How Does a MacPherson Strut Work?

A MacPherson strut uses a hub carrier with two mounting points that connect and dictate orientation of the wheel assembly. The axis of the strut itself is the upper steering pivot.

By utilizing a hub carrier or steering knuckle with two mounting points, a MacPherson strut dictates the lateral and longitudinal orientation of the wheel assembly. This is done by one mounting point being attached to a track control arm, while another is attached to an assembly with a shock absorber or coil spring. The axis of the strut works as the upper steering pivot, which is attached to a tie rod end connected to a steering gear.

The MacPherson strut uses a single component to replace two components: a suspension mount for a wheel and a pivot for the steering. Prior systems used a shock absorber or a spring for the suspension and something similar to a kingpin for the steering pivot. The upper control arm is eliminated in this system; this has the advantage of requiring less components and taking up less space.

A disadvantage in the way the MacPherson strut works is the changing of the camber angle when the vertical position of the wheel changes. This causes the system to be inferior in regards to handling characteristics when compared to other suspension systems.