Chassis dynamometers can read RPM without removing the engine.
Dynamometers are specialized instruments used to measure the revolutions per minute (RPM) and torque of an engine. RPM is a measure of the number of times the crankshaft rotates within an engine. The more revolutions a crankshaft makes per minute, the faster and more powerful the engine.
There are many parts inside a car engine, including the crankshaft and pistons. The crankshaft is similar to the pedals on a bicycle, with the rider’s legs being the pistons. The pistons push on the crankshaft and cause it to rotate. As a result, the crankshaft causes the driveshaft to move, which is like a bicycle chain. This causes the axle and tires to rotate, which causes the car to move.
Inventor and mathematician Charles Babbage created the first dynamometer in the late 19th century.
RPM must be within a specific range for a person’s car to run smoothly and efficiently. Incorrect engine measurements can be a sign of engine problems. Dynamometers allow the car owner or mechanic to test the RPM’s to make sure they are where they need to be.
Charles Babbage, often referred to as the “father of computing,” created the first dynamometers in the late 19th century. As a mathematician and engineer, he was aware of the wide margin of error found in many mathematical tables. So his dream was to create a machine that could perform mathematical operations without errors.
Many credit Charles Babbage with the idea behind computers. However, using the same concept, he also realized that a machine could be created to count the number of times an engine rotated the tires of a vehicle. That’s where dynamometers were born.
Charles Babbage’s original dynamometers were developed on two machines. One, called an engine dynamometer, is connected directly to the engine. Engine dynamometers require the engine to be removed from the vehicle before measurements can be taken. Therefore, it is not always the most practical option.
Chassis dynamometers are the other type. These dynamometers allow you to read RPM without removing the engine. The vehicle’s tires are placed on the chassis’ dynamometric rollers and the vehicle is accelerated to a certain speed. Chassis dynamometers provide readings of the car’s power output, as well as how many times the wheels have been spun.
Both types of dynamometers absorb power from a running engine and measure the torque required to absorb that power. Once the machine has these readings, it calculates the RPM of the engine. Many dynamometers today are connected to computers, which can graph the capabilities and output of the engine.