Caterpiller tracks (HELP)

[doug72]

When building MOCs with caterpiller tracks I always seem to end up with the track being either too tight or  too loose.

Does anyone have data on the correct number of caterpiller track elements for the large and small sprocket wheels with spocket centres at various distances apart.

For a new MOC I have sproket centres at 21L with large sprokets & 37 track pieces.
Tried 22L apart with an extra track piece but still too loose.

The black track seems better than the grey track.

Should the sprocket centres be an even or odd number of holes apart ?

Edited October 11, 2016 by Doug72

[Tommy Styrvoky]

31 minutes ago, Doug72 said:

When building MOCs with caterpiller tracks I always seem to end up with the track being either too tight or  too loose.

Does anyone have data on the correct number of caterpiller track elements for the large and small sprocket wheels with spocket centres at various distances apart.

For a new MOC I have sproket centres at 21L with large sprokets & 37 track pieces.
Tried 22L apart with an extra track piece but still too loose.

The black track seems better than the grey track.

Should the sprocket centres be an even or odd number of holes apart ?

It depends on the suspension but sometimes I will use half stud offsets to obtain optimal tension, or a worm gear and 8z gear on a swing arm to tension the idler wheel. Basically you want the optimal tension to have some slack, but not enough for the sprocket to skip teeth. 

Edited October 11, 2016 by Tommy Styrvoky

[doug72]

Tommy, thanks for the reply.

After some experimenting I have found that 20L between sprocket axles works OK for my MOC giving a sightly tensioned track which will not have any suspension with just support / guide rollers. The track speed required is very slow.

[Milan]

Hey Doug,

Beside that tip that Tommy gave you, I can offer two more:

1. When you place your sprockets, you can always "cheat" a bit with adding support rollers above and beneath, to raise the middle section of the tracks, thus making it more tensioned. Also, this techniques gives you a lot of precision. For the rollers, you can use simple 2L smooth connectors.

 

2. You can make, like real tracked machines have. a track tensioner, a common shock absorber. I use this few times, great results. Here it is on 4kg loader:

[doug72]

Milan, thanks for those tips.

I like the idea of a tensioning device but don't have enough of the grey shock absorbers at the moment.

 

[Tommy Styrvoky]

5 hours ago, Doug72 said:

Milan, thanks for those tips.

I like the idea of a tensioning device but don't have enough of the grey shock absorbers at the moment.

 

You could always use something like this for tensioning the tracks.

Lego Panther Ausf. G 1/15 (RC) by Tommy Styrvoky, on Flickr

or this( look at the rear of the model) 

Lego STuG Ausf F 1/15 (RC) by Tommy Styrvoky, on Flickr

Edited October 12, 2016 by Tommy Styrvoky

[roppie11]

thanks for asking doug. I have the same struggles but the ideas here are pretty good. Thanks people!

[doug72]

Using Milan’s idea # 2: I have built a track tensioning device unit for the MOC I am currently building.
It also incorporates a track support sprocket. The drive spocket section will attach to this.

Awaiting delivery of more grey shock absorbers with soft spring to complete the track unit for the other side.

IMG_4121 by Doug Ridgway, on Flickr

IMG_4120 by Doug Ridgway, on Flickr

Edited October 13, 2016 by Doug72
duplicate image changed

[doug72]

Completed track unit.

With track looped around sprockets there was a gap of about 5mm, when joined tension is enough to keep the whole track in tension.

IMG_4122 by Doug Ridgway, on Flickr