What are couplings, reducers, and brakes?
Coupling: A mechanical part used to connect two shafts (the driving shaft and the driven shaft) in different mechanisms so that they can rotate together to transmit torque. In a broad sense, couplings also include expansion sleeves, universal joints, etc. The connection forms are also extended to shaft and hole connection, shaft and flange connection, flange and flange, flange and hole connection, etc.
Reducer: a mechanical part used in transmission equipment to reduce the speed of the motor and increase the output torque, also known as the reducer. It is a kind of transmission, the most common is the transmission device used to change the speed on the car (the main function is still deceleration).
Brake: A mechanical part that enables the running equipment to overcome inertia and stop quickly, also called a brake. There are electromagnetic, mechanical, hydraulic and so on. Commonly used are hub and disc brakes on bicycles and automobiles.