Half Tracks

[MrNumbskull13]

Anyone here ever made a technic half track vehicle or seen any good ones? I want to make one with awesome off road capabilities but I am wondering is it possible to get the wheels and tracks to rotate at the same speed with lego?

[D3K]

should be possible, if you have the same outer diameter on the wheel and on the drive sprocket+tracks, if you know what I mean.. that would probably be simplest.. if you want to use bigger wheels, you'd have to calculate the gear ratios you'll need.

[MrNumbskull13]

should be possible, if you have the same outer diameter on the wheel and on the drive sprocket+tracks, if you know what I mean.. that would probably be simplest.. if you want to use bigger wheels, you'd have to calculate the gear ratios you'll need.

I only have small sprockets so I think it will be simpler to just power the tracks, thank you for you answer Dek! I think I'll try that some day on a different scale. :)

Next question; what is cooler & better, independent or bogie suspension for the tracks?

[trekman]

Anyone here ever made a technic half track vehicle or seen any good ones? I want to make one with awesome off road capabilities but I am wondering is it possible to get the wheels and tracks to rotate at the same speed with lego?

If you wanting the other wheels to rotate at the same ground speed, then just put a differential in between the drive to the half track and the other axles. The differential will do it's job and balance out the drive to the half track and the other axle. But you need to just send drive to the differential only.

Also if you can get the gear ratios right so that the ground speed of both axles is as close a possible, then there would be less slippage in the differential.

[dhc6twinotter]

I don't think the early half-track had power to the front axle. You could just not add power to the front axle and say you built an early model.

This topic may be helpful:

http://www.eurobricks.com/forum/index.php?showtopic=51300

[Lakop]

Here's one.

Google lego technic half track. i think it's on brickshelf.

H

Edited December 5, 2013 by Horace T

[dr_spock]

There are many of them on Brickshelf -> http://www.brickshelf.com/cgi-bin/search.cgi?q=half+track&stype=fi

[Milan]

I am building one right now, but only with tracks powered.

It is driving very well, but only with diff between tracks.

[MrNumbskull13]

I am building one right now, but only with tracks powered.

It is driving very well, but only with diff between tracks.

What if there isn't a diff?

[Milan]

What if there isn't a diff?

Then front tires have no function, regarding steering. The vehicle will always go in a pretty straight line whatever angle you make in front tires. In other words, it cant steer.

[MrNumbskull13]

I don't have any diffs... Anyone got any ideas on what I could build next?

[efferman]

i have made one long time ago, but it was not powered and only the tracks was connected by a diff to the fake engine

<-link

[MrNumbskull13]

Just figured out how to do this without diffs, I'll post WIP photos when I make so e progress.

[Milan]

Just figured out how to do this without diffs, I'll post WIP photos when I make so e progress.

One solution to do it without diff, is if you use two motors to drive two tracks, and use motor as a brake for one side of the vehicle.

[NevynPA]

I built one years ago with rubber tracks. I'd like to build one 8868-sized, but I haven't spent the money to buy tread links yet.

[VKTechnic]

I made this one a while ago:

Only the tracks were powered,but if you wanted to sync the rotation of tracks and tires, you'd want to use a differential.

[skriblez]

That thing was awesome Victor Kojenov! Do you happen to have instructions for it? Or more pictures?

[VKTechnic]

That thing was awesome Victor Kojenov! Do you happen to have instructions for it? Or more pictures?

More pictures here.

[MrNumbskull13]

Interesting machine, Victor! Should I power the front, rear or both sprockets?

[Milan]

Any sprocket, one per track should be fine.

Edited December 7, 2013 by Milan

[MrNumbskull13]

Sweet, which one do they use in real life? Also, wouldn't powering all the sprockets make it more efficient?

[Milan]

Sweet, which one do they use in real life? Also, wouldn't powering all the sprockets make it more efficient?

In real life, it depends, tanks usually have back sprockets driven, engine is placed at the back.

On some supporting tractor units from ww2, front sprocket wheels were driven, engine is in front of the vehicle.

On half tracks, on most famous ww2 half track, SdKfz 9 2, has front sprockets driven, but those sprockets were fixed to the chassis. The buggies were suspended.

On other types of halftracks, which has tracks mounted instead of tires, but they were replaceable with tires, like on ZIS trucks, there is a chain going from trucks axle, powering front sprocket, which is fixed to the whole buggie module.

Regarding efficiency, powering all the sprockets would actually cause more friction, and less efficient vehicle.

One powered sprocket will drive the track as good as any number of powered sprockets.

Edited December 7, 2013 by Milan

[MrNumbskull13]

Ok, I'm gonna go with front sprockets, thanks a lot for the info!!