All types of dynamometers, or dynos, are used to measure the performance of a particular item, whether that item is a vehicle’s engine horsepower, or the strength of a human hand. Since the range of applications for which a dynamometer can be used is so broad, there are some types of dynamometers available that are built to measure a specific item. One of those types are brake dynamometers, which are dynamometers used to measure an engine’s horsepower at its output shaft, and are used most extensively in measuring force generated by motors.
Brake dynamometers are named for the way they take measurements of the force generated by an engine. A brake is a mechanism that deters motion in a machine. When a brake is applied to a motor, it provides resistance to the force that the motor produces It is possible to measure the amount of force necessary to reduce motion. Thus, brake dynamometers are utilized to provide a visible reading of this particular measurement. Brake dynamometers can be categorized as a subcategory of engine dynamometers, or motor testers.
Brake dynos consist of a platform the size of a car, with a series of plates, sensors, and rollers. The vehicle is driven onto the platform, with the wheels lining up with the underlying plates. Depending on the type of test, the dyno’s operator can apply certain conditions to the plates, such as vibrating them in a way that they mimic rough terrain. By analyzing the results, the tester cam determine whether or not the vehicle is in need of other changes to the braking system, or a different braking system altogether. Once the vehicle passes the tests given by the brake dyno, it is free to move on to other tests.
In testing the specifications and safety ratings of a vehicle, a brake test is crucial to perform in order to determine whether or not the vehicle is capable of safely stopping under numerous driving conditions. There are three things that brake dynos check for during a brake test. The first is slippage. When a vehicle is placed onto the dyno, the rollers underneath the platform bring the vehicle to its top speed, and the brake is applied. This test closely monitors the traction of the wheels as they are slowed to a stop. This particular test assists in the prevention of the wheels slipping and sliding under slick road conditions. The second issue that brake dynos watch for is braking power, and how much force is needed for a brake to slow down and stop a vehicle under certain speeds and conditions. The third test is suspension. The dyno’s test plates are vibrated to test how well the vehicle responds to uneven road conditions. All of these tests work together in determining how safe a vehicle is to drive.
Brake dynamometers have significantly evolved since they were first invented in 1821. The de Prony brake, invented by Gaspard de Prony, is a mechanical friction brake that produces a calculation by measuring the force transferred to a belt or cord that is wrapped around an engine’s output shaft. A pair of spring balances are attached to the brake, with one of the balances showing an increase in tension, while the other shows a decrease in tension. These spring balances help the brake produce a final measurement.
Another type of brake dynamometers is water brake, or hydraulic dynamometers. These types of dynos have a high power capability, while at the same time are inexpensive to operate. These features make them highly popular for engine testing. Variable level water brakes are the most common type of water brakes. In this type of brake, water is added until the engine reaches a steady RPM speed. The water level is maintained and is replaced by regularly filling and draining, which takes away heat generated by absorbing horsepower. The housing attempts to rotate in response to the torque, but the torque metering cell holds it back.
Brake dynamometers are essential in the vehicle safety testing process, as they identify problematic aspects of a vehicle long before a person even gets into it. Should the vehicle fail any tests, it may require the installation of a different braking system or a more suitable set of wheels. The numerous tests that brake dynos perform are crucial to the safety of the public. They all work together to identify concerns within a vehicle before the final touches are added. Without these tests, the annual number of motor vehicle accidents would drastically increase. Brake dynos play a vital role in maintaining everyday safety for motorists.
More Brake Dynamometers
Brake Dynamometers Informational Video