Again from industrial applications iron wound ropes seemed to stay the course for a long while. A good friend advises me that people were slow on the up take of steels were iron would do (cheap, tried & trusted) and these ropes survived in mining for years (as late as 1900 he tells me on shafts used for lowering props and maintenance in the coal fields). I am advised that iron ropes are more slippery, I believe its because wrought Iron is structurally grained in the manufacturing process and has a tendency to self lubricate due to its metallurgy, steel has a different structure altogether and does not have the same property as it has a better structure, steel ropes tension far better and have better elastic/spring properties. Plus iron wears quickers hence gets smooth flats quicker.
Certainly by 1866 there were very strong steel wire ropes about, some being associated with laying the cables from the SS Great Britain across the Atlantic when the cables were lost and needed lifting and recovering... There were various sections available based around different cores, fibre, patents etc, the navy were even using them in rigging applications.
Given the duty/application of the tunneler I would like to believe they would have opted for the better strength and tensionional properties of steel cables and forged steel teeth thus making their product more viable and controllable.
In truth i think the era of the tunneler defines its materials, certainly as someone has said before on this site the teeth are the key and I think the manufacturer was making use of the latest steel technology probably including high grade alloys (inc wolfram) certainly available by then. The teeth shown would chip once worn just like modern machine tools. My point re bonding is just what you say, yes the motion would push the teeth positively into the holder but what would prevent them springing out or de-centering when the unit was with drawn from a heading for maintenance as it dragged? . Hence why I wondered if they were re-moulded in even after removal or sharpening, just a thought. Did they counter rotate the head to remove the machine from a heading for repair?? The version of tooth with the tail would have very positively located in the holder but with no resilience and would have transmitted a lot if not all of the force and vibration back through the tunneler. I think it would have had no resilience to sudden hard spots hence the move to the rubber.
Re vibration I cant say but i would imagine it would have been a low frequency/noise with powerful forces generated back thru the structure as a whole attacking the bigger joints and assemblies but not the nuts and bolts, but again this would be dependent on rate of feed, depth of cut. Given that the teeth were apparently forged then machined to a cone hence a circular edge I wonder if the teeth were prone to chip along the grain.... correct me if I'm wrong but are not tunnel borer teeth square (or rectangular) now days with out exception so that the cross sectional area of the tooth under load is greater thus absorbing more punishment.
In a saw blade application the rounded cutting edge would be fine but given a lateral force on it in tunneling at same time you have two directional forces on the tooth edge distributed over 180 degrees and a bending moment across the tooth also. The same would apply to a square tooth but the cross sectional area is greater so absorbs the punishment more.
But given the right rate of feed this would have worked a treat, probably grinding its way along smoothly, and precisely rather than gouging.
Thats my thought..... its late and i'm probably hopelessly wrong. :zzz:
Aaaaaaaaaaaaaaaaaaagh Creeper!!!!!