8 Speed Sequential and Progressive transmission - NEED HELP

[jfb9301]

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.

Edited November 30, 2016 by jfb9301

[suffocation]

Hi there,

I can't open lxf files on this computer so this is just a shot in the dark. Have you tried implementing Didumos69's 90° limiter? You can find it here. More info also here.

(Any Italian reading the second sentence is going to have a laugh).

Edited November 29, 2016 by suffocation
Italian humour bleeding into British aplomb

[jfb9301]

The stepper shifter I created has a 90 degree limiter, this is more of an issue on how to gear/connect it to the transmission. My limiter is similar, but not the same, and has to 90 degree stop 2 axles not just one.

Edited November 29, 2016 by jfb9301

[jfb9301]

hmmmm, I seem to have been using the wrong terms, that would cause some confusion. I have been saying stepper and meaning shifter. I have not even made it far enough to worry about a stepper. Heck I might consider using Didumos's until I get one worked out.

Edited November 29, 2016 by jfb9301

[jfb9301]

I'm on to something, I solved the interference, made the shifter change more smoothly, and added a 8-1/1-8 shift block all in one design. I don't have time to make the changes to the lxf, but will work on it tonight or tomorrow. I've got to go to work, I need to pay for more parts somehow.

Edited November 29, 2016 by jfb9301

[Didumos69]

Welcome @jfb9301! I know @Jeroen Ottens did some work on an 8-speed sequential shifter for his DB11. Note that the auxiliary shifter axle with green +0 liftarm needs to have a 45 degree orientation. Also note that the track rod driving the green secondary clutch needs to make twice as much travel to make sure it always engages one of the adjacent clutch gears, hence the yellow construction between the secondary shifting axle and the attached track rod. If you are to use the 90-degree limiter, be sure to use one for each shifting axle.

And when al works well you could of course try using my stepper (without limiter) to drive your shifters .

Courtesy of Jeroen Ottens.

Edited November 29, 2016 by Didumos69

[brunojj1]

1 hour ago, Didumos69 said:

...

I know @Jeroen Ottens did some work on an 8-speed sequential shifter for his DB11.

...

 

Are you sure if it really works? As far as I know this shows a nice concept created in LDD and if it works - IMO it would mean really the pinnacle of Technic gearboxes. 

But I haven´t seen it working yet, nor have I seen the complete Aston Martin, therefore I´m very curious and hopefully my doubts are wrong ..

[jfb9301]

Not sure about the work of others, but I build mine with real parts. I build with parts on hand. After I know it works mechanically, I build it in LDD. I have quite a bit of spare parts on hand.

Often, I build a small mock up, make sure it does what I want, then incorporate it into a larger design. My shifter is the mock up of how I will build the shifter onto the transmission.

[Jeroen Ottens]

32 minutes ago, brunojj1 said:

Are you sure if it really works? As far as I know this shows a nice concept created in LDD and if it works - IMO it would mean really the pinnacle of Technic gearboxes. 

But I haven´t seen it working yet, nor have I seen the complete Aston Martin, therefore I´m very curious and hopefully my doubts are wrong ..

They are , just posted an update

[jfb9301]

(file removed new version available below)

So I got a chance to build my new shifter in LDD. Due to size and layout, it will not fit the transmission, but now that I have the 90/180 changes with 90 degree stops, 8 to 1/1 to 8 block and smooth operation, I can work out how to attach it to the transmission.

 

Does anyone have feedback on the gear ratios? having 3 over drives seems a bit odd, but I don't know what real 8 speeds have for ratios. Could I need another reduction? Could a layout change to have 1:0.75 for the low and 1:1 for the high improve things? This later would result in 2 over drives and a first gear around 1:0.2 if I recall correctly. I have the exact maths for all ratios stored somewhere on this computer box, but knowing all the ratios exactly is not really relevant right now.

All feedback is appreciated, though I expect some might have to actually build the transmission to help out.

Edited November 30, 2016 by jfb9301

[jfb9301]

11 hours ago, Didumos69 said:

Also note that the track rod driving the green secondary clutch needs to make twice as much travel to make sure it always engages one of the adjacent clutch gears,

Courtesy of Jeroen Ottens.

Ingenious. I had to read your post a couple of times to fully grasp what it was he had done. I kind of like mine, but I might just have to go back to the drawing board as this might work even better.

[jfb9301]

(Broke the link, new lxf below)

More false shifting solved. I noted that the H/L transmission would find N when shifting above 8 or below 1 this was due to the 4 speed transmission being blocked, but not blocking the 2 speed transmission. The addition of the red lift arms will prevent the shifter from going below first or above eighth gear.

Edited November 30, 2016 by jfb9301

[brunojj1]

It would be nice if you would share some interesting highlighting pictures links (max width 1000 px allowed here) instead of simply document your progress. Good example from Jeroen is shown above. E.g. people like me don´t want to dive deeply into your LDD file, then rip everything apart to see all gears trying to understand it. I´m interested in your gearbox anyway . Thanks in advance!

[jfb9301]

This is the 4 speed

This is the 8 speed, the 4 speed is obviously to the left, and the high/low 2 speed is to the right.

This is the ver 3 of the shifter 

new lxf https://www.bricksafe.com/files/jfb9301/Shifter ver 3.lxf

Edited November 30, 2016 by jfb9301