Expert advice on "sliding" gears

[Countdown]

Hi all,

I have a problem that's been bugging me for at least a week now. I'm in the process of designing a 4 section boom powered by lego chains for a large-scale sky-trak (telehandler). Now I'm stuck on how to make a "sliding gear" on a axle a lot like how a worm gear "slides" freely and "grips" on the axle but with a 16t or 24t gear.

By trying different combinations of odd pieces I found that a driving ring actually slides on axles joiners; but now how do i power this ring?

Or is there another solution by using different pieces?

Any advice is welcome

-Nick

Edited August 26, 2010 by Countdown

[mahjqa]

Take one (or two) of these:

Stick it inside this:

And put an axle through both of them.

There's a little slack, but it should work nicely.

[Zerobricks]

Take one (or two) of these:

Stick it inside this:

And put an axle through both of them.

There's a little slack, but it should work nicely.

I dont get it

[mahjqa]

Try this, then. Edited August 26, 2010 by mahjqa

[shimon]

Just make an "inner axle idea" by taking connect it to an axle and

put long axles in 2 holes and then put another 2 wheels and they will move free and spin.

if you dont understand i can explain in more details.

@ Zblj : Mahjqa meant that if you put the red part inside the differential it will move freely on the axle and will rotate the differential if the axle is activated

EDIT : havent seen the previous comment.

Edited August 26, 2010 by shimon

[Zerobricks]

Yeah get it now, I thought it had something to do with tranmission gear.

[CP5670]

I have a problem that's been bugging me for at least a week now. I'm in the process of designing a 4 section boom powered by lego chains for a large-scale sky-trak (telehandler). Now I'm stuck on how to make a "sliding gear" on a axle a lot like how a worm gear "slides" freely and "grips" on the axle but with a 16t or 24t gear.

It's worth mentioning that this is not actually a legal assembly, since the clip on the driving ring is always in compression and would get deformed over time. What we need is a new axle joiner piece that is the same width as the old one, but doesn't have the ribs. I brought this up in the 8043 thread too, as that model would have especially benefited from such a piece. For now, mahjqa's solution is a better alternative and will slide over the axle without any friction.

[Blakbird]

It's worth mentioning that this is not actually a legal assembly, since the clip on the driving ring is always in compression and would get deformed over time.

I only partly agree with this. The clip on the driving ring is in bending and therefore has a sustained tensile stress, but this does not necessarily hurt anything. Only if that stress is over a certain threshold will it cause any problem, and without specific material properties it is not possible to predict whether or not there will be long term damage. Calculating the actual bending stress is a fairly trivial matter though.

[TechnicJuan]

I bet you could have a driving ring over a connector like that for years and remove it without any deformation what so ever, and it would work just like if it was new because there is barely any tension on those 2 little inner clips at all. This is just like saying that the 3L blue pin in the excavator set is getting deformed.

[Blakbird]

I bet you could have a driving ring over a connector like that for years and remove it without any deformation what so ever, and it would work just like if it was new because there is barely any tension on those 2 little inner clips at all. This is just like saying that the 3L blue pin in the excavator set is getting deformed.

You are right, it is the same issue. I don't think the 3L blue pin in the 8043 will ever suffer any ill effects from the deformation either. But there ARE certain parts in old Technic sets which can have such a problem. Especially the old friction pins which did not have a slot tended to have problems over time. I have also fractured quite a few of these:

and several of these right at the cross axle from just sitting on the shelf:

[CP5670]

It's hard to say how these things will turn out after a period of several years. There have been a number of cases even in official models where a piece seems fine for a while but has problems down the line. If nothing else though, the clip will still result in extra friction when sliding on the axle joiners.

I have personally become wary of any illegal connections after messing up several old gray stud pins in a commonly used detailing technique, on which the clips had lost their grip entirely after a few years.

Edited August 27, 2010 by CP5670

[TechnicJuan]

It's hard to say what is legal and what is illegal anymore. Especially after building the 8043. I never thought that I would see a technic set released from Lego that would have only 1/2 a stud of the end of an axle catching only a 1/2 of a stud of another piece.

[Zerobricks]

Back to topic, you can also use a worm gear to slide on the axle.

Edited August 27, 2010 by Zblj

[shimon]

Back to toopic, you can also use a worm gear to slide on the axle.

But you cant do it in the differential

i just tried this and the pin in the center of the differential wont let the axle go through..

it could have been nice though..

other than the worm gear it self will be activated i cant see any other ideas for gears between it.

good idea though .. to bad it matters how long the axle is, and the 32L ones are too much flexible.

Edited August 27, 2010 by shimon

[Zerobricks]

But you cant do it in the differential

i just tried this and the pin in the center of the differential wont let the axle go through..

it could have been nice though..

other than the worm gear it self will be activated i cant see any other ideas for gears between it.

good idea though .. to bad it matters how long the axle is, and the 32L ones are too much flexible.

Did you see Mahj's video?

[Countdown]

Try this, then.

Thanks mahjqa,

that's exactly the assembly that I was looking for. Actually i was playing with an old style differential and diffenrent gears last night, but the use of a changeover catch is genius.

-Nick

[shimon]

Did you see Mahj's video?

yes i figured it from the picture

i just thought you mean that its possible putting a worm gear inside the differential instead of the 2 red parts

[Countdown]

Just make an "inner axle idea" by taking connect it to an axle and

put long axles in 2 holes and then put another 2 wheels and they will move free and spin.

if you dont understand i can explain in more details.

Is that what you meant shimon? Because I like the compactness of it... Now on to Bricklink to get a handful of 32 long axles.

-Nick

[Ayumi]

Sariel's idea.

[Sam42]

I'm looking forward to seeing this implemented in a model.....

[shimon]

Is that what you meant shimon? Because I like the compactness of it... Now on to Bricklink to get a handful of 32 long axles.

-Nick

Yes, but i think it would be more compact with the wheels, it will move more freely.

[poduncan309]

This is an old thread, but I wanted to add that a new 8-tooth gear came out in 2013 that can slide along the axle: https://brickset.com/parts/6036545/z8-gear-without-friction

This and other similar mechanisms can be found in this thread: