AddOns to 1906 Lathe transmission are	The selectors both neutural in the vertical position. Each selects one of 2 forward speeds when set left or right.	First  two speed controls.
3rd speed control	4th speed control
A view of change gears from below QC box.
Since speed selector 4 MUST work in conjuntion with "Very Low Select" above; I suppose there are really only 3 speed controls....
How are the 3 positions of the Lead Screw Engager used??

When is HW-Coupler used?    How are Knurled Knobs 1&2 used?