Swing axle

A swing axle is a simple type of independent suspension designed and patented by Edmund Rumpler in 1903. This was a revolutionary invention in the automotive industry, allowing wheels to react to irregularities of road surfaces independently, and enable the vehicle to maintain a strong road holding. The first automotive application was the Rumpler Tropfenwagen (emulated by the Mercedes 170), the Standard Superior and the Volkswagen Beetle.

Some later automobile rear 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. It was also used in early aircraft (1910 or before), such as the Sopwith and Fokker, usually with rubber bungee and no damping.

The swing axle suspension has two advantages over the typical live axle:

Several engineering options can limit swing axle handling problems, with varying success:

Ralph Nader in his 1965 book Unsafe at Any Speed detailed accidents and lawsuits related to the shortcomings in 1960-1963 models of the first generation Chevrolet Corvair, swing-axle design, and identified a Chevrolet engineer that had fought management who eliminated a front anti-roll bar for cost reasons. 1964 models were fitted with a front anti-roll bar as standard equipment, in addition to a rear transverse leaf spring, thus improving emergency maneuver stability. Second generation Corvairs (1965–1969) used a true independent rear suspension (IRS) system.

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