Why do tractors need hand-cranking?

When it comes to tractors, we will definitely think of its unique "car key": crank. In fact, both gasoline engines and diesel engines can be started manually. Hand cranking is mainly to make the engine rotate into the working cycle, and then the relevant units can work step by step to complete the engine start. Both gasoline engines and diesel engines need external force to start first, but some of them are manually started, such as tractors, motorcycle pedals and Logger Vick chainsaws. There are also some electric starters, such as our cars, but the essence is the same: let the engine rotate and enter the working cycle.