Turbine engines have pretty much taken oven in the aviation world, but
there a lot of radial engines out there still. An interesting thing
about radial engines. If it's a single bank or row of cylinders, there
is only one crank throw - doesn't matter if it's a 5 cylinder, 7
cylinder or 9 cylinder engine - one crank throw. So how do they get 9
cylinders onto a single crank throw. That is the question. Well, they do
it with a Master Rod. A single rod that has a bunch of holes in it to
which all the other rods attach. The only rod to travel in a perfect
circle is the master rod. The rest, because of the way they attach, the
rod end travels in an ellipse. What is really interesting is the master
rod is held on there with stretch bolts. In some cases the cranks shaft
is two part and a clamp holds them together - but again - it's stretch
bolts that hold the clamp tight. They are high torque, one time only
use. If you over torque , you have wasted a whole lot of money because
those puppies cost dearly.  Stretch bolts to me were always kind of
scarey, but the engineers put them in all kinds of places and claim they
are good.

John

John Rodgers
Clayartist and Moldmaker
88'GL VW Bus Driver
Chelsea, AL
Http://www.moldhaus.com

On 9/25/2011 10:20 PM, Scott Daniel - Turbovans wrote:
> there's a stretch bolt holding the timing belt
> sprocket onto the flat noise of the crankshaft ( very dumb design I
> think..........no, I know.......because I've seen it screw up ..