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Mastermime
01-21-2012, 08:51 PM
Hello everyone,

Is there any issues I may not be aware about when using a suspension system very similar to this (link below) on my 200 lb tracked robot.
http://www.youtube.com/watch?v=DHKy6GR9RB4&feature=results_video&playnext=1&list=PL6BF86B6697F40CDE
(http://www.youtube.com/watch?v=DHKy6GR9RB4&feature=results_video&playnext=1&list=PL6BF86B6697F40CDE)
Also here is the shape of what my treads will look like. The two outermost (highest) wheels are the drive wheels http://tinyurl.com/73e8d52

Will I need a chain tightening mechanism or will the flexibility of the Brecoflex timing belts (what I am using) take care of it?

Thanks

Warsloth
03-22-2013, 05:28 PM
In my studies of tanks... I think the lego suspension is flawed in a lot of ways. Most real tanks that have double wheels per truck will have them sharing a vertically oriented suspension (spring or pneumatic/hydraulic) and the drive gear/sprocket is not usually in contact with the ground. This makes it so the drive train can be fixed and more solid. At least from my rudimentary observations.
Having motors or a driveshaft/axle supplying a floating drive gear with ground contact is going to have lots of issues IMO. It is much easier to put them on an elevated hard mount and use the idlers to apply tension to the track.
I dont think you were planning on having the drive sprocket as part of that suspension rig, but the guy in the video made it sound like that was his plan. The necessary accomodations to make that work are mucb harder than what I described. I have a book showing a lot of ww2 tank suspension components, Ill see if I can throw some on here for you.
But i am also working on a tracked robot, and the great flex he has with that simple setup loks good, but I can see it throwing track like mad.

Warsloth
03-22-2013, 07:57 PM
Sorry, I'm an idiot.
after looking at your post again I realize you weren't planning on following that video exclusively.
That picture has a decent layout. but the combination reminded me more of a system like the M4 halftrack. I found some pictures and loaded them up- 4596 4597

Also, one of the important changes with suspensions for tanks between WW1 and WW2 was the development of a volute spring. Instead of a leaf spring or a round coil spring, they made a flat coiled spring. I have a picture of that in one of my books if you would like to see it, but I am also thinking of making some simple springs and doing a write up.
On a vehicle around 200lbs I can see the need for some good heavy springs, and they are easy to make. All you need is some small flat steel of the appropriate thickness, and a torch or good hot fire.