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Stronger diff (4 planet gears)


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#1 Nazgarot

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Posted 19 July 2012 - 12:53 AM

Hi,

I've been to busy to work (play) with lego for a while, but finally I'm on my summer vacation. I visited a friend, and one of her sons is a Lego fan. He wanted me to build him something new, and I've been thinking of making stronger diffs for an adder/subtraction gearbox (It will go into my 3. revision of RipSaw). The standard diffs only has a single planet gear, but I've heard rumors of a version with two planet gears. Well, I think even that would be to vulnerable for a solution with several XL motors...  

So I made a diff with 4 planet gears, but as the kid had a very limited supply of parts it got quite bulky. I made another version in LDD, but [WARNING!] it will be impossible to dismantle...

Posted Image

I would appreciate it if anybody could make a more compact and elegant version.

The LDD file is called strong diff, and can be found here once the files has been approved by brickshelf.


And for those who would claim that it's impossible to build it, look here:

Posted Image


Hope somebody with access to their collection will be creative for me, thanks!

-ED-

EDIT: Had to re-size the last picture.

Edited by Nazgarot, 19 July 2012 - 12:58 AM.

We are traveling through time, forward... That is an amazing prospect.

#2 garson

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Posted 19 July 2012 - 02:36 AM

Try this, it uses 4 knob gears for max strength.
edit: the images show up in editor but won't show in the actual post?

Edited by garson, 19 July 2012 - 02:42 AM.


#3 Nazgarot

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Posted 19 July 2012 - 02:56 AM

View Postgarson, on 19 July 2012 - 02:36 AM, said:

Try this, it uses 4 knob gears for max strength.
edit: the images show up in editor but won't show in the actual post?

Yes, I'm aware of that solution, but it doesn't give the same smooth operation. Thanks anyway though!

-ED-
We are traveling through time, forward... That is an amazing prospect.

#4 garson

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Posted 19 July 2012 - 03:13 AM

View PostNazgarot, on 19 July 2012 - 02:56 AM, said:

Yes, I'm aware of that solution, but it doesn't give the same smooth operation. Thanks anyway though!

-ED-

you could swap in double thick 20 tooth then, they fit in the same space

#5 jorgeopesi

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Posted 19 July 2012 - 08:22 AM

Now we can use the new and small turntable to do it smaller all the system.
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Posted Image Only 9546 for 10000

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#6 SNIPE

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Posted 19 July 2012 - 02:12 PM

You could try this, it is as small as I could get it using 4 planet gears (they are not really planet gears BTW, they are bevel [used in my model]/double sided bevel [used in your model])

http://db.tt/I0o7P1Lw

You can use the holes on the grey half of the turntable or the axles to attach it to the model if used in one.maybe different turntables can be used depends on if you want it to be thinner, the bevel gears are a bit fiddly to get in, the turntable is easy to open up you just have to lever it open when you do one time it will stay open a little then you move along a little then do the same again and it will open, I used a small flat head screwdriver (the watchmaker type).fo best results, you want to make sure that the bevel gear that is floating in there is not overhanging, it has to be in line with the one opposite as if it was on one of those tiny pins.

Edited by SNIPE, 19 July 2012 - 02:22 PM.


#7 daniele

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Posted 19 July 2012 - 03:37 PM

Sorry my noob question, but why it can not be dismantled?
Any axle can be removed and gears too or am I blind? :)

Thanks  :wacko:
Excuse my bad english :)

#8 allanp

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Posted 19 July 2012 - 06:35 PM

In the top picture, the left hand version has a 3L axle pushed into a 3 deep hole (so it can't be pulled out cos it's sunk all the way in) that is also blocked at the end (so you can't use anything to push it out from the other side). You can remove these parts by drilling a small hole into the axle and screwing in a tiny wood screw to give you a handle to remove them. Sometimes the axle can still be used as normal. As the axle goes through a cross block you could also try using a needle in the slot to slide it out, but be carefull as that's pretty much the easiest way to stab yourself!

Edited by allanp, 19 July 2012 - 06:36 PM.

Even the best can be made better, but most important is to be excellent to each other and party on dudes!!!!!!

#9 daniele

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Posted 19 July 2012 - 06:41 PM

Ok, but I think the left one is impossibile to build  :laugh:
There's no way you can build due to two black pins.
:classic:
Excuse my bad english :)

#10 SNIPE

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Posted 19 July 2012 - 06:45 PM

you can dismantle it, there there is a slight cutout on the holes of the turntable and the grey support rings that let's you see part of the axle, put a small Flathead screwdriver in ther and lever it while pushing down on the axle eventually it will push out enough to be able to grab the end

Edited by SNIPE, 19 July 2012 - 06:46 PM.


#11 Alasdair Ryan

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Posted 19 July 2012 - 07:29 PM

View Postallanp, on 19 July 2012 - 06:35 PM, said:

But be carefull as that's pretty much the easiest way to stab yourself!

You can say that again.......:laugh:
It's good to see people trying to improve some of the lego parts that exist already.
Posted Image

Updated 02/08/12
Posted Image

#12 Nazgarot

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Posted 19 July 2012 - 11:04 PM

View Postdaniele, on 19 July 2012 - 06:41 PM, said:

Ok, but I think the left one is impossibile to build  :laugh:
There's no way you can build due to two black pins.
:classic:


Yes, you are right. Thanks! They would of course have to be replaced with "long pin with stop bush".

But as I said it was only built on CAD because there was a lack of parts...



View PostSNIPE, on 19 July 2012 - 02:12 PM, said:

You could try this, it is as small as I could get it using 4 planet gears (they are not really planet gears BTW, they are bevel [used in my model]/double sided bevel [used in your model])

http://db.tt/I0o7P1Lw

You can use the holes on the grey half of the turntable or the axles to attach it to the model if used in one.maybe different turntables can be used depends on if you want it to be thinner, the bevel gears are a bit fiddly to get in, the turntable is easy to open up you just have to lever it open when you do one time it will stay open a little then you move along a little then do the same again and it will open, I used a small flat head screwdriver (the watchmaker type).fo best results, you want to make sure that the bevel gear that is floating in there is not overhanging, it has to be in line with the one opposite as if it was on one of those tiny pins.


First, your diff doesn't have 4 planet gears... only two, and besides, the second one is not supported by a central pin, and thus almost no stronger than a normal diff. Bevels are a common name for both planet and solar gears (ref Wikipedia, see illustration on left side), and my diff has a total of 6 bevels, 4 planet gears and two sun gears.


View PostSNIPE, on 19 July 2012 - 06:45 PM, said:

you can dismantle it, there there is a slight cutout on the holes of the turntable and the grey support rings that let's you see part of the axle, put a small Flathead screwdriver in ther and lever it while pushing down on the axle eventually it will push out enough to be able to grab the end


No, you can't. There is a "pin with axle end" on one side of the "Axle and Pin Connector #2", and a 3 stud axle on the other. It's the 3 stud axle that makes the problem. It can how ever be removed using the techniques described her, with a needle or by drilling a hole. But I would rather not have to do it that way...



The problem still is the same. Can anybody come up with a more compact/elegant solution for a diff with 4 planet gears? I'm back home on Monday, and will work more on the problem then.


Thanks for all the replays so far.

-ED-
We are traveling through time, forward... That is an amazing prospect.

#13 SNIPE

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Posted 19 July 2012 - 11:27 PM

I can't make it smaller without the LDD file your link isn't working I still think you can dismantle it but I don't know how its built.

When I added a 4th gear it made the diff case wobble less when the axles spin than if it had 2 or 3 gears and it is different too, I get bored of using the same core parts in every car so I try and change it a bit.I know there isnt another pin there but the gear needs to be put in AS IF there was.

Edited by SNIPE, 19 July 2012 - 11:30 PM.


#14 THENOOB

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Posted 19 July 2012 - 11:33 PM

Why is the second one impossible to dismatle?

#15 Nazgarot

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Posted 19 July 2012 - 11:43 PM

View PostTHENOOB, on 19 July 2012 - 11:33 PM, said:

Why is the second one impossible to dismatle?


Because of the 3 long axle extending through these 3 parts:

Axle and Pin Connector Perpendicular
Posted Image

Axle and Pin Connector Angled #2
Posted Image

Pin Long with Friction Ridges Lengthwise and Center Pin Hole
Posted Image


If you try to build it, you will see for your self...  :tongue:
Just remember to switch the black pins for these:
Posted Image

-ED-

EDIT: @SNIPE: Seems it's not yet public... I don't know why. Will try to find out.

Edited by Nazgarot, 19 July 2012 - 11:54 PM.

We are traveling through time, forward... That is an amazing prospect.

#16 SNIPE

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Posted 20 July 2012 - 12:37 AM

okay I just built part of it and I cant even get the two 5L lift arms in using pins as first done.

#17 Nazgarot

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Posted 20 July 2012 - 01:18 AM

View PostSNIPE, on 20 July 2012 - 12:37 AM, said:

okay I just built part of it and I cant even get the two 5L lift arms in using pins as first done.

did you swap the black pins?
We are traveling through time, forward... That is an amazing prospect.

#18 Nazgarot

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Posted 20 July 2012 - 01:59 AM

I just reworked it in CAD. This version has more rotating mass, but is more compact. I have an idea for one edition that will be at least one stud shorter, but can't work it out without parts to try...

This version how ever seems to be possible even though it will ba hard to keep the core parts in place while building everything around it. It will probably have to be built with the assist of needles to keep everything in place.

As I'm having trouble with Brickshelf I have uploaded three images showing more details then the previous ones.


1: The diff as it would look when completed. (the 5x7 brace is turned transparent to better show connections. Wouldn't it be great if this part came in transparent?)  :sweet:
Posted Image


2: The brace and a few other parts are removed to show the connections and the inner workings of the diff.
Posted Image


3: Closeup of the inner parts. Note the half stud bushes in the center of the diff. There is supposed to be one on every axle end, so that they support each other. It worked on the first edition I made, so it's possible, but hard to make.
Posted Image


There is how ever still the problem with dismantling it... But I think the needle trick should help.

-ED-

EDIT: Ops, sorry for the double post. They just didn't belong naturally together...

Edited by Nazgarot, 20 July 2012 - 02:00 AM.

We are traveling through time, forward... That is an amazing prospect.

#19 SNIPE

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Posted 20 July 2012 - 11:49 AM

You could try using this gear configuration only thing is, the turntable is split in half and your only using the geared half, OR you could use a 24 tooth gear or the t2 tooth gear from the diff (not the bevel type) or maybe a 24 toth clutch gear.

I can't build the outside using LDD because the parts are not there but it uses Posted Image


Here is the LXF file http://www.brickshel...mfr/diff_v9.lxf

it has 6 'planet gears' like the other one and the large gear or turntable.

The second one uses two bevel gears with pinholes instead of axle holes so they spin at different times if you don't have any bevel gears with the pinhole use two pin to axle connectors without friction on the yellow pin joiner

The whole thing is meant to spin too which means all of the grey gears you see will spin round, this would happen if both axles are moved at the same speed in the same direction (the axles going to the wheels)

Edited by SNIPE, 20 July 2012 - 12:04 PM.


#20 nicjasno

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Posted 20 July 2012 - 02:28 PM

This is all well and good, but those diffs are way too big. I have experimented with such diffs (mine were smaller but still too big)

http://www.nicjasno.com/image/tid/85

untill making myself a custom one.

https://www.dropbox....7c04/JLMFNNpG16

Both were used and tested in the LPEpower mustang (a 5kg car with a torquey V8 and big wheels). The small one performs much better than the big one.

Also, the black gears are thick 12 tooth gears cut in half, because the teth on those are much more durable than on the small ones.

Edited by nicjasno, 20 July 2012 - 02:31 PM.

www.LPEpower.com

#21 daniele

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Posted 20 July 2012 - 09:28 PM

this, 100% lego, is more compact and very strong. What do you think?

Posted Image
Posted Image

edit: it's dismanteable and no gears cutted  :tongue:

Edited by daniele, 20 July 2012 - 09:32 PM.

Excuse my bad english :)

#22 nicjasno

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Posted 20 July 2012 - 10:00 PM

View Postdaniele, on 20 July 2012 - 09:28 PM, said:

this, 100% lego, is more compact and very strong. What do you think?

Posted Image
Posted Image

edit: it's dismanteable and no gears cutted  :tongue:
Too big and won't really hold torque. The body will start to fall apart.
www.LPEpower.com

#23 daniele

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Posted 21 July 2012 - 10:56 AM

Another try... Less pieces, more powerfull, VERY limited slip.
The next step is move little gears into, so the diff will be more compact.
:)
version 1
Click here

version 2
Posted Image

Edited by daniele, 21 July 2012 - 11:04 AM.

Excuse my bad english :)

#24 Nazgarot

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Posted 11 August 2012 - 02:54 PM

Hi,

I completed my strong diff a couple of weeks ago, but haven't found time to upload it before now.

I've been reviewing some of the ideas her. Many of them are good, and I may use some of them i upcoming projects. There are how ever several problems that make them not ideal for this Moc; they are either not completely lego, heavily  modified bricks, not smooth enough (knob wheels) or will destroy themself... So to my idea.

Everyone who has read the tread know there has been some evolution from my first idea, and the final edition is both easy to build, nearly indestructible and purely lego. It's still big, cumbersome and has a lot of rotating mass, but for my application that doesn't madder. I have managed to make it possible to disassemble it, and keeping the outer gear of the turntable free of interruptions (There are no parts sticking far enough out to interfere with the gear), so I have reached my goal. Next step will be to integrate it in my RipSaw v3. It will be the main components in a add/sub driveline using 3 or 5 XL PF motors...

Pic: Final diff
Posted Image


CAD: Internal parts and final diff
Posted Image


CAD: Evolution of
Posted Image


I have also put out a new .lxf file, containing a versions of the diff on my Brickshelf page. It should be available soon.
Deep link to .lxf file: Strong Diff

-ED-

EDIT: Added a deep link to the .lxf file

Edited by Nazgarot, 11 August 2012 - 04:42 PM.

We are traveling through time, forward... That is an amazing prospect.

#25 TechnicTobi

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Posted 12 August 2012 - 02:04 PM

Hi,

I built a diff like this a while ago. I didn't need it to transfer high torque but to reach high speed. I want to build a fast big race truck and as I do not own rc buggy motors I had to try it with PF-motors. I connected two PF-XL motors to the "outputs" of the diff and used the diffs' input (turntable) as "output" and used a 12 tooth gear with double bevel to drive the axis of the truck. It worked quite well and offered a remarkable speed...

Greetings

Tobi



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