How much less power does a steam locomotive's rear cylinder volume produce compared to front?

[Robert Gift]

Some of the rear cylinder volume is taken up by the piston shaft* . *Sorry I do not knowhat it is called.
Thank you.

 

[bnsf971]

Any difference in power output is minimal. Steam is a vapour, and it simply doesn't expand quite as much due to the volume of the rod. The potential energy is virtually the same.

 

[Robert Gift]

Thank you.
Yes, it would be minimal.
Buthere would be less power due to the less space in the rear volume of the cylinder.
As the piston moves forward bringing more of the piston rod into that increasing space thexpansion space ratio is decreased, taken up by more piston rod coming into that space.
Presumably the locomotive design engineers would know the difference between forward of the piston and rearward of the piston.

 

[Bob]

There is a slight difference, yes. You can hear it in the exhaust, that’s why it’s a sort of 4 beat rhythm rather than just a constant chug, chug, chug.
It evens out, since when one side is using the front, the other side uses the back half. There is enough of a difference that in extreme circumstances, you can feel the engine swing from side to side a bit.
Practically speaking, it’s not an issue.