Solenoid for gear shift

[themountain]

Is it possible or are there solenoids who are able to shift a wraith two speed gear box ??

[jakemaxwell806]

I think a servo is used to shift my twin hammers is the set up

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[ferp420]

im sure you can but i would think a servo would be easyer and cheaper

[themountain]

Originally Posted by ferp420

im sure you can but i would think a servo would be easyer and cheaper

No doubt about that but for my build I would like to have it as small as possible. So I asked here if anybody have done that already.
I was wondering if small solenoids are strong enough to make the shift...whats the minimum for that?? Any recommendations from Axial od other brands?

[HumboldtEF]

That's an interesting Idea, I've never seen it done.

I did a bit of googling and learned a few things. Push Pull solenoids use a simple coil spring (a return spring) for the pull action, whether these small springs are up to the task of moving the shifter is questionable as you wont have much control beyond trying different springs if you can find them. Maybe you'll need to use 2 solenoids to get enough power on the pull action?
The other factor which might limit you is that solenoids have a fixed amount of travel so you wont be able to fine tune end points like with a servo. Another thing I noticed or rather didn't notice was what the torque specs are (the dont seem to list any) so I'm not sure how to judge how up to the task one might be. Then there's the actuation rod, most are just plain old rods though some have a clevis on the end, anyway connecting them to a shift rod will take a bit of creativity.
I dont know if this is different from a servo but to have the solenoid on the push stroke I think you'll be sending constant power to it, then at pull it removes this voltage. I'm just wondering how that might effect battery life or other components using the same voltage.


Dont take that as me poo pooing your idea I just wanted to layout the difficulties I see. I think it would be an interesting experiment worth exploring, though it does seem like it will take some time and patience.

[themountain]

Originally Posted by HumboldtEF

That's an interesting Idea, I've never seen it done.

Dont take that as me poo pooing your idea I just wanted to layout the difficulties I see. I think it would be an interesting experiment worth exploring, though it does seem like it will take some time and patience.

No,not at all....interesting points there to consider! I found some P/P solenoids and the torque was given at 5 N whatever that means . The solenoids have 11mm stroke which would be perfect for my gearbox. I might order two and see whats happening ;)

...to be continued.

[Itali83]

I think you’re going to find that the amperage draw that a solenoid uses will be more than what you want to deal with. Killing batteries in fast order. Keep that into consideration.

Ben

[altd896]

My thoughts on using a solenoid would be
1 the Wraith dig is 3 position, using a solenoid will limit you to just 2, drive & locked, you'll lose the freewheel option in the middle
2 most solenoids I've come across are sprung one way & powered the other, in this case I'm guessing you'd spring to drive, power to dig. However the problem may be how much power the solenoid draws when operating. A servo just sitting at a position unloaded (which a properly trimmed shift/dig servo should be) actually uses very little power.

[Greatscott]

Originally Posted by altd896

My thoughts on using a solenoid would be
1 the Wraith dig is 3 position, using a solenoid will limit you to just 2, drive & locked, you'll lose the freewheel option in the middle
2 most solenoids I've come across are sprung one way & powered the other, in this case I'm guessing you'd spring to drive, power to dig. However the problem may be how much power the solenoid draws when operating. A servo just sitting at a position unloaded (which a properly trimmed shift/dig servo should be) actually uses very little power.

Great points...

Also, a servo is very adjustable. A solenoid pretty much moves full throw no matter what.

[Voodoobrew]

They do make worm drive linear actuaters though.

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[themountain]

Originally Posted by altd896

My thoughts on using a solenoid would be
1 the Wraith dig is 3 position, using a solenoid will limit you to just 2, drive & locked, you'll lose the freewheel option in the middle
2 most solenoids I've come across are sprung one way & powered the other, in this case I'm guessing you'd spring to drive, power to dig. However the problem may be how much power the solenoid draws when operating. A servo just sitting at a position unloaded (which a properly trimmed shift/dig servo should be) actually uses very little power.

Originally Posted by Greatscott

Great points...

Also, a servo is very adjustable. A solenoid pretty much moves full throw no matter what.

All great points to consider
My gearbox has only two position though and the throw would be exactly as that solenoid I found (11mm). Secondly...as I mentioned before ..I do not have much space so a servo , even a micro, is dificult to install.
Anyway...I ordered two of these things because the are very cheap (7 bucks each) to tinker with it ....lets see when they are here.

[themountain]

Originally Posted by Voodoobrew

They do make worm drive linear actuaters though.

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Interesting...do you have a link to that?

[ferp420]

u could use some kind of cable like traxxasss uses for there diff lock or some tiny rod and mount your servo anywere on the rig one oc my rigs the servo is almost 8" from the trans in the back were i had room

i can say that the shifter dosent take hardly any force to shift it its the binding from the end points being out of adjustment that are usualy the issue

[Voodoobrew]

Just Google micro linear actuator
https://rover.ebay.com/rover/0/0/0?m...2F263661398249

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[themountain]

Originally Posted by ferp420

i can say that the shifter dosent take hardly any force to shift it its the binding from the end points being out of adjustment that are usualy the issue

Yes ..I certainly thought so too.

Originally Posted by Voodoobrew

Just Google micro linear actuator

Thanks , but 72 $ ??

[MrAMath]

All of the TRX shift and locker servos also have a two piece horn and spring. Just setting up my R1 for dig I realize i will need the same. I'm thinking of finding a single TRX one from an aftermarket company. The teeth of the dig or shift dog don't always line up 100% of the time. The spring takes the servo force and then releases it when the parts line up. That way you don't burn your servo. If I remember correctly the TRX has 4 or 6 teeth in the shift dog making the trans only turn 60 or 90 degrees to engage. The lockers I think have 8 teeth so only 22.5 degrees of axle rotation to engage. The R1 dig has engagement 180 degrees apart. If you're crawling slow, or stopped, without the spring the servo could be with extreme tension for a while.

[themountain]

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I got the little solenoid installed and in theory it could work but the little bugger gets waaay too hot so I will go with a micro servo

[mewalsh100]

Definitely a cool idea. Could’ve been a game changer in terms of spatially restricted builds. I wonder what caused it to get so hot during operation? What voltage did they operate at?

[JatoTheRipper]

I've never seen a solenoid this small.

The scale construction and semi guys may know of something, but I doubt it. They'll probably suggest a micro, linear actuator.

[themountain]

Originally Posted by mewalsh100

I wonder what caused it to get so hot during operation? What voltage did they operate at?

they run on 6V...I guess the problem is that they are made for engage/disengage only and if they are engaged constantly there is the full 6V load on them, so they heat up....anywho I am going with a servo.