were held together with a series of bolts running around the outside perimeter. As was common for the era,

5250-427: Was an early research hydrofoil watercraft developed by the scientist Alexander Graham Bell . In 1919, it set a world marine speed record of 70.86 miles per hour (114.04 km/h) powered by two 350 hp Liberty L-12s. Inventor, entrepreneur, and boat racer Gar Wood set a new water speed record of 74.870 miles per hour (120.492 km/h) in 1920 in a new twin Liberty V-12 powered boat called Miss America . In

5325-444: Was asked to supply cylinders for the new engine and rapidly developed an improved technique for cutting and pressing steel, which resulted in cylinder production rising from 151 per day to over 2,000; the company eventually manufactured all 433,826 cylinders produced, as well as 3,950 complete engines. Lincoln constructed a new plant in record time, devoted entirely to Liberty engine production, and assembled 2,000 engines in 12 months. By

5400-546: Was instituted by the Royal Automobile Club and was used to denote the power of early 20th-century British cars. Many cars took their names from this figure (hence the Austin Seven and Riley Nine), while others had names such as "40/50 hp", which indicated the RAC figure followed by the true measured power. Taxable horsepower does not reflect developed horsepower; rather, it is a calculated figure based on

5475-420: Was later used by James Watt to help market his improved steam engine. He had previously agreed to take royalties of one-third of the savings in coal from the older Newcomen steam engines . This royalty scheme did not work with customers who did not have existing steam engines but used horses instead. Watt determined that a horse could turn a mill wheel 144 times in an hour (or 2.4 times a minute). The wheel

5550-724: Was licensed and produced in World War II by the UK car manufacturer Nuffield . It was used in early cruiser tanks , the Crusader , the Cavalier , and finally Centaur tanks. It was a 27 L (1,649 in) engine with an output of 340  hp (250  kW ; 340  PS ), which was inadequate for the increasing vehicle weights as the war progressed and also suffered numerous problems with cooling and reliability. The Nuffield Liberty ran through multiple versions: The primary use of

5625-420: Was sometimes applied in British colonies as well, such as Kenya (British East Africa) . where Since taxable horsepower was computed based on bore and number of cylinders, not based on actual displacement, it gave rise to engines with "undersquare" dimensions (bore smaller than stroke), which tended to impose an artificially low limit on rotational speed , hampering the potential power output and efficiency of

#998001