question about tracked vehicle

[old guy]

OK, I'm trying to work out details for a tracked vehicle similar to a GI weasel. I would like to use a jeep rear end with sprockets for the drive system. I can't seem to get a clear answer, it's my understanding on a car/pickup rear end without posi-traction, only one wheel will pull. I want to use independent brakes on each side for steering (skid steer) The question is if this rear end was used will only one side pull going straight, & would brake steering work with two master cylinders, one for each side? I figure a locked rear end would not work since something has to give if braking was applied to only one side. I understand the concept on my D-4, & military vehicles such as tanks where it consists of clutch release & braking, but that does not answer my question for using a standard jeep third member. Thanks in advance, would appreciate any ideas!

 

[Verticaltrx]

An open rear diff with steering brakes will work for what you are describing. In fact some of the early Cletrac dozers used a differential for steering, but they might have also been locked when going straight, I can't recall.

I have thought about building a small ~30hp dozer using a similar setup (but probably a 1-ton rear end). My only concern with this setup is making it pull straight under a heavy load since you still have an open diff. This could be especially bad with something like and angled front blade trying to push the rig off to one side, not sure if that would be a problem for your setup however.

 

[Trkrd]

Back in my younger "off road days" I remember reading about a differential that had an electrically actuated diff lock. Was quite a while ago but I'd bet they're still around. I'm sure a Google search would turn one up.

 

[beenthere]

Old Guy
Welcome to the forum.

If I understand the question, when going straight..both wheels will pull equally if they have traction.

If one slows down the other goes that much faster (the way a differential works).

If one wheel is stopped, the other will go twice as fast. So braking one wheel seemingly wouldn't work.

 

[SPIKER]

you would need some type of AIR LOCKER or ELECTRICAL locker to lock the dif in to go straight for sure. using the brakes to lock one side will work but not as well as a standard clutching system on more modern tracked tractors. what may work better is a hydraulic system using motors and valving to drive it. there are also mechanical ways to do this using 4x4 transfer cases and the clutch system to isolate side to side instead of front to rear. it gets more complicated this way though. costs if you can find good used hyd parts off fork trucks and or industrial equipment then that would be best way for cost and repair ability.


Mark

 

[RPW]

Not completely sure but the the diffs that I've seen had the drive shaft turn the right side axle shaft directly and the left side floated. Personally I think a better solution would be to use some hydraulic drive hubs.

Good luck on your project.

 

[alchemysa]

I don't know anything about tracked vehicles but I know the rear diffs on my 4WD and Kubota only becomes 'one wheel drive' when one wheel loses traction and starts spinning. Presumably on a tracked vehicle 'loss of traction' would be rare so an ordinary diff would be OK to use and the vehicle would travel straight in most circumstance. (But I'm just guessing)

 

[Taylortractornut]

There was a show on TLC back before it became the Fashion Birthing and Diet channel That came on after Junk Yard Wars. It was called Full Metal Challenge. It had the Lady from JYW as the host and they gave the contestants money to build a vehicle to compete in different challenges. There was a group of young folks that were machinist and they built a rear sprocket drive machine like a Terra King or snow cat. They used 3/4 inch belting that had a channel bolted across the 2 belts per track. Then they had a 1 ton o4 3/4 ton Floating axle for the drive. it worked good thewhole season till the last race I think the transmission took out. Do a google on Foremost truck converions on LandRovrs and Fords in the UK. they had a similar set up using theFors original axle. I ve seen them withsmall backhoes on them and ditchersworking in marshes.
One time when I was around 21 I went to LA to apply for work as an operator on Gas linethat ran through a swamp. They had Marshbuggies that carried personell and one with a small dragline out on the swamp andmashesto ditch. It had mill chain tracks butthe funn thing tosee them on the older mechanical drive ones was the Mack Motor and transmission hooked to the rear axle out of a truck that had Air brakes. The operator had 2 littls stubby levered air valves that he lockedon side or the other to make it steer. I remeberthe dragline carrier got hung on a stump out there andone side when to spinning and the other wasnt pulling. He just applied a little drag to the spinning track to run off the stump. For the most part they tracked straight.

 

[MikeD74T]

A non-positrack rear end will do what you want to do. Early Bombardier track vehicles used ford rearends turned upside down (because they were front mounted) and indepentant braking. tracked vehicles don't have the slippage that a wheeled vehicle does so the differential will normally divide the power pretty much equally. With independant braking you simply apply the brake on the spinning track & power shifts to the other. The power to either track is determined by the brake applied to the other track. MikeD74T

 

[PILOON]

In the days of VW dunebuggies the brake cables were split and 2 hand brakes were used foe traction control.

I once owned a snowmobile, made in Austria, based on a VW chassis.
Steering was attained by applying the brake on the inside track.
Very simple and effective system.
They also used variable pulleys to drive the differential more from one side than the other
very much like most skidoos do.
The unit was 'tractor style' with the differential up front along with the motor facing backwards. (envision it as the VW backing up but actually driving forward)
They somehow had a shaft, attached vertically, that used a big Vbelt that changed the amount of power that went to either drive hub.
I always figured that they were controlling the pinion gears with the Vbelt device, but never explored those details.

That snowmobile could drive at about 40 MPH in all kinds of snow and almost climb a cliff and did turn on a dime.

The manufacturer was, as I said, in Austria and the name was Wesmeiserskinner.
Perhaps Google might find them