Clutch Gear, 16 and 24 teeth ... (requires some surgery)

[DrJB]

In another thread, we've been discussing ideas on how to make auto transmissions more 'realistic'. One common 'desire' was to have different size clutch gears as the current gearboxes (8448/8466) are far from real life. I was just looking at one of the previous generation differentials, and with some skills and a sharp blade, one can in fact obtain a 24 teeth clutch. (The current clutch has only 16 teeth). This is not for the purists but nonetheless one 'option'. The real question is: When are we going to see a transmission based on the newly found clutch?

[Technyk32231]

If you hollow out the middle part of a 20t gear, and cut the teeth off of a 16t clutch gear, the 16t fits perfectly inside the 20t.

[DrJB]

I agree but ... I think my solution is far 'easier' ... as you only need to sacrifice a single part ... . I bought a set of ten 6573 from Lego Education a while back .... now I could put them to good use. EDIT: I got it wrong, you were talking about making a different size clutch. Thank You!

Edited August 31, 2013 by DrJB

[Technyk32231]

I agree but ... I think my solution is far 'easier' ... as you only need to sacrifice a single part ... . I bought a set of ten 6573 from Lego Education a while back .... now I could put them to good use.

You can't get a 20t from a differential.

[Junpei]

I think he meant 24t. I would love to see lego make the kind of clutch gear suggested here. Once I took the metal plates in a white 24t clutch gear, but it was limited to only spinning freely on the axle.

[DrJB]

I think Technyk32231 is talking about making a 20-tooth clutch gear by machining 32269 and 6542, then gluing them together. I however was talking about cutting a 6573 which has 24 teeth on one side and 16 on the other. In fact, combining the above two ideas, we can start with one differential cage 6573 and one 20 teeth gear 32269, and end up with 2 clutches: a 24 tooth and a 20 tooth. Simply Brilliant Technyk32231 ... now, where is my dremel tool?

Edited August 31, 2013 by DrJB

[Lipko]

To be honest, this is nothing new. You can see people doing this (cutting) for gearboxes, since the differential was designed to mesh with the clutch piece, I guess for differential locking. I can't remember any links though...

[allanp]

Nicjasno has done it for one of his gearboxes.

[DrJB]

Thank you for pointing that out. History is often replete with re-invented ideas. What I get from this however is that this 'mod' works ... no need to 'sacrifice' any of my gears then. Cheers!

Edited August 31, 2013 by DrJB

[aol000xw]

Please excuse me if I don't express correctly or I am plainly wrong on any of my statements, my technical knoweladge on the matter is pretty low.

From what I know a proper non Lego typical gearbox consists of two shafts, one with "fixed" cogs and a second one with floating ones where the gear selectors engage on the different cogs.

So for 5 gear ratios at least 5 Lego cog sizes that can float/engage on one shaft and stay fixed on the other are needed right? All that while keeping the same distance between both shafts. The standard 16 cogs are 2 studs apart and so are 12/20 and 8/24 right?

8:24 / 12:20 / 16:16 / 20:12 / 24:8

If this is the thing I can figure how to mod everything but the 8 cog. I am missing anything or it is extremly hard to achieve this?

[nicjasno]

You don't need to cut the teeth out of a 16t clutch. You just use the extension ring and glue that into the hollowed out center of the 20t gear.

I did a 4 speed+reverse with that setup. I however used also a clutch extension glued to a 12tooth gear, for one of the gears, so that the 24tooth gear was the largest one.

i meshed:

1st 12 > 24

2nd 16 > 20

3rd 20>16

4th 24 > 12

Edited August 31, 2013 by nicjasno

[allanp]

Please excuse me if I don't express correctly or I am plainly wrong on any of my statements, my technical knoweladge on the matter is pretty low.

From what I know a proper non Lego typical gearbox consists of two shafts, one with "fixed" cogs and a second one with floating ones where the gear selectors engage on the different cogs.

So for 5 gear ratios at least 5 Lego cog sizes that can float/engage on one shaft and stay fixed on the other are needed right? All that while keeping the same distance between both shafts. The standard 16 cogs are 2 studs apart and so are 12/20 and 8/24 right?

8:24 / 12:20 / 16:16 / 20:12 / 24:8

If this is the thing I can figure how to mod everything but the 8 cog. I am missing anything or it is extremly hard to achieve this?

That's right. The only problem I see is that you go from a 3:1 ratio all the way to a 1:3 ratio, so when motorised, either way you end up with a 1:3 up gearing in top gear, which is pretty high. However if you are modifying current gears then it's probably the simplest way to go. You could mod the 8t gear by drilling out the hole so it's round then superglueing it to a 16t cluch gear with the teeth removed or an extention piece with the end cut off.

[nicjasno]

8t gears should not be used in gearboxes that are supposed to transmit power.

[trekman]

Go ahead and cut the differential down to a 24T clutch. I was tempted to do the same thing a while back. It would expand the possibilities, especially when needing to transmit rotation through a gear, whilst allowing the gear to turn in a different direction.

[DrJB]

Just some background on how speed ratios are achieved in transmissions. Typically, for a fixed input shaft rpm, the output speeds are related through factors of 1.26 (or something close). In a 5 speed transmission, this means the highest speed is 1.26^5 = 3.17 times higher than the lowest. Incidentally 1.26 is the cubic root of 2. Now, achieving such low progression ratio in lego might be a bit tricky since, if we mount all gears/cogs on the same shafts (same distance between them), then the number of teeth increases not as 1.26 but as sqrt(1.26) ... The Lego gears simply do not have that fine of a resolution. In my discussion I've assumed a progression of 1.26 ... in fact auto makers typically use numbers close to that. The approach is to pick lowest and highest speed ratio, and then decide how many speeds in the transmission. For example, if the ratio is 4, and we want a 4-speed transmission, the factor is 4^(1/4) = 1.414. If however we want a 6 speed transmission, then the factor is 4^(1/6)=1.26. With the multiple clutches discussed above, we can get close to a 'realistic' transmission layout/geometry .... but might not be possible to get realistic speed ratios... my 0.02

You don't need to cut the teeth out of a 16t clutch. You just use the extension ring and glue that into the hollowed out center of the 20t gear.

I did a 4 speed+reverse with that setup. I however used also a clutch extension glued to a 12tooth gear, for one of the gears, so that the 24tooth gear was the largest one.

i meshed:

1st 12 > 24

2nd 16 > 20

3rd 20>16

4th 24 > 12

Nicely done!!!

[jantjeuh]

8t gears should not be used in gearboxes that are supposed to transmit power.

Not even the new, reinforced ones?

[Technyk32231]

I think Technyk32231 is talking about making a 20-tooth clutch gear by machining 32269 and 6542, then gluing them together. I however was talking about cutting a 6573 which has 24 teeth on one side and 16 on the other. In fact, combining the above two ideas, we can start with one differential cage 6573 and one 20 teeth gear 32269, and end up with 2 clutches: a 24 tooth and a 20 tooth. Simply Brilliant Technyk32231 ... now, where is my dremel tool?

Thank you. I used it in a realistic gearbox with only two shafts. It was really long though. I'll put up pictures when I get to a computer.(most of my posts were from my phone) Edited September 8, 2013 by Technyk32231

[nicjasno]

Not even the new reinforced ones.

Not because they are weak, but because they do not have enough teeth.

[Lipko]

Bigger forces act on smaller wheels to transmit the same torque. According to action-reaction, this means that the forces acting on the axle of the gear are bigger too. Action-reaction: the forcer are bigger between the axles and the axle holes too. Bigger force between the axle and the axle hole means proportionally bigger friction.

[Technyk32231]

Nicjasno has done it for one of his gearboxes.

And that's what inspired me to do this. To be specific, I was inspired by the one he hooked up to Barman's V8 engine.

[nicjasno]

The picture above is from that gearbox.

[Technyk32231]

The picture above is from that gearbox.

Yeah, I know. That doesn't change the fact that it is a very nice gearbox and it inspired me to build my own.