This model is of a prototype "transmission" I'm working on to add motion reversal and a power take off to an upcoming design. The shaft extending from the right face in the photo is the "shift" lever, allowing the reversal of the main shaft (the closest gear shaft in the photo) and activation of the power take off (the furthest gear shaft in the photo). The gear train is idle between operating modes.

A video of the prototype transmission is here: https://youtu.be/3St48Z5emT0.
A video of the prototype shifting mechanism is here: https://youtu.be/Ixf1nCeKHkI.
And a video of the combined mechanisms is here: https://youtu.be/KycMIk3yxyE.