Tank track question

[Burf2000]

I planning to build a very very large Lego robot and my main issue is moving it.

Now has anyone done any testing on single track per side verses double track per side (see below). Do you get better power to weight ratio if you have smaller length tracks in many sections?

Bad example

[olaf9198]

it's the same as a truck

the more the tire's the less weight get onto a wheel double tire's is the same

(so the more tracks you take the less weight rest onto it

[Burf2000]

it's the same as a truck

the more the tire's the less weight get onto a wheel double tire's is the same

(so the more tracks you take the less weight rest onto it

Right so your saying the larger the tracks are the better for moving heavy weight?

[DLuders]

One manufacturer (Mattracks) has a "Frequently-Asked Questions" (FAQ) webpage that state the advantages of tracks over conventional tires:

"What type of terrain can you go through and how does Mattracks reduce compaction?

With Mattracks, you really not going through it… you’re going on top of it! You see, Mattracks has a unique ability to reduce ground pressure. When you reduce ground pressure, you travel on top where the going is easy!

Mattracks large surface area (26 square feet!) will allow you to travel on snow, mud, sand, swamp, or bogs with ease! A standard truck with tires will exert up to 40 p.s.i. of down pressure on it’s tire contact area. A person standing will exert 6 to 8 p.s.i. of down pressure. The Mattracks system on a vehicle has as low as 1.5 p.s.i. of down pressure. This eliminates compaction and ruts."

Edited November 9, 2011 by DLuders

[olaf9198]

Right so your saying the larger the tracks are the better for moving heavy weight?

yes butt with many wheel's like the 8043

[Burf2000]

One manufacturer (Mattracks) has a "Frequently-Asked Questions" (FAQ) webpage that state the advantages of tracks over conventional tires:

"What type of terrain can you go through and how does Mattracks reduce compaction?

With Mattracks, you really not going through it… you’re going on top of it! You see, Mattracks has a unique ability to reduce ground pressure. When you reduce ground pressure, you travel on top where the going is easy!

Mattracks large surface area (26 square feet!) will allow you to travel on snow, mud, sand, swamp, or bogs with ease! A standard truck with tires will exert up to 40 p.s.i. of down pressure on it’s tire contact area. A person standing will exert 6 to 8 p.s.i. of down pressure. The Mattracks system on a vehicle has as low as 1.5 p.s.i. of down pressure. This eliminates compaction and ruts."

But I suppose this can't turn on the spot like a normal tank. I am going for 3 wide track so I am going to need a lot of power!

[DLuders]

It's a matter of contact pressure on the ground. Larger "footprints" create less pressure -- that's why snowgroomers and snowmobiles run on tracks and not tires. Snowshoes spread your body weight over a larger area so that you don't sink into the powder. Yes, if you have a heavy truck operating on soft sand/snow/mud, using the treads will help displace the weight over a larger area.

1-Ton pickup trucks frequently have "duelie" rear tire setups (pictured below) to spread their heavy loads out. 18-wheeler semis have more tires to spread their heavy loads out. It's the same principle -- reduce the chances of rutting hot asphalt or soft ground.

[Burf2000]

I completely understand that, just trying to apply that to lego terms with lego tracks and carpet!

[Blakbird]

I completely understand that, just trying to apply that to lego terms with lego tracks and carpet!

There's no problem with contact pressure on carpet because you do not sink into it. Tracks will not give you any traction advantage. Adding even more tracks will probably make no difference. In fact, they will probably make it worse. You get better traction by sinking into the carpet a bit which gives you something to push against instead of just using friction.

[Burf2000]

There's no problem with contact pressure on carpet because you do not sink into it. Tracks will not give you any traction advantage. Adding even more tracks will probably make no difference. In fact, they will probably make it worse. You get better traction by sinking into the carpet a bit which gives you something to push against instead of just using friction.

Sorry I think I am explaining myself wrong.

So I build heavy big behind robots, 20KG + and so maybe no one can answer this question but what I am trying to work out is having more or less track helps the robot move especially when turning

So I guess this is a turning question and not a traction question

[Blakbird]

Sorry I think I am explaining myself wrong.

So I build heavy big behind robots, 20KG + and so maybe no one can answer this question but what I am trying to work out is having more or less track helps the robot move especially when turning

So I guess this is a turning question and not a traction question

If you already know you are using tracks and assuming that you are skid steering, then it will steer best with the smallest number of tracks because there will be the least lateral slippage. However, it will also be less stable.

[Burf2000]

If you already know you are using tracks and assuming that you are skid steering, then it will steer best with the smallest number of tracks because there will be the least lateral slippage. However, it will also be less stable.

So shorter tracks will be better but what about width? wider tracks better as they would slide better?

Blakbird, you know a lot about technic, how would you move a huge lego model about?

Any idea's welcome. I want to make something in the 30-40KG area