re: rear (?) engines and the De Dion "IRS"

["John Hertzman" <johnhertzman@domain.elided>]

Joe Elliott makes a tenable point on the mid-engine/rear-engine distinction;
late prewar/early postwar passenger cars in several cases had engines behind
the rear axle, and the few sports cars derived from them normally had the
engines also behind the rear axle. "Mid-engine" was a highly useful
distinction for those later variants which relocated the engine in front of
the rear axle but still behind the driver. The obvious quibble is that a
"front engine" should then be one which was entirely in front of the front
axle, with an engine behind the front axle considered a mid engine also. Won't
do; we would need at least front-front, front-mid, mid-rear, and rear-rear
differentiations, with some shadings, like "relatively front" for the
750/101/105/115/116/162 Alfas. Historically, however, the prewar Auto-Unions,
their Benz predecessor from the twenties, and the Alfa 512, all of which were
"mid"-engined, were invariably called "rear engined"; the position of the
engine relative to the driver, not relative to the wheels, was apparently the
critical distinction.

Joe's argument that "the fact is that for many people's purposes, a sprung
(fixed) differential is the defining factor of an IRS" is an interesting one.
Most early cars (for the first thirty years or so) had chain-drive systems
which were virtual De Dions: the differential and gearbox mounted to the
chassis frame, driving a jackshaft with chain-sprockets which drove the chains
which turned driven sprockets mounted on the wheels which were at the ends of
a dead axle. The first Benz in 1885, first Daimler in 1886, first Panhard in
1890, and first F.I.A.T. in 1899 all had this system. (The second Panhard, in
1891, was the first front-engined car.) The earliest car I know of offhand
which had the drive through a rotating (or "live") axle was an 1899
Locomobile, although there were probably earlier instances. If we go along
with Joe's two arguments, the ur-auto was a mid-engined car with IRS, and the
front-engined car with non-independent rear suspension (like the first
A.L.F.A.s in 1910) was a combination of two seminal innovations.

As Joe says, "To each his own,"

John H.
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