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Aerolight

New wheel hub + CV moc possibilites

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With the new elements what kind improvement should we see in RC capabilities?

First let us calculate the improvement of torque at the wheels.

Before this the main way was to use the portals from the Unimog and old RC 4x4 which had a gear reduction of 3-1 where as with the new hubs reduction is up to just over 5/1, so just with this we gain 66% more torque at the wheels (probably more in practice due to the reduced friction with the new hubs when under load).

With my tests the old style joins where not the weak point of the old system, while they where the first to down right break the axle going through the lower wheel in the portal twisted permanently before this. While most of us probably don't mind this as it still works if you lock the axle in, as the twist will cause the axle to work out with load without and it can be considered the point of failure with the old hubs.

While I don't have the new CVs to test (nor have I seen any tests yet please link if someone has done some) a few years ago I did machine lego compatible UV joints that where, as far as lego motors are concerned, indestructible. I expect this is what the new CVs will in effect be, i.e. the axles driving the joints will twist before joint breaks.

So if the old limitation is the axle twisting in the output of the old hub and the new limitation is the axle twisting when entering the new hub what kind of improvement can we expect?

We get a 66% increase due to the gearing in the new hubs itself and a whopping 200% from the axle being before rather than after the gearing (old hub has 3/1 gearing so the input is under 1/3 the stress of the output, therefore the new hub gains 3 times the torque threshold).

So a good guess would be 1.66*3 =  4.98 WOW! Please bear in mind that to see this increase you have to gear down the pre-hub drivetrain 3/1 when apposed to the old hub and sorry if the maths confusing but at the start I talk about percentage increase and to calculate the final number I use total relative percentage (100% plus increase so 166% and 300% which compound together to give just under 500%). 

The 2 new elements each have a weakness when compared to the old system however.

With the new CVs the problem is the length of the male shaft,firstly only one length is available which makes it annoying to use without a diff as with no diff the input shafts must have 1 stud different lengths. You could design the drivetrain to be off-centre to account for this but no only would you get ganked by all the modellers with OCD the overall length of the CVs is still superfluous not allowing for the maximum length of suspension arms for a given MOCs width, the new 4x4 shows both these problems. The best solution is probably just to use the new CV for the hub and 90 degree capable gears for the end that connects to the frame.

As for the new hub I only see one possible downside and that is the reduction in ground clearance when apposed to the old style, however this is minor if you don't use straight lower wishbones (use ones that step up around the drive to be the same height as the drive) in practice a few studs will be a good payoff for the increase in torque. Unless your using them in a solid axle where the new hub's shortcomings are much more apparent though all in all still an improvement in most cases. 

While the massive increase in torque is great I don't see as varied designs happening as apposed to the old system due to wishbone being so much better than solid this time around (although the use of the hubs as gearboxes is promising). And remember the new CV needs a stud gap around it which will make packaging that much less optimal.

(RANT ALERT)

Just remember that even with objectively 5 times better parts lego could no produce a model that rivalled the performance of  MOCs that are 8 years old! (when the Unimog released) this is even with changing the gearing for better crawling (unofficial B model). Not to flock a dead horse but I don't mean just the lack of wheel torque but the rickety barge levels of stability due to height and length and an un-sprung pendular front axle; with a turntable mounted so high the wheels do the shuffle when articulating, even the first traction engines used a pivot on the centreline of the wheels. I'm one of the ones who refuse to buy the set but am still checking bricklink everyday for the new elements.

What are your planes for the new elements?

 

 

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Posted (edited)

I just built the 42099 and noticed that the notched end of a 1L bush fits perfectly and still swivels. :D :D just line the notches up with the nubs and hey presto it clicks into place.

Edited by SNIPE

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On 8/5/2019 at 11:36 PM, Aerolight said:

am still checking bricklink everyday for the new elements.

Why don't you buy it straight from lego? It's available in the UK.

On 8/5/2019 at 11:36 PM, Aerolight said:

What are your planes for the new elements?

Cars, trucks, maybe a bobcat, but no planes for sure. :classic:

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Posted (edited)
12 hours ago, SNIPE said:

I just built the 42099 and noticed that the notched end of a 1L bush fits perfectly and still swivels. :D :D just line the notches up with the nubs and hey presto it clicks into place.

I tried this and it didn't seem to work for me. Does it take quite a bit of force? I found that the "old" female CV joint piece fits quite nicely. I would like to find a way of driving it with a gear as close as possible to the input drive to make an excavator. The base of most excavators are "H" shaped, not a vast square like most Lego excavators and I'd like to keep the legs of the H nice and thin to make the H shape more recognisable and authentic.

excavatorbase2.jpg

There's sooooo many vehicles that use planetary gear reduction, like bulldozers, tractors, excavators, back hoes, monster trucks, telehandlers, cranes, tatra trucks, front loaders, bucket wheel excavators (both for the tracks and to drive the bucket wheel) so there's a lot of possibilities. 

Edited by allanp

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Posted (edited)
On 8/6/2019 at 12:36 AM, Aerolight said:

the main way was to use the portals from the Unimog and old RC 4x4 which had a gear reduction of 3-1

Are you sure ? I can't find one, and I'm very interrested by the subject

Edited by LegoTT
Typo

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Posted (edited)
2 hours ago, allanp said:

I tried this and it didn't seem to work for me. Does it take quite a bit of force? I found that the "old" female CV joint piece fits quite nicely. I would like to find a way of driving it with a gear as close as possible to the input drive to make an excavator. The base of most excavators are "H" shaped, not a vast square like most Lego excavators and I'd like to keep the legs of the H nice and thin to make the H shape more recognisable and authentic.

Yes it goes in with not that much force, try angling it so one side goes in first

And it has to be the end of the bush with the cutouts on it for to go between studs

Edited by SNIPE

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5 hours ago, Attika said:

Why don't you buy it straight from lego? It's available in the UK.

Cars, trucks, maybe a bobcat, but no planes for sure. :classic:

its just to much, £50 for enough for a 4x4, brick link is already has listings at a similar price but when they verify the new parts list they should drop - at least I hope. 

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They're cheaper direct from lego! £7.22

17 hours ago, Aerolight said:

ts just to much, £50 for enough for a 4x4

Its £34 actually... £7.22 for the hub, £1.45 for the ball joint/cv 

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