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92-457: The M61 Vulcan is a hydraulically , electrically, or pneumatically driven, six- barrel , air-cooled, electrically fired Gatling-style rotary cannon which fires 20 mm × 102 mm (0.787 in × 4.016 in) rounds at an extremely high rate (typically 6,000 rounds per minute). The M61 and its derivatives have been the principal cannon armament of United States military fixed-wing aircraft for over sixty years. The M61

184-543: A foreign object damage hazard with discarded links. A linkless ammunition feed system was developed for the upgraded M61A1 , which subsequently became the standard cannon armament of U.S. fighters. In 1993, General Electric sold its aerospace division, including GE Armament Systems along with the design and production tooling for the M61 and GE's other rotary cannon, to Martin Marietta . After Martin's merger with Lockheed ,

276-408: A hydrostatic transmission . Directional control valves route the fluid to the desired actuator. They usually consist of a spool inside a cast iron or steel housing. The spool slides to different positions in the housing, and intersecting grooves and channels route the fluid based on the spool's position. The spool has a central (neutral) position maintained with springs; in this position

368-473: A sabot , raises the muzzle velocity. Once the shell clears the barrel, the sabot is no longer needed and falls off in pieces. This leaves the projectile traveling at high velocity with a smaller cross-sectional area and reduced aerodynamic drag during the flight to the target (see external ballistics and terminal ballistics ). Germany developed modern sabots under the name " treibspiegel " ("thrust mirror") to give extra altitude to its anti-aircraft guns during

460-409: A burst controller is generally used to limit the number of rounds fired at each trigger pull. Bursts of from two or three up to 40 or 50 can be selected. The size of the airframe and available internal space limits the size of the ammunition drum and thus limits the ammunition capacity. When vehicle-mounted, the only limiting factor is the vehicle's safe carry weight, so commensurately larger ammo storage

552-540: A cannon as it was believed that missiles had made guns obsolete. Combat experience in Vietnam showed that a gun could be more effective than guided missiles in many combat situations and that an externally carried gun pod was less effective than an internal gun; the first generation of gun pods such as the SUU-16 were not oriented with the sights of the fighter. The improved pods were self-powered and properly synchronized to

644-413: A floating piston. On the one side of the piston there is a charge of pressurized gas, and on the other side is the fluid. Bladders are used in other designs. Reservoirs store a system's fluid. Examples of accumulator uses are backup power for steering or brakes, or to act as a shock absorber for the hydraulic circuit. Also known as tractor fluid , hydraulic fluid is the life of the hydraulic circuit. It

736-566: A fluid system in terms of discrete components is inspired by the success of electrical circuit theory . Just as electric circuit theory works when elements are discrete and linear, hydraulic circuit theory works best when the elements (passive components such as pipes or transmission lines or active components such as power packs or pumps ) are discrete and linear. This usually means that hydraulic circuit analysis works best for long, thin tubes with discrete pumps, as found in chemical process flow systems or microscale devices. The circuit comprises

828-681: A force of 10 North American F-100 Super Sabres (two of which were assigned weather reconnaissance duties) escorting 48 Vulcan-armed and "bomb-laden" F-105 Thunderchiefs , shooting down two of the latter. The MiG leader and only survivor from the four MiGs, Captain Tran Hanh, reported that U.S. jets had pursued them and that F-105s had shot down three of his aircraft, killing lieutenants Pham Giay, Le Minh Huan and Tran Nguyen Nam. Captain Donald Kilgus, piloting an F-100, received an official probable kill with his four M39 20 mm cannons during

920-415: A hundred inches to move C2 one inch. The most common use for this is the classical hydraulic jack where a pumping cylinder with a small diameter is connected to the lifting cylinder with a large diameter. If a hydraulic rotary pump with the displacement 10 cc/rev is connected to a hydraulic rotary motor with 100 cc/rev, the shaft torque required to drive the pump is one-tenth of the torque then available at

1012-503: A hydraulic drive motor through a system of flexible drive shafts. The round is fired by an electric priming system where an electric current from a firing lead passes through the firing pin to the primer as each round is rotated into the firing position. The self-powered version, the GAU-4 (called M130 in Army service), is gas-operated , tapping gun gas from three of the six barrels to operate

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1104-513: A loaded weight of 733 and 780 kilograms (1,615 and 1,720 lb) respectively. During service in the Vietnam War , the pods proved to be relatively inaccurate: the pylon mounting was not rigid enough to prevent deflection when firing, and repeated use would misalign the pod on its pylon, making matters worse. A variant with much shorter barrels, designated the M195, was also developed for use on

1196-399: A mechanical force or torque ratio for optimum machine designs such as boom movements and track drives for an excavator. Cylinder C1 is one inch in radius, and cylinder C2 is ten inches in radius. If the force exerted on C1 is 10 lbf , the force exerted by C2 is 1000 lbf because C2 is a hundred times larger in area ( S  = π r ²) as C1. The downside to this is that you have to move C1

1288-514: A much higher volume of fire. While captured German designs (principally the Mauser MG 213C ) showed the potential of the single-barrel revolver cannon , the practical rate of fire of such a design was still limited by ammunition feed and barrel wear concerns. The Army wanted something better, combining an extremely high rate of fire with exceptional reliability. In 1947, the Air Force became

1380-453: A much more concentrated effect than plain metal shot of the same weight and size. The air resistance and other effects were the same as for the shell of identical size. High-velocity armor-piercing (HVAP) rounds were primarily used by tank destroyers in the US Army and were relatively uncommon as the tungsten core was expensive and prioritized for other applications. Between 1941 and 1943,

1472-494: A penetrator is incapable of penetrating deeper than its own length, as the sheer stress of impact and perforation ablates it. This has led to the current designs which resemble a long metal arrow . For monobloc penetrators made of a single material, a perforation formula devised by Wili Odermatt and W. Lanz can calculate the penetration depth of an APFSDS round. In 1982, an analytical investigation drawing from concepts of gas dynamics and experiments on target penetration led to

1564-424: A problem due to limited exchange of oil flow. High power closed loop systems generally must have a 'flush-valve' assembled in the circuit in order to exchange much more flow than the basic leakage flow from the pump and the motor, for increased cooling and filtering. The flush valve is normally integrated in the motor housing to get a cooling effect for the oil that is rotating in the motor housing itself. The losses in

1656-533: A separate branch of the military. The new Air Force made a request for a new aircraft gun. A lesson of World War II air combat was that German, Italian, and Japanese fighters could attack American aircraft from long range with their cannon main armament. American fighters with .50 caliber (12.7 mm) main armament, such as the P-51 and P-47 , had to be close to enemy aircraft in order to hit and damage them. The 20 mm (0.79 in) Hispano cannon carried by

1748-453: A six-barrel weapon capable of firing 7,200 rounds per minute (rpm). Although European designers were moving towards heavier 30 mm (1.181 in) weapons for better hitting power, the U.S. initially concentrated on a powerful 0.60-inch (15 mm) cartridge designed for a pre-war anti-tank rifle, expecting that the cartridge's high muzzle velocity would be beneficial for improving hit ratios on high-speed targets. The first GE prototypes of

1840-558: A smaller area was initially attained by replacing the single metal (usually steel ) shot with a composite shot using two metals, a heavy core (based on tungsten ) inside a lighter metal outer shell. These designs were known as armour-piercing composite rigid (APCR) by the British, high-velocity armor-piercing (HVAP) by the US, and hartkern (hard core) by the Germans. On impact, the core had

1932-409: A unique trademark depending on the manufacturer of the valves, for example "LSC" (Linde Hydraulics), "LUDV" ( Bosch Rexroth Hydraulics) and "Flowsharing" (Parker Hydraulics) etc. No official standardized name for this type of system has been established but flowsharing is a common name for it. Hydraulic pumps supply fluid to the components in the system. Pressure in the system develops in reaction to

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2024-564: Is a semi-armor-piercing high-explosive incendiary (SAPHEI) round, providing improvements in range, accuracy, and power over the preceding M56A3 HEI round. The PGU-28/B is a "low-drag" round designed to reduce in-flight drag and deceleration, and has a slightly increased muzzle velocity of 1,050 metres per second (3,450 ft/s). However, the PGU-28/B has not been without problems. A 2000 USAF safety report noted 24 premature detonation mishaps (causing serious damage in many cases) in 12 years with

2116-542: Is a system comprising an interconnected set of discrete components that transport liquid . The purpose of this system may be to control where fluid flows (as in a network of tubes of coolant in a thermodynamic system) or to control fluid pressure (as in hydraulic amplifiers). For example, hydraulic machinery uses hydraulic circuits (in which hydraulic fluid is pushed, under pressure, through hydraulic pumps , pipes, tubes, hoses, hydraulic motors , hydraulic cylinders , and so on) to move heavy loads. The approach of describing

2208-541: Is a type of ammunition designed to penetrate vehicle armour using a flechette -like, high- sectional density projectile . Like a bullet or kinetic energy weapon , this type of ammunition does not contain explosive payloads and uses purely kinetic energy to penetrate the target. Modern KEP munitions are typically of the armour-piercing fin-stabilized discarding sabot (APFSDS) type. Early cannons fired kinetic energy ammunition, initially consisting of heavy balls of worked stone and later of dense metals . From

2300-403: Is around 2 MPa (290 psi). If the pump flow is high the extra loss can be considerable. The power loss also increases if the load pressures vary a lot. The cylinder areas, motor displacements and mechanical torque arms must be designed to match load pressure in order to bring down the power losses. Pump pressure always equals the maximum load pressure when several functions are run simultaneously and

2392-455: Is available. Until the late 1980s, the M61 primarily used the M50 series of ammunition in various types, typically firing a 99-gram (3.5 oz) projectile at a muzzle velocity of about 1,030 metres per second (3,380 ft/s). A variety of armor-piercing incendiary (API), high-explosive incendiary (HEI), and training rounds are available. A new PGU-28/B round was developed in the mid-1980s. It

2484-455: Is due to the large amount of power that can be transferred through small tubes and flexible hoses, the high power density and a wide array of actuators that can make use of this power, and the huge multiplication of forces that can be achieved by applying pressures over relatively large areas. One drawback, compared to machines using gears and shafts, is that any transmission of power results in some losses due to resistance of fluid flow through

2576-517: Is in excess of 10,000 rounds, making it an extremely reliable weapon. The success of the Vulcan Project and its progeny, the very-high-speed Gatling gun, has led to guns of the same configuration being referred to as "Vulcan cannons" , which can sometimes confuse nomenclature on the subject. Most aircraft versions of the M61 are hydraulically driven and electrically primed. The gun rotor, barrel assembly and ammunition feed system are rotated by

2668-418: Is one of the most expensive and sensitive parts of a hydraulic circuit. The hydraulic fluid reservoir holds excess hydraulic fluid to accommodate volume changes from: cylinder extension and contraction, temperature driven expansion and contraction, and leaks. The reservoir is also designed to aid in separation of air from the fluid and also work as a heat accumulator to cover losses in the system when peak power

2760-418: Is stainless steel. Components of a hydraulic system [sources (e.g. pumps), controls (e.g. valves) and actuators (e.g. cylinders)] need connections that will contain and direct the hydraulic fluid without leaking or losing the pressure that makes them work. In some cases, the components can be made to bolt together with fluid paths built-in. In more cases, though, rigid tubing or flexible hoses are used to direct

2852-417: Is supplied with sufficient ammunition for a full minute of firing, due to its weight (at 6,000 rpm, the projectiles alone would represent a mass of about 600 kg (1,300 lb) for one minute of firing; and by including the brass shell, filling and primer the weight is slightly double that at 1,225 kg (2,701 lb)). In order to avoid using the 600 to 1,000 rounds carried by aircraft all at once,

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2944-414: Is surrounded by multiple layers of woven wire and rubber. The exterior is designed for abrasion resistance. The bend radius of hydraulic hose is carefully designed into the machine, since hose failures can be deadly, and violating the hose's minimum bend radius will cause failure. Hydraulic hoses generally have steel fittings swaged on the ends. The weakest part of the high pressure hose is the connection of

3036-539: Is to provide in each component a female-threaded port, on each hose or tube a female-threaded captive nut, and use a separate adapter fitting with matching male threads to connect the two. This is functional, economical to manufacture, and easy to service. Fittings serve several purposes; A typical piece of machinery or heavy equipment may have thousands of sealed connection points and several different types: Kinetic energy penetrator A kinetic energy penetrator ( KEP ), also known as long-rod penetrator ( LRP ),

3128-520: Is typically 6,000 rounds per minute, although some versions (such as that of the AMX and the F-106 Delta Dart ) are limited to a lower rate, and others ( A-7 Corsair , F-15 Eagle ) have a selectable rate of fire of either 4,000 or 6,000 rounds per minute. The M61A2's lighter barrels allow a somewhat higher rate of fire, up to 6,600 rounds per minute. Practically no powered rotary cannon

3220-402: Is used. Reservoirs can also help separate dirt and other particulate from the oil, as the particulate will generally settle to the bottom of the tank. Some designs include dynamic flow channels on the fluid's return path that allow for a smaller reservoir. Accumulators are a common part of hydraulic machinery. Their function is to store energy by using pressurized gas. One type is a tube with

3312-410: Is usually a major problem when using hydrostatic transmissions at high vehicle speeds for longer periods, for instance when transporting the machine from one work place to the other. High oil temperatures for long periods will drastically reduce the lifetime of the transmission. To keep down the oil temperature, the system pressure during transport must be lowered, meaning that the minimum displacement for

3404-410: Is usually petroleum oil with various additives. Some hydraulic machines require fire resistant fluids, depending on their applications. In some factories where food is prepared, either an edible oil or water is used as a working fluid for health and safety reasons. In addition to transferring energy, hydraulic fluid needs to lubricate components, suspend contaminants and metal filings for transport to

3496-525: The F-22 Raptor , designated M61A2, is mechanically the same as the M61A1, but with thinner barrels to reduce overall weight to 92 kilograms (202 lb). The rotor and housing have also been modified to remove any piece of metal not absolutely needed for operation and replaces some metal components with lighter-weight materials. The F/A-18E/F Super Hornet also uses this version. The Vulcan's rate of fire

3588-656: The Lockheed AC-130 gunships , and was used in the tail turrets of both the Convair B-58 Hustler and Boeing B-52H Stratofortress bombers. Japan's Mitsubishi F-1 carried one internally mounted JM61A1 Vulcan with 750 rounds. Two gun pod versions, the SUU-16/A (also designated M12 by the US Army) and improved SUU-23/A (US Army M25), were developed in the 1960s, often used on gunless versions of

3680-879: The M35 Armament Subsystem as used on the AH-1G Cobra helicopter . This variant fed from ammunition boxes fitted to the landing skid and was developed to provide the AH-1 helicopter with a longer-range suppressive fire system before the adoption of the M97 universal turret mounting the M197 cannon. The M61 is also the basis of the US Navy Mk 15 Phalanx close-in weapon system and the M163 VADS Vulcan Air Defense System, using

3772-535: The P-38 and P-61 , while formidable against propeller-driven planes, had a relatively low rate of fire in the age of jets, while other cannons were notoriously unreliable. In response to this requirement, the Armament Division of General Electric resurrected an old idea: the multi-barrel Gatling gun . The original Gatling gun had fallen out of favor because of the need for an external power source to rotate

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3864-621: The Second World War . Before this, primitive wooden sabots had been used for centuries in the form of a wooden plug attached to or breech loaded before cannonballs in the barrel, placed between the propellant charge and the projectile. The name "sabot" (pronounced / ˈ s æ b oʊ / SAB -oh in English usage) is the French word for clog (a wooden shoe traditionally worn in some European countries). Concentration of force into

3956-517: The 0.60-inch (15 mm) caliber T45 were ground-fired in 1949; it achieved 2,500 rpm, which was increased to 4,000 rpm by 1950. By the early 1950s, the USAF decided that high velocity alone might not be sufficient to ensure target destruction and tested 20 and 27 mm (0.787 and 1.06 in) alternatives based on the 0.60-inch (15 mm) caliber cartridge. These variants of the T45 were known as

4048-477: The British combined the two techniques in the armour-piercing discarding sabot (APDS) round. The sabot replaced the outer metal shell of the APCR. While in the gun, the shot had a large base area to get maximum acceleration from the propelling charge but once outside, the sabot fell away to reveal a heavy shot with a small cross-sectional area. APDS rounds served as the primary kinetic energy weapon of most tanks during

4140-463: The CP system. The LS system generates a constant power loss related to the regulating pressure drop for the pump regulator : Power loss = Δ p LS ⋅ Q tot {\displaystyle {\text{Power loss}}=\Delta p_{\text{LS}}\cdot Q_{\text{tot}}} The average Δ p L S {\displaystyle \Delta p_{LS}}

4232-633: The F-4. The SUU-16/A uses the electric M61A1 with a ram-air turbine to power the motor. This proved to cause serious aerodynamic drag at higher speeds, while speeds under 640 kilometres per hour (400 mph) did not provide enough airflow for the maximum rate of fire. The subsequent SUU-23/A uses the GAU-4/A self-powered Vulcan, with an electric inertia starter to bring it up to speed. Both pods ejected empty cases and unfired rounds rather than retaining them. Both pods contained 1,200 rounds of ammunition, with

4324-493: The M168 variant. Soviet Union/Russian Federation/CIS Hydraulic machinery Hydraulic systems, like pneumatic systems , are based on Pascal's law which states that any pressure applied to a fluid inside a closed system will transmit that pressure equally everywhere and in all directions. A hydraulic system uses an incompressible liquid as its fluid, rather than a compressible gas. The popularity of hydraulic machinery

4416-622: The SAPHEI round, compared to only two such mishaps in the entire recorded history of the M56 round. The report estimated that the PGU-28/B had a potential failure rate 80 times higher than USAF standards permit. Due to safety issues, it was limited to emergency wartime use in 2000. The main types of combat rounds and their main characteristics are listed in the table: The Vulcan was first used in aerial combat on 4 April 1965, when four North Vietnamese Vietnam People's Air Force (VPAF) MiG-17s ) attacked

4508-674: The T171 and T150 respectively and were first tested in 1952. Eventually, the standard 20×102 mm cartridge was determined to have the desired balance of projectile/explosive mass and muzzle velocity, resulting in an optimum balance of range, accuracy and kinetic energy on target. The development of the Lockheed F-104 Starfighter revealed that the T171 Vulcan (later redesignated M61 ) suffered problems with its linked ammunition , being prone to misfeed and presenting

4600-413: The armor is defeated, the heat and spalling (particle spray) generated by the penetrator going through the armor, and the pressure wave that develops, ideally destroys the target. The modern kinetic energy weapon maximizes the stress (kinetic energy divided by impact area) delivered to the target by: The penetrator length plays a large role in determining the ultimate depth of penetration. Generally,

4692-428: The barrel assembly, but the new generation of turbojet-powered fighters offered sufficient electric power to operate the gun, and electric operation was more reliable than gas-operated reloading . With multiple barrels, the rate of fire per barrel could be lower than a single-barrel revolver cannon while providing a greater overall rate of fire. The idea of powering a Gatling gun from an external electric power source

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4784-440: The beginning, combining high muzzle energy with projectile weight and hardness have been the foremost factors in the design of such weapons. Similarly, the foremost purpose of such weapons has generally been to defeat protective shells of armored vehicles or other defensive structures , whether it is stone walls , sailship timbers, or modern tank armour. Kinetic energy ammunition, in its various forms, has consistently been

4876-402: The choice for those weapons due to the highly focused terminal ballistics . The development of the modern KE penetrator combines two aspects of artillery design, high muzzle velocity and concentrated force. High muzzle velocity is achieved by using a projectile with a low mass and large base area in the gun barrel. Firing a small-diameter projectile wrapped in a lightweight outer shell, called

4968-514: The complete weapon. Most aircraft installations are double-ended, because the ejection of empty cartridges can cause a foreign-object damage hazard for jet engines and because the retention of spent cases assists in maintaining the center of gravity of the aircraft. The first aircraft to carry the M61A1 was the C model of the F-104 , starting in 1959. A lighter version of the Vulcan developed for use on

5060-558: The conclusion on the efficiency of impactors that penetration is deeper using unconventional three-dimensional shapes. The opposite method of KE-penetrators uses chemical energy penetrators. Two types of such shells are in use: high-explosive anti-tank (HEAT) and high-explosive squash head (HESH). They have been widely used against armour in the past and still have a role but are less effective against modern composite armour , such as Chobham as used on main battle tanks today. Main battle tanks usually use KE-penetrators, while HEAT

5152-459: The diesel engine rpm while reducing the vehicle speed in order to increase the available hydraulic power output for the working hydraulics at low speeds and increase the tractive effort. The function is similar to stalling a converter gearbox at high engine rpm. The inch function affects the preset characteristics for the 'hydrostatic' gear ratio versus diesel engine rpm. The closed center circuits exist in two basic configurations, normally related to

5244-459: The early-Cold War period, though they suffered the primary drawback of inaccuracy. This was resolved with the introduction of the armour-piercing fin-stabilized discarding sabot (APFSDS) round during the 1970s, which added stabilising fins to the penetrator, greatly increasing accuracy. The principle of the kinetic energy penetrator is that it uses its kinetic energy, which is a function of its mass and velocity, to force its way through armor. If

5336-407: The efficiency and developments in the software have also improved the characteristics, for example selectable gear shifting programs during operation and more gear steps, giving them characteristics close to the hydrostatic transmission. Hydrostatic transmissions for earth moving machines, such as for track loaders, are often equipped with a separate ' inch pedal ' that is used to temporarily increase

5428-520: The engagement; however no other US pilot reported destroying any MiGs during the battle, leaving open the possibility that at least two of the MiG-17s may have been downed by their own anti-aircraft fire. The first confirmed Vulcan gun kill occurred on 29 June 1966 when Major Fred Tracy, flying his F-105 with the 421st TFS, fired 200 rounds of 20 mm into a MiG-17 that had just fired a 23 mm shell which entered one side of his cockpit and exited

5520-407: The filter, and to function well to several hundred degrees Fahrenheit or Celsius. Filters are an important part of hydraulic systems which removes the unwanted particles from fluid. Metal particles are continually produced by mechanical components and need to be removed along with other contaminants. Filters may be positioned in many locations. The filter may be located between the reservoir and

5612-434: The flow from one component to the next. Each component has entry and exit points for the fluid involved (called ports) sized according to how much fluid is expected to pass through it. There are a number of standardized methods in use to attach the hose or tube to the component. Some are intended for ease of use and service, others are better for higher system pressures or control of leakage. The most common method, in general,

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5704-422: The following components: For the hydraulic fluid to do work, it must flow to the actuator and/or motors, then return to a reservoir. The fluid is then filtered and re-pumped. The path taken by hydraulic fluid is called a hydraulic circuit of which there are several types. Open-loop: Pump-inlet and motor-return (via the directional valve) are connected to the hydraulic tank. The term loop applies to feedback;

5796-451: The gun gas-driven mechanism. The self-powered Vulcan weighs about 4.5 kilograms (10 lb) more than its electric counterpart, but requires no external power source to operate, except for an electric inertia starter to initiate gun rotation, allowing the first rounds to be chambered and fired. The initial M61 used linked ammunition, but the ejection of spent links created considerable (and ultimately insuperable) problems. The original weapon

5888-481: The hose to the fitting. Another disadvantage of hoses is the shorter life of rubber which requires periodic replacement, usually at five to seven year intervals. Tubes and pipes for hydraulic n applications are internally oiled before the system is commissioned. Usually steel piping is painted outside. Where flare and other couplings are used, the paint is removed under the nut, and is a location where corrosion can begin. For this reason, in marine applications most piping

5980-414: The larger diameters the pipe can usually be inspected internally after welding. Black pipe is non-galvanized and suitable for welding . Hydraulic hose is graded by pressure, temperature, and fluid compatibility. Hoses are used when pipes or tubes can not be used, usually to provide flexibility for machine operation or maintenance. The hose is built up with rubber and steel layers. A rubber interior

6072-466: The larger sizes and pressures), welding cones/nipples (with o-ring seal), several types of flare connection and by cut-rings. In larger sizes, hydraulic pipes are used. Direct joining of tubes by welding is not acceptable since the interior cannot be inspected. Hydraulic pipe is used in case standard hydraulic tubes are not available. Generally these are used for low pressure. They can be connected by threaded connections, but usually by welds. Because of

6164-399: The load and operating conditions. The hydrostatic transmission is generally limited to around 200 kW maximum power, as the total cost gets too high at higher power compared to a hydrodynamic transmission. Large wheel loaders for instance and heavy machines are therefore usually equipped with converter transmissions. Recent technical achievements for the converter transmissions have improved

6256-614: The load. Hence, a pump rated for 5,000 psi is capable of maintaining flow against a load of 5,000 psi. Pumps have a power density about ten times greater than an electric motor (by volume). They are powered by an electric motor or an engine, connected through gears, belts, or a flexible elastomeric coupling to reduce vibration. Common types of hydraulic pumps to hydraulic machinery applications are: Piston pumps are more expensive than gear or vane pumps, but provide longer life operating at higher pressure, with difficult fluids and longer continuous duty cycles. Piston pumps make up one half of

6348-399: The low pressure side. Closed-loop circuits are generally used for hydrostatic transmissions in mobile applications. Advantages: No directional valve and better response, the circuit can work with higher pressure. The pump swivel angle covers both positive and negative flow direction. Disadvantages: The pump cannot be utilized for any other hydraulic function in an easy way and cooling can be

6440-483: The more correct term is open versus closed "circuit". Open center circuits use pumps which supply a continuous flow. The flow is returned to the tank through the control valve's open center; that is, when the control valve is centered, it provides an open return path to the tank and the fluid is not pumped to a high pressure. Otherwise, if the control valve is actuated it routes fluid to and from an actuator and tank. The fluid's pressure will rise to meet any resistance, since

6532-399: The motor housing from rotating effects and losses in the ball bearings can be considerable as motor speeds will reach 4000-5000 rev/min or even more at maximum vehicle speed. The leakage flow as well as the extra flush flow must be supplied by the charge pump. A large charge pump is thus very important if the transmission is designed for high pressures and high motor speeds. High oil temperature

6624-410: The motor must be limited to a reasonable value. Circuit pressure during transport around 200-250 bar is recommended. Closed loop systems in mobile equipment are generally used for the transmission as an alternative to mechanical and hydrodynamic (converter) transmissions. The advantage is a stepless gear ratio (continuously variable speed/torque) and a more flexible control of the gear ratio depending on

6716-448: The motor shaft, but the shaft speed (rev/min) for the motor is also only one-tenth of the pump shaft speed. This combination is actually the same type of force multiplication as the cylinder example, just that the linear force in this case is a rotary force, defined as torque. Both these examples are usually referred to as a hydraulic transmission or hydrostatic transmission involving a certain hydraulic "gear ratio". A hydraulic circuit

6808-692: The other. When the VPAF MiG flew in front of him after making its pass, Tracy opened fire on it. The gun was installed in the Air Force's A-7D version of the LTV A-7 Corsair II where it replaced the earlier United States Navy A-7's Colt Mk 12 cannon and was adopted by the Navy on the A-7C and A-7E. It was integrated into the newer F-4E Phantom II variants. The F-4 was originally designed without

6900-419: The piping. Joseph Bramah patented the hydraulic press in 1795. While working at Bramah's shop, Henry Maudslay suggested a cup leather packing. Because it produced superior results, the hydraulic press eventually displaced the steam hammer for metal forging. To supply large-scale power that was impractical for individual steam engines, central station hydraulic systems were developed. Hydraulic power

6992-452: The power input to the pump equals the (max. load pressure + Δ p LS ) x sum of flow. Technically the down-stream mounted compensator in a valve block can physically be mounted "up-stream", but work as a down-stream compensator. System type (3) gives the advantage that activated functions are synchronized independent of pump flow capacity. The flow relation between two or more activated functions remains independent of load pressures, even if

7084-453: The pump has a constant output. If the pressure rises too high, fluid returns to the tank through a pressure relief valve. Multiple control valves may be stacked in series. This type of circuit can use inexpensive, constant displacement pumps. Closed-loop: Motor-return is connected directly to the pump-inlet. To keep up pressure on the low pressure side, the circuits have a charge pump (a small gear pump) that supplies cooled and filtered oil to

7176-407: The pump intake. Blockage of the filter will cause cavitation and possibly failure of the pump. Sometimes the filter is located between the pump and the control valves. This arrangement is more expensive, since the filter housing is pressurized, but eliminates cavitation problems and protects the control valve from pump failures. The third common filter location is just before the return line enters

7268-430: The pump reaches the maximum swivel angle. This feature is important for machines that often run with the pump at maximum swivel angle and with several activated functions that must be synchronized in speed, such as with excavators. With the type (4) system, the functions with up-stream compensators have priority, for example the steering function for a wheel loader. The system type with down-stream compensators usually have

7360-434: The regulator for the variable pump that supplies the oil: Load-sensing systems (LS) generate less power losses as the pump can reduce both flow and pressure to match the load requirements, but require more tuning than the CP system with respect to system stability. The LS system also requires additional logical valves and compensator valves in the directional valves, thus it is technically more complex and more expensive than

7452-697: The reservoir. This location is relatively insensitive to blockage and does not require a pressurized housing, but contaminants that enter the reservoir from external sources are not filtered until passing through the system at least once. Filters are used from 7 micron to 15 micron depends upon the viscosity grade of hydraulic oil. Hydraulic tubes are seamless steel precision pipes, specially manufactured for hydraulics. The tubes have standard sizes for different pressure ranges, with standard diameters up to 100 mm. The tubes are supplied by manufacturers in lengths of 6 m, cleaned, oiled and plugged. The tubes are interconnected by different types of flanges (especially for

7544-594: The rotary cannon became the responsibility of Lockheed Martin Armament Systems. Lockheed Martin Armament Systems was later acquired by General Dynamics , which produces the M61 and its variants as of 2000. Each of the cannon's six barrels fires once in turn during each revolution of the barrel cluster. The multiple barrels provide both a very high rate of fire—around 100 rounds per second—and contribute to prolonged weapon life by minimizing barrel erosion and heat generation. The average time between jams or failures

7636-471: The sights, while the USAF versions of the F-4 were hastily fitted with internal M61 cannons in a prominent fairing under the nose, well before the war ended (Navy Phantoms never received cannons, continuing to rely on air-to-air missiles alone). The next generation of fighters built post-Vietnam incorporated the M61 gun internally. The Vulcan was later fitted into the weapons bay of some Convair F-106 Delta Dart and General Dynamics F-111 Aardvark models. It

7728-401: The spool left or right. A seal allows part of the spool to protrude outside the housing, where it is accessible to the actuator. The main valve block is usually a stack of off the shelf directional control valves chosen by flow capacity and performance. Some valves are designed to be proportional (flow rate proportional to valve position), while others may be simply on-off. The control valve

7820-539: The supply fluid is blocked, or returned to tank. Sliding the spool to one side routes the hydraulic fluid to an actuator and provides a return path from the actuator to tank. When the spool is moved to the opposite direction the supply and return paths are switched. When the spool is allowed to return to neutral (center) position the actuator fluid paths are blocked, locking it in position. Directional control valves are usually designed to be stackable, with one valve for each hydraulic cylinder, and one fluid input supplying all

7912-491: The valves in the stack. Tolerances are very tight in order to handle the high pressure and avoid leaking, spools typically have a clearance with the housing of less than a thousandth of an inch (25 μm). The valve block will be mounted to the machine's frame with a three point pattern to avoid distorting the valve block and jamming the valve's sensitive components. The spool position may be actuated by mechanical levers, hydraulic pilot pressure, or solenoids which push

8004-741: Was also adopted as standard in the "teen"-series air superiority fighters: the Grumman F-14 Tomcat , the McDonnell Douglas F-15 Eagle , General Dynamics F-16 Fighting Falcon , and McDonnell Douglas F/A-18 Hornet . Other aircraft include the Italian/Brazilian AMX International AMX (on Italian aircraft only), and the F-22 Raptor . It was fitted in a side-firing installation on the Fairchild AC-119 and some marks of

8096-466: Was called the "Father of Industrial Hydraulics" by ASME . A fundamental feature of hydraulic systems is the ability to apply force or torque multiplication in an easy way, independent of the distance between the input and output, without the need for mechanical gears or levers, either by altering the effective areas in two connected cylinders or the effective displacement (cc/rev) between a pump and motor. In normal cases, hydraulic ratios are combined with

8188-481: Was not a novel idea at the end of World War II, as Richard Jordan Gatling himself had done just that with a patent he filed in 1893. During World War I , a similar 12-barreled Fokker-Leimberger aircraft rotary machine gun, powered by either the aircraft engine or an electric motor, had been under development by the German Empire . In 1946, the Army issued General Electric a contract for "Project Vulcan",

8280-496: Was originally produced by General Electric . After several mergers and acquisitions, it is produced by General Dynamics as of 2000. At the end of World War II , the United States Army Air Forces began to consider new directions for future military aircraft guns. The higher speeds of jet-powered fighter aircraft meant that achieving an effective number of hits would be extremely difficult without

8372-502: Was soon replaced by the M61A1, with a linkless feed system. Depending on the application, the feed system can be either single-ended (ejecting spent cases and unfired rounds) or double-ended (returning casings back to the magazine). A disadvantage of the M61 is that the bulk of the weapon, its feed system, and ammunition drum make it difficult to fit it into a densely packed airframe. The feed system must be custom-designed for each application, adding 140 to 180 kg (300 to 400 lb) to

8464-618: Was used to operate cranes and other machinery in British ports and elsewhere in Europe. The largest hydraulic system was in London. Hydraulic power was used extensively in Bessemer steel production. Hydraulic power was also used for elevators, to operate canal locks and rotating sections of bridges. Some of these systems remained in use well into the twentieth century. Harry Franklin Vickers

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