To get the water spout to pull the chain over the sheaves, I had to move its centre of balance away from the tank. To do so, I made the far end out of brass and the near end from acetal, which turns nicely in the lathe. The two parts fit together with a post and hole and a dollop of epoxy; although most of the joint is mechanical.
Then I tackled something that might pass for sheaves. While the Detail Associates chain is the finest I’ve found, it is of course, far over-scale, and so the sheaves must be too. Even so, I didn’t make working sheaves, but rather used a length of 1mm brass rod held in a U-shaped length of .005″ brass sheet.
Getting the sheaves to work smoothly consumed a number of evenings, and produced a fair amount of blue air. When the sheaves were still attached to a length of 1mm rod, they worked fine. However, once they were left to swing on an eye loop, they didn’t work nearly as well. Rather than staying straight, they floated and twisted beneath the moving chain. The counterweights in particular are so light, that the slightest amount of friction stops them from working.
I think the sheaves can be made to work best if they are fixed in place against the suspending beam, and if not, the counterweights can be posed in either position for photographs with the barest touch with tweezers. So, I’m calling this part done for now.
Pembroke:87 
Rene – Why not have the chain in 2 pieces? One part is permanently fixed with the sheaves, while the other part has one end attached to the spout but the other end travels inside the tank for the mechanism to raise and lower the spout.
Jim
But then the counterweights wouldn’t move! In the end it’s all quite silly, but such is the hobby!
Have you considered making closer to scale chain?
AH
That is definitely beyond my ability!