The earliest car door lock is a mechanical door lock, just used to prevent the car door automatically opened when the accident, only play a driving safety role, not anti-theft role. With the progress of society, the development of science and technology and the continuous increase of car ownership, the doors of cars and trucks manufactured later are equipped with a door lock with a key. This door lock only controls a door, and other doors are opened or locked by the door lock button on the inside of the car. In order to better play the role of anti-theft, some cars are equipped with a steering lock. The steering lock is used to lock the steering shaft of a car. The steering lock is located with the ignition lock under the steering dial, which is controlled by a key. That is, after the ignition lock cuts off the ignition circuit to turn off the engine, turn the ignition key left again to the limit position, and the lock tongue will extend into the steering shaft slot to mechanically lock the steering shaft of the car. Even if someone illegally opens the door and starts the engine, the steering wheel is locked and the car cannot turn, so it cannot drive away, thus playing the role of anti-theft. Some cars are designed and manufactured without a steering lock, but use another so-called crutch lock to lock the steering wheel, so that the steering wheel can not turn, can also play a anti-theft role.
Point switch is used to switch on or off the engine ignition circuit, according to a key to open a lock, but also plays a certain role in anti-theft.
