How do shock absorbers use oil flow to provide damping?

A shock absorber is a hydraulic device designed to control the unwanted vibratory motion of a vehicle's springs. While springs cushion the impact of road irregularities by storing energy, they can cause the vehicle to bounce excessively; shock absorbers function as a control system to dampen or dissipate that energy.123

In a typical direct-acting shock absorber, a piston slides within an oil-filled cylinder. When the vehicle encounters a bump or dip, the resulting relative motion between the frame and the axle forces the piston to move against the oil. The oil is then compelled to flow through small openings or spring-loaded valves.1

This restricted flow creates a resistive force that opposes both the compression and the stretching of the springs. By limiting the rate at which the oil can move, the device effectively slows down the movement of the suspension, thereby dampening the vibration of the vehicle body and ensuring a more stable ride.132