The dynamometer is crucial testing equipment for many engines, motors and turbines. It must produce any level of power and torque that the engine, motor or machine under test requires.
Those straight lines on performance graphs represent safe limits that most dynamometer producers expect users not to exceed. Pushing DC dynamometers beyond their rated overload capacity can damage commutators.
Power and Torque Measurement
A wide range of dynamometers meet the needs of various testing applications. Each dynamometer type is designed to measure, record, observe, and assess specific forms of data.
One of the most important things a dynamometer can do is provide information about power. Two main types of dyno test equipment can help with this: engine dynos and chassis dynos.
An engine dyno tests the performance of an individual automotive engine and is often used to troubleshoot problems that might be associated with the vehicle’s performance. On the other hand, a chassis dyno measures the performance of an entire vehicle’s chassis.
Most modern dynos feature devices that can determine torque, which is the elastic twist of a shaft. These devices either use sensors that can sense the mechanical energy of a post and convert it to an electrical signal or use a special axial force transducer that records an electrical output proportional to the applied axial forces.
Another way to determine power is through an absorption dynamometer. This device can absorb the useful power a motor or other prime mover produces and generate AC electricity or return it to the commercial electrical grid.
Most edjunior dynamometer can record simultaneous tachometer and torque gauge readings on a computerized data acquisition system. This eliminates the need for an observer to take manual notes during a test, which can become quite noisy and exciting.
Fuel Efficiency Measurement
One important aspect of dynamometer testing is fuel efficiency measurement. A dyno helps separate the power output of a vehicle’s engine from its overall performance and enables the user to evaluate the impact of various improvements on fuel consumption.
To perform a dynamometer test, the dyno must be connected to a load designed to simulate external forces on the engine. This load is often called an absorber because it “absorbs” the engine’s torque and converts it into another form of energy, such as heating water or air. Absorption dynamometers can be built from various materials, including a brake dynamometer, rope dynamometer, hydraulic dyno, or eddy current dyno.
While absorption dynamometers are the most popular choice, several dyno types can measure force, power, and speed. One such type is the hydraulic dyno, which uses semicircular vanes inside a rotor and stator to create torque reactions in the dynamometer’s casing. This process creates heat that is recorded and analyzed.
Unlike many other dynamometers, hydraulic dynos can measure static power at a constant velocity. This makes them ideal for straight-line rigging and lifting applications. Sadly, unscrupulous dyno operators sometimes use this ability to produce flash power readings augmented by inertial energy. A well-designed dyno can accurately display peak and average power readings, allowing users to make more informed performance decisions.
Brake Performance Measurement
In addition to engine torque measurement, dynamometers can be used to measure brake performance. Brake dynamometers are generally very easy to set up and provide accurate, detailed data on how the equipment under test performs. This can assist in lowering maintenance costs and improving equipment reliability.
The basic dynamometer system has an absorber or brake-type device that provides a loading force on the vehicle’s wheel during testing. Depending on the dynamometer type and application, this load can be applied in various ways. The dynamometer can also measure the torque, such as an inline torque sensor or other mechanical transducer.
A computer can then calculate power horsepower (or kilowatts) from the measured rotational speed and torque. A simple dynamometer may consist of only the absorber/brake and a speed sensor, or it may include a governor to control throttle opening and fuel delivery rate.
With the advent of electronic data acquisition systems, a computer is usually used to program the dynamometer and record the simultaneous tachometer and torque gauge readings. A good dynamometer system will then automatically transfer the recorded data to a data display and calculator. This eliminates the need for an observer to take notes by hand. Once the tachometer and torque gauge readings have been extended to horsepower numbers, it’s time to stop the test and begin analyzing results.
Transmission Performance Measurement
There are a few types of dynamometers used to measure transmission performance. One of the most common, a mechanical dynamometer, measures force using a mechanical spring that deforms when the estimated pressure is applied. The point is then converted to an electrical signal, which can be read on a display. The most sophisticated dynamometers use digital load cells to convert the mechanical force into an electrical signal. These dynamometers can provide readings of both pull and push power.
In the automotive industry, dynamometers simulate road loads for engine power testing and chassis/powertrain tests. A chassis dyno, for example, is designed to simulate road conditions while putting an entire vehicle through its paces. These tests are essential to developing new vehicles and can help reduce fuel consumption by optimizing a car’s driving habits.
A dynamometer can also be used to test the braking capacity of a vehicle. For this type of testing, a dyno machine is attached to the vehicle’s wheels and then placed on the simulated road. These dyno machines can be configured to simulate different types of roads and to allow the car to accelerate, turn and brake as it would under real-world road conditions.
Dynamometers are used in a wide variety of fields and applications. From the automotive industry to medical fields, these devices help evaluate and analyze strength objectively, accurately and reliably.
