Tiny Axle for 42128 mod problem

[SNIPE]

Hi,

I've been hitting a brick wall for weeks now, on how to connect the steering, pendular turntables, and wheel hubs to one small housing.

The problem is that the gear rack is both raised 0.5L and the turntables and gear rack are both also 0.5 offset to the diff, which is why I used 12 tooth half bevel gears that connect to the 28 tooth differential.

I have just about every technic part IRL so that shouldn't be  a problem.

Here is the LDR file of the important parts in their correct positions, the hard part is trying to connect them.

The tires overlapping is just mimicking two VW T2 tires on one rim, which works perfectly fine IRL.

Any questions, leave a reply

Regards, Snipe.

[Jurss]

I'm afraid that there are compactness limits for standard parts.

That file is for ldraw?

[SNIPE]

6 minutes ago, Jurss said:

I'm afraid that there are compactness limits for standard parts.

That file is for ldraw?

yes, the cv joints are just clamped in by the surrounding parts.

There are limits to lego yes but people are too quick to draw the line and either give up or cheat with non lego parts/gluing/etc.

I know that the only part that I can think of to use for the bottom is the 5x3 thin liftarm. As I say, ive tested the tire idea and they move just fine, ive also tested steering and drive on its down but combining it all is hard. I've got close though.

Edited October 23, 2021 by SNIPE

[Jurss]

You plan to hold differantial only on those CV joints?

Are You shure, that You will be able to fit tyres like this? Those form T2 goes on narrow rims, or You will try to fit both on wide rim?

[SNIPE]

I am sure yes. the diff is kind of held in by the small pins too.

Yes the tires work fine on one rim, I have had this build for a while now.

[Jurss]

Idea for one end. It is compromise, but it works

But I think, I need to make it digital.

[Jeroen Ottens]

How about this?

[SNIPE]

3 hours ago, Jeroen Ottens said:

How about this?

how does it steer?

Edited October 23, 2021 by SNIPE

[Void_S]

On 10/22/2021 at 9:08 PM, SNIPE said:

I've been hitting a brick wall for weeks now, on how to connect the steering, pendular turntables, and wheel hubs to one small housing.

Well, the wall you're hitting is very thick and strong - for real-life trucks not so many companes dared to try making steered and driven axles with double tires. Just due to the same limitations you faced here:

• Quite limited space for steering hubs and arms due to tight placemet of "underfarme" assemlies.
• Nearly impossible to meet requrements for load capacity - it must be durabke enught to hold an impressive per-axle weight. Otherwise, it is pointess to keep double tries (and all related limitations due to them) for light-loaded axle.

So, you can be proud that you're not doing some questionable work but triyng to beat really hard challenge. Even harder concidering the LEGO parts imitations.

Added: may we know wich modification it will be? If I'm not mistaken, US trucks normally have fixed dually/single-tired axles or steered/self-steered (self-alligned) single-tired axles only. I just can't recall I have ever heard about steered+driven+dually axles, which are commonly too overcomplicated for US trucks.
So, your mod looks promissing to be a uqinue one .

Edited October 23, 2021 by Void_S

[Jurss]

10 hours ago, SNIPE said:

how does it steer?

How do You imagine connecting steering at all. Some axle with gear or something.It also needs to swing somehow. So axle for steering also should go trough those turntables.

Maybe something is possible with some linkage, but it will again affect steering, when that axle will swing.

Maybe that steering gearrack could be possible to conect somehow using parts from crankshaft (I was thinkig about that), but then that gear rack won't be at that level anymore.

Also, those 1L bushes with pin are rubbing rim. Yes, just a littlebit, but it is also no really proper connection there.

Maybe it is posible to bild what You need from bricks?

[Jeroen Ottens]

11 hours ago, SNIPE said:

how does it steer?

Like this?

This also solves Jurss question about the steering in combination with the pendular action. My only concern is the attachment of the axle-with-towball pieces. They are not all the way in the 3L liftarms even with the ring of LotR, so they might work themselves loose if too much force is exerted.

Edited October 24, 2021 by Jeroen Ottens

[SNIPE]

1 hour ago, Jurss said:

How do You imagine connecting steering at all. Some axle with gear or something.It also needs to swing somehow. So axle for steering also should go trough those turntables.

Maybe something is possible with some linkage, but it will again affect steering, when that axle will swing.

Maybe that steering gearrack could be possible to conect somehow using parts from crankshaft (I was thinkig about that), but then that gear rack won't be at that level anymore.

Also, those 1L bushes with pin are rubbing rim. Yes, just a littlebit, but it is also no really proper connection there.

Maybe it is posible to bild what You need from bricks?

The steering axle just moves off centre left or right since the pivot is at the turntables.

[SNIPE]

20 hours ago, Jurss said:

Idea for one end. It is compromise, but it works

But I think, I need to make it digital.

this wont work because you have moved the turntables outwards and therefore 3 axles will not fit anymore in the back of the truck.

[Void_S]

Conciderimg a huge play in these ball-to-link joints and relativelly small steerign arm length the pivot offste is not the biggest problem: the arms should be much longer, or have some allignment link which hold the hubs in parralell. The current setup has too much play in all connections.

6 hours ago, Jurss said:

Maybe something is possible with some linkage, but it will again affect steering, when that axle will swing.

Ideally, the "steereing rack ratio" should be as high as possible, so even signiticat turns of the pendular suspension will have no any countable effect on the sterrign angles.

Or, follow Jeroen's idea but with some additional embrasement.