Struts are used in most modern suspensions and combine the task of suspending the vehicle's weight and controlling wheel movement. A shock absorber is part of the strut assembly and is used to control suspension movement.
Struts are essentially a combination coil spring with a shock absorber in the middle. The coil spring and shock push against large, round mounts, which are connected to the top of the wheel hub on one side and chassis on the other.
Struts are mounted almost vertically in most cars but maintain a slight lean in both the lateral and longitudinal directions to compensate for suspension movement.
Shock absorbers resist movement in both the upward and downward directions, which prevents the spring from sending its associated wheel into an uncontrolled harmonic bounce.
Struts do an acceptable job but can cause unwanted wheel lean when cornering. Struts can be adjusted to negate this effect somewhat but are primarily designed to save weight, space and cost when manufactured.
Struts are used almost exclusively on front and all-wheel drive cars because the driveshafts pass below the entire assembly and do not interfere with spring placement.
