I have taken possession of a new 'old' lathe, a very hefty Lang Junior 6.5" from the 1950s, and have a query as to gearbox change wheels. The lathe has twin systems, a fixed set of wheels from headstock down into the gearbox, which I have not revealed yet, behind covers visible in this picture, and I do not know quite what they connect to in the screw cutting gearbox.
Then, there is further provision for externally mounted change wheels, to the exterior of the screw cutting gearbox, a banjo and three mounts for wheels.
I have no change wheels with the lathe, and from dry, dusty state of the architecture here, I am uncertain this lathe ever had them. Neither does it have a thread dial indicator.
Only guidance from a Lang Junior Owner's Manual states that change wheels were used for Whitworth and Metric threads, and that when the lathe was not being used for screw cutting that these were to remain unengaged.
This has suggested to me that the inner wheel train connects down not to the lead screw but to the power shaft, but it is by no means certain until I do a bit more dismantling.
Have any members any knowledge of this lathe, or such a system, which seems to me a bit of an oddity.
It is not easy to understand this, without further steps.
The gearbox information plate has no screw cutting guidance, only cutting speeds, surfacing and sliding.
It has six speeds, set by twin levers, and runs in a full oil bath.
Any help will be much appreciated.
Many thanks.
Chris Mills.

Edited By CHRISTOPHER MILLS 1 on 10/02/2016 10:51:52