What are four types of structures?

The four core structures of an automobile include the engine, chassis, body, and electrical equipment. As the power source, the engine consists of the crankshaft-connecting rod mechanism, valve mechanism, as well as fuel supply, cooling, lubrication, ignition (for petrol engines), and starting systems, with diesel engines not requiring an ignition system. The body is categorized into unitary construction (passenger cars/buses) and non-unitary construction (truck cabs and cargo boxes), encompassing the outer panels, doors, seats, and comfort features such as air conditioning. The electrical equipment incorporates the battery, alternator, and electrical components (e.g., lighting and signaling systems) to form the vehicle's electrical network. These structures function in concert to guarantee power transmission, safe operation, and ride comfort, while regular maintenance prolongs the service life.