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Beier Variable-ratio Gear
The Beier variable-ratio gear or Beier variator is a mechanical drive offering a continuously variable gear ratio between input and output. The gear relies on the inter-meshing of a number of thin disks. By varying their separation, the effective radius of one disk varies, thus changing the overall gear ratio. This varying-radius principle is shared by a number of other variator mechanisms. An advantage of the Beier is that a large number of disks may be stacked on a common shaft, thus increasing its torque capacity for only a small increase in overall length. The mechanism consists of a spring-loaded stack of thin disks on a central shaft. Around this are arranged other stacked disk packs on a number of planetary shafts, usually three. These shafts are mounted on swinging arms, so that they may be moved in and out together. The central disks are thin, with a thickened rim. The planet disks are tapered across their radius, at an included angle of around 3°. When the disks are i ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Gear Ratio
A gear train is a mechanical system formed by mounting gears on a frame so the teeth of the gears engage. Gear teeth are designed to ensure the pitch circles of engaging gears roll on each other without slipping, providing a smooth transmission of rotation from one gear to the next. Features of gears and gear trains include: * The gear ratio of the pitch circles of mating gears defines the speed ratio and the mechanical advantage of the gear set. * A planetary gear train provides high gear reduction in a compact package. * It is possible to design gear teeth for gears that are non-circular, yet still transmit torque smoothly. * The speed ratios of chain and belt drives are computed in the same way as gear ratios. See bicycle gearing. The transmission of rotation between contacting toothed wheels can be traced back to the Antikythera mechanism of Greece and the south-pointing chariot of China. Illustrations by the Renaissance scientist Georgius Agricola show gear trains with ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Variator
A variator is a device that can change its parameters, or can change parameters of other devices. Often a variator is a mechanical power transmission device that can change its gear ratio continuously (rather than in steps). Examples * Beier variable-ratio gear * Continuously variable transmission * Evans friction cone * NuVinci Continuously Variable Transmission * Variator (variable valve timing) * Variomatic * VANOS See also * Epicyclic gearing An epicyclic gear train (also known as a planetary gearset) consists of two gears mounted so that the center of one gear revolves around the center of the other. A carrier connects the centers of the two gears and rotates the planet and sun gea ... Mechanical power control {{Mech-engineering-stub ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Torque
In physics and mechanics, torque is the rotational equivalent of linear force. It is also referred to as the moment of force (also abbreviated to moment). It represents the capability of a force to produce change in the rotational motion of the body. The concept originated with the studies by Archimedes of the usage of levers, which is reflected in his famous quote: "''Give me a lever and a place to stand and I will move the Earth''". Just as a linear force is a push or a pull, a torque can be thought of as a twist to an object around a specific axis. Torque is defined as the product of the magnitude of the perpendicular component of the force and the distance of the line of action of a force from the point around which it is being determined. The law of conservation of energy can also be used to understand torque. The symbol for torque is typically \boldsymbol\tau, the lowercase Greek letter ''tau''. When being referred to as moment of force, it is commonly denoted by . In ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Hele-Shaw Clutch
The Hele-Shaw clutch was an early form of multi-plate wet clutch, in use around 1900. It was named after its inventor, Professor Henry Selby Hele-Shaw, who was noted for his work in viscosity and flows through small gaps between parallel plates. The clutch was innovative in not relying upon friction, as other clutches did. Description The clutch appears outwardly similar to most other multi-plate clutches. A stack of plates is enclosed in a housing with a divided central shaft. Alternate plates are keyed to either the input or output shafts, through either the inner or outer housings. A pressure plate is arranged at one end of the stack so that an axial force may be applied, compressing the stack and causing it to transmit the drive. Releasing the pressure releases the clutch. In the Hele-Shaw clutch, the many plates are lightweight pressings from thin sheets of steel. Each plate has a ring pressed into it, V-shaped in section and forming a frustum of a cone with each side. ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Friction
Friction is the force resisting the relative motion of solid surfaces, fluid layers, and material elements sliding against each other. There are several types of friction: *Dry friction is a force that opposes the relative lateral motion of two solid surfaces in contact. Dry friction is subdivided into ''static friction'' ("stiction") between non-moving surfaces, and ''kinetic friction'' between moving surfaces. With the exception of atomic or molecular friction, dry friction generally arises from the interaction of surface features, known as asperities (see Figure 1). *Fluid friction describes the friction between layers of a viscous fluid that are moving relative to each other. *Lubricated friction is a case of fluid friction where a lubricant fluid separates two solid surfaces. *Skin friction is a component of drag, the force resisting the motion of a fluid across the surface of a body. *Internal friction is the force resisting motion between the elements making up a so ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Viscosity
The viscosity of a fluid is a measure of its resistance to deformation at a given rate. For liquids, it corresponds to the informal concept of "thickness": for example, syrup has a higher viscosity than water. Viscosity quantifies the internal frictional force between adjacent layers of fluid that are in relative motion. For instance, when a viscous fluid is forced through a tube, it flows more quickly near the tube's axis than near its walls. Experiments show that some stress (such as a pressure difference between the two ends of the tube) is needed to sustain the flow. This is because a force is required to overcome the friction between the layers of the fluid which are in relative motion. For a tube with a constant rate of flow, the strength of the compensating force is proportional to the fluid's viscosity. In general, viscosity depends on a fluid's state, such as its temperature, pressure, and rate of deformation. However, the dependence on some of these properties is ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Automatic Transmission
An automatic transmission (sometimes abbreviated to auto or AT) is a multi-speed transmission used in internal combustion engine-based motor vehicles that does not require any input from the driver to change forward gears under normal driving conditions. It typically includes a transmission, axle, and differential in one integrated assembly, thus technically becoming a transaxle. The most common type of automatic transmission is the hydraulic automatic, which uses a planetary gearset, hydraulic controls, and a torque converter. Other types of automatic transmissions include continuously variable transmissions (CVT), automated manual transmissions (AMT), and dual-clutch transmissions (DCT). An electronic automatic transmission (EAT) may also be called an electronically controlled transmission (ECT), or electronic automatic transaxle (EATX). A hydraulic automatic transmission may also colloquially called a " slushbox" or simply a "torque converter", although the latter term c ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Napier Nomad
The Napier Nomad is a British diesel aircraft engine designed and built by Napier & Son in 1949. They combined a piston engine with a turbine to recover energy from the exhaust and thereby improve fuel economy. Two versions were tested, the complex Nomad I which used two propellers, each driven by the mechanically independent stages, and the Nomad II, using the turbo-compound principle, coupled the two parts to drive a single propeller. The Nomad II had the lowest specific fuel consumption figures seen up to that time. Despite this the Nomad project was cancelled in 1955 having spent £5.1 million on development, as most interest had passed to turboprop designs. Design and development In 1945 the Air Ministry asked for proposals for a new class engine with good fuel economy. Curtiss-Wright was designing an engine of this sort of power known as the turbo-compound engine, but Sir Harry Ricardo, one of Britain's great engine designers, suggested that the most economical comb ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Flight (magazine)
''Flight International'' is a monthly magazine focused on aerospace. Published in the United Kingdom and founded in 1909 as "A Journal devoted to the Interests, Practice, and Progress of Aerial Locomotion and Transport", it is the world's oldest continuously published aviation news magazine. ''Flight International'' is published by DVV Media Group. Competitors include Jane's Information Group and ''Aviation Week''. Former editors of, and contributors include H. F. King, Bill Gunston, John W. R. Taylor and David Learmount. History The founder and first editor of ''Flight'' was Stanley Spooner. He was also the creator and editor of ''The Automotor Journal'', originally titled ''The Automotor Journal and Horseless Vehicle''.Guide To British Industrial History: Biographies: ''Stan ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Turbo-compound Engine
A turbo-compound engine is a reciprocating engine that employs a turbine to recover energy from the exhaust gases. Instead of using that energy to drive a turbocharger as found in many high-power aircraft engines, the energy is instead sent to the output shaft to increase the total power delivered by the engine. The turbine is usually mechanically connected to the crankshaft, as on the Wright R-3350 Duplex-Cyclone, but electric and hydraulic power recovery systems have been investigated as well. As this recovery process does not increase fuel consumption, it has the effect of reducing the specific fuel consumption, the ratio of fuel use to power. Turbo-compounding was used for commercial airliners and similar long-range, long-endurance roles before the introduction of turbojet engines. Examples using the Duplex-Cyclone include the Douglas DC-7B and Lockheed L-1049 Super Constellation, while other designs did not see production use. Concept Most piston engines have a hot exhau ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Supercharger
In an internal combustion engine, a supercharger compresses the intake gas, forcing more air into the engine in order to produce more power for a given displacement. The current categorisation is that a supercharger is a form of forced induction that is mechanically powered (usually by a belt from the engine's crankshaft), as opposed to a turbocharger, which is powered by the kinetic energy of the exhaust gasses. However, up until the mid-20th century, a turbocharger was called a "turbosupercharger" and was considered a type of supercharger. The first supercharged engine was built in 1878, with usage in aircraft engines beginning in the 1910s and usage in car engines beginning in the 1920s. In piston engines used by aircraft, supercharging was often used to compensate for the lower air density at high altitudes. Supercharging is less commonly used in the 21st century, as manufacturers have shifted to turbochargers to reduce fuel consumption and/or increase power outputs. Des ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Boost Control
In turbocharged internal combustion engines, a boost controller is a device sometimes used to increase the boost pressure produced by the turbocharger. It achieves this by reducing the boost pressure seen by the wastegate. Operation The purpose of a boost controller is to reduce the boost pressure seen by the wastegate's reference port, in order to trick the wastegate into allowing higher boost pressures than it was designed for. Many boost controllers use a needle valve that is opened and closed by an electric solenoid. By varying the pulse width to the solenoid, the solenoid valve can be commanded to be open a certain percentage of the time. This effectively alters the flow rate of air pressure through the valve, changing the amount of air that is bled out instead of going to the wastegate's reference port. Solenoids may require small diameter restrictors be installed in the air control lines to limit airflow and even out the on/off nature of their operation. Two-port solenoi ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
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