A live axle, sometimes called a solid axle, is a type of beam axle suspension system that uses the drive shafts that transmit power to the wheels to connect the wheels laterally so that they move together as a unit.
A live axle consists of a central differential in a single housing that also contains the driveshafts that connect the differential to the driven wheels. The differential is connected to the engine via a swinging drive shaft and a universal joint. The complete assembly may typically be suspended with leaf springs, coil springs or air bags.
In small trucks solid front axles have generally been replaced by independent front suspension.
Some live axles use trailing arms, semi-trailing arms, Panhard rod, or Watt's linkage to control the vertical and lateral movements of the axle. Others, particularly older vehicles, use Hotchkiss drive, in which the leaf springs provide axle location as well as suspension.
View of My old Ford escort mk1 solid axle 1970s