Thermal Hopper Crankcase bearing?

I had a little session restoring/rebuilding at the weekend. I tend to stack similar jobs together an extract parts that would normally be scrap ready for reusing.

I realised that I had the remnants of a Thermal Hopper that had been soaking in one of my "highly inflammable" concoctions as it was seized solid. Everything piston, cylinder, crankshaft (also broken) and the backplate had been "glued" on as a gasket substitute.

However after the long soaking - it became clear that as the gunge had peeled away - the crankcase sported a bronze/brass liner/bearing for the crankshaft. (See second picture below)



Everything was still seized solid (really solid!) but a slight amount of heat and the backplate came free.




All carboned up but ready for cleaning.

I cleaned up the crankcase and then went to peruse my collection of Thermal Hopper Crankcases. I found that some have the liner and some don't. I did not find one with a lip at the back that did.


Everything else - still solid. Even the piston rod could not be moved.

Now for a more vigorous application of heat resulting in smoke and flames!



That did the trick and a quick twist in a wooden vice and off came the cylinder head.



In the next photos the middle crankcase does not have the liner/bearing the outer ones do.




My questions are:-

1. Was the bronze/brass bearing only applied to the Thermal Hopper Crankcase? (Straight through mounting lugs no thread)?
2. Was it applied to the crankcases with the lip at the rear?
3. Was this only in early crankcases?