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About Dynamometers
Dynamometers, also called “dynos,” are
machines used to measure the power of an engine. More specifically, the
torque of an engine is determined by a complex system of absorption and
reaction. Dynamometer manufacturers construct their products using basic
components: frame, engine mounts, absorption unit, which is usually some
sort of roller or drum, heat exchanger and torque measuring device. Water
or oil brakes are needed for certain types of dynamometers to provide
proper resistance and absorption. Engines are hooked up to the dynamometers
in various ways and then run. The dynamometers simulate actual conditions
by allowing the engine to run at long intervals and at peak levels without
ever having a vehicle in motion or an operator inside a vehicle.
The commercial auto industry relies on dynamometer manufacturers in the
development and testing of their vehicle engines. Those who specialize
in the rebuilding and customization of engines also use dynamometers
extensively. Makers and designers of high-performance vehicles, such
as race cars and speed bikes, use dynamometers for similar reasons as
those of the commercial auto industry and as part of the recalibration
process of an engine, which has been used in race environments. Dynamometers
are also sometimes used in the testing of other types of internal combustion
engines used for industrial purposes, such as engines in water pumps
and large earth-moving tractors.
Most modern dynamometers are computer controlled, and allow the operator
to select the points and range of speeds through which an engine’s
torque is measured. The operator then opens the throttle of the engine
and the dynamometers react with an appropriate amount of load to maintain
the chosen condition. The horsepower and other measurements are read
out directly to a real time gauge and from this the torque is usually
calculated. Analog gauges are still used to determine the torque of an
engine, but operators of dynamometers need some knowledge of physics
to come up with the final reading.
When looking at dynamometer manufacturers, consider important performance
specifications: torque capacity, maximum rotary speed and power absorption.
For chassis dynamometers, keep in mind the maximum linear speed on chassis
style. The torque capacity is the highest continuous torque transmission
for which the shaft is designed. The maximum rotary speed is the highest
rated rotational speed under load. The highest rotational power at which
dynamometers can be operated while still running within specifications
is the maximum rotational speed. This speed is often regulated by the
braking technology and configuration. In terms of chassis-style dynamometers,
the highest linear speed of the vehicle under test is rendered in miles
per hour.
Featured
Articles
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Types of Dynamometers
- are good for measuring the torque of engines, which
remains constant in output, such as in tractors. These machines are
declining in use for testing racing engines because of the way the brakes
tend to overheat and the oil or water used to pump the brake becomes
too thin as the engine changes speeds.
- are dynamometers where braking drag is applied.
-
are a sub-type of engine-torque testing device, which measures the output
of torque at the wheel. The wheels of a vehicle either spin a drum or
a series of rollers, which are attached to the dynamometer, or the wheels
are removed and the wheel hub is mounted directly to the testers' input
shaft.
- is a machine that measures the power of an engine.
- are another sub-type of torque testing machines, which are hooked
to the engine directly as opposed to the wheel chassis. Research and
development departments at workshops and auto manufacturing plants use
this style of testing, as the engine can be tested without being inside
a vehicle.
-
are becoming the most widely used type of dynamometer in the torque-testing
sectors of both the commercial and racing automobile industries, because
they provide real-world results. The inertia of the roller drums is
measured to calculate torque, revealing the rate at which an engine
can accelerate a known rotational inertia from one rpm to another.
-
are chassis devices used to simulate actual road driving conditions
on a motor vehicle. Repair grade dynamometers consist of rollers, power
absorbers and inertia simulation, either mechanical or electrical.
-
function basically the same way as dynamometers do, but are designed
to test the torque of smaller mechanical devices other than engines.
Devices, such as precision screwdrivers and wrenches, need to have their
torque tested to ensure quality function.
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