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A dynamometer, or "dyno" for short, is a machine used to measure torque and rotational speed (rpm) from which power produced by an engine, motor or other rotating prime mover can be calculated. Torque applied via an adjustable end wrench Relationship between force, torque, and momentum vectors in a rotating system In physics, torque can informally be thought of as rotational force or angular force which causes a change in rotational motion. ...
Rotational speed (sometimes called speed of revolution) indicates for example how fast the motor is running. ...
Revolutions per minute (abbreviated rpm, RPM, r/min, or min-1) is a unit of frequency, commonly used to measure rotational speed, in particular in the case of rotation around a fixed axis. ...
In physics, power (symbol: P) is the rate at which work is performed. ...
In engineering and thermodynamics, a heat engine performs the conversion of heat energy to mechanical work by exploiting the temperature gradient between a hot source and a cold sink. Heat is transferred from the source, through the working body of the engine, to the sink, and in this process some...
A motor is a device that converts energy into mechanical power, and is often synonymous with engine. ...
For the philosophical/theological concept of a prime mover (that is, a self-existent being that is the ultimate cause or mover of all things), see cosmological argument. ...
A dynamometer can also be used to determine the torque and power required to operate a driven machine such as a pump. In that case, a motoring or driving dynamometer is used. A dynamometer that is designed to be driven is called an absorption dynamometer. A dynamometer that can either drive or absorb is called a universal dynamometer.
In the medical realm, hand dynamometers are used for routine screening of grip strength and initial and ongoing evaluation of patients with hand trauma and dysfunction.
Principles of operation
An absorbing dynamometer acts as a load that is driven by the prime mover that is under test. The dyno must be able to operate at any speed, and load the prime mover to any level of torque that the test requires. A dynamometer is usually equipped with some means of measuring the operating torque and speed.
The dynamometer must absorb the power developed by the prime mover. The power absorbed by the dynamometer must generally be dissipated to the ambient air or transferred to cooling water. Regenerative dynamometers transfer the power to electrical power lines.
Dynamometers can be equipped with a variety of control systems. If the dynamometer has a torque regulator, it operates at a set torque while the prime mover operates at whatever speed it can attain while developing the torque that has been set. If the dynamometer has a speed regulator, it develops whatever torque is necessary to force the prime mover to operate at the set speed.
A motoring dynamometer acts as a motor that drives the equipment under test. It must be able to drive the equipment at any speed and develop any level of torque that the test requires.
Only torque and speed can be measured Power must be calculated from the torque and speed figures according to the formula: In physics, power (symbol: P) is the rate at which work is performed. ...
 Where K is determined by the units of measure used as can be seen below:
To calculate power in horsepower (hp) use: The horsepower (hp) is the name of several non-metric units of power. ...
 - where:
- Torque is in pound-feet (lbf·ft)
- Rotational speed is in revolutions per minute (rpm)
To calculate power in kilowatts use: The foot-pound force (symbol: ft·lbf) is an English unit of work or energy. ...
Rotational speed (sometimes called speed of revolution) indicates for example how fast the motor is running. ...
Revolutions per minute (abbreviated rpm, RPM, r/min, or min-1) is a unit of frequency, commonly used to measure rotational speed, in particular in the case of rotation around a fixed axis. ...
The watt (symbol: W) is the SI derived unit of power, equal to one joule per second. ...
 - where:
- Torque is in newton-metres (N·m)
- Rotational speed is in revolutions per minute (rpm)
(On graphs of torque vs. rpm the numerical values of torque and power are always equal when the rpm value is equal to the constant, K. The numerical values of horsepower and lbf·ft of torque are always equal at 5252 rpm because 5252 rpm in the numerator cancels out the constant, 5252 in the denominator leaving only the torque figure equal to the power figure.) Torque applied via an adjustable end wrench Relationship between force, torque, and momentum vectors in a rotating system In physics, torque can informally be thought of as rotational force or angular force which causes a change in rotational motion. ...
Newton metre is the unit of moment in the SI system. ...
See also internal combustion engine (performance section). A colorized automobile engine The internal combustion engine is a heat engine in which the burning of a fuel occurs in a confined space called a combustion chamber. ...
Detailed dynamometer description
 Electrical dynamometer setup showing engine, torque measurement arrangement and tachometer A dynamometer consists of an absorption (or absorber/driver) unit, and usually includes a means for measuring torque and rotational speed. An absorption unit consists of some type of rotor in a housing. The rotor is coupled to the engine or other equipment under test and is free to rotate at whatever speed is required for the test. Some means is provided to develop a braking torque between dynamometer's rotor and housing. The means for developing torque can be frictional, hydraulic, electromagnetic etc. according to the type of absorption/driver unit. Image File history File links Dynamometer01CJC.png‎ Drawing of a dynamometer setup with an engine connected. ...
Image File history File links Dynamometer01CJC.png‎ Drawing of a dynamometer setup with an engine connected. ...
One means for measuring torque is to mount the dynamometer housing so that it is free to turn except that it is restrained by a torque arm. The housing can be made free to rotate by using trunnions connected to each end of the housing to support the dyno in pedestal mounted trunnion bearings. The torque arm is connected to the dyno housing and a weighing scales is positioned so that it measures the force exerted by the dyno housing in attempting to rotate. The torque is the force indicated by the scales multiplied by the length of the torque arm measured from the center of the dynamometer. A load cell transducer can be substituted for the scales in order to provide an electrical signal that is proportional to torque. The trunnions are the part of the cannon that mounts the barrel to the carriage A Trunnion is a cylindrical protrusion used for mounting. ...
A weighing scale (usually just scale in common usage) is a device for measuring the weight of an object. ...
A single-point load cell A load cell is typically an electronic device (transducer) that is used to convert a force into a differential electrical signal. ...
A transducer is a device, usually electrical or electronic, that converts one type of energy to another. ...
In the fields of communications, signal processing, and in electrical engineering more generally, a signal is any time-varying quantity. ...
Another means for measuring torque is to connect the engine to the dynamometer through a torque sensing coupling or torque transducer. A torque transducer provides an electrical signal that is proportional to torque. A torque sensor or torque transducer is a device for measuring the torque on a rotating system such as an engine crankshaft or a bicycle crank. ...
A torque sensor or torque transducer is a device for measuring the torque on a rotating system such as an engine crankshaft or a bicycle crank. ...
In the fields of communications, signal processing, and in electrical engineering more generally, a signal is any time-varying quantity. ...
With electrical absorption units, it is possible to determine torque by measuring the current drawn (or generated) by the absorber/driver. This is generally a less accurate method, but it may be adequate for some purposes.
A wide variety of tachometers are available for measuring speed. Some types can provide an electrical signal that is proportional to speed. Tachometer showing engine rotations per minute (RPM), and a redline from 6000 RPM. A tachometer measures the speed of rotation of a shaft or disk (from Greek: tachos = speed, metron = measure), as in a motor or other machine. ...
In the fields of communications, signal processing, and in electrical engineering more generally, a signal is any time-varying quantity. ...
When torque and speed signals are available, test data can be transmitted to a data acquisition system rather than being recorded manually. Speed and torque signals can also be recorded by a chart recorder or plotter. Data acquisition is the sampling of the real world to generate data that can be manipulated by a computer. ...
A chart recorder is an electro mechanical device that records an electrical or mechanical input trend onto a piece of paper (the chart). ...
This article or section does not cite its references or sources. ...
Types of dynamometers In addition to classification as absorption, motoring or universal as described above, dynamometers can be classified in other ways. A dyno that is coupled directly to an engine is known as an engine dyno. A dyno that can measure torque and power delivered by the power train of a vehicle without removing the engine from the frame of the vehicle, is known as a chassis dyno. Generally, coupling means a mechanical connection between two things. ...
Dynamometers can also be classified by the type of absorption unit or absorber/driver that they use. Some units that are capable of absorption only can be combined with a motor to construct an absorber/driver or universal dynamometer. The following types of absorption/driver units have been used:
Types of absorption/driver units Rotating magnetic field as a sum of magnetic vectors from 3 phase coils. ...
Generator redirects here. ...
The Prony Brake is a simple device invented by Gaspard de Prony to measure the torque produced by an engine. ...
Hydraulics is a branch of science and engineering concerned with the use of liquids to perform mechanical tasks. ...
Electromagnetic brakes seek to cause deceleration in a moving system. ...
Water brake dynamometer The water brake dynamometers are very popular, due to their high power capability, controllability, and relatively low cost compared to other types. The schematic shows the most common type of water brake, the variable level type. Water is added until the engine is held at a steady rpm against the load. Water is then kept at that level and replaced by constant draining and refilling, which is needed to carry away the heat created by absorbing the horsepower (which in itself is a measure of power output of the engine). The housing attempts to rotate in response to the torque produced but is restrained by the scale or torque metering cell which measures the torque.
 This schematic shows a water brake which is actually a fluid coupling with the housing restrained from rotating. It is very similar to a water pump with no outlet. Image File history File links Dyno_schematic. ...
Electric motor/generator dynamometer Electric motor/generator dynamometers are a specialized type of adjustable-speed drives. The absorption/driver unit can be either an alternating current (AC) motor or a direct current (DC) motor. Either an AC motor or a DC motor can operate as a generator which is driven by the unit under test or a motor which drives the unit under test. When equipped with appropriate control units, electric motor/generator dynamometers can be configured as universal dynamometers. The control unit for an AC motor is a variable-frequency drive and the control unit for a DC motor is a DC drive. In both cases, regenerative control units can transfer power from the unit under test to the electric utility. Where permitted, the operator of the dynamometer can receive payment (or credit) from the utility for the returned power. Rotating magnetic field as a sum of magnetic vectors from 3 phase coils. ...
Generator redirects here. ...
Adjustable speed drive (ASD) is one of the most general terms applied to equipment used to control the speed of machinery. ...
City lights viewed in a motion blurred exposure. ...
Direct current (DC or continuous current) is the continuous flow of electricity through a conductor such as a wire from high to low potential. ...
Small Variable Frequency Drive (VFD) A variable-frequency drive (VFD) is a system for controlling the rotational speed of an alternating current (AC) electric motor by controlling the frequency of the electrical power supplied to the motor. ...
Adjustable speed drive (ASD) is one of the most general terms applied to equipment used to control the speed of machinery. ...
In engine testing, universal dynamometers can not only absorb the power of the engine but also, drive the engine for measuring friction, pumping losses and other factors.
Electric motor/generator dynamometers are generally more costly and complex than other types of dynamometers.
How dynamometers are used for engine testing Dynamometers are useful in the development and refinement of modern day engine technology. The concept is to use a dyno to measure and compare power transfer at different points on a vehicle, thus allowing the engine or drivetrain to be modified to get more efficient power transfer. For example, if an engine dynamo shows that a particular engine achieves 400 N·m (300 lbf·ft) of torque, and a chassis dynamo shows only 350 N·m (260 lbf·ft), one would know to look to the drivetrain for the major improvements. Dynamometers are typically very expensive pieces of equipment, reserved for certain fields that rely on them for a particular purpose.
General testing method The dynamometer applies various loads on the engine and measures the engine's ability to move the load. The dynamometer may be connected to a computer which calculates the output of the engine. The engine is run from idle to its maximum rpm and the output is measured and plotted on a graph. Nearly all aspects of engine operation are measured during a dyno run. Image File history File links A dyno graph of the 2. ...
Download high resolution version (825x1215, 165 KB)Dynamometer graph of a 1700 cc Ford Taunus V4 engine in a 1977 Saab 96. ...
A Lego RCX Computer is an example of an embedded computer used to control mechanical devices. ...
Engine dynamometer An engine dynamometer measures power and torque directly from the engine's crankshaft (or flywheel), when the engine is removed from the vehicle. These dynos do not account for power losses in the drivetrain, such as the gearbox, transmission or differential etc. An engine test stand is a facility used to develop, characterize and test engines. ...
Crankshaft, pistons, and flywheel Continental engine marine crankshafts, 1942 For the comic strip about an old, curmudgeonly bus driver, see Crankshaft (comic strip). ...
Spoked flywheel Simple flywheel in motion. ...
A gearbox is an assembly of gears allowing the rotational speed of an input shaft to be changed to a different speed. ...
Image:Gearbox. ...
In an automobile and other four-wheeled vehicles, a differential is a device, usually consisting of gears, for allowing each of the driving wheels to rotate at different speeds, while supplying equal torque to each of them. ...
ETC can refer to: Electronic toll collection Electronic throttle control Estimated Time of/to Completion Et cetera Electronic Theatre Controls Electron transport chain in mitochondria responsible for creating a proton gradient that allows the formation of ATP. ATM card service by HSBC and Hang Seng Bank only for withdrawal of...
 HORIBA engine dynamometer TITAN
Image File history File links TitanTestStand. ...
Image File history File links TitanTestStand. ...
Chassis dynamometer A chassis dynamometer measures power from the engine through the wheels. The vehicle is parked on rollers which the car then turns and the output is measured. These dynos can be fixed or portable. A chassis (plural: chassis) consists of a framework which supports an inanimate object, analogous to an animals skeleton; for example in the construction of an automobile or of a firearm. ...
A driving wheel on a steam locomotive. ...
Because of frictional and mechanical losses in the various drivetrain components, the measured horsepower is generally 15-20 percent less than the brake horsepower measured at the crankshaft or flywheel on an engine dynamometer.[1]
Saab 96 on chassis dynamometer Photograph taken, scanned and uploaded by MH 20:58, 2004 Aug 20 (UTC) File history Legend: (cur) = this is the current file, (del) = delete this old version, (rev) = revert to this old version. ...
Saab 96 on chassis dynamometer Photograph taken, scanned and uploaded by MH 20:58, 2004 Aug 20 (UTC) File history Legend: (cur) = this is the current file, (del) = delete this old version, (rev) = revert to this old version. ...
Saab 96 The Saab 96 is an automobile made by Saab. ...
Common misconceptions about dynos Horsepower and torque figures are a strong predictor but do not guarantee a specific 0-60 mph or 1/4 mile E.T. (elapsed time). An engine accelerating in a vehicle experiences different conditions than on a dyno. G forces and different temperatures as well as different modes of vibration in a vehicle can cause significant differences in power output.
History Gaspard de Prony invented the de Prony brake in 1821. The de Prony brake (or Prony brake) is considered to be one of the earliest dynamometers. Gaspard Clair François Marie Riche de Prony (July 22, 1755 - July 29, 1839) was a French mathematician and engineer, who worked on hydraulics. ...
The Prony Brake is a simple device invented by Gaspard de Prony to measure the torque produced by an engine. ...
Froude Hofmann of Worcester, UK manufactures engine and vehicle dynamometers. They credit William Froude with the invention of the hydraulic dynamometer in 1877 and say that the first commercial dynamometers were produced in 1881 by their predecessor company, Heenan & Froude. The hulls of swan (above) and raven (below). ...
In 1928, the German company "Carl Schenck Eisengießerei & Waagenfabrik" built the first vehicle dynamometers for brake tests with the basic design of the today's vehicle test stands. Carl Schenck established 1881 in Darmstadt, Germany the Carl Schenck Eisengießerei & Waagenfabrik (today a subsidiary company of Dürr). ...
The eddy current dynamometer was invented by Martin and Anthony Winther in about 1931. At that time, DC Motor/generator dynamometers had been in use for many years. A company founded by the Winthers, Dynamatic Corporation, manufactured dynamometers in Kenosha, Wisconsin until 2002. Dynamatic was part of Eaton Corporation from 1946 to 1995. In 2002, Dyne Systems of Jackson, Wisconsin acquired the Dynamatic dynamometer product line. Starting in 1938, Heenan and Froude manufactured eddy current dynamometers for many years under license from Dynamatic and Eaton.[2]
Electromagnetic brakes seek to cause deceleration in a moving system. ...
Kenosha is a city in Kenosha County, Wisconsin. ...
Eaton Corporation (NYSE: ETN), a Fortune 500 company based in Cleveland, Ohio, USA, is a global diversified industrial manufacturer with 2002 sales of $7. ...
There are some other places named Jackson in Wisconsin. ...
Dyno manufacturers
See also The Southern Pacific Railroads dynamometer car #137, July 1937. ...
An engine test stand is a facility used to develop, characterize and test engines. ...
External links
References
Citations - ^ John Dinkel, "Chassis Dynamometer", Road and Track Illustrated Automotive Dictionary, (Bentley Publishers, 2000) p. 46.
- ^ Winther, Martin P. (1976). Eddy Currents. Cleveland, Ohio: Eaton Corporation.
General references - Winther, J. B. (1975). Dynamometer Handbook of Basic Theory and Applications. Cleveland, Ohio: Eaton Corporation.
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