First draft calculations for balancing is complete. Having input the masses and inertias of each reciprocating component as derived from CAD modelling, and assuming ⅔ of it was balanced on the leading axle, I get a force at 6 revs/s of 148kN, as compared with 141kN (10kN = 1 ton near enough) reported by the Bridge Stress Committee in 1926. Obviously these figures are way beyond anything allowed now the railway knows about the problem. It was OK with Sir Richard Moon with average speeds of 40 mph so it was assumed OK at any speed!
If we balance equally over the two driving axles we halve the hammer-blow; then if we reduce the weight of reciprocating components by 40%; add a reduction in mass balanced to 40% we reduce hammer blow to 27kN, and still compared to the original have less out-of balance horizontally.
OK, mass reduction is a challenge, but at least we have a handle on it now, we can ask what speed we would be allowed and set objectives accordingly.