The vehicle chassis typically consists of five major systems: the fuel system, the powertrain, the steering system, the running gear, and the braking system. The fuel system includes the fuel tank, fuel pump, and fuel lines, among other components. The powertrain comprises the engine, final drive, transmission, differential, and driveshaft, among others. The steering system consists of the steering wheel, steering column (with a universal joint), and steering gear, among other parts.

Suspension systems are classified into three types: independent, non-independent, and semi‑independent. 1. In an independent suspension system, each wheel on either side is suspended individually from the vehicle frame or body via an elastic suspension mechanism. Most modern passenger cars employ independent suspensions, which can be further categorized—depending on their structural design—into transverse‑arm, longitudinal‑arm, multi‑link, strut, and MacPherson types. The advantages of independent suspension include: reduced vehicle weight, which minimizes impact forces on the body and enhances tire traction; the use of softer, lower‑stiffness springs to improve ride comfort; the ability to lower the engine mounting position and reduce the vehicle’s center of gravity, thereby improving stability; and independent vertical movement of the left and right wheels, with minimal interaction between them, which helps reduce body roll and vibration. However, independent suspensions also have drawbacks, such as a complex structure, higher cost, and more difficult maintenance. Moreover, their intricate design may encroach upon interior passenger space. 2. A non‑independent suspension system connects the left and right wheels via a single axle (or structural member). Depending on the specific suspension architecture and its attachment to the vehicle body, there are various configurations of non‑independent suspensions. Common types include leaf‑spring, torsion‑bar axle, and torsion‑beam designs.

The suspension system serves to transmit the forces and torques acting between the wheels and the vehicle frame, while also cushioning impacts transmitted from uneven road surfaces to the frame or body and attenuating the resulting vibrations, thereby ensuring smooth vehicle operation.

The air suspension system comprises air springs, shock absorbers, a guiding mechanism, and a vehicle‑height control system. 2. Air suspension systems typically employ bellows-type air springs. 3. Shock absorbers are primarily used to dampen body vibrations. 4. The guiding mechanism consists of longitudinal and lateral thrust rods, among other components, and serves to transmit longitudinal and lateral forces as well as torques generated during driving and braking between the vehicle body and the axles. 5. Vehicle‑height control systems are classified into mechanical systems and electronically controlled systems.

Simply put, the suspension system refers to the entire support structure that connects the vehicle body to the wheels via springs and shock absorbers. Its primary functions are to support the vehicle’s weight and enhance both driving and ride comfort. Since different suspension systems are employed, the suspension is one of the four major subsystems of the vehicle chassis, linking the wheels to the frame and consisting mainly of three fundamental components: elastic elements (such as springs and bushings), guiding mechanisms (like control arms), and dampers.