This is the 3rd wood mechanical marvel I have designed from thebook507 Mechanical Movements by Henry Brownwhich is a reprint of a book first written in 1868. Here is the concept drawing and description of operation from the book:
232. Intermittent circular motion is i parted to the toothed wheel by vibrating arm, B. When the arm, B, is lifted, the pawl, C, is raised from between the teeth of the wheel, and, traveling backward over the circumference, again drops between two teeth on lowering the arm, and draws with it the wheel.
Rather than raise and lower arm B by hand, I wanted to make a crank type mechanical model, so I added a crank and connecting rod to operate the model. Here is the Google 3D sketchup model of my design:
Friction turned out to be a major factor in this model working well. There has to be enough friction between the gear wheel and the rear mounting plate for the gear to stop between indexes. I was careful where I applied the Johnson Wax at final assembly so the friction came out right (no Johnson Wax between back of gear and rear mounting plate, etc).
Here is the finished model:
Here is a close-up of the ratcheting mechanism:
The yellow dyed piece of maple adds some color to the model. This is one of the coolest models I have made.......it terms of mesmorizing to watch it run.
I took this model to work, and my co-workers think it is one of the neatest models I have made. They are also memorized watching the mechanicsm lift the pawl up and over the gear teeth when it indexes