According to the working principle, starters are divided into DC starters, gasoline starters, compressed air starters, etc. Most internal combustion engines use DC starters, which are characterized by compact structure, simple operation and easy maintenance. Gasoline starter is a small gasoline engine with clutch and speed change mechanism. It has high power and is less affected by temperature. It can start large internal combustion engine and is suitable for high and cold areas. Compressed air starters are divided into two types: one is to inject compressed air into the cylinder according to the working sequence, and the other is to drive the flywheel with a pneumatic motor. The purpose of compressed air starter is similar to gasoline starter, which is usually used for the starting of large internal combustion engine.