So,
1) I'm new, so Hi.
2) I've managed to work out all the gearing and framing for a 8 speed sequential progressive transmission.
3) I have found that I really not fully sure how I want to go about designing a stepper to shift this transmission.
This transmission is what I have been building up to over the last few months.
8 speed sequential progressive transmission
I am utilizing my 4 speed sequential progressive transmission (which is based upon the gearing of TLG's 42056 transmission), and my 2 speed sequential transmission as a low/high stepper to double the gearing. Both of these are available as MOC's on Rebrickable. I want to thank my son for the idea of using a low/high stepper for more gears.
This results in the following gear ratios:
1 - 1:0.33
2 - 1:0.44
3 - 1:0.60
4 - 1:0.80
5 - 1:1
6 - 1:1.33
7 - 1:1.67
8 - 1:2.22
The gear map is a bit more tricky than my 4 speed. With output at the top and input at the bottom (this would be the 3 16t gears).
For the high/low (top part) High is selected up and low is selected down.
For the 4 speed it is again mapped:
2---3
4---1
so the gearing to get those ratios is:
1L, 1H, 2L, 2H, 3L, 3H, 4L, and 4H
So now that I came bearing gifts, this is what I need help on. I loosely designed a stepper shifter. It is currently not functional due to interference, and I have no idea how to attach it.
(file removed new version available below)
To bring this stepper shifter closer to functional, a rubber band has to be threaded through the left upper arm, down under the center 5l cross axle and back up to the right friction arm. This band's tension will force the stepper shifter to want to stop every 90 degrees. The stepper shifter has been built such that the left axle is set to first gear, and the right is set to low. The steppers shifters fuction is such that the right axle shifts the H/L transmission, and rotates 180 degrees per step. Every other 180 rotation, it will step the left axle 90 degrees, selecting the next gear up. The orange outputs would be connected to the shifting pawls . At 3rd gear/Low the stepper shifter experiences interference. I know that it would be easy to remove this interference, but I am stumped on how to connect the shifter to the transmission and have not bothered to solve the interference at 3L. Once the step shifter is solved, I need to make a paddle shifter stepper that develops 180 degrees of rotation, or take a 90 degree paddle shifter stepper and gear it up to 180.
Maybe you guys have some thoughts.