Project Mini Hägglund

[Steinbruchsoldat]

Hi guys,
every winter we do some trips to our house in austria. There`s about 5-8feet of snow, so it`s impossible to reach it with a 4x4 (at least with the ones we can built in germany). So i was looking for a snowmobile, but i didn`t like the prices and the fact that i only can use it in the snow...

Then i found this video:



I started looking for parts and decided that i want to build something like this. Then i saw this picture:



I soon decided that i have to built a smaller version of this...

The specs:

It needs to be small enough to fit in the back of my L300. Availible space is about 120cm x 240cm. The width will be ok, but the length not. But this won`t be a problem, because i can unhook the second car und load it on top of the first. I think dimensions will be about 120cm x 300cm.

Drivetrain:
I`ll use everything out of a Subaru Justy. Engine, tranny, both axles, radiator, driveshaft, steering, just everythings that`s needed. Should have a lot of power with the 75hp engine.

Here`s a quick sketch of what i`m talking about:





I`m just trying to get some measurements of the components together, so i can do some detailed drawings...

[Steinbruchsoldat]

Started with the first track today:









Mockup:



Dimension. The OSB equals the second track:



This would be the driveshaft angle with the engine in the rear like i wanted it to build.



Ok, so the engine goes in the front. Problem is that i won`t see anything with that setup:



So i need some ideas for that...

[78Bronco]

I suppose the steering will use left brake right brake and the open differential.

[Steinbruchsoldat]

No, it'll use a hydraulic ram between both cars to tilt them. I'm possibly going to weld the differentials if needed...

[Steinbruchsoldat]

Did a few drawings today:











Hopefully the engine fit`s between the tracks like it`s shown here. If not, i need some new ideas...







Found the first mistake. The joint should look like this:

[Ala5ka]

I'd trying using some real snowmobile tracks for the treads. The tracks are wider spreading the weight out more so you won't get stuck as often. For steering I'd use a control stick system like a Bobcat.

[Steinbruchsoldat]

Well, snowmobile tracks cost about $800/piece. So it's a bit too much money to spend. I still think i can do the whole thing for less than a grand...

Steering will use a normal steering wheel...

[Ala5ka]

Steering will use a normal steering wheel...

How is a steering wheel going to work? Aren't those rams rather spendy? If you have a gear box that splits power between the two tracks it'd be bomb proof and simple I'm assuming. You also could do away with throttle and brakes if you do that. As for the snowmobile tracks don't buy new, get a worked pair used, should be really cheap that way, you don't need it to be in awesome shape cause you won't be able to burn out like a sled would, maybe even one meant for a longer track would work if cut in two? They'd be wider too so you could "float" snow, won't tires be too thin unless there was no weight on it? If you had more power and more traction on the "vehicle" end you could save money by having a simple sled behind it and no PTO out. that saves weight, money, and complexity. Just an idea, where I'm from snow is a big deal haha. The Right Track personnel carrier is "skid steer like," "independent stick with cable control for each track" http://www.vmcrighttrack.com/rt-01/specs/index.html
A steering wheel, pedals, and independent brakes sound cool but for cheap, and reliable I think less complex is better (for the record independent brakes are a good idea) A lawnmower throttle could suffice for idle control. Sorry for a long post you have just got me thinking dangerous

[Steinbruchsoldat]

Hi, the $800/track is for used ones, don't forget that I'm in Germany. So snowmobile tracks won't happen...
The trail this thing is driving on is always groomed, because the hunters use it with ATV's with mattracks on.
As for power and traction, don't forget that there's a big surface covered by the tracks, I'd say three times the surface a snowmobile covers. And for power, well i think 67hp should be more then enought...

For the steering i'll just use the whole system from the donor car. The steering rack will be used as a hydraulic ram. The skid steer (front and rear car tilting against each other) should work really well, as it does on the big ones...

I could do independent brakes without any problems, but there's no need for it. I even think that I'm going to weld both differentials for better traction...

[Ala5ka]

Hi, the $800/track is for used ones, don't forget that I'm in Germany.

No need for hostility, I knew you were in Germany but unsure of the german used track market, they can be had here for a little over $100 or less if you know someone

As for power and traction, don't forget that there's a big surface covered by the tracks, I'd say three times the surface a snowmobile covers

a snowmobile's tracks have paddles and are at least 15" wide, with an average length of 120"-174" (normal consumer sleds) plus skis, I'm not being critical only trying to help, I think in 5-8ft snow like you may encounter the tires will not give you traction and bury the "machine" up to the undercarriage, it may be cool on dirt or packed snow but I think you'd be spinning your tracks a lot in the snow

For the steering i'll just use the whole system from the donor car. The steering rack will be used as a hydraulic ram. The skid steer (front and rear car tilting against each other) should work really well, as it does on the big ones...

skid steer is when one track moves faster or slower than the other, not like the neat "kinking/twisting" cab of the big Hagglunds. How about trying a hand throttle and apply braking force to one track or the other with open differentials, I know the true Hagglund drive mechanism is neat but it's complex where complexity is not needed.
Again not being critical just trying to help brainstorm, I built my first sled when I was 15 and blew up my last one when I was 22 so I may not be the most qualified person just another helping hand