Topic: AL106 D.M Weigel and his straight-8 crankshaft around 1907

[Allan L]

Inspired by Nicanary's iconic image of Jenks here's another iconic image which will be familiar to many - so if one of the many is still a Rookie an Expert tell us who, what and when for a point.

[Fёdor]

  Fernand Charron

[Allan L]

Not him

[Allan L]

I seem to have forgotten this so up to the expert section!

[richard cuyler]

Is it a 1900-ish straight eight and is he American?

[sixtee5cuda]

D.M. Weigel with a Weigel crankshaft in 1908  The Weigel is described as being the first British straight-8 automobile.

[Allan L]

Is it a 1900-ish straight eight and is he American?

Yes and no because:

D.M. Weigel with a Weigel crankshaft in 1908  The Weigel is described as being the first British straight-8 automobile.

Correct and a point for you.
Over a century later it's obvious that the rather flimsy design would have given trouble. Even in 1907/8 nearly 15 litres pushing all the power through the rear main journal via the webs and crankpin for cylinders 7 & 8 must have wound the crankshaft up rather a lot.

[richard cuyler]

I think the crankshaft was for a GP engine using two four cylinder blocks in tandem, which would probably explain that enormously long centre main bearing. The two cars entered in the French GP of 1907 did not finish - I wonder if, as Allan L suggests, the crankshafts were insufficiently engineered for their task and broke apart. To me it's a wonder they worked at all! 

[Allan L]

Yes it is normally stated that two four-cylinder blocks were used to make the GP engine.
The more obvious crankshaft for that type of engine would have the two halves at rightangles, so spacing the firing impulses at 90 deg. intervals, where the Weigel design fires two cylinders at a time so a double impulse happens at 180 deg. intervals - that would greatly increase the chance of torsional fracture of the drive end of the shaft.

[richard cuyler]

In addition to this, Allan, measuring Mr Wiegel's hand in the shot (using my own hand as a reference), it would seem to be about 100mm from top to base, so when that's extrapolated to refer to the crankshaft, it seems that the throw in total is around 200mm, or nearly 8". Whilst that's possibly the accepted norm for an Edwardian car engine, such a long stroke would additionally have provided enormous twisting forces on the crank.

I love these wacky engines, like the Monaco Trossi prototype GP car, with a 16 cylinder, two-stroke radial engine right at the front, driving the front wheels. It's worth a read - the car and engine were unmitigated failures, but you have to hand it to people who are prepared to swim against the engineering stream and pursue ideas which, most probably, everyone else said wouldn't work.  Of course, no computers in those days to tell a designer 'no, really, it won't work. Really. Have a cup of nice hot tea - and another think'.

Saves so much time and money.

But is the World not richer for such people? Some of these stubborn dreamers have come up with amazing, workable ideas as well.

[richard cuyler]

As an aside, I would love to have read LJK Setright's comments on a crankshaft like this!

[Allan L]

As an aside, I would love to have read LJK Setright's comments on a crankshaft like this!

Yes there are a number of things that I would have liked to read his views on - He and I were in the same library reading room at Beaulieu once, many years ago, but both so engrossed that we hardly said hello. I was a bit surprised that he was still researching Bristol Cars but then why not, just because we thought of him as The Bristol Expert.

Back to the long stroke engine the Grand Prix engine was supposed to be two of the 40 h.p. four-cylinders and I've seen 140mm stroke (5½ inches) quoted for that engine.