13 Studs wide pendular steered suspension on 6x6 CHASSIS

[lukeandahalf]

Greetings,

As my first post, a 6x6 chassis that I've been working on. I have always been fixated on 6x6, 8x8 etc, so when I got six Wheel 62.4 x 20 with Short Axle Hub I was excited to start building. I soon ran into the problem of steering models built to that scale...

This 13 stud wide pendular steered axle has taken me some time. I still haven't worked out where to put the gear reduction for the steering rack, or attach suspension. But a work in progress!

http://lukeandahalf.imgur.com/

Thanks!

And looking forward to any (constructive) criticism!

[Alasdair Ryan]

I think your design could do with another layer of studless beams running the full length of the chassis.

Apart from that it looks good.

[lukeandahalf]

Thanks Alasdair! Once the steering/suspension is settled, I think I will (gulp) endeavour to build a body, never been my strong suit! The plan is to have the body be integral to the structure of the frame to save space. I haven't decided on a vehicle to model yet, the Mercedes Benz Zetros has always been an appealing truck, but I know dimensions are all wrong on the current chassis. I would like a "cralwer" chassis as much as possible for playability, and the wheel base of the Zetros pretty much rules that out. Having said that...any other suggestions? As a side note, I have been trying at studfull bodies on studless chassis, I have found the weight of the body negates the playability. Am I alone on this? ...Or maybe that is simply a factor of my 2 M Motor propulsion (My XL motor inexplicably died! )

some minutes later...

I have a solution for suspension!

Flex up

Flex down

Edited June 10, 2013 by lukeandahalf

[aqaz]

Sorry to bring this up... Perhaps I am mistaken, but... As I view your photos it appears that you have 3 pendular axles. If this is indeed the case, your truck will not work, it will roll over at the slightest lateral incline.

Only the front axle can be pendular in a 6x6 configuration, the rear axles must work either; independently, or, have suspension pivoting on each side between the axles. (It is called 'Walking beam suspension')

Look at these: here, here and here

Loads of good examples of 6x6 off road trucks at this website.

Of course, if I am wrongly interpreting your pictures, ignore all the above.

Another thought....

If you are still stuck for body ideas....

You may get inspired to try to build one of the trucks at that site..... Many of them are screaming out: 'Build me with Lego... I am angular and easy'

(Maybe it is just me that can hear that.... )

[lukeandahalf]

Thanks for the comments

You are correct in assuming 3 pendular axles, although I haven't experienced the problems you have described on lateral inclines. With a relatively low centre of gravity I suppose this is all but mitigated? The only problem I have experienced is low wheel contact (4 wheels out of six at a time sometimes) but this was expected with no real vertical travel on any axle.

Time to try walking beam!

As for design of the body, that will be on hold until mechanical details are ironed out.

[aqaz]

Try this: http://www.flickr.com/photos/88544671@N07/9016101906/in/photostream you should find that it hugs any terrain, all wheels in contact, without any suspension while remaining level.

Now try some equally simple arrangement with 3 pendular axles, see how level this stays

This is what I meant.

(Note to Mod:

Picture found on web and copied, but it looks to be the same one in as in Sariels book, p205. If this is a copyright infringement, please remove it.)

[Nazgarot]

Try this: http://www.flickr.co.../in/photostream you should find that it hugs any terrain, all wheels in contact, without any suspension while remaining level.

Now try some equally simple arrangement with 3 pendular axles, see how level this stays

This is what I meant.

This is the same solution as Doosan (former Moxy) dumpers use. They have a semi independent front suspension as well (the cabin with front axle is pendular to the chassis) to increase ride comfort for the driver. And it works VERY well!

Se this link for more info on the Doosan/Moxy dumpers.

-ED-

EDIT: corrected text

Edited June 11, 2013 by Nazgarot

[lukeandahalf]

Thanks both aqaz and Nazgarot for the ideas! Even with the differentials it performs very well off-desk. I haven't been building much lately as work only gets busier the nicer the weather gets, but here's what I've got so far.

Edited June 14, 2013 by lukeandahalf

[aqaz]

lukeandahalf:

Very impressive, you really have cracked this concept.....

Did any of those 'angular' trucks get into your head, so that it is working in your subconscious for the bodywork?

By the way, there is just about any wheel (& track) arrangement of off road vehicle at that site.... Lots of inspiration to be had.

[750ACE]

http://www.eurobricks.com/forum/index.php?showtopic=82820&st=0

This person started his project with the same type of suspension.

[lukeandahalf]

750ACE, I would love to see your solution for 13 studs walking beam. The part of this project that I really like is the front pendular axle, the rear axles are only a solution to accommodate 6x6 in this scale And the body will have to wait!

[750ACE]

750ACE, I would love to see your solution for 13 studs walking beam. The part of this project that I really like is the front pendular axle, the rear axles are only a solution to accommodate 6x6 in this scale And the body will have to wait!

Gsia17 created the truck in the link I provided. If you scan through it he has a link to the chassis photo. You can also see an updated version later in the post.