Well………

The traction engine bits first.  Possibly is a 2” scale Burrell double crank compound showman’s loco “Thetford Town”.  The worm and “screw” thing you cite is the steering scroll for the steering chains and would mount across the front of the firebox.  However the boilers (which look basically the same to me!) left hand one possibly old and used, right hand one in process of build, maybe a replacement for the left hand.  The confusing thing is the chimney assembly looks like a roller headstock which would not be part of the Thetford Town.  The cylinder with the large and small bores (compound) would be for the Thetford Town (if that is what it is) the other cylinder casting is I would say a loco or stationary engine so not related to the bits you have grouped it with.

The loco looks a bit like a Hunslet (Alice Class) possibly the Don Young design.

Stationary engine, no idea!

Paul.