ETF Truck steering

[BobBongo1895]

Here is an idea that might benefit you: an extendible axle using wedge belt wheels and axles with stop.

Great! Thank you for the hint.

[nico71]

I see here a big problem of efficiency. The axle of the wheel is the same of the axle or the spring. Consequently, you will have repercussion of the efficiency of the drivetrain under load. You must separate the driving axle and the suspension axle, as in real model, otherwise, the model might be ineffective.

:)

[Tobbe Arnesson]

Here is an idea that might benefit you: an extendible axle using wedge belt wheels and axles with stop.

Neat, clever thinking and well done!

How much "twist" does it store in the general sloppiness? Would it be a problem to keep the different wheel-sets in parallel?

Perhaps the suspension parts can be made of pneumatic cylinders that are connected to each other? Firmness can be adjusted by increasing the pressure in the common system and an air-tank or two can act as suspension reservoir - if all the hoses won't be enough. If all the wheel-sets are connected tube wise there would also be some pressure sharing amongst them, so some sort of controlled suspension if you will.

Not all four of the suspension legs need be pneumatic either, there can be a mix.

[Burf2000]

Ok, I will do it tommorow morning without the tires. I need a bit of daylight for the photos.

Thanks for doing the photos mate :)

[basbase]

Neat, clever thinking and well done!

How much "twist" does it store in the general sloppiness? Would it be a problem to keep the different wheel-sets in parallel?

Perhaps the suspension parts can be made of pneumatic cylinders that are connected to each other? Firmness can be adjusted by increasing the pressure in the common system and an air-tank or two can act as suspension reservoir - if all the hoses won't be enough. If all the wheel-sets are connected tube wise there would also be some pressure sharing amongst them, so some sort of controlled suspension if you will.

Not all four of the suspension legs need be pneumatic either, there can be a mix.

Thanks for the compliments. The twisting of the axles with stop is less then 1/2L so I think driving multiple wheel-sets in parallel will not be a problem.

It looks like 4 pneumatic cylinders will fit. I'll start working on a design for it in a few days. Mixing the cylinders with suspension springs may cause the construction to be less stable, because of the different resistances that both offer, but I'll see what I can do.

Also the pneumatic hoses will limit the setup from infinite turning. One solution for this might be to have the cylinders for each wheel set have it's own circuit. The hoses will need to be as short as possible, so pressure will build up quickly when the cylinders are compressed. This has some downsides: firstly the suspension height can not be controlled. Secondly, the cylinders won't extend further than half their length, due to low initial pressure. Thirdly, if the cylinders leak air due to too much pressure, that air can't be put back in and the cylinders will stay retracted. Maybe adding a small pump and driving it through the turntable will work... Enough food for thought