Mini dozer idea..

[firemanjim]

Now your thinking!! Good idea......

 

[machinist@large]

U could atach your sprocket to the diff
But u need some methods of turning

Something like the Argo atv vehicals use this method
The output is taken straight from a diff
Yhen there is large disc brakes on each output
To turn u simply lock up one side

Then to stop go u have a standard clutch on the engine

This is a fairly decent method
But itll cost u
U will requre two large 12in rotors 2 capilers
2 large master cylenders that will be able to activate the caplipers without a vacume booster

The only down side is u cant reverse one track and forward the other
But bulldozers cant do that either
Also the steering inputs wil be quite violent if your not careful

This is the basic ideals behind how id do it though

Fowler, the reason I didn't suggest using differential braking is the lack of fineness in operation. When at full stop on one track, the other is forced to turn at double the speed that it would run with out the brakes.

Also, I believe the OP said he was planning on using a kart differential, which isn't rated for that kind of abuse...

Ill have to check my basement, but im sure i have a set of forks and front hub from a street bike. It has duel rotors and calipars. I think i could make some mounts and adaptors to use these. Then two hand brake master cylinders and levers. Hopefully this will allow me to avoid violent directional changes.

The reason I posted about some type of belt drive or clutch for steering was because it gives a greater degree of fine control. A great deal of the commercial walk behind lawn mowers out there, if it doesn't have hyd. drive, then it uses belt final drives with the belts and tensioner for each side serving as the steering clutch's.

 

[fowler]

the reason i suggested the diff was because itll be the cheapest
assuming u have a wreckers near by

u dont have to lock one track to turn
simply slow it

belts wold work certainly
im not sure it'll add any more finesses to the situation
being as belts tend to be an on off situation as appose to a feel it in thing

might just be a learn your machine situation

a kart diff might not be the best
id be useing a car diff
with car brakes

 

[jonboy]

Check this mini dozer build out. It has a few videos to show how well it works.
http://www.garagejournal.com/forum/showthread.php?t=132812&highlight=dozer

 

[Gouldian]

Jonboy, i saw a few similar to this on mytractorfourum. I shied away from hydro because of the price. Plus i think the mechanical drive will allow for higher speed should this thing prove strong enough to handle it.

 

[firemanjim]

That dozer was pretty cool. Then I watched that video for the DIY kit dozer. It looks lame, but actually does a pretty good job.... I wonder if you could just buy the drive cogs and some excess # foot of track?. It would speed up a tracked vehicle build, being able to buy pre made mini tracks and drive cogs.... I'm gonna so look around. I'm intrigued.... Here is a link to the one I'm talking about.... www.youtube.com/watch?v=NIUI3fLwBLg

 

[machinist@large]

That's the modern version of the one I saw at a local show years ago. That one was from the early 1970's; I believe it only had like a 5 HP B&S engine. It was physically a bit smaller than the one you linked to, but the owner was proud as punch at what it could do.

He had purchased it at an estate sale; said it had sat for who knows how long. He had to rebuild the carb, and mice had gotten the drive belts on one side. Since he was in there anyway, he did them all. Other than that, he just put it to work.

In his model, there were only five drive belts for the transmission. One coming back from the engine to the central common shaft, and a pair on each side of the chassis for each track; one for forward, one for reverse. The joystick's control the belt tensioners for each direction. Push forward to engage the forward belt, pull back to engage the reverse belt. No complex differential/brake system, no complex hydraulic system.

This is why I keep recommending this type of design. If you can rebuild the mower deck on a lawn tractor, then you already have the skills to build this transmission.

One question for you though Jim; what made you think that the video was lame? If you use QVC and all the other cable network infomercials as your base line, I guess it could seem to be. All they showed was an honest machine, doing what it was advertised to do, no more, no less.....

 

[itsid]

...
In his model, there were only five drive belts for the transmission. One coming back from the engine to the central common shaft, and a pair on each side of the chassis for each track; one for forward, one for reverse. The joystick's control the belt tensioners for each direction. Push forward to engage the forward belt, pull back to engage the reverse belt. No complex differential/brake system, no complex hydraulic system.
.....

I have the MD1600 belt diagram...

(ah there it is...)



and here is the MD50 (the five belt version ):
http://www.youtube.com/watch?v=nrPnODYnYbc


'sid

 

[Gouldian]

My biggest reason for wanting to use the diff and steering brakes is because i alreadt have it sitting around . The engineer at work is drawing up the drive sprockets. These will be 1/2" thick. After those are done ill start the tracks out of 2x2x 1/4 angle iron and steel plate. It may take some time. As he is working during his lunch break for me.