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Freewheel
image:Freewheel en.svg, Freewheel mechanism In mechanical engineering, mechanical or automotive engineering, a freewheel or overrunning clutch is a device in a transmission (mechanics), transmission that disengages the driveshaft from the driven shaft when the driven shaft rotates faster than the driveshaft. An Overdrive (mechanics), overdrive is sometimes mistakenly called a freewheel, but is otherwise unrelated. The condition of a driven shaft spinning faster than its driveshaft exists in most bicycles when the rider stops Bicycle pedal, pedaling. In a fixed-gear bicycle, without a freewheel, the rear wheel drives the pedals around. An analogous condition exists in an automobile with a manual transmission going downhill, or any situation where the driver takes their foot off the Car controls#Throttle control, gas pedal, closing the throttle: the wheels drive the engine, possibly at a higher RPM. In a two-stroke engine, this can be catastrophic—as many two stroke engines de ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Freewheel En
Freewheel mechanism In mechanical or automotive engineering, a freewheel or overrunning clutch is a device in a transmission that disengages the driveshaft from the driven shaft when the driven shaft rotates faster than the driveshaft. An overdrive is sometimes mistakenly called a freewheel, but is otherwise unrelated. The condition of a driven shaft spinning faster than its driveshaft exists in most bicycles when the rider stops pedaling. In a fixed-gear bicycle, without a freewheel, the rear wheel drives the pedals around. An analogous condition exists in an automobile with a manual transmission going downhill, or any situation where the driver takes their foot off the gas pedal, closing the throttle: the wheels drive the engine, possibly at a higher RPM. In a two-stroke engine, this can be catastrophic—as many two stroke engines depend on a fuel/oil mixture for lubrication, a shortage of fuel to the engine starves oil from the cylinders, and the pistons can soon seize ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Cogset
On a bicycle, the cassette or cluster is the set of multiple sprockets that attaches to the hub on the rear wheel. A cogset works with a rear derailleur to provide multiple gear ratios to the rider. Cassettes come in two varieties, freewheels or cassettes, of which cassettes are a newer development. Although cassettes and freewheels perform the same function and look almost the same when installed, they have important mechanical differences and are not interchangeable. Freewheels A freewheel (also known as a block) consists of either a single sprocket or a set of sprockets mounted on a body which contains an internal ratcheting mechanism and mounts on a threaded hub. Threaded rear hubs were available in different thread patterns depending on the country of manufacture, French and British threads being the most common. The British Cycle Engineers Institute (CEI) thread was adopted as the international standard and is now known as British Standard Cycle (BSC). It is a standardi ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Fixed-gear Bicycle
A fixed-gear bicycle or fixie is a bicycle that has a drivetrain with no freewheel mechanism, meaning the pedals always spin together with the rear wheel. The freewheel was developed early in the history of bicycle design but the fixed-gear bicycle remained the standard track racing design. More recently the "fixie" has become a popular alternative among mainly urban cyclists, offering the advantage of simplicity compared with the standard multi-geared bicycle. Most bicycle hubs incorporate a freewheel to allow the pedals to remain stationary while the bicycle is in motion, so that the rider can coast, i.e., ride without pedalling using forward momentum. A fixed-gear drivetrain has the drive sprocket (or cog) threaded or bolted directly to the hub of the back wheel, so that the pedals are directly coupled to the wheel. During acceleration, the pedal crank drives the wheel, but in other situations, the rear wheel can drive the pedal cranks. This direct coupling allows a cycli ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Car Controls
Car controls are the components in automobiles and other powered road vehicles, such as trucks and buses, used for driving and parking. While controls like steering wheels and pedals have existed since the invention of cars, other controls have developed and adapted to the demands of drivers. For example, manual transmissions became less common as technology relating to automatic transmissions became advanced. Earlier versions of headlights and signal lights were fueled by acetylene or oil. Acetylene was preferred to oil, because its flame is resistant to both wind and rain. Acetylene headlights, which gave a strong green-tinted light, were popular until after World War I; even though the first electric headlights were introduced in 1898 (and those were battery-powered), it wasn't until high-wattage bulbs and more powerful car electrical generating systems were developed in the late 1910s that electric lighting systems entirely superseded acetylene. Steering The first autom ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Saab 96
The Saab 96 is an automobile manufactured and marketed by Swedish automaker Saab from 1960 to January 1980, replacing the Saab 93. The 96 featured aerodynamic two-door bodywork, four-passenger seating and at first a two-stroke, three-cylinder engine, later a four-stroke V4. Body design Compared with its predecessor, the Saab 93, the 96 featured greater and more easily accessible storage space and a larger rear window. The front end was lengthened for 1965 models, in preparation for a new engine, and the radiator was placed ahead of the engine, rather than above and behind, a leftover from when earlier models had thermosiphon cooling. Both front and rear windows were enlarged slightly for 1968 models. Engine The Saab 96 had a longitudinally mounted engine layout. As first designed, it had an 841 cc displacement, three-cylinder Saab two-stroke engine. By 1965 this was increased to . An optional version of the engine, with triple carburetors and oil injection, was ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Bicycle
A bicycle, also called a pedal cycle, bike, push-bike or cycle, is a human-powered transport, human-powered or motorized bicycle, motor-assisted, bicycle pedal, pedal-driven, single-track vehicle, with two bicycle wheel, wheels attached to a bicycle frame, frame, one behind the other. A is called a cyclist, or bicyclist. Bicycles were introduced in the 19th century in Europe. By the early 21st century there were more than 1 billion bicycles. There are many more bicycles than cars. Bicycles are the principal Mode of transport, means of transport in many regions. They also provide a popular form of recreation, and have been adapted for use as Toy, children's toys. Bicycles are used for Physical fitness, fitness, Military bicycle, military and Police bicycle, police applications, Bicycle messenger, courier services, Cycle sport, bicycle racing, and artistic cycling. The basic shape and configuration of a typical Safety bicycle, upright or "safety" bicycle, has changed lit ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Saab 99
The Saab 99 is a car produced by Swedish manufacturer Saab from 1968 to 1984; their first foray into a larger class than the Saab 96. While considered a large family car in Scandinavia, it was marketed as a niche compact executive car in most other markets. It was manufactured both in Sweden and Finland and was succeeded by the Saab 900, although the 99 continued to be produced alongside its successor. The Saab 90, an updated, less complex version using many 900 parts took over from the 99 in late 1984. Development On 2 April 1964, Gudmund's day in Sweden, after several years of planning, the Saab board started ''Project Gudmund''. This was a project to develop a new and larger car to take the manufacturer beyond the market for the smaller Saab 96. This new car became the Saab 99, designed by Sixten Sason and unveiled in Stockholm on November 22, 1967. The first prototypes of the 99 were built by cutting a Saab 96 lengthwise and widening it by ; this created the so-cal ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Overdrive (mechanics)
Overdrive is the operation of an automobile cruising at sustained speed with reduced engine speed (rpm), leading to better fuel consumption, lower noise, and lower wear. The term is ambiguous. The most fundamental meaning is that of an overall gear ratio between engine and wheels, such that the car is ''over-geared'', and cannot reach its potential top speed, i.e. the car could travel faster if it were in a lower gear, with the engine turning at higher RPM. The power produced by an engine increases with the engine's RPM to a maximum, then falls away. The point of maximum power is somewhat lower than the absolute maximum engine speed to which it is limited, the "redline". A car's speed is limited by the power required to drive it against air resistance, which increases with speed. At the maximum possible speed, the engine is running at its point of maximum power, or ''power peak'', and the car is traveling at the speed where air resistance equals that maximum power. There ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Saab Automobile
Saab Automobile AB () was a automotive industry, car manufacturer that was founded in Sweden in 1945 when its parent company, Saab AB, began a project to design a small automobile. The first production model, the Saab 92, was launched in 1949. In 1968, the parent company merged with Scania-Vabis, and ten years later the Saab 900 was launched, in time becoming Saab's best-selling model. In the mid-1980s, the new Saab 9000 model also appeared. In 1989, the automobile division of Saab-Scania was restructured into an independent company, Saab Automobile AB. The American manufacturer General Motors (GM) took 50 percent ownership. Two well-known models to come out of this period were the Saab 9-3 and the Saab 9-5. Then, in 2000, GM exercised its option to acquire the remaining 50 percent. In 2010, GM sold Saab Automobile AB to the Dutch automobile manufacturer Spyker Cars N.V. After many years establishing a sound engineering reputation and ultimately a luxury car, luxury price tag, ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
V4 Engine
A V4 engine is a four-cylinder piston engine where the cylinders share a common crankshaft and are arranged in a V engine, V configuration. The V4 engine is less common compared to straight-four engines. However, V4 engines have been used in automobiles, motorcycles, and other applications. Design Some V4 engines have two crankpins that are shared by opposing cylinders. The crankshaft is usually supported by three main bearings in this type of engines. However this arrangement results an uneven firing engine. Split crankpins are preferred for even firing intervals. Compared to the more common inline-four engine layout, a V4 engine is much shorter. Although different V angles can be used, if the two pistons are at a 90° V-angle with shared crankpins, the engine also achieves a perfect Engine balance#Primary and secondary balance, primary balance and offers the additional advantage of better Engine balance#Primary and secondary balance, secondary balance that reduces vibration. ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Ratchet (device)
A ratchet (occasionally spelled rachet) is a mechanical device that allows continuous linear or rotary motion in only one direction while preventing motion in the opposite direction. Ratchets are widely used in machinery and tools. The word ''ratchet'' is also used informally to refer to a ratcheting socket wrench. __TOC__ Theory of operation A ratchet consists of a round gear or a linear rack with teeth, and a pivoting, spring-loaded finger called a '' pawl'' (or ''click'', in clocks and watches) that engages the teeth. The teeth are uniform but are usually asymmetrical, with each tooth having a moderate slope on one edge and a much steeper slope on the other edge. When the teeth are moving in the unrestricted (i.e. forward) direction, the pawl easily slides up and over the gently sloped edges of the teeth, with a spring forcing it (often with an audible 'click') into the depression between the teeth as it passes the tip of each tooth. When the teeth move in the oppo ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Fuel Efficiency
Fuel efficiency (or fuel economy) is a form of thermal efficiency, meaning the ratio of effort to result of a process that converts chemical energy, chemical potential energy contained in a carrier (fuel) into kinetic energy or Mechanical work, work. Overall fuel efficiency may vary per device, which in turn may vary per application, and this spectrum of variance is often illustrated as a continuous energy profile. Non-transportation applications, such as Industrial sector, industry, benefit from increased fuel efficiency, especially fossil fuel power plants or industries dealing with combustion, such as ammonia production during the Haber process. In the context of transport, fuel economy is the energy efficiency in transportation, energy efficiency of a particular vehicle, given as a ratio of distance traveled per unit of Motor fuel, fuel consumed. It is dependent on several factors including engine efficiency, transmission (mechanics), transmission design, and tire design. In ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
