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54-488: The Beardmore Tornado is an eight-cylinder inline diesel aircraft engine built in 1927 by William Beardmore and Company of Glasgow, Scotland, and used in the British R101 airship when petrol engines were thought unsafe in the tropics. The model is given as Tornado IIIA or Tornado III C.I. The fuel is described as Diesel heavy-oil . The engine was designed by combining two four-cylinder units used for railcars into

108-410: A 'con rod', is the part of a piston engine which connects the piston to the crankshaft . Together with the crank , the connecting rod converts the reciprocating motion of the piston into the rotation of the crankshaft. The connecting rod is required to transmit the compressive and tensile forces from the piston. In its most common form, in an internal combustion engine , it allows pivoting on

162-425: A (4.0" bore × 3 13 ⁄ 64 " stroke = 322 in³ (5.277 L)) V8 in 1953, with similar displacement as their (3 7 ⁄ 16 " bore × 4 5 ⁄ 16 " stroke = 320.2 in³ (5.247 L)) straight-8, the latter being produced until the end of the 1953 model year. Pontiac maintained production on their straight-eight, as well as a L-head inline six, through the end of the 1954 model year, after which

216-526: A V8 became standard. Packard ended production of their signature straight-eight at the end of 1954, replacing it with an overhead valve V8. By the end of the 1970s overhead valve V8s powered 80% of automobiles built in the US, and most of the rest had six-cylinder engines. In Europe, many automobile factories had been destroyed during World War II, and it took many years before war-devastated economies recovered enough to make large cars popular again. The change in

270-408: A limitation on the maximum rpm and consequently a reduction in power output. The Tornado had steam cooling; water in the cylinder jackets was allowed to come to boiling point, and then condensed in three small triangular radiators on the hull above the power cars, or for the two midships engines was condensed in a retractable radiator and used to heat the passenger accommodation. Running the engines at

324-458: A one piece design where the crankshaft must be pressed together through them, rather than a two piece design that can be bolted around the journal of a one piece crankshaft. Typically there is a pinhole bored through the bearing on the big end of the connecting rod so that lubricating oil squirts out onto the thrust side of the cylinder wall to lubricate the travel of the pistons and piston rings . A connecting rod can rotate at both ends, so that

378-418: A relatively high thermal temperature was expected to improve the specific fuel consumption . The Tornado engines used Ricardo petrol starting engines, and there had only been time to replace one with a Beverley heavy-oil starting engine (itself started by compressed air) on one Tornado. The engines were intended to have reversing propellers, but they failed. At one point during development of R101, one engine

432-454: A result, the design has been displaced almost completely by the shorter V8 engine configuration. The first straight-eight was conceived by Charron, Girardot et Voigt (CGV) in 1903, but never built. Great strides were made during World War I , as Mercedes made straight-eight aircraft engines like the Mercedes D.IV . Advantages of the straight-eight engine for aircraft applications included

486-463: A six-year gap in the middle caused by the war). By 1951, their 1.5 L supercharged engines could produce 425 bhp (317 kW) at 9,300 rpm, and could rev as high as 10,500 rpm. However, the engines were at the end of their potential, and rule changes for the 1952 season made the Alfettas obsolete. Mercedes-Benz would create the last notable straight-eight racing cars in 1955, with

540-426: A solid billet of metal, rather than being cast or forged. Other materials include T6- 2024 aluminium alloy or T651- 7075 aluminium alloy , which are used for lightness and the ability to absorb high impact at the expense of durability. Titanium is a more expensive option which reduces the weight. Cast iron can be used for cheaper, lower performance applications such as motor scooters. During each rotation of

594-441: Is also documentation of cranks with connecting rods in the sketch books of Taccola from Renaissance Italy and 15th century painter Pisanello . The 1712 Newcomen atmospheric engine (the first steam engine) used chain drive instead of a connecting rod, since the piston only produced force in one direction. However, most steam engines after this are double-acting , therefore the force is produced in both directions, leading to

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648-463: Is sufficient to require the use of a harmonic damper at the accessory end of the crankshaft. Without such damping, fatigue cracking near the rear main bearing journal may occur, leading to engine failure. Although an inline six -cylinder engine can also be timed for inherent primary and secondary balance, a straight-eight develops more power strokes per revolution and, as a result, will run more smoothly under load than an inline six. Also, due to

702-574: The Centurion ARV, and various Dennis fire engines. Despite the shortcomings of length, weight, bearing friction, and torsional vibrations that led to the straight-eight's post-war demise, the straight-eight was the performance engine design of choice from the late 1920s to the late 1940s, and continued to excel in motorsport until the mid-1950s. Bugatti, Duesenberg, Alfa Romeo , Mercedes-Benz , and Miller built successful racing cars with high-performance dual overhead camshaft straight-eight engines in

756-694: The aerodynamic efficiency of the long, narrow configuration, and the inherent balance of the engine making counterweights on the crankshaft unnecessary. The disadvantages of crank and camshaft twisting were not considered at this time, since aircraft engines of the time ran at low speeds to keep propeller tip speed below the speed of sound. Unlike the V8 engine configuration, examples of which were used in De Dion-Bouton , Scripps-Booth , and Cadillac automobiles by 1914, no straight-eight engines were used in production cars before 1920. Italy's Isotta Fraschini introduced

810-402: The crankshaft can cause the cylinders to wear into an oval shape. This significantly reduces engine performance, since the circular piston rings are unable to properly seal against the oval-shaped cylinder walls. The amount of sideways force is proportional to the angle of the connecting rod, therefore longer connecting rods will reduce the amount of sideways force and engine wear. However,

864-429: The gudgeon pin (also called 'piston pin' or 'wrist pin' in the U.S.), which allows for rotation between the connecting rod and the piston. Typically, the big end connects to the crankpin using a plain bearing to reduce friction; however some smaller engines may instead use a rolling-element bearing , in order to avoid the need for a pumped lubrication system. Connecting rods with rolling element bearings are typically

918-409: The overhead camshaft , three-valve-per-cylinder engine produced 115 brake horsepower (86  kW ) at 4,250  rpm , and was capable of revving to an astonishing (at the time) 5,000 rpm. No Grand Prix engine before the war had peaked at more than 3,000 rpm. Bugatti experimented with straight-eight engines from 1922, and in 1924, he introduced the 2 L Bugatti Type 35 , one of

972-426: The piston rod ). On smaller steam locomotives, the connecting rods are usually of rectangular cross-section, however marine-type rods of circular cross-section have occasionally been used. On paddle steamers , the connecting rods are called 'pitmans' (not to be mistaken for pitman arms ). A connecting rod for an internal combustion engine consists of the 'big end', 'rod' and 'small end'. The small end attaches to

1026-526: The 1920s and 1930s. The Duesenberg brothers introduced the first successful straight-eight racing engine in 1920, when their 3 L engine placed third, fourth, and sixth at the Indianapolis 500 . The following year one of their cars won the French Grand Prix , while two others placed fourth and sixth in the race. Based on work the company had done on 16-cylinder aircraft engines during World War I ,

1080-476: The Alvis FV 600 armoured vehicle family. The Alvis Saladin armoured car was a 6x6 design with the engine compartment in the rear, a 76.2mm low pressure gun turret in the centre and the driver in front. The Saracen armoured personnel carrier had the engine in front with the driver in the centre and space for up to nine troops in the rear. The Stalwart amphibious logistics carrier has the driver's compartment over

1134-601: The Duesenberg brothers for the Cord-owned Duesenberg Inc. The automobile manufacturers within the Cord Corporation, comprising Auburn, Cord, and Duesenberg, were shut down in 1937. Lycoming continues to this day as an aircraft engine manufacturer. In the late 1920s, volume sellers Hudson and Studebaker introduced straight-eight engines for the premium vehicles in their respective lines. They were followed in

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1188-451: The Imperial luxury model. The British R101 rigid airship was fitted with five Beardmore Tornado Mk I inline eight-cylinder diesel engines. These engines were intended to give an output of 700 bhp (520 kW) at 1,000 rpm but in practice had a continuous output rating of only 585 bhp (436 kW) at 900 rpm. After World War II , changes in the automobile market resulted in

1242-476: The angle between the connecting rod and the piston can change as the rod moves up and down and rotates around the crankshaft . The materials used for connecting rods widely vary, including carbon steel, iron base sintered metal, micro-alloyed steel, spheroidized graphite cast iron. In mass-produced automotive engines, the connecting rods are most usually made of steel . In high performance applications, "billet" connecting rods can be used, which are machined out of

1296-454: The championship-winning W196 Formula One racing car and the 300SLR sports racing car. The 300SLR was famous for Stirling Moss and Denis Jenkinson 's victory in the 1955 Mille Miglia , but notorious for Pierre Levegh 's deadly accident at the 1955 24 Hours of Le Mans . The 300SLR was the final development of the Alfa Romeo design of the early 1930s as not only the camshaft, but now also

1350-559: The connecting length is the mechanical linkage used by Roman-era watermills . An early example of this linkage has been found at the late 3rd century Hierapolis sawmill in Roman Asia (modern Turkey) and the 6th century saw mills at Ephesus in Asia Minor (modern Turkey) and at Gerasa in Roman Syria. The crank and connecting rod mechanism of these machines converted the rotary motion of

1404-416: The crankshaft, a connecting rod is often subject to large and repetitive forces: shear forces due to the angle between the piston and the crankpin, compression forces as the piston moves downwards, and tensile forces as the piston moves upwards. These forces are proportional to the engine speed (RPM) squared. Failure of a connecting rod, often called "throwing a rod", often forces the broken rod through

1458-402: The crankshaft. A common arrangement for the big-end bearing is for the fork rod to have a single wide bearing sleeve that spans the whole width of the rod, including the central gap. The blade rod then runs, not directly on the crankpin, but on the outside of this sleeve. This causes the two rods to oscillate back and forth (instead of rotating relative to each other), which reduces the forces on

1512-648: The decline and final extinction of the straight-eight as an automobile engine. The primary users of the straight-eight were American luxury and premium cars that were carried over from before the war. A Flxible inter-city bus used the Buick straight-eight. During World War II, improvements in the refinery technology used to produce aviation gasoline resulted in the availability of large amounts of inexpensive high octane gasoline. Engines could be designed with higher compression ratios to take advantage of high-octane gasoline. This led to more highly stressed engines which amplified

1566-554: The design of cars from a long engine compartment between separate fenders to the modern configuration with its shorter engine compartment quickly led to the demise of the straight-8 engine. As a result of this, and of gasoline prices several times as expensive as in the U.S., four- and six-cylinder engines powered the majority of cars in Europe, and the few eight-cylinder cars produced were in the V8 configuration. The British Army selected Rolls-Royce B80 series of straight-eight engines in

1620-453: The different banks are slightly offset along the crankshaft axis (which creates a rocking couple ). Another solution is to use master-and-slave connecting rods, where the master rod also includes one or more ring pins which are connected to the big ends of slave rods on other cylinders. A drawback of master-slave rods is that the stroke lengths of all slave pistons not located 180° from the master piston will always be slightly longer than that of

1674-591: The early 1930s by Nash (with a dual-ignition unit), REO , and the Buick , Oldsmobile , and Pontiac divisions of General Motors . The Buick straight-eight was an overhead valve design, while the Oldsmobile straight-8 and Pontiac straight-8 straight-eights were flathead engines . Chevrolet, as an entry-level marque, did not have a straight-eight. Cadillac, the luxury brand of General Motors, stayed with their traditional V8 engines. In order to have engines as smooth as

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1728-402: The edge of the master rod. Multi-bank engines with many cylinders, such as V12 engines , have little space available for many connecting rod journals on a limited length of crankshaft. The simplest solution, as used in most road car engines, is for each pair of cylinders to share a crank journal , but this reduces the size of the rod bearings and means that matching (i.e. opposite) cylinders in

1782-559: The eight-cylinder (MkI) engine. These were intended to give an output of 700 bhp (520 kW) at 1,000 rpm but in practice, had a continuous output rating of only 585 bhp (436 kW) with a maximum of 650 hp (485 kW). At 17 tons for the five, they were six tons above design weight. The weight with the power car was over three tons per engine. The big end bearings were also found to be prone to early failure, In addition, there were two critical vibration frequencies which coincided with idling and cruising speeds, resulting in

1836-432: The engine did not reach production. Fork-and-blade rods, also known as "split big-end rods", have been used on V-twin motorcycle engines and V12 aircraft engines. For each pair of cylinders, a "fork" rod is split in two at the big end and the "blade" rod from the opposing cylinder is thinned to fit into this gap in the fork. This arrangement removes the rocking couple that is caused when cylinder pairs are offset along

1890-434: The even number of power strokes per revolution, a straight-eight does not produce unpleasant odd-order harmonic vibration in the vehicle's driveline at low engine speeds. The smooth running characteristics of the straight-eight made it popular in luxury and racing cars of the past. However, the engine's length demanded the use of a long engine compartment, making the basic design unacceptable in modern vehicles. Also, due to

1944-865: The first production automobile straight-eight in their Tipo 8 at the Paris Salon in 1919 Leyland Motors introduced their OHC straight-eight powered Leyland Eight luxury car at the International Motor Exhibition at Olympia, London in 1920. The Duesenberg brothers introduced their first production straight-eight in 1921. Straight-eight engines were used in expensive luxury and performance vehicles until after World War II. Bugattis and Duesenbergs commonly used double overhead cam straight-eight engines. Other notable straight-eight-powered automobiles were built by Daimler , Mercedes-Benz , Isotta Fraschini , Alfa Romeo , Stutz , Stearns-Knight and Packard . One marketing feature of these engines

1998-486: The first to react to the engineering problems of the straight-eight: in their racing car engines for the P2 and P3 and in their Alfa Romeo 8C 2300/2600/2900 sports cars of Mille Miglia and Le Mans fame the camshaft drive had been moved to the engine centre, between cylinders four and five, thus reducing the aforementioned limitations. The straight-eight was actually built as a symmetrical pair of straight-four engines joined in

2052-508: The front wheels, the larger B81 engine in the rear and a large load compartment over the middle and rear. The Salamander firefighting vehicle was unarmoured, and resembled the Stalwart with a conventional fire engine superstructure. The Rolls-Royce B80 series of engines were also used in other military and civilian applications, such as the Leyland Martian military truck, the winch engine in

2106-405: The gearbox was driven from the engine's centre. Engineers calculated that torsional stresses would be too high if they took power from the end of the long crankshaft, so they put a central gear train in the middle (which also ran the dual camshafts, dual magnetos, and other accessories) and ran a drive shaft to the clutch housing at the rear. Connecting rod A connecting rod , also called

2160-413: The length of the engine, torsional vibration in both crankshaft and camshaft can adversely affect reliability and performance at high speeds. In particular, a phenomenon referred to as "crankshaft whip," caused by the effects of centrifugal force on the crank throws at high engine rpm , can cause physical contact between the connecting rods and crankcase walls, leading to the engine's destruction. As

2214-412: The limitations of the long crankshaft and camshaft in the straight-eight engines. Oldsmobile replaced their straight-eight flathead engine with an overhead valve V8 engine in 1949, at which time Cadillac's V8 was changed to one with overhead valves. Chrysler replaced its straight-eight with its famous Hemi V-8 for 1951. Hudson retired its straight-eight at the end of the 1952 model year. Buick introduced

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2268-474: The master piston, which increases vibration in V engines. One of the most complicated examples of master-and-slave connecting rods is the 24-cylinder Junkers Jumo 222 experimental airplane engine developed for World War II. This engine consisted of six banks of cylinders, each with four cylinders per bank. Each "layer" of six cylinders used one master connecting rod, with the other five cylinders using slave rods. Approximately 300 test engines were built, however

2322-470: The maximum length of a connecting rod is constrained by the engine block size; the stroke length plus the connecting rod length must not result in the piston travelling past the top of the engine block. Radial engines typically use master-and-slave connecting rods, whereby one piston (the uppermost piston in the animation), has a master rod with a direct attachment to the crankshaft. The remaining pistons pin their connecting rods' attachments to rings around

2376-485: The middle at common gear trains for the camshafts and superchargers. It had two overhead camshafts, but only two valves per cylinder. The Alfa Romeo straight-eight would return after World War II to dominate the first season of Formula One racing in 1950, and to win the second season against competition from Ferrari 's V12-powered car in 1951. The Alfa Romeo 158/159 Alfetta was originally designed in 1937 and won 47 of 54 Grands Prix entered between 1938 and 1951 (with

2430-507: The middle class. Engine manufacturer Lycoming built straight-eight engines for sale to automobile manufacturers, including Gardner, Auburn, Kissel, and Locomobile . Hupmobile built their own engine. Lycoming was purchased by Auburn owner Errett Lobban Cord , who used a Lycoming straight-eight in his front-drive Cord L-29 automobile, and had Lycoming build the straight-eight engine for the Duesenberg Model J , which had been designed by

2484-611: The most successful racing cars of all time, which eventually won over 1000 races. Like the Duesenbergs, Bugatti got his ideas from building aircraft engines during World War I, and like them, his engine was a high-revving overhead camshaft unit with three valves per cylinder. It produced 100 bhp (75 kW) at 5,000 rpm and could be revved to over 6,000 rpm. Nearly 400 of the Type 35 and its derivatives were produced, an all-time record for Grand Prix motor racing . Alfa Romeo were

2538-531: The piston end and rotation on the shaft end. The predecessor to the connecting rod is a mechanic linkage used by water mills to convert rotating motion of the water wheel into reciprocating motion. The most common usage of connecting rods is in internal combustion engines or on steam engines . A connecting rod crank has been found in the Celtic Oppida at Paule in Brittany, dated to 69BC The predecessor to

2592-636: The project was cancelled in 1931 after the crash of the R101 and the end of the Imperial Airship Scheme . The R100 would have used the Tornado, but petrol engines were chosen to avoid delays. Data from Masefield: Straight-eight engine A straight-eight can be timed for inherent primary and secondary balance , with no unbalanced primary or secondary forces or moments. However, crankshaft torsional vibration , present to some degree in all engines,

2646-418: The side of the crankcase and thereby renders the engine irreparable. Common causes of connecting rod failure are tensile failure from high engine speeds, the impact force when the piston hits a valve (due to a valvetrain problem), rod bearing failure (usually due to a lubrication problem), or incorrect installation of the connecting rod. The sideways force exerted on the piston through the connecting rod by

2700-467: The straight-eights of its competitors, Cadillac introduced the crossplane crankshaft for its V8 , and added V12 and V16 engines to the top of its lineup. Ford never adopted the straight-eight; their entry-level Ford cars used flathead V8 engines until the 1950s while their Lincoln luxury cars used V8 from the 1930s to the 1980s and V12 engines in the 1930s and 1940s. Chrysler used flathead straight-eights in its premium Chrysler cars, including

2754-427: The use of a connecting rod. The typical arrangement uses a large sliding bearing block called a crosshead with the hinge between the piston and connecting rod placed outside the cylinder, requiring a seal around the piston rod . In a steam locomotive , the cranks are usually mounted directly on the driving wheels . The connecting rod is used between the crank pin on the wheel and the crosshead (where it connects to

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2808-480: The waterwheel into the linear movement of the saw blades. An early documentation of the design occurred sometime between 1174 and 1206 AD in the Artuqid State (modern Turkey), when inventor Al-Jazari described a machine which incorporated the connecting rod with a crankshaft to pump water as part of a water-raising machine, though the device was more complex than typical crank and connecting rod designs. There

2862-478: Was their impressive length — some of the Duesenberg engines were over 4 ft (1.2 m) long, resulting in the long hoods (bonnets) found on these automobiles. In the United States in the 1920s, automobile manufacturers, including Hupmobile (1925), Chandler (1926), Marmon (1927), Gardner (1925), Kissel (1925), Locomobile (1925) and Auburn (1925) began using straight-eight engines in cars targeted at

2916-516: Was used only for astern running at the start and finish of flights, a decision that astonished Nevil Shute and the other engineers on the R100 team. Later two engines were made reversible by an adjustment to the camshaft. The R101 had five Tornado engines. The proposed R102 airship was to have seven engines of an improved version of the Tornado, having an output of 850 bhp (630 kW, maximum) or 700 bhp (520 kW, cruising, continuous), but

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