Steam engine question

[Fluesheet]

As far as interesting facts are concerned , Steam locos were very hard on the rails. The side rods thrashing back and forth and cylinders moving them caused a right left motion which was detrimental to the track.

This is true. The majority of the weight in the counterweights was there to offset this rocking couple. It was always a compromise though - completely offsetting the piston thrust with counterweight would leave the wheel so unbalanced that it could begin hopping on the rail at higher speeds. This hammering was very destructive - C&O's T1 2-10-4, N&W's K3 4-8-2 and B&O's "Big Six" 2-10-2's spring to mind as locomotives that had a reputation of breaking rail.

The rocking couple is why higher speed locomotives generally had four-wheel lead trucks - more wheels to damp the oscillation. The mechanism for doing so is interesting, but that's another story.

That and other shortcomings aside, steam, as wel all know, is still > diesel....

Matt