OK, so on steam engine (and GE 45-ton) drivers, there are side-rods set at 90 degree angles, to keep all axles in sync. Setting those drivers at that angle is called "quartering".

Was there ever occasion to use angles other than 90 degrees? Say, with a third cylinder, maybe 60/120 degrees?

I think the UP 3 cylinder jobs used 120, and I KNOW Shays do. Somewhere I have a copy of "3 Barrels of Steam". I believe the British 3 cylinder models did, too, but I don't have documentation on more than 1 or 2 classes at most, and it's pretty sketchy fan stuff. Trevor and Nigel probably know much more about them firsthand.

dave

This is actually a Willamette, not a Shay, but they both work the same way. The "quartering" is done on the drive shaft not the wheels. It's very similar to the crankshaft in an internal combustion engine.

In order to make the power as smooth as possible, Shay and Willamette (Essentially a Shay clone) use a crankshaft with 120 degree offsets for each cylinder.

I would expect that all three cylinder engines do this for the same reasons.

The UP 9000's (and probably other 3-cylinder locomotives) had the outers cylinders 120° apart but the relationship to the center cylinder has to take into account the angle that the center is at.

Steve

I thought this was how you quarter a driver!

http://www.rrpicturearchives.net/showPicture.aspx?id=1262071

A Niles Quartering Machine could be arranged for "Thirding" but I don't know if they ever sold one as such. I guess that would be called a Thirding Machine. I presume the journal on the crank axles was turned separately. I am curious how they allowed setting the wheel up in the machine and zeroing off the crank axle journal to ensure the other crank pins are machined at 60 degrees.

My understanding is that some 3-cylinder (non-Shay) locomotives had the three cylinders set at 120 degrees while others had the two outside cylinders set at 90 degrees (as on a standard 2-cylinder engine) and the inside cylinder was set to bisect the angle between the outside cranks. This gave these engines an uneven exhaust beat as there was an irregular interval in the cylinder exhausts.

I think this is called "halving".....

Wonder what the story is behind that leftover?