Electric motors, bearings and gearboxes are the parts that turn almost everything in a factory. A motor turns electricity into rotation. A bearing lets the motor's shaft spin smoothly, with little friction. A gearbox changes the speed of the rotation and increases its force.
Consider a 7.5 kW motor that drives a conveyor in a packaging plant. The motor turns at about 1,440 revolutions a minute, which is far too fast for a conveyor belt. A gearbox with a ratio of 20 to 1 reduces this to 72 revolutions a minute and raises the turning force to about twenty times, less a small loss in the gears. Two bearings hold the shaft in place. Each bearing is a ring of small steel balls or rollers.
Motors are labelled with an efficiency class, such as IE3. A higher class wastes less electricity as heat. Since a motor runs for thousands of hours a year, a plant that pays for electricity gets back the extra price of an efficient motor within a few years. Bearings are of two common kinds: ball bearings, for light and fast loads, and roller bearings, for heavy loads. A bearing needs the right grease in the right amount. Too little causes wear, and too much makes it hot.
Bearings are the part that fails most often. They wear, they run short of grease, and they heat up. A failing bearing makes more vibration and more heat before it breaks. That is why predictive maintenance sensors are fixed to motors to measure vibration and heat. The readings go to asset performance management software, which warns the maintenance team weeks ahead.
Motors and bearings are sold in two markets. One is the new-machine market, where the machine maker chooses them. The other is the replacement market, where the factory buys them again when they wear out. The second is large, and it is a part of aftermarket services.
The speed of a motor is set by a variable frequency drive. In a vehicle, the same parts make up the powertrain.