How to connect the main switch of automobile electromagnetic power supply

There are two ways to connect the main switch of automobile electromagnetic power supply:

1. Usually, the negative electrode is controlled. One large terminal is connected to the negative electrode of the battery, and the other is connected to the beam of the vehicle. One small terminal is connected to the big terminal, and the other is connected to the first gear of the ignition lock. ?

2. There are few positive terminals to be controlled, and the connection mode is big terminal, with one end connected to the positive terminal of the battery, one end connected to the general positive terminal of the vehicle starting motor and the assembly line, and the small end connected to the negative terminal and the ignition lock.

The wire core is generally copper, because copper is a common metal with low resistivity and good toughness, which is more economical. ?

If the wire used is short, aluminum wire is sometimes used, but the resistivity of aluminum wire is higher than that of copper wire, so the core of aluminum wire will be thicker to reduce the resistance, but the obvious advantage of aluminum wire is that the price is much lower than that of copper wire. ?

Automobile shell is made of steel plate, carbon fiber, aluminum and reinforced plastic. The materials of automobile shell and different parts are different for different purposes. Generally, it is steel plate, Audi luxury car is aluminum, racing car is carbon fiber, and the hood of Hummer H2 is FRP.

Filament is a metal wire in a light bulb or electron tube, mostly a thin tungsten wire, which can emit light, heat, emit electrons or produce rays after being electrified.

The cylinder block and cylinder head of traditional engines are made of cast iron.

However, cast iron has many inherent disadvantages, such as heavy weight, poor heat dissipation and high friction coefficient. Therefore, many engine manufacturers are looking for more suitable materials to manufacture engine parts. ?

The materials of exhaust pipe and muffler are generally divided into "ordinary steel" and "stainless steel products".