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A tachometer is an instrument that measures the speed of rotation of a shaft or disk, as in a motor or other machine. The device usually displays the rate of revolutions per minute on a calibrated analog dial, but digital displays are increasingly common. The term comes from Greek Ταχος, tachos, "speed", and metron, "to measure". Image File history File linksMetadata Download high-resolution version (1024x681, 182 KB) [edit] Summary [edit] Licensing File links The following pages on the English Wikipedia link to this file (pages on other projects are not listed): Tachometer User:SnapJag Metadata This file contains additional information, probably added from the digital...
Image File history File linksMetadata Download high-resolution version (1024x681, 182 KB) [edit] Summary [edit] Licensing File links The following pages on the English Wikipedia link to this file (pages on other projects are not listed): Tachometer User:SnapJag Metadata This file contains additional information, probably added from the digital...
For other uses, see Revolutions per minute (disambiguation). ...
Tachometer showing red lines above 14,000 rpm. ...
History
The first, mechanical, tachometers were based on measuring the centrifugal force. The inventor is assumed to be the German engineer Diedrich Uhlhorn; he used it for measuring the speed of machines in 1817. Since 1840, it was used to measure the speed of locomotives. Centrifugal force (from Latin centrum centre and fugere to flee) is a term which may refer to two different forces which are related to rotation. ...
Engineering is the applied science of acquiring and applying knowledge to design, analysis, and/or construction of works for practical purposes. ...
Great Western Railway No. ...
In automobiles, trucks, tractors and aircraft Tachometers on automobiles, aircraft, and other vehicles show the rate of rotation of the engine's crankshaft, and typically have markings indicating a safe range of rotation speeds. This can assist the driver in selecting an appropriate throttle and gear settings for the driving conditions. Prolonged use at high speeds may cause excessive wear and other damage to engines. This is more applicable to manual transmissions than to automatics. On analog tachometers the maximum speed is typically indicated by an area of the gauge marked in red, giving rise to the expression of "redlining" an engine—running it at (dangerously) high speed. The red zone is superfluous on most modern cars, since their engines typically have a rev limiter which electronically limits engine speed to prevent damage. Diesel engines with traditional mechanical injector systems have an integral governor which prevents over-speeding the engine, so the tachometers in vehicles and machinery fitted with such engines often lack a redline. “Car†and “Cars†redirect here. ...
“Flying Machine†redirects here. ...
For other uses, see Engine (disambiguation). ...
Crankshaft (red), pistons (gray) in their cylinders (blue), and flywheel (black) Continental engine marine crankshafts, 1942 Components of a typical, four stroke cycle, DOHC piston engine. ...
A manual transmission (also known as a stick shift, straight drive, or standard transmission) is a type of transmission used in automotive applications. ...
Tachometer showing red lines above 14,000 rpm. ...
A Rev limiter is a device fitted to a petrol internal combustion engine to restrict its maximum rotational speed. ...
This article does not cite any references or sources. ...
A governor is a device used to measure and regulate the speed of a machine, such as an engine. ...
Tachometer showing red lines above 14,000 rpm. ...
In vehicles such as tractors and trucks, the tachometer often has other markings, usually a green arc showing the speed range in which the engine produces maximum torque, which is of prime interest to operators of such vehicles. Tractors fitted with a power take off (PTO) system have tachometers showing the engine speed needed to rotate the PTO at the standardised speed required by most PTO-driven implements. In many countries, tractors are required to have a speedometer for use on a road. To save fitting a second dial, the vehicle's tachometer is often marked with a second scale in units of speed. This scale is only accurate in a certain gear, but since many tractors only have one gear that is practical for use on-road, this is sufficient. Tractors with multiple 'road gears' often have tachometers with more than one speed scale. Aircraft tachometers have a green arc showing the engine's designed cruising speed range. “Lorry†redirects here. ...
Torque applied via an adjustable end wrench Relationship between force, torque, and momentum vectors in a rotating system In physics, torque (or often called a moment) can informally be thought of as rotational force or angular force which causes a change in rotational motion. ...
A tractor PTO A power take-off (PTO) is a spinning shaft, usually on a tractor or truck that can be used to provide power to an attachment or separate machine. ...
Speedometer gauge on a car, showing the speed of the vehicle in miles and kilometres per hour on the out– and inside respectively. ...
Spur gears found on a piece of farm equipment A gear is a wheel with teeth around its circumference, the purpose of the teeth being to mesh with similar teeth on another mechanical device -- possibly another gear wheel -- so that force can be transmitted between the two devices in a...
In older vehicles, the tachometer is driven by the pulses from the low tension (LT) side of the ignition coil, while on others (and nearly all diesel engines, which have no ignition system) engine speed is determined by the frequency from the alternator tachometer output. This is a special circuit inside the alternator to convert from rectified sine wave to square wave, and the electrical potential difference is directly proportional to engine speed. Tachometers driven by a rotating cable from a drive unit fitted to the engine (usually on the camshaft) also exist- usually on simple diesel-engined machinery with basic or no electrical systems. On modern engine management systems found on modern vehicles, the tachometer is driven directly from the engine management ECU. An ignition coil (also called a spark coil) is an electrical device in a automobiles ignition system which transforms a storage batterys 12 volts to the thousands of volts needed to spark the spark plugs. ...
This article is about the fuel. ...
Early 20th century Alternator made in Budapest, Hungary, in the power generating hall of a hydroelectric station. ...
In trigonometry, an ideal sine wave is a waveform whose graph is identical to the generalized sine function y = Asin[ω(x − α)] + C, where A is the amplitude, ω is the angular frequency (2π/P where P is the wavelength), α is the phase shift, and C...
A square wave is a kind of basic waveform. ...
For the fictional characters of the same name, see Camshaft (Transformers). ...
Hours meters When used in stationary engines or vehicles where an odometer would not give an accurate reading of the vehicle's use (such as in aircraft or tractors), tachometers frequently incorporate a display showing the total number of hours the engine has run. Service intervals are given and measured in hours. Generally, hours meters are accurate only at one specific engine speed—an hours meter calibrated for, say, 'Hours At 2000 RPM' will only advance one hour per hour if the engine is run at 2000 RPM. If the engine is run below this speed, hours will accumulate more slowly, and if the engine is run above the meter will gain hours more quickly. This discrepancy does not detract from the accuracy of service intervals, for an engine running at slow speeds may gain hours more slowly, but will also be put under less mechanical stress and will not require servicing work as frequently as an engine used generally at high speeds. To prevent lightly- or little-used engines going unserviced, manufacturers also apply a calendar limit—services take place (for example) 'every 200 hours or 12 months'. A modern non-digital odometer A Smiths speedometer from the 1920s showing odometer and trip meter An odometer is a device used for indicating distance traveled by an automobile or other vehicle. ...
“Flying Machine†redirects here. ...
rpm or RPM may mean: revolutions per minute RPM Package Manager (originally called Red Hat Package Manager) RPM (movie) RPM (band), a Brazilian rock band RPM (magazine), a former Canadian music industry magazine In firearms, Rounds Per Minute: how many shots an automatic weapon can fire in one minute On...
A page from the Hindu calendar 1871-72. ...
In trains and light rail vehicles Speed sensing devices, termed variously "wheel impulse generators" (WIG), speed probes, or tachometers are used extensively in rail vehicles. Common types include opto-isolator slotted disk sensors[1] and Hall effect sensors. An opto-isolator integrated circuit. ...
The magnetic piston (1) in this pneumatic cylinder will cause the Hall effect sensors (2 and 3) mounted on its outer wall to activate when it is fully retracted or extended. ...
Hall effect sensors typically use a rotating target attached to a wheel, gearbox or motor. This target may contain magnets, or it may be a toothed wheel. The teeth on the wheel vary the flux density of a magnet inside the sensor head. The probe is mounted with its head a precise distance from the target wheel and detects the teeth or magnets passing its face. One problem with this system is that the necessary air gap between the target wheel and the sensor allows ferrous dust from the vehicle's underframe to build up on the probe or target, inhibiting function.
Opto-isolator sensors are completely encased to prevent ingress from the outside environment. The only exposed parts are a sealed plug connector and a drive fork, which is attached to a slotted disk internally through a bearing and seal. The slotted disk is typically sandwiched between two circuit boards containing a photo-diode, photo-transistor, amplifier, and filtering circuits which produce a square wave pulse train output customized to the customers voltage and pulses per revolution requirements. These types of sensors typically provide 2 to 8 independent channels of output that can be sampled by other systems in the vehicle such as automatic train control systems and propulsion/braking controllers. Bearing is the following: Often, bearing is the state of having something as a quality, characteristic, or permanent attribute. ...
Close-up photo of one side of a motherboard PCB, showing conductive traces, vias and solder points for through-hole components on the opposite side. ...
It has been suggested that Peak Inverse Voltage be merged into this article or section. ...
For other uses, see Transistor (disambiguation). ...
The opto devices, mounted around the circumference of the disk, provide signals that are phase-shifted relative to one another and thus allow the vehicle computer to determine the direction of rotation of the wheel. This is a legal requirement in Switzerland to prevent rollback when starting from standstill. Strictly, such devices are not tachometers since they do not provide a direct reading of the rotational speed of the disk. The speed has to be derived externally by counting the number of pulses in a time period. It is difficult to prove conclusively that the vehicle is stationary, other than by waiting a certain time to ensure that no further pulses occur. This is one reason why there is often a time delay between the train stopping, as perceived by a passenger, and the doors being released. Slotted-disk devices are typical sensors used in odometer systems for rail vehicles; such as are required for train protection systems - notably the European Train Control System. A modern non-digital odometer A Smiths speedometer from the 1920s showing odometer and trip meter An odometer is a device used for indicating distance traveled by an automobile or other vehicle. ...
The European Train Control System (ETCS) is a signalling and control system designed to replace the 14 incompatible safety systems currently used by European Railways, especially on high-speed lines. ...
A weakness of systems that rely on wheel rotation for tachometry and odometry is that the train wheels and the rails are very smooth and the friction between them is low, leading to high error rates if the wheels slip or slide. To compensate for this, secondary odometry inputs employ Doppler radar units beneath the train to measure speed independently. Doppler Effect Doppler radar uses the Doppler effect to measure the radial velocity of targets in the antennas directional beam. ...
As well as speed sensing, these probes are often used to calculate distance travelled by multiplying wheel rotations by wheel diameter.
They can also be used to automatically calibrate wheel diameter by comparing the number of rotations of each axle against a master wheel that has been measured manually. Since all wheels travel the same distance, the diameter of each wheel is proportional to its number of rotations compared to the master wheel. This calibration must be done while coasting at a fixed speed to eliminate the possibility of wheel slip/slide introducing errors into the calculation. Automatic calibration of this type is used to generate more accurate traction and braking signals, and to improve wheel slip detection.
In medicine In medicine, tachometers are used to measure the rate of blood flow at a particular point in the circulatory system. The specific name for these devices is haematachometer. Medicine is the science and art of maintaining andor restoring human health through the study, diagnosis, and treatment of patients. ...
Human blood smear: a - erythrocytes; b - neutrophil; c - eosinophil; d - lymphocyte. ...
For transport in plants, see Vascular tissue. ...
In analog audio recording In analog audio recording, a tachometer is a device that measures the speed of audiotape as it passes across the head. On most audio tape recorders the tachometer (or simply "tach") is a relatively large spindle near the ERP head stack, isolated from the feed and take-up spindles by tension idlers. Methods and media for sound recording are varied and have undergone significant changes between the first time sound was actually recorded for later playback until now. ...
Methods and media for sound recording are varied and have undergone significant changes between the first time sound was actually recorded for later playback until now. ...
On many recorders the tachometer spindle is connected by an axle to a rotating magnet that induces a changing magnetic field upon a Hall effect transistor. Other systems connect the spindle to a stroboscope, which alternates light and dark upon a photodiode. For other uses, see Magnet (disambiguation). ...
Magnetic field lines shown by iron filings In physics, the space surrounding moving electric charges, changing electric fields and magnetic dipoles contains a magnetic field. ...
Hall effect diagram, showing electron flow (rather than conventional current). ...
For other uses, see Transistor (disambiguation). ...
A stroboscope , also known as a strobe, is an instrument used to make a cyclically moving object appear to be slow-moving or stationary. ...
Photodiode closeup A photodiode A photodiode is a semiconductor diode that functions as a photodetector. ...
The tape recorder's drive electronics use signals from the tachometer to ensure that the tape is played at the proper speed. The signal is compared to a reference signal (either a quartz crystal or alternating current from the mains). The comparison of the two frequencies drives the speed of the tape transport. When the tach signal and the reference signal match, the tape transport is said to be "at speed." (To this day on film sets, the director calls "Roll sound!" and the sound man replies "Sound speed!" This is a vestige of the days when recording devices required several seconds to reach a regulated speed.) A quartz clock A quartz clock is a timepiece that uses an electronic oscillator which is made up by a quartz crystal to keep precise time. ...
City lights viewed in a motion blurred exposure. ...
Mains may mean or refer to, or be a subject of: Mains electricity Electricity transmission Public utility, about mains services, including electricity, natural gas, water, and sewage disposal Mains (Scotland), about the central steading of a townland BMX racing See also: Main Mane Category: ...
FreQuency is a music video game developed by Harmonix and published by SCEI. It was released in November 2001. ...
The film director, on the right, gives last minute direction to the cast and crew, whilst filming a costume drama on location in London. ...
Having perfectly regulated tape speed is important because the human ear is very sensitive to changes in pitch, particularly sudden ones, and without a self-regulating system to control the speed of tape across the head the pitch could drift several percent. This effect is called a wow-and-flutter, and a modern, tachometer-regulated cassette deck has a wow-and-flutter of 0.07%. Wow and flutter may refer to: Wow (recording) and flutter, two forms of noise which emanate from cassette tapes; The title of a critically-acclaimed single, from the 1994 recording by Stereolab, entitled Mars Audiac Quintet; and Wow & Flutter, an indie rock band from Portland, Oregon. ...
A typical front loading consumer autoreverse hi-fi cassette deck from lte 1980s (SONY TC-RX55), features full electronic transport, Dolby B, C noise reduction and HXPro dynamic headroom expansion A cassette deck is a type of tape recorder for playing or recording audio compact cassettes. ...
Tachometers are acceptable for high-fidelity sound playback, but not for recording in synchronization with a movie camera. For such purposes, special recorders that record pilottone must be used. This article is about audiophile sound systems. ...
The Arricam ST, a popular 35 mm film camera currently used on major productions. ...
Pilottone and the related neo-pilottone are special synchronization signals recorded by analog audio recorders designed for use in motion picture production. ...
Tachometer signals can be used to synchronize several tape machines together, but only if in addition to the tach signal, a directional signal is transmitted, to tell slave machines in which direction the master is moving.
See also Wikipedia does not have an article with this exact name. ...
Wiktionary (a portmanteau of wiki and dictionary) is a multilingual, Web-based project to create a free content dictionary, available in over 150 languages. ...
A modern non-digital odometer A Smiths speedometer from the 1920s showing odometer and trip meter An odometer is a device used for indicating distance traveled by an automobile or other vehicle. ...
A hubometer (hub, center of a wheel + -ometer, measure of), or hubodometer, is a device mounted on the axle of an automobile or other vehicle that measures distance traveled. ...
Speedometer gauge on a car, showing the speed of the vehicle in miles and kilometres per hour on the out– and inside respectively. ...
The Tachograph Disc A tachograph combines the functions of a clock and a speedometer. ...
A taximeter is a mechanical or electronic device installed in taxicabs, similar to an odometer, which calculates passenger fares based on a combination of distance travelled and waiting time. ...
References - ^ HaslerRail Speed Sensors
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