tracked vehicle differential questions

[Taylortractornut]

Look at the old Arps tracks. Arps made several tractor Implements including half track kits. They added a mid set of idler wheels and then the belted tracks It has a 2 belts per track with a U shaped channel to follow the tires. Dad lived in SouthCarolina in the 60's and he said they used them in pulp wooding and early feild sprying.


http://s110.photobucket.com/albums/...Half tracks/?action=view&current=HPIM2701.jpg
http://s110.photobucket.com/albums/...%20tracks/?action=view&current=HPIM2624-2.jpg

Heres a few I found on pb's for a Farmall Cub

 

[David Devuono]

Track kits are extremely expensive. Don't worry about it self steering, tracks have so much traction you will have to work at it to get it to actually turn. You have to apply the brake to get it to turn. My 4,000 lb Massey 135 with the diff open easily locks one brake with old style drums so you should not need double calipers. You will need two master cylinders. If you could clear the body, I would leave both front and rear axles (steering welded up on front axle. ) This way you can run tires like an argo instead of a gear drive like a Bombadier. I put about $400 in parts and a 100 hours on my tracks and I am still not happy. I may go to an argo style.

 

[Mace Canute]

An alternative to double master cylinders is to plumb in two "line locks". These are electrically operated solenoid valves that prevent the passage of brake fluid when they are activated and you have hit the brake pedal. Attach the switches to the steering wheel and you can probably activate them with your thumbs.
These are easy to find, just google brake line lock

 

[davedj1]

Thanks for the input, keep it coming.
David, what aren't you happy with on your tracks?
I know I can't clear the body so I will have to have the rear drive and drop the tracks.
It's just a pipe dream at the moment. Someday.............................
dave

 

[DQ28]

Sounds like a fun project, and yes your standard open diff will work fine. I have built several 15 passenger Snowvan's for use in Northern AZ for the Grand Canyon Lodge on the northrim that operated in 7-9 ft of snow fun stuff. . The 2 concerns you need to look at in your design , are FLOATION, total area in pounds per sq inch of track surface on the ground divided by vehicle weight, and LENGTH of track on the ground . Split brakes will turn your vehicle, provided your tracks are not too long, and they offer good flotation, wider shorter tracks will perform better and be more manuverable.

 

[davedj1]

Sounds like a fun project, and yes your standard open diff will work fine. I have built several 15 passenger Snowvan's for use in Northern AZ for the Grand Canyon Lodge on the northrim that operated in 7-9 ft of snow fun stuff. . The 2 concerns you need to look at in your design , are FLOATION, total area in pounds per sq inch of track surface on the ground divided by vehicle weight, and LENGTH of track on the ground . Split brakes will turn your vehicle, provided your tracks are not too long, and they offer good flotation, wider shorter tracks will perform better and be more manuverable.

Good info to have, thank you.

 

[MikeD74T]

OK, I'm having thoughts about building a tracked vehicle. It will be used primarily on the snow to pull a grooming drag. I'm wondering if a typical car/truck rear differential would be ok to use? I am thinking of a ford explorer rear axle that has disk brakes and maybe adding a second caliper to each side to have more stopping power. Then use two large master cylinders, one for each side.

My question is, will the open diff. work the way I picture it?
Apply brakes on which ever side you want to go in? Thereby slowing down that side and putting the power to the opposite side.

I don't see the need for a tank like diff as I won't need to have one track go backwards, the turning radius doesn't have to be that tight.
Any input is greatly appreciated as always,
dave

Just for some added reading, I will be using a stock vehicle (small rear wheel drive) Like a Samuri/tracker or something. I will remove the front steering and all components, mount the rear axle solid to the frame. Then building my own undercarriage and tracks.
So the tracks will be driven from the rear.

Dave, Do a search for Bombardier "Bombi". They work as you describe except the differential is up front & turned upside down. Have changed the brakes many times, disks should work much better. If I were building the groomer it would definitely be articulated to the drag (like Bombardier BR 110). Much easier to steer with hydraulics than with brakes. Building tracks from used conveyor belting & metal cleats is time consuming but doable. NO matter what you build - we want pics! MikeD74T

 

[davedj1]

I will definitively have pictures when the time comes!

 

[SensibleNick]

Ello there Dave

As many others have said already, Differential Braking (the concept you describe) is an effective and proven method, and your The Auto-Box and fairly hefty axle that your proposed drive-train is equipped with will be brilliant for the job.

I too have been looking into making a small tracked toy, but haven't yet got the budget for it yet. When I do I'll be going for a hydrostatic transmission as I want to run a big snowblower or flail mower too. Hyrdo seems the way.
My tracks will be from a BV202 (a BandVagn made by Volvo, the predecessor to the Hè‡*glunds BV206)

Here's a video you may find inspirational: Some guys (who've ruined a BV206 by putting a daft body on it) making uprgraded tracks. A relatively simple process: and you don't need to go so extreme I'm sure.
[ame=http://www.youtube.com/watch?v=zrWx8yxtsWo]Extreme Hagglunds - Track Building - YouTube[/ame]

Here's a set of BV202 tracks being put to good use - simple differential braking on this one too: [ame=http://www.youtube.com/watch?v=QvxtDQaJ4eo]Homemade Bandwagon testdrive - YouTube[/ame] Note how unstable the suspension renders it.

And another set, on a slightly more tame machine with a more useable suspension setup - though it seems under-powered. (a problem you're not going to have) [ame=http://www.youtube.com/watch?v=f1uq7ftKaL4&feature=related]Telahärveli, omavalmiste - YouTube[/ame]

There's also a lot to be said for the extreme and ingenious simplicity of the Russian machines designed for driving around on the Tundra. This is absolutely one of my favourite machines, but do have a look at the related videos. [ame=http://www.youtube.com/watch?v=kYha7RSGlmc&feature=related]???????? ???? 8 - YouTube[/ame]

Even more inspiration can come from looking at the Kristi Snowcats Their tracks are simplicity: Hickory cleats won't work for the Power you're considering, but it should make understand more about how easy it can be to make things.

http://home.earthlink.net/~wilkinsn...tebuilderpictures/gary_with_kristi-soda-1.jpg

Nearly Lastly from me... Suspension: Why bother? if you're on snow most of the time, you'll need little track articulation. This guy on his rear-driven, differential-steered machine makes it look easy. [ame=http://www.youtube.com/watch?v=b07wocGkLlk&feature=related]Aurausta tela-ajoneuvolla - YouTube[/ame] Look for his other videos, especially the one where he hauls a ton or so of wood in deep snow on a trailer with wheels...

.. And the last thing: You asked about your disk-brakes.
Brakes build up heat, and heat leads to snow melting on them. Drums don't get snow inside them as much as disks will get snow on them, and In my initial stages of thinking about building a toy like this, I wondered if the disks would cycle above and below freezing point and get ice build-up? .... I decided that a "get out of jail free card" would be to route the exhaust so that it warms the disks.
When it comes to extra calipers there really is no need. I'd assume that your drive wheels would be made from steel rims with bars welded across them, you'd be removing the diameter of the rubber tyre, thus reducing the effective rolling diameter of your "wheel". This would lower the gearing of your machine compared to the original truck (no bad thing) but because you're reducing the wheel diameter, you're also effectively raising the leverage that your caliper has over the "wheel" which would make your single caliper far more effective than it is on a large diameter wheel.

erm... That got a wafflish at the end... hope you see what I'm attempting to get across!

 

[davedj1]

SensibleNick, thank you for your post, you sound as enthused as I! Great! One day when we hit the lottery we can build away.
I have watched tons of videos on youtube, I do like some of the Russian vehicles.
I knew that by removing the rubber and using a rim for the drive that I would reduce the gearing but never thought about the increased leverage of the braking.
I am more used to building off road jeeps with bigger tires and big lifts. I guess I have to learn to think differently.
I'm not sure if I mentioned before but the machine I want to build will only be used for snow.
If I had the funds I would start tomorrow...LOL
Happy Holidays ,
stay in touch,
dave