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69-551: The VK 45.01 (P) , also informally known as Tiger (P) or Porsche Tiger , was a heavy tank prototype designed by Porsche in Germany . With a dual engine gasoline-electric drive that was complex and requiring significant amounts of copper, it lost out to its Henschel competitor on trials, it was not selected for mass production and the Henschel design was produced as the Tiger I . Most of

138-399: A ferromagnetic core. Electric current passing through the wire causes the magnetic field to exert a force ( Lorentz force ) on it, turning the rotor. Windings are coiled wires, wrapped around a laminated, soft, iron, ferromagnetic core so as to form magnetic poles when energized with current. Electric machines come in salient- and nonsalient-pole configurations. In a salient-pole motor

207-430: A magnetic field that passes through the rotor armature, exerting force on the rotor windings. The stator core is made up of many thin metal sheets that are insulated from each other, called laminations. These laminations are made of electrical steel , which has a specified magnetic permeability, hysteresis, and saturation. Laminations reduce losses that would result from induced circulating eddy currents that would flow if

276-503: A tank gun 's range, and sheer armour mass was no longer a guarantee of survivability against the largest HEAT warheads of tank guns or missiles. Chamberlain, Peter; Ellis, Chris (1981) [1969], British and American Tanks of World War II , Arco Publishing Background: History of the tank , Tank classification , Tanks in World War I Background: History of the tank , Tank classification , interwar period Background: History of

345-404: A 100- horsepower induction motor currently has the same mounting dimensions as a 7.5-horsepower motor in 1897. In 2022, electric motor sales were estimated to be 800 million units, increasing by 10% annually. Electric motors consume ≈50% of the world's electricity. Since the 1980s, the market share of DC motors has declined in favor of AC motors. An electric motor has two mechanical parts:

414-431: A 20-hp squirrel cage and a 100-hp wound rotor with a starting rheostat. These were the first three-phase asynchronous motors suitable for practical operation. Since 1889, similar developments of three-phase machinery were started Wenström. At the 1891 Frankfurt International Electrotechnical Exhibition, the first long distance three-phase system was successfully presented. It was rated 15 kV and extended over 175 km from

483-428: A 3-step speed switch took over the work. The electric motors transferred their power to a final drive with a ratio of 15: 1 directly to the drive wheels located at the rear. The fuel tanks carried 520 litres of petrol and allowed a driving range of 105 kilometers. Two compressed air tanks in the front crew compartment area assisted the driver during braking maneuvers. Unlike the Henschel design's mid-hull mounting for

552-464: A commutator-type direct-current electric motor was built by American inventors Thomas Davenport and Emily Davenport , which he patented in 1837. The motors ran at up to 600 revolutions per minute, and powered machine tools and a printing press. Due to the high cost of primary battery power , the motors were commercially unsuccessful and bankrupted the Davenports. Several inventors followed Sturgeon in

621-463: A comparatively small air gap. The St. Louis motor, long used in classrooms to illustrate motor principles, is inefficient for the same reason, as well as appearing nothing like a modern motor. Electric motors revolutionized industry. Industrial processes were no longer limited by power transmission using line shafts, belts, compressed air or hydraulic pressure. Instead, every machine could be equipped with its own power source, providing easy control at

690-422: A generator and the other as motor. The drum rotor was introduced by Friedrich von Hefner-Alteneck of Siemens & Halske to replace Pacinotti's ring armature in 1872, thus improving the machine efficiency. The laminated rotor was introduced by Siemens & Halske the following year, achieving reduced iron losses and increased induced voltages. In 1880, Jonas Wenström provided the rotor with slots for housing

759-509: A heavy tank force and did not want to compromise its 4,800 km (3,000 miles) supply line to Europe. The M6 heavy tank was designed in 1940 but held few advantages over medium tanks and planned production of several thousand was stopped. The Anglo-American T14 heavy tank project started in 1941 did not deliver a pilot model until 1944. The US preferred to use tank destroyers (mobile but relatively lightly armoured vehicles) for anti-tank defence, and prior to 1944 there were few indications that

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828-625: A larger arc. Heavy tank Heavy tanks achieved their greatest, albeit limited, success when fighting lighter tanks and destroying fortifications. Heavy tanks often saw limited combat in their intended roles, instead becoming mobile pillboxes or defensive positions, such as the German Tiger I and Tiger II designs, or the Russian KV and IS designs. Heavy tanks feature very heavy armor and weapons relative to lighter tanks. Many heavy tanks shared components with lighter tanks. For example,

897-437: A model electric vehicle that same year. A major turning point came in 1864, when Antonio Pacinotti first described the ring armature (although initially conceived in a DC generator, i.e. a dynamo). This featured symmetrically grouped coils closed upon themselves and connected to the bars of a commutator, the brushes of which delivered practically non-fluctuating current. The first commercially successful DC motors followed

966-425: A rotating bar winding rotor. Steadfast in his promotion of three-phase development, Mikhail Dolivo-Dobrovolsky invented the three-phase induction motor in 1889, of both types cage-rotor and wound rotor with a starting rheostat, and the three-limb transformer in 1890. After an agreement between AEG and Maschinenfabrik Oerlikon , Doliwo-Dobrowolski and Charles Eugene Lancelot Brown developed larger models, namely

1035-398: A solid core were used. Mains powered AC motors typically immobilize the wires within the windings by impregnating them with varnish in a vacuum. This prevents the wires in the winding from vibrating against each other which would abrade the wire insulation and cause premature failures. Resin-packed motors, used in deep well submersible pumps, washing machines, and air conditioners, encapsulate

1104-525: A total of 12 individual wheels, 6 road wheels/axles, in 3 bogies. The wheels were not 'interleaved' like those of the Tiger I. The 57 to 59 tons combat weight in combination with 640 mm wide "slack-tracks" (KGS 62/640/130) using no return rollers, produced a ground pressure of about 1.06 kg / cm. The gasoline-electric drive specially developed by Ferdinand Porsche entered "uncharted territory" for road vehicles; this led to numerous development issues with

1173-579: A type of actuator . They are generally designed for continuous rotation, or for linear movement over a significant distance compared to its size. Solenoids also convert electrical power to mechanical motion, but over only a limited distance. Before modern electromagnetic motors, experimental motors that worked by electrostatic force were investigated. The first electric motors were simple electrostatic devices described in experiments by Scottish monk Andrew Gordon and American experimenter Benjamin Franklin in

1242-488: A world record, which Jacobi improved four years later in September 1838. His second motor was powerful enough to drive a boat with 14 people across a wide river. It was also in 1839/40 that other developers managed to build motors with similar and then higher performance. In 1827–1828, Jedlik built a device using similar principles to those used in his electromagnetic self-rotors that was capable of useful work. He built

1311-592: A wound rotor forming a self-starting induction motor , and the third a true synchronous motor with separately excited DC supply to rotor winding. One of the patents Tesla filed in 1887, however, also described a shorted-winding-rotor induction motor. George Westinghouse , who had already acquired rights from Ferraris (US$ 1,000), promptly bought Tesla's patents (US$ 60,000 plus US$ 2.50 per sold hp, paid until 1897), employed Tesla to develop his motors, and assigned C.F. Scott to help Tesla; however, Tesla left for other pursuits in 1889. The constant speed AC induction motor

1380-487: Is often assumed that heavy tanks suffered inferior mobility to medium tanks , this was not always the case, as many of the more sophisticated heavy tank designs featured advanced suspension and transmissions to counteract this drawback. As mentioned previously, heavy tanks are often extremely expensive and resource-intensive to produce and operate. The German Tiger I , for example, had similar speed and better terrain-handling characteristics when compared to its main competitor,

1449-462: The Interwar period , these larger vehicles with stronger defensive and offensive capabilities became known as "heavy" tanks. Heavy tanks had gradually progressed from their trench warfare and bunker destroying role to dedicated anti-tank purposes by the onset of World War II . Heavy tanks saw limited deployment by France at the beginning of the war, and were only ever used in conflict by Nazi Germany and

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1518-471: The South Side Elevated Railroad , where it became popularly known as the " L ". Sprague's motor and related inventions led to an explosion of interest and use in electric motors for industry. The development of electric motors of acceptable efficiency was delayed for several decades by failure to recognize the extreme importance of an air gap between the rotor and stator. Efficient designs have

1587-775: The T28 GMC and ' Tortoise ' had casement designs and weighed around 80 tonnes but did not enter service. The immediate post-war period saw the final fielding of heavy tanks, including the US M103 heavy tank , the British FV214 Conqueror , and the French ARL 44 (in very limited numbers for the ARL 44), all in response to the Soviet heavy tanks of the period . The largest tank guns were approaching maximum calibre whose shell could still be handled by

1656-573: The Tiger I , was adopted for production instead. The VK 45.01 (P) chassis was later chosen to be the basis of a new heavy Jagdpanzer (although designated a Panzerjäger ) which would eventually be called the Ferdinand and mount the new, longer, 88 mm Pak 43/2 . Only one tank went into service as a command tank in the Ferdinand ( Elefant ) unit, and served in Panzerjäger Abteilung 653. It

1725-606: The VK 30.01 (P) medium tank, Porsche's medium tank prototype, and adapted parts used on it for the new tank. The new Porsche tank, designated the VK 45.01 (P) was to be powered by twin V-10 air cooled Porsche Type 101 gasoline engines which were mounted to the rear of the tank. Each of the twin engines would then drive a separate generator , one for either side of the tank, which would then power each of two electric motors , one powering each track from

1794-439: The armature . Two or more electrical contacts called brushes made of a soft conductive material like carbon press against the commutator. The brushes make sliding contact with successive commutator segments as the rotator turns, supplying current to the rotor. The windings on the rotor are connected to the commutator segments. The commutator reverses the current direction in the rotor windings with each half turn (180°), so

1863-416: The 1740s. The theoretical principle behind them, Coulomb's law , was discovered but not published, by Henry Cavendish in 1771. This law was discovered independently by Charles-Augustin de Coulomb in 1785, who published it so that it is now known by his name. Due to the difficulty of generating the high voltages they required, electrostatic motors were never used for practical purposes. The invention of

1932-573: The Lauffen waterfall on the Neckar river. The Lauffen power station included a 240 kW 86 V 40 Hz alternator and a step-up transformer while at the exhibition a step-down transformer fed a 100-hp three-phase induction motor that powered an artificial waterfall, representing the transfer of the original power source. The three-phase induction is now used for the vast majority of commercial applications. Mikhail Dolivo-Dobrovolsky claimed that Tesla's motor

2001-619: The Soviet IS series . Note that "heavy" versus "medium" is more a question of tactical roles than weight; the Panther , for example, was a "medium" tank that outweighed most Allied "heavy" tanks. American forces rarely fielded heavy tanks, as they still held on to the infantry-support doctrine like the British; in addition, the Americans recognized the logistical and mobility issues that came with possessing

2070-432: The US M103 heavy tank shared many components with the lighter Patton tank , including transmission and engine. As a result, they tend to be either underpowered and comparatively slow, or have engine and drive train reliability issues. In case of an entirely new design development, which was the case with the German Tiger I , designs often became needlessly complex and costly, resulting in low production numbers. Although it

2139-595: The US M4 Sherman was outclassed in terms of armor and weapons by German heavy tanks which were few in number. Near the end of World War II, a few early model M26 Pershings were sent to Europe to gain combat experience. Aside from these the closest the Americans came to putting a heavy tank into service were up-armored M4 Sherman "Jumbos" which were used as assault guns . Both the US and UK developed very well-armoured and armed tanks intended for assaulting heavily defended areas -

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2208-552: The USSR from about 1943 to the war's end. This tank type remained a decisive factor in the early years of the Cold War. The purpose of heavies would not change until their replacement by the main battle tank . Often referred to as MBTs, these designs effectively filled all roles required by armies, thus rendering more specialized designs obsolete. The first British tank, the Mark I of World War I,

2277-496: The already produced chassis were rebuilt as Elefant Panzerjäger tank destroyers. On 26 May 1941, Henschel and Porsche were asked to submit designs for a 45-ton heavy tank capable of mounting the high velocity 8.8 cm Kwk 36 L/56 gun which was derived from the German 88 mm Flak 37 antiaircraft gun . Both the Henschel and Porsche tanks were to be fitted with the same turret supplied by Krupp . The Porsche company worked on updating

2346-403: The crew, even using awkward two-part ammunition (separate projectile and propellant case, similar to battleship guns), which greatly slowed their rate of fire. Thanks to improved shell designs and fire control technology improving accuracy, postwar medium tanks were catching up to heavy tanks in firepower. The tactical value of heavy tanks thus declined to the point that no new designs were fielded;

2415-520: The development of DC motors, but all encountered the same battery cost issues. As no electricity distribution system was available at the time, no practical commercial market emerged for these motors. After many other more or less successful attempts with relatively weak rotating and reciprocating apparatus Prussian/Russian Moritz von Jacobi created the first real rotating electric motor in May 1834. It developed remarkable mechanical output power. His motor set

2484-478: The developments by Zénobe Gramme who, in 1871, reinvented Pacinotti's design and adopted some solutions by Werner Siemens . A benefit to DC machines came from the discovery of the reversibility of the electric machine, which was announced by Siemens in 1867 and observed by Pacinotti in 1869. Gramme accidentally demonstrated it on the occasion of the 1873 Vienna World's Fair , when he connected two such DC devices up to 2 km from each other, using one of them as

2553-429: The drive system. The two air-cooled 15-litre V-10 engines designated Porsche Type 101 , which were each coupled with a Siemens-Schuckert 500 kVA generator , generated the necessary electric power to operate each of the two Siemens 230 kW (312.7 PS ) individual-output electric motors driving the rear sprockets. In this drive system, a mechanical power transmission system and gearbox could be omitted, since now

2622-460: The electric energy produced in the US. In 1824, French physicist François Arago formulated the existence of rotating magnetic fields , termed Arago's rotations , which, by manually turning switches on and off, Walter Baily demonstrated in 1879 as in effect the first primitive induction motor . In the 1880s many inventors were trying to develop workable AC motors because AC's advantages in long-distance high-voltage transmission were offset by

2691-566: The electric grid, provided for electric distribution to trolleys via overhead wires and the trolley pole, and provided control systems for electric operations. This allowed Sprague to use electric motors to invent the first electric trolley system in 1887–88 in Richmond, Virginia , the electric elevator and control system in 1892, and the electric subway with independently powered centrally-controlled cars. The latter were first installed in 1892 in Chicago by

2760-470: The electrochemical battery by Alessandro Volta in 1799 made possible the production of persistent electric currents. Hans Christian Ørsted discovered in 1820 that an electric current creates a magnetic field, which can exert a force on a magnet. It only took a few weeks for André-Marie Ampère to develop the first formulation of the electromagnetic interaction and present the Ampère's force law , that described

2829-472: The first device to contain the three main components of practical DC motors: the stator , rotor and commutator. The device employed no permanent magnets, as the magnetic fields of both the stationary and revolving components were produced solely by the currents flowing through their windings. The first commutator DC electric motor capable of turning machinery was invented by English scientist William Sturgeon in 1832. Following Sturgeon's work,

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2898-721: The heavily armed mediums came to be known as the main battle tank (MBT). Doctrine held that less expensive self-propelled artillery could serve in the infantry support role. The weight of MBTs quickly increased during the Cold War , and most third generation MBTs including the M1 Abrams , Challenger 2 , Leopard 2 , Merkava , Arjun MBT , and Type 99 have weights similar to those of 1950s heavy tanks. Older heavy tanks with steel armour were rendered obsolete by anti-tank guided missiles and high-explosive anti-tank (HEAT) ammunition. The much more flexible missiles are effective at ranges beyond

2967-579: The inability to operate motors on AC. The first alternating-current commutatorless induction motor was invented by Galileo Ferraris in 1885. Ferraris was able to improve his first design by producing more advanced setups in 1886. In 1888, the Royal Academy of Science of Turin published Ferraris's research detailing the foundations of motor operation, while concluding at that time that "the apparatus based on that principle could not be of any commercial importance as motor." Possible industrial development

3036-530: The increasing demands of the U-boat fleet (which used very similar diesel-electric transmissions , which worked perfectly well); while it was easy enough to obtain quality copper to build a single prototype, once series production began, this became more difficult. These problems, and the fact that trials proved the tank to be less maneuverable than its competitor, were the reason why Henschel's identically armed and more conventional VK 45.01 (H) H1 prototype, which became

3105-644: The load are exerted beyond the outermost bearing, the load is said to be overhung. The rotor is supported by bearings , which allow the rotor to turn on its axis by transferring the force of axial and radial loads from the shaft to the motor housing. A DC motor is usually supplied through a split ring commutator as described above. AC motors' commutation can be achieved using either a slip ring commutator or external commutation. It can be fixed-speed or variable-speed control type, and can be synchronous or asynchronous. Universal motors can run on either AC or DC. DC motors can be operated at variable speeds by adjusting

3174-538: The magnet, showing that the current gave rise to a close circular magnetic field around the wire. Faraday published the results of his discovery in the Quarterly Journal of Science , and sent copies of his paper along with pocket-sized models of his device to colleagues around the world so they could also witness the phenomenon of electromagnetic rotations. This motor is often demonstrated in physics experiments, substituting brine for (toxic) mercury. Barlow's wheel

3243-1363: The motor's shaft. An electric generator is mechanically identical to an electric motor, but operates in reverse, converting mechanical energy into electrical energy. Electric motors can be powered by direct current (DC) sources, such as from batteries or rectifiers , or by alternating current (AC) sources, such as a power grid, inverters or electrical generators. Electric motors may be classified by considerations such as power source type, construction, application and type of motion output. They can be brushed or brushless , single-phase , two-phase , or three-phase , axial or radial flux , and may be air-cooled or liquid-cooled. Standardized motors provide power for industrial use. The largest are used for ship propulsion, pipeline compression and pumped-storage applications, with output exceeding 100 megawatts . Applications include industrial fans, blowers and pumps, machine tools, household appliances, power tools, vehicles, and disk drives. Small motors may be found in electric watches. In certain applications, such as in regenerative braking with traction motors , electric motors can be used in reverse as generators to recover energy that might otherwise be lost as heat and friction. Electric motors produce linear or rotary force ( torque ) intended to propel some external mechanism. This makes them

3312-485: The point of use, and improving power transmission efficiency. Electric motors applied in agriculture eliminated human and animal muscle power from such tasks as handling grain or pumping water. Household uses (like in washing machines, dishwashers, fans, air conditioners and refrigerators (replacing ice boxes ) of electric motors reduced heavy labor in the home and made higher standards of convenience, comfort and safety possible. Today, electric motors consume more than half of

3381-477: The production of mechanical force by the interaction of an electric current and a magnetic field. Michael Faraday gave the first demonstration of the effect with a rotary motion on 3 September 1821 in the basement of the Royal Institution . A free-hanging wire was dipped into a pool of mercury, on which a permanent magnet (PM) was placed. When a current was passed through the wire, the wire rotated around

3450-479: The rear drive sprocket. But the engines and drive train were generally new and unorthodox designs for a tank (other than some brief experiments in the very early years), and due to being underdeveloped were prone to break down or require frequent maintenance. It was also difficult for the Third Reich to obtain additional amounts of quality copper to build whole new fleets of vehicles with electric drives in addition to

3519-428: The rotor and stator ferromagnetic cores have projections called poles that face each other. Wire is wound around each pole below the pole face, which become north or south poles when current flows through the wire. In a nonsalient-pole (distributed field or round-rotor) motor, the ferromagnetic core is a smooth cylinder, with the windings distributed evenly in slots around the circumference. Supplying alternating current in

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3588-465: The rotor and the stator. The product between these two fields gives rise to a force and thus a torque on the motor shaft. One or both of these fields changes as the rotor turns. This is done by switching the poles on and off at the right time, or varying the strength of the pole. Motors can be designed to operate on DC current, on AC current, or some types can work on either. AC motors can be either asynchronous or synchronous. Synchronous motors require

3657-402: The rotor, which moves, and the stator, which does not. Electrically, the motor consists of two parts, the field magnets and the armature, one of which is attached to the rotor and the other to the stator. Together they form a magnetic circuit . The magnets create a magnetic field that passes through the armature. These can be electromagnets or permanent magnets . The field magnet is usually on

3726-474: The significantly lighter Panzer IV medium tank. However, low reliability and limited resources meant that just 1,347 were produced, compared to roughly 8,800 Pz.Kpfw. IV. The origins of the class date to World War I and the first tank designs, which were intended to operate in close concert with infantry . Virtually all early tanks possessed thick armor to allow them to survive in no man's land . As lighter and more maneuverable designs were introduced during

3795-454: The stator and the armature on the rotor, but these may be reversed. The rotor is the moving part that delivers the mechanical power. The rotor typically holds conductors that carry currents, on which the magnetic field of the stator exerts force to turn the shaft. The stator surrounds the rotor, and usually holds field magnets, which are either electromagnets (wire windings around a ferromagnetic iron core) or permanent magnets . These create

3864-435: The stator in plastic resin to prevent corrosion and/or reduce conducted noise. An air gap between the stator and rotor allows it to turn. The width of the gap has a significant effect on the motor's electrical characteristics. It is generally made as small as possible, as a large gap weakens performance. Conversely, gaps that are too small may create friction in addition to noise. The armature consists of wire windings on

3933-492: The tank , Tank classification , Tanks in the Cold War Background: History of the tank , Tank classification Electric motor An electric motor is a machine that converts electrical energy into mechanical energy . Most electric motors operate through the interaction between the motor's magnetic field and electric current in a wire winding to generate force in the form of torque applied on

4002-406: The torque applied to the rotor is always in the same direction. Without this reversal, the direction of torque on each rotor winding would reverse with each half turn, stopping the rotor. Commutated motors have been mostly replaced by brushless motors , permanent magnet motors , and induction motors . The motor shaft extends outside of the motor, where it satisfies the load. Because the forces of

4071-422: The turret, the VK 45.01 (P) had its Krupp-designed turret mounted at the front. The turret, which mounted the 8.8 cm KwK 36 and a 7.92 mm MG 34 coaxial machine gun , was essentially the same Krupp design also used for Henschel's contract-winning VK45.01(H) prototype design. The first eight turrets produced had lower sides and a flat roof with raised centre section to allow the gun to be depressed through

4140-663: The voltage applied to the terminals or by using pulse-width modulation (PWM). AC motors operated at a fixed speed are generally powered directly from the grid or through motor soft starters . AC motors operated at variable speeds are powered with various power inverter , variable-frequency drive or electronic commutator technologies. The term electronic commutator is usually associated with self-commutated brushless DC motor and switched reluctance motor applications. Electric motors operate on one of three physical principles: magnetism , electrostatics and piezoelectricity . In magnetic motors, magnetic fields are formed in both

4209-406: The winding, further increasing the efficiency. In 1886, Frank Julian Sprague invented the first practical DC motor, a non-sparking device that maintained relatively constant speed under variable loads. Other Sprague electric inventions about this time greatly improved grid electric distribution (prior work done while employed by Thomas Edison ), allowed power from electric motors to be returned to

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4278-431: The windings creates poles in the core that rotate continuously. A shaded-pole motor has a winding around part of the pole that delays the phase of the magnetic field for that pole. A commutator is a rotary electrical switch that supplies current to the rotor. It periodically reverses the flow of current in the rotor windings as the shaft rotates. It consists of a cylinder composed of multiple metal contact segments on

4347-508: Was an early refinement to this Faraday demonstration, although these and similar homopolar motors remained unsuited to practical application until late in the century. In 1827, Hungarian physicist Ányos Jedlik started experimenting with electromagnetic coils . After Jedlik solved the technical problems of continuous rotation with the invention of the commutator , he called his early devices "electromagnetic self-rotors". Although they were used only for teaching, in 1828 Jedlik demonstrated

4416-529: Was deployed in April 1944 and lost that subsequent July. The VK 45.01 (P)'s chassis and many of the Elefant's components were later used in developing the VK 45.02 (P) prototype heavy tank. Ferdinand Porsche developed the spring rod roller carriage; there were 6 road wheels, each road wheel formed of an inner and outer paired wheel per axle. The six paired road wheels were divided into three 2-axle bogies per side, for

4485-439: Was designed under the British infantry tank concept, which is similar to the heavy tank, having thick armour and tending to weigh more than their other tanks. However, it is usually considered separate because infantry tanks generally had less firepower, with their cruiser tanks (comparable to mediums) at the time having the same main armament but more machine guns. Later war examples were the German Tiger I and II , as well as

4554-445: Was envisioned by Nikola Tesla , who invented independently his induction motor in 1887 and obtained a patent in May 1888. In the same year, Tesla presented his paper A New System of Alternate Current Motors and Transformers to the AIEE that described three patented two-phase four-stator-pole motor types: one with a four-pole rotor forming a non-self-starting reluctance motor , another with

4623-453: Was found not to be suitable for street cars, but Westinghouse engineers successfully adapted it to power a mining operation in Telluride, Colorado in 1891. Westinghouse achieved its first practical induction motor in 1892 and developed a line of polyphase 60 hertz induction motors in 1893, but these early Westinghouse motors were two-phase motors with wound rotors. B.G. Lamme later developed

4692-522: Was introduced to break through German defensive lines of trenches and barbed wire . When lighter, faster tanks were introduced, the larger tanks were classified as heavy. The French Char 2C was one of the largest tanks ever produced. At the start of World War II, France and the Soviet Union were the only countries to have inventories of heavy tanks, such as the Char B1 , T-35 , and KV-1 . The Matilda II

4761-438: Was not practical because of two-phase pulsations, which prompted him to persist in his three-phase work. The General Electric Company began developing three-phase induction motors in 1891. By 1896, General Electric and Westinghouse signed a cross-licensing agreement for the bar-winding-rotor design, later called the squirrel-cage rotor . Induction motor improvements flowing from these inventions and innovations were such that

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