What Is A Brake Dynamometer

What Is A Brake Dynamometer

Once in a great while, we stumble onto one of those technologically related terms with a faintly familiar ring, but we still need to learn about its meaning. You may have seen the term only frequently enough to identify the letters, but other than that, the word may not have any meaning. Now, then, what exactly is a dynamo?

To be more specific, what exactly is a brake dynamometer? A device with changeable resistance to physical motion is called a brake dynamometer. This instrument is often used to measure the power output of an engine to ascertain a variety of facts about the engine’s functionality. They are also compatible with motors in specific applications.

However, even though they may seem to be the most tedious thing in the world, dynamometers serve several essential functions. These gadgets are the key to the success of everything that uses an internal combustion engine or an electric motor. It is possible to detect issues long before the customer becomes aware of them.

What Is A Brake Dynamometer

Brake dynamometers are instruments that are used to measure the forces that are generated by an engine. Because of this, it might be regarded as one of the many different engine dynamometers, also often referred to as motor testers.

The name derives from the technique that they use to determine the force of a motor: Put a brake on the engine (anything that exerts a point in the opposite direction) and then determine how much energy is required to slow down or stop the engine.

The primary objective of the dynamometer is to provide a measurement and any other relevant expressions that may be derived from that measurement. These are instruments for measuring forces. Torque multiplied by the rotational speed equals power. This is a straightforward formula that is often used in conjunction with dynamometers.

The de Prony brake, which was designed in 1821 by Gaspard de Prony, is credited as being one of the first known mechanical devices. This particular dynamometer used a mechanical friction brake, which is only one of the numerous varieties available.

The results of a dynamometer test will be exhibited on a display incorporated into the dynamometer these days. This is a long cry from what de Prony developed about 200 years ago, but the applications and fundamental theory underlying these devices are still the same.

It is essential to the development of almost every engine to measure the output of the machine being developed accurately.

Imagine investing millions of dollars in the design and construction of an engine for a considerable truck, then going straight to mass production without knowing whether the engine is powerful enough to drive a heavy vehicle successfully. This is precisely what happened to a company called Cummins.

Before attempting to do a job requiring a specific level of power, we need a method to evaluate that power to determine whether or not a given instrument has that level of control.

Because of this, the world of engines runs much more smoothly, and businesses are spared the embarrassment of having to tell a customer that the massive and costly motor they purchased isn’t going to operate.

Different Types

Eddy Current (EC) Dynamometer – When a conductive substance is moved or rotated in a magnetic field, “eddy currents” are produced due to the material’s resistance to movement through the area. The voltage of the electromagnet may be adjusted, and most of the time, is by a computer that monitors the changes in the magnetic field and makes an effort to replicate them.

Cast iron discs construct many current EC dynamos, giving these devices a design similar to the rotors.

Powder Dynamometer

This is similar to the EC dynamo, except that a tiny magnetic powder is inserted into the gap between the rotor and the coil. The magnetic particles begin to “line up” with the field when a voltage is introduced to the device; however, this alignment is continually disrupted by the revolving rotor.

This increases the resistance, but since these variants have a reduced capacity to dissipate heat, they can only be utilized at lower RPMs.

Hysteresis Dynamometer

These are also quite similar to EC dynamos; however, one of the most significant distinctions lies in that these can generate torque even when not spinning, but the EC version cannot. This particular iteration is capable of producing consistent torque that is proportionate to either the permanent magnet that is being used or the magnetizing current.

Electric Motor/Generator Dynamometer

These devices are sometimes referred to as universal dynamometers. These are often more difficult to construct and costly, but they can wear from the connected engine and drive it to measure various.

Fan brake

The engine that is being measured has a fan connected to it. Altering the fan’s gearing, changing the fan’s blades, or modifying the airflow into the fan are some ways to adjust the fan’s air resistance.

Due to the low viscosity of the air (which means that the air has very little “flowing resistance”), this design is more restricted in the amount of torque that may be applied.

Force Lubricated Oil Shear Brake

A shaft has many friction disks and steel plates fixed at various intervals. The motor creates a circular motion, and a piston that is either hydraulically or pneumatically propelled brings these plates into contact with one another.

It is possible to prevent the plates from wearing out faster than necessary by pushing a layer of oil into the spaces between them. Because of this, any motion may be carried out without any jerkiness since the plates won’t become stuck and won’t slide repeatedly when they come to a halt.

Hydraulic Brake

A hydraulic fluid is pushed via a network of pipelines and a valve that may be adjusted. While the engine is operating, the valve is gradually closed to limit the movement of the fluid. This is done to determine the power output by monitoring the flow volume, fluid pressure, and engine RPM.

Even though this computation technique is patently distinct from the others, the result is nonetheless quite precise.

Water-Brake Absorber

This instrument, first developed in 1877 to measure the power of enormous naval engines, performs precisely the job suggested by its name. These are relatively common and have several benefits to offer:

  • The capability of withstanding significant power
  • Size appropriate
  • Easy on the shoulders
  • Minimal costs associated with production
  • The use of Compound Dynamometers

To put it another way, there are certain instances in which it would be more prudent to integrate the results of two distinct dynamometers rather than to rely on the findings of just one. Both will be employed simultaneously, which may make the measuring, powering, cooling, and regulating processes more difficult.


As you’ve seen, dynamometers are a rather complicated topic that may take on various shapes and serve various purposes. Because it may be difficult to conceptualize the many advantages, a condensed summary of them is presented in the following paragraphs. Because of these instruments, we can:

  • Accurately grasp what aspects of the engine, motor, or pump are performing correctly and which need to be fixed.
  • Make use of the information that has been acquired to optimize the machinery in issue and avoid wasting any fuel.
  • Please use the preceding two principles to foster and cultivate faith in your equipment and its processes.
  • Perform the necessary adjustments to other pieces of apparatus, such as the engine management controllers, which in turn help with the execution of the first three steps.
  • Keep a record of performance measures; the data you gather may be useful for creating new features or adjustments in the near or distant future.

Testing engines, pumps, and motors is one of many uses for these devices; they also have other benefits. In some areas of medicine, dynamometers are used to measure things like:

  • Hand and grip strength for individuals suspected of having nerve damage or suffering from another malfunction or trauma connected to this area.
  • Patients, athletes, and workers may all benefit from having their back, arms, or legs tested for strength to establish their capacity, performance, and the demands of various jobs.

Does The Average Person Need One?

Unless you have any engines to measure or patients to treat, you’ll probably need one. A brake dynamometer is a specialist instrument useful to engineers and businesses producing items to be marketed. Still, it is not practical for the typical individual to attach one to their family’s minivan for whatever reason they may have.

It is essential to remember that when we use the term “dynamometer,” we are talking particularly to measurement devices and not just any old electric motor operated in reverse, which might be comparable but serves distinct purposes.

Consider yourself quite lucky that you won’t need to use the dynamometer that your family has to determine whether or not the engine in your brand-new automobile will be powerful enough to transport you to work in the morning.

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