A swing axle suspension is a simple type of independent suspension used in automobiles. Swing axles have universal joints connecting the driveshafts to the differential, which is attached to the chassis. They do not have universal joints at the wheels - the wheels are always perpendicular to the driveshafts. Swing axle suspensions traditionally used leaf springs and shock absorbers.
This type of suspension was considered better than the more typical solid axle for two reasons:
It reduced unsprung weight since the differential is mounted to the chassis
It eliminates sympathetic camber changes on opposite wheels
However, there are a number of shortcomings to this arrangement:
Swing Axle characteristics
A great amount of single-wheel camber change is experienced since the wheel is always perpendicular to the driveshaft
"Jacking" on suspension unloading (or rebound) causes negative camber changes on both sides
Swing axles were supplanted by de Dion axles in the late 1960s, though live axles remained the most common. Most rear suspensions have been replaced by more modern independent suspensions in recent years, and both swing and de Dion types are virtually unused today.