Originally Posted By: Stan
I would love to see what that bolster looks like on the inside, underneath the tumbler. Is the purpose of it to give a longer bearing surface for the axle?

I've never seen one like that disassembled.

SRH


Stan,
The lockplate is quite flat behind the tumbler: the bolster was only on the outside. Yes it was put there to increase the bearing surface for the tumbler pivot. They fell out of use as it became clear they were unnecessary.
Best Toby