Which type of suspension uses two control arms, both upper and lower?

The type of suspension that utilizes two control arms, both upper and lower, is known as the Short-Long Arm (SLA) suspension. This design incorporates one long control arm and one short control arm, allowing for more precise control of the wheel's motion during suspension travel. The dual control arms serve to effectively manage the vertical and horizontal movement of the wheel and tire assembly, providing improved handling characteristics.

SLA suspension offers advantages such as better camber control, enhancing tire contact with the road when the vehicle goes through corners or over bumps, which ultimately improves stability and handling performance. This system is commonly found in many modern vehicles, particularly those that require a balance of comfort and performance, such as sedans and sports cars.

In contrast, the other types of suspension listed do not use a similar dual control arm configuration. MacPherson suspension typically employs a single lower control arm, I-Beam suspension generally consists of a rigid beam connecting two wheels, and leaf spring suspension features stacked leaves that provide support rather than articulated control arms. Understanding these differences highlights the unique advantages and applications of SLA suspension in automotive engineering.