Gearboxes With New Orange Selector & 20z Clutch Gear

[Hrafn]

Looks like I will not get a chance to finish mine any time soon, unfortunately.  The latest is here if anyone wants to use it as a jumping off point; it now just lacks a 180 degree limiter for the shift axle.

The pictures show it in R; note you can only shift to 1 from here thanks to the blue cross blocks.

6 hours ago, T Lego said:

Note: I am almost done with the dual clutch system and rear axle integration

 

I am curious to see your dual clutch solution.  It seems like you will need separate clutches for both the input and the output, since the half-gearbox that has it's selector at 45 degrees will have two gears engaged simultaneously and will therefore lock up both the input and the output - or have I misunderstood your design?  I certainly ran into that problem when I experimented with using 45 degree shifts.

[T Lego]

2 hours ago, Hrafn said:

I am curious to see your dual clutch solution.  It seems like you will need separate clutches for both the input and the output, since the half-gearbox that has it's selector at 45 degrees will have two gears engaged simultaneously and will therefore lock up both the input and the output - or have I misunderstood your design?  I certainly ran into that problem when I experimented with using 45 degree shifts.

This is what I have right now:

The odd and even gearbox outputs are connected via the dual clutch system that you can see on the right. The shifter axle is connected to the third rotatry catch via  two 12t gears, a 16t gear and an 8t gear. When I use the gearbox, I do not experience that the input is locking up. 

[Hrafn]

58 minutes ago, T Lego said:

The odd and even gearbox outputs are connected via the dual clutch system that you can see on the right. The shifter axle is connected to the third rotatry catch via  two 12t gears, a 16t gear and an 8t gear. When I use the gearbox, I do not experience that the input is locking up. 

Thanks for sharing it!  I am glad you were able to make it work.  It must have been something about my particular prototype that made it lock up.

[woodstock]

How do I prevent the orange selector from going from "4th gear" to "1st gear". Some folks here mentions the need to prevent it from "7th gear" to "reverse". I guess it is the same thing.

Also, do you have any suggestion on a compact motorized limiter for the orange selector?

Thanks alot!

[SNIPE]

23 hours ago, woodstock said:

How do I prevent the orange selector from going from "4th gear" to "1st gear". Some folks here mentions the need to prevent it from "7th gear" to "reverse". I guess it is the same thing.

Also, do you have any suggestion on a compact motorized limiter for the orange selector?

Thanks alot!

Good question.

You need a +/- 90° stepper mechanism with its input axle hooked up to a servo motor. The orange gear shifter is hooked up to the stepper output.

Here is one example of one: https://www.youtube.com/watch?v=m4ZYVX9cAh0

This stepper output needs to be limited to +/-90°. so that it cannot go past 4th gear when upshifting  or go past 1st gear when downshifting

You'll also need a white clutch gear since you're mechanically limiting the output rotation to 180° unless you can somehow use the motors rotational degree limitation for the stepper output too. Probably using liftarms as levers.

Luckily the elastic bands used in stepper mechanisms are weaker than the springs in a white clutch gear, so the stepper should work first then when it gets limited to 180° it should trigger the white clutch gear. thus, not stressing anything.

The stepper is needed because if you let go of the remote-control lever when driving a servo motor, the servo will go back to its neutral state and then it will downshift, which is not what we want :)

Regards, Snipe.

Edited October 24, 2018 by SNIPE

[SNIPE]

HI,

So I think I'm on the right track with something like this:

It is a modified version of Lego Technic Masterys simple stepper.

The lime pulleys limit the gray connector that is above it to +/- 90° thus it is limiting the orange shifter to 180° in total.

I've yet to build and test it with real parts, however if it works, I have an idea for a simper, smaller and stronger stepper by using a rubber 2x2 liftarm instead.

Happy Building, Snipe

 

Edited October 24, 2018 by SNIPE

[woodstock]

On 10/23/2018 at 4:32 PM, SNIPE said:

 

The stepper is needed because if you let go of the remote-control lever when driving a servo motor, the servo will go back to its neutral state and then it will downshift, which is not what we want :)

Regards, Snipe.

Thanks. So if I use an EV3 medium motor then I don't need to use a stepper? Can I assume that the motor is accurate enough to do 90 degree turn without a stepper?

[SNIPE]

Actually, I build the mechanism exactually as shown in the video and it simply does not engage properly half of the time so thats that There are other stepper mechanisms out there however such as in technic supercar MOCS.

On 10/30/2018 at 8:18 AM, woodstock said:

Thanks. So if I use an EV3 medium motor then I don't need to use a stepper? Can I assume that the motor is accurate enough to do 90 degree turn without a stepper?

You should be ok by relying on the motor to be programmed to stop at a certain point in rotation, since NXT/EV3 motors have rotary encoders built into them. I suspect the new mindstorms forum will have more idea on this than I. bare in mind that these motors are much slower than power functions motors, and bulkier.

If not, you can simply limit how much the motor rotates by attaching a connactor to the motors output and having beams that limit how much the motor can rotate.

You'll want a white clutch gear attached too, so that when the motors rotation is limited, it does not put strain on the motor or break your model.

Edited October 31, 2018 by SNIPE

[woodstock]

9 hours ago, SNIPE said:

Actually, I build the mechanism exactually as shown in the video and it simply does not engage properly half of the time so thats that There are other stepper mechanisms out there however such as in technic supercar MOCS.

You should be ok by relying on the motor to be programmed to stop at a certain point in rotation, since NXT/EV3 motors have rotary encoders built into them. I suspect the new mindstorms forum will have more idea on this than I. bare in mind that these motors are much slower than power functions motors, and bulkier.

If not, you can simply limit how much the motor rotates by attaching a connactor to the motors output and having beams that limit how much the motor can rotate.

You'll want a white clutch gear attached too, so that when the motors rotation is limited, it does not put strain on the motor or break your model.

Thanks, I agree. EV3 motor + white clutch + liftarm blocker should be sufficient. Thanks!

[BusterHaus]

On 10/30/2018 at 4:18 AM, woodstock said:

Thanks. So if I use an EV3 medium motor then I don't need to use a stepper? Can I assume that the motor is accurate enough to do 90 degree turn without a stepper?

 

On 10/31/2018 at 4:58 AM, SNIPE said:

You should be ok by relying on the motor to be programmed to stop at a certain point in rotation, since NXT/EV3 motors have rotary encoders built into them. I suspect the new mindstorms forum will have more idea on this than I. bare in mind that these motors are much slower than power functions motors, and bulkier.

If not, you can simply limit how much the motor rotates by attaching a connactor to the motors output and having beams that limit how much the motor can rotate.

You'll want a white clutch gear attached too, so that when the motors rotation is limited, it does not put strain on the motor or break your model.

The small EV3 motor is comparable in size to a PF L motor.  It is very precise and will stop at exact positions.  You will not need a white clutch gear, as the position is always known and you can use a homing cycle when starting the program to find the rotation limits.

The drawback is that the controller brick is bulky in comparison to a PF battery box and IR receiver.  You will likely have to sacrifice some of the interior to fit the controller brick and a gearbox.

[1963maniac]

Hey Didumos69! I've been thinking about your transmission tunnel lately. I was wondering why not add reverse in the 2 speed gearbox, using a third clutch gear? Can that be done?

Edited January 18, 2019 by 1963maniac

[Didumos69]

23 hours ago, 1963maniac said:

Hey Didumos69! I've been thinking about your transmission tunnel lately. I was wondering why not add reverse in the 2 speed gearbox, using a third clutch gear? Can that be done?

You can do that, but the thing is that when you would want to shift from 1st gear to R, you would need to shift the 4-speed back from 1st to 4th gear. So the gear ratio of R in the 2+R gearbox would have to compensate for that 4th gear to get close to the 1st gear ratio, while the third clutch gear you are suggesting, would be on the 5th to 8th output axle, which is the fast one used for 2nd gear in that gearbox.

I also don't see a way to add a gear block preventing shifting further back from 4th to 3rd to 2nd to 1st gear in the 4-speed gearbox while the 2+R gearbox is in R.

Hope this makes sense.

Edited January 19, 2019 by Didumos69

[msk6003]

 

Orange selector can mesh with other piece rather than transmission driving ring. This will be useful?