The distributor consists of a circuit breaker, a distributor, a capacitor and an ignition advance adjustment device. The function of the circuit breaker is to control the on and off of the primary circuit of the ignition coil so as to induce high voltage in the secondary circuit. It consists of a breaker cam, a breaker contact connected in series in the primary winding circuit of the ignition coil, and a breaker movable contact arm. The number of lobes of the breaker cam is equal to the number of cylinders of the engine, so that each cylinder of the engine can be ignited once in a working cycle. The breaker cam is driven by the engine camshaft and rotates at the same speed. When the circuit breaker cam rotates, the lobe of the cam continuously pushes against the movable contact arm of the circuit breaker, so that the contacts open and close continuously, and control the on and off of the primary circuit of the ignition coil and the work of the ignition system. Therefore, the circuit breaker is equivalent to a switch controlled by a circuit breaker cam.