Caterpillar Tracks

[doug72]

t

Sorry but only have thumbnail image.
 

For my next planned MOC I want to use the arrangement shown above for the caterpillar tracks but so far have been unable to find a workable solution. 

 

The problem is getting the two bogies with the 3 rollers correct so they support the track but don’t cause it to bump as it passes under & over the rollers.

Technic wheels are either to small a diameter causing parts & axles to rub on the track tread centre section, other are too large a diameter, meaning the track is not straight between the two large sprocket wheels.
Using wedge wheels makes the track unit too high.

 

The Lego rubber track is not long enough.

 

The problem with using large sprockets is the framing required to support them at each end plus the bogies inbetween, if they were only 1L wide as per the small sprocket wheels, building would be simpler.

 

The length of the tracks has to be long enough to able to install a turntable ring of new BWE gear quadrants above the tracks.

 

Has anyone got solutions to achieve constructing this type of caterpillar tracks ?

 

Edited June 14, 2017 by Doug72

[jorgeopesi]

That is the problem I like the most, my advice is search, test and invent different combinations, the funny part is the process and If I tell you the answer I'm taking a lot of fun, I say that because I love build tracked vehicles. This is my brickshelf page (http://www.brickshelf.com/cgi-bin/gallery.cgi?m=jorgeopesi), you will see a lot of tracks.

[Void_S]

@Doug72, maybe four 11mm D. x 8mm wheels (seems that you meant them for "technic wheels") with tires, mounted at the triangle liftarms would help you? It should raise the construction and prevent the contact with central section of a track.

[offroadcreations]

Maybe you could use something like this?

[doug72]

11 hours ago, jorgeopesi said:

That is the problem I like the most, my advice is search, test and invent different combinations, the funny part is the process and If I tell you the answer I'm taking a lot of fun, I say that because I love build tracked vehicles. This is my brickshelf page (http://www.brickshelf.com/cgi-bin/gallery.cgi?m=jorgeopesi), you will see a lot of tracks.

Thanks, I have tried many permutations but so far none have proved satisfactory. I am continuing to explore more ideas on how to support the large sprocket wheels and rollers.

 

11 hours ago, Void_S said:

@Doug72, maybe four 11mm D. x 8mm wheels (seems that you meant them for "technic wheels") with tires, mounted at the triangle liftarms would help you? It should raise the construction and prevent the contact with central section of a track.

Yes I have tried using those wheels & triangular frame but need to order more rubber tires.
Have also tried using the larger disc wheels with pin hole.

[doug72]

After a lot of build, reject, re-build have finally come up with an viable track unit for my next MOC.

Originally the sprocket axle centres was 21L but the track was either too tight causing the support frames to bow or if I added an extra tread the track kept slipping off the rollers as it was too slack..

By reduceing this to 20L the track tension is now good with all rollers fully supporting the treads without resorting to a track tensioning device.

Now to build the other track unit and connect them together.

Side View:

Rear View:

Overhead view:

Edited June 13, 2017 by Doug72

[jotta93]

Nicely done! 

What will you use them for?

[Jurss]

But those triangles are not moving? They are fixed, as I see from picture.

[doug72]

6 minutes ago, Jurss said:

But those triangles are not moving? They are fixed, as I see from picture.

Correct the build is still evolving !
Now proved that the location of the 3 wheel arrangement and track sprocket centres works OK.
Will see if I  can devise pivoted mounting for the triangular frames for one track unit and compare with fixed rollers set up.

Watch this space !!

2 hours ago, jotta93 said:

Nicely done! 

What will you use them for?

Undecided at the moment - a posssible clue is in my BCE post.

Once decided I will start a new topic.

Intention is to build a base track unit with turntable that many different types of heavy plant can be mounted on.
The drive for the tracks will possibly use a subtractor drive , if enough space using  XL or L  for drive & M motor for steering.. 

 

[doug72]

56 minutes ago, Jurss said:

But those triangles are not moving? They are fixed, as I see from picture.

There wasn't any before (fixed frame) but there is now and they pivot.

Edited June 13, 2017 by Doug72

[Jurss]

Much better.