Ponte posteriore con alberi oscillanti (was: roll centers)

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

Will Owen writes "simple swing axles, such as were used on VWs and early
Porsches, have a roll center well above the axle centerline - -  "

 Such as were used on VWs and early Porsches AND on all road-going Alfas from
1935 through 1949 and on all competition Alfas from the 1935 tipo C through
1950, the last year of the tipo 158/47 before it became a 159 with a De Dion.
(Skipping the De Dions on the 512 prototype and the 163 project-) Swing axles
were also used on Mercedes and Auto Union and their antecedents, and on Tatras
and on Triumph Heralds and on slews of other cars. Offhand I can't think of a
vintage RWD car with IRS which did not have swing axles, although there must
have been some. (The MB did a nice trick using swing axles with a single low
pivot.)

 On the whole roll-center bit, Racecar Engineering Vol. 3 No.5 has a pair of
articles, one ABOUT Arthur Mallock and the other BY Arthur Mallock, published
posthumously. The extended caption under figure 3, "Sideways location using
the Mumford system", starts "We have tried nine different systems of sideways
axle location. The requirement is to provide a rollcentre which stays constant
relative to the chassis with suspension travel. In this respect, the popular
axle-mounted Watts linkage is the worst." I'm an agnostic (and/or ignoramus)
on suspensions, being happy enough with what Alfa gave me, but they looks to
me like what should be interesting reading for improvement-minded track
people.

 Cheers

John H.

Raleigh, N.C.

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