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Tachometers
A tachometer (revolution-counter, tach, rev-counter, RPM gauge) is an instrument measuring the rotation speed of a shaft or disk, as in a motor or other machine. The device usually displays the revolutions per minute (RPM) on a calibrated analogue dial, but digital displays are increasingly common. The word comes from Greek ''τάχος'' (''táchos'' "speed") and ''μέτρον'' (''métron'' "measure"). Essentially the words tachometer and speedometer have identical meaning: a device that measures speed. It is by arbitrary convention that in the automotive world one is used for engine revolutions and the other for vehicle speed. In formal engineering nomenclature, more precise terms are used to distinguish the two. History The first tachometer was described by an Donkin in a paper to the Royal Society of Arts in 1810 for which he was awarded the Gold medal of the society. This consisted of a bowl of mercury constructed in such a way that centrifugal force caused the level ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Opto-isolator
An opto-isolator (also called an optocoupler, photocoupler, or optical isolator) is an electronic component that transfers electrical Signal, signals between two isolated circuits by using light. Opto-isolators prevent high voltages from affecting the system receiving the signal.Lee et al., p. 2. Commercially available opto-isolators withstand input-to-output voltages up to 10 Volt, kVHasse, p. 145. and voltage transients with speeds up to 25 kV/microsecond, μs.Joffe and Kai-Sang Lock, p. 279. A common type of opto-isolator consists of an Light emitting diode, LED and a phototransistor in the same opaque package. Other types of source-sensor combinations include LED-photodiode, LED-thyristor#photothyristors, LASCR, and lamp (electrical component), lamp-photoresistor pairs. Usually opto-isolators transfer digital (on-off) signals, but some techniques allow them to be used with analog signals. History The value of optically coupling a solid state light emitter to a semi ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Redline
Redline refers to the maximum engine speed at which an internal combustion engine or traction motor and its components are designed to operate without causing damage to the components themselves or other parts of the engine. The redline of an engine depends on various factors such as stroke, mass of the components, displacement, composition of components, and balance of components. The word is also used as a verb, meaning to ride or drive an automotive vehicle above the redline. The actual term ''redline'' comes from the red bars that are displayed on tachometers in cars starting at the rpm that denotes the redline for the specific engine. Operating an engine in this area is known as ''redlining''. Straying into this area usually does not mean instant engine failure, but may increase the chances of damaging the engine. Variation of redline The acceleration, or rate of change in piston velocity, is the limiting factor. The piston acceleration is directly proportional to the magn ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Loop Detector
An induction or inductive loop is an electromagnetic In physics, electromagnetism is an interaction that occurs between particles with electric charge. It is the second-strongest of the four fundamental interactions, after the strong force, and it is the dominant force in the interactions of a ... communication or detection system which uses a moving magnet or an alternating current to Electromagnetic induction#Faraday's law, induce an electric current in a nearby wire. Induction loops are used for transmission and reception of communication signals, or for detection of metal objects in metal detectors or vehicle presence indicators. A common modern use for induction loops is to provide hearing assistance to hearing-aid users. Applications Vehicle detection Vehicle detection loops, called ''inductive-loop traffic detectors'', can detect vehicles passing or arriving at a certain point, for instance approaching a traffic light or in motorway traffic. An insulated, elec ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Engine Control Unit
An engine control unit (ECU), also commonly called an engine control module (ECM), is a type of electronic control unit that controls a series of actuators on an internal combustion engine to ensure optimal engine performance. It does this by reading values from a multitude of sensors within the engine bay, interpreting the data using multidimensional performance maps (called lookup tables), and adjusting the engine actuators. Before ECUs, air–fuel mixture, ignition timing, and idle speed were mechanically set and dynamically controlled by mechanical and pneumatic means. If the ECU has control over the fuel lines, then it is referred to as an electronic engine management system (EEMS). The fuel injection system has the major role of controlling the engine's fuel supply. The whole mechanism of the EEMS is controlled by a stack of sensors and actuators. Workings Control of air–fuel ratio Most modern engines use some type of fuel injection to deliver fuel to the cylinders. ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Engine Management System
An engine control unit (ECU), also commonly called an engine control module (ECM), is a type of electronic control unit that controls a series of actuators on an internal combustion engine to ensure optimal engine performance. It does this by reading values from a multitude of sensors within the engine bay, interpreting the data using multidimensional performance maps (called lookup tables), and adjusting the engine actuators. Before ECUs, air–fuel mixture, ignition timing, and idle speed were mechanically set and dynamically controlled by mechanical and pneumatic means. If the ECU has control over the fuel lines, then it is referred to as an electronic engine management system (EEMS). The fuel injection system has the major role of controlling the engine's fuel supply. The whole mechanism of the EEMS is controlled by a stack of sensors and actuators. Workings Control of air–fuel ratio Most modern engines use some type of fuel injection to deliver fuel to the cylinders. ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Camshaft
A camshaft is a shaft that contains a row of pointed cams, in order to convert rotational motion to reciprocating motion. Camshafts are used in piston engines (to operate the intake and exhaust valves), mechanically controlled ignition systems and early electric motor speed controllers. Camshafts in piston engines are usually made from steel or cast iron, and the shape of the cams greatly affects the engine's characteristics. History Trip hammers are one of the early uses of a form of cam to convert rotating motion, e.g. from a waterwheel, into the reciprocating motion of a hammer used in forging or to pound grain. Evidence for these exists back to the Han Dynasty in China, and they were widespread by the medieval period. The camshaft was described in 1206 by engineer Al-Jazari. He employed it as part of his automata, water-raising machines, and water clocks such as the castle clock. Once the rotative version of the steam engine was developed in the late 18th century, the ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Alternator (auto)
An alternator is a type of electric generator used in modern automobiles to charge the battery and to power the electrical system when its engine is running. Until the 1960s, automobiles used DC dynamo generators with commutators. As silicon-diode rectifiers became widely available and affordable, the alternator gradually replaced the dynamo. This was encouraged by the increasing electrical power required for cars in this period, with increasing loads from larger headlamps, electric wipers, heated rear windows, and other accessories. History The modern type of vehicle alternators were first used in military applications during World War II, to power radio equipment on specialist vehicles. After the war, other vehicles with high electrical demands — such as ambulances and radio taxis — could also be fitted with optional alternators. Alternators were first introduced as standard equipment on a production car by the Chrysler Corporation on the Valiant in 1960, several years a ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Diesel Engine
The diesel engine, named after Rudolf Diesel, is an internal combustion engine in which ignition of the fuel is caused by the elevated temperature of the air in the cylinder due to mechanical compression; thus, the diesel engine is a so-called compression-ignition engine (CI engine). This contrasts with engines using spark plug-ignition of the air-fuel mixture, such as a petrol engine (gasoline engine) or a gas engine (using a gaseous fuel like natural gas or liquefied petroleum gas). Diesel engines work by compressing only air, or air plus residual combustion gases from the exhaust (known as exhaust gas recirculation (EGR)). Air is inducted into the chamber during the intake stroke, and compressed during the compression stroke. This increases the air temperature inside the cylinder to such a high degree that atomised diesel fuel injected into the combustion chamber ignites. With the fuel being injected into the air just before combustion, the dispersion of the fuel is une ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Ignition Coil
An ignition coil (also called a spark coil) is an induction coil in an automobile's ignition system that transforms the battery's voltage to the thousands of volts needed to create an electric spark in the spark plugs to ignite the fuel. Some coils have an internal resistor, while others rely on a resistor wire or an external resistor to limit the current flowing into the coil from the car's 12-volt supply. The wire that goes from the ignition coil to the distributor and the high voltage wires that go from the distributor to each of the spark plugs are called spark plug wires or high tension leads. Originally, every ignition coil system required mechanical contact breaker points and a capacitor (condenser). More recent electronic ignition systems use a power transistor to provide pulses to the ignition coil. A modern passenger automobile may use one ignition coil for each engine cylinder (or pair of cylinders), eliminating fault-prone spark plug cables and a distributor to ro ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Contact Breaker
A contact breaker (or "points") is a type of electrical switch, found in the ignition systems of spark-ignition internal combustion engines. The switch is automatically operated by a cam driven by the engine. The timing of operation of the switch is set so that a spark is produced at the right time to ignite the compressed air/fuel mixture in the cylinder of the engine. A mechanism may be provided to slightly adjust timing to allow for varying load on the engine. Since these contacts operate frequently, they are subject to wear, causing erratic ignition of the engine. More recent engines use electronic means to trigger the spark, which eliminated contact wear and allows computer control of ignition timing. Purpose The purpose of the contact breaker is to interrupt the current flowing in the primary winding of the ignition coil. When this occurs, the collapsing current induces a high voltage in the secondary winding of the coil, which has many more windings. This causes a very high ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Power Take-off
A power take-off or power takeoff (PTO) is one of several methods for taking power from a power source, such as a running engine, and transmitting it to an application such as an attached implement or separate machine. Most commonly, it is a splined drive shaft installed on a tractor or truck allowing implements with mating fittings to be powered directly by the engine. Semi-permanently mounted power take-offs can also be found on industrial and marine engines. These applications typically use a drive shaft and bolted joint to transmit power to a secondary implement or accessory. In the case of a marine application, such shafts may be used to power fire pumps. In aircraft applications, such an accessory drive may be used in conjunction with a constant speed drive. Jet aircraft have four types of PTO units: internal gearbox, external gearbox, radial drive shaft, and bleed air, which are used to power engine accessories. In some cases, aircraft power take-off systems also provid ... [...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] |
