Mini Dozer Idea Factory (potential build)

[sawdustdad]

Originally Posted by DRohacek

Dan Hoefler built this one probably 20 years ago. I expect some of you may have actually seen it at the shows.

I've seen that one. There's another WF version on Youtube.

I wonder if the control levers are just brakes? If you brake one side, doesn't the other side start driving? So could you just build this with one rear end and use brakes to steer? He's got the front sprockets with tensioners, so it appears that's what he's done.

[sawdustdad]

Originally Posted by DRohacek

School me on this a bit please. Do you figure the diameter of the drive sprocket or the outside diameter of the track at the sprocket? Back in the early 70’s when GM owned Terex I worked at the Hudson plant in Ohio as a welder. We actually built our own drive cases and had gear hobs to make our own gears. We had a horizontal broach that was 12 ft long that we broached the inside splines on the spindles. The floor would shake when it pressed the broach tool. Anyway I digress. My point was I was around some pretty neat machines back then but unfortunately I don’t have any experience with the track system of the crawlers.

Ground speed is a function of the rotational speed of the axle (RPMs) and the radius of the wheel or track circle.

Cut the radius in half (use a 10 inch sprocket with a 12 inch track diameter, which is about half of the 23 inch diameter tractor tires, should reduce max ground speed from 8 mph to 4 mph. What matters is the effective radius of the surface in contact with the ground if that makes sense.

[DRohacek]

Originally Posted by sawdustdad

I've seen that one. There's another WF version on Youtube.

I wonder if the control levers are just brakes? If you brake one side, doesn't the other side start driving? So could you just build this with one rear end and use brakes to steer? He's got the front sprockets with tensioners, so it appears that's what he's done.

I don't remember how he did the brakes. I followed this build years ago when he did it but I don't have the details anymore. I know at the time he had a machine shop and made a lot of specialized parts for it.

As for the steering you can definitely steer it with brakes and one rear end. Effectively you would be doing the same as independent brakes on a farm tractor. As long as your differential is not locked it will work. I remember plowing with our Super M as a kid and at the end of the field I would tramp the brake because the front end was dancing a bit. The tractor would turn 90 degrees as I lifted the plows. You can stop one track at a time with good brakes.

[sawdustdad]

Originally Posted by DRohacek

I don't remember how he did the brakes. I followed this build years ago when he did it but I don't have the details anymore. I know at the time he had a machine shop and made a lot of specialized parts for it.

As for the steering you can definitely steer it with brakes and one rear end. Effectively you would be doing the same as independent brakes on a farm tractor. As long as your differential is not locked it will work. I remember plowing with our Super M as a kid and at the end of the field I would tramp the brake because the front end was dancing a bit. The tractor would turn 90 degrees as I lifted the plows. You can stop one track at a time with good brakes.

My Ford 2000 has independent brakes and yes, you can spin the tractor around easily.

Here's where my mind is at this point. Some rough sketches:

[Ambush]

I'm confused why you're turning the engine around. If you welded the rear of one frame to the front of the other frame, with the motor in between, everything would line up and turn the correct way. But for a more Cat like look, I'd mount the motor high and forward. Right over the "front" axle.

I don't think a single axle and "brake" steering would work without a brake up grade and even then probably wouldn't last long if actually working it. Good enough for shows probably.

[DRohacek]

Originally Posted by Ambush

I'm confused why you're turning the engine around. If you welded the rear of one frame to the front of the other frame, with the motor in between, everything would line up and turn the correct way. But for a more Cat like look, I'd mount the motor high and forward. Right over the "front" axle.

I don't think a single axle and "brake" steering would work without a brake up grade and even then probably wouldn't last long if actually working it. Good enough for shows probably.

This project would be a good time to install a hydraulic caliper. The steering levers could be hooked to a pair of master cylinders from a motorcycle. This is a pretty cool configuration too. I don't think anyone has done one like this yet with the high mounted drive wheel

[sawdustdad]

Originally Posted by Ambush

I'm confused why you're turning the engine around. If you welded the rear of one frame to the front of the other frame, with the motor in between, everything would line up and turn the correct way. But for a more Cat like look, I'd mount the motor high and forward. Right over the "front" axle.

I don't think a single axle and "brake" steering would work without a brake up grade and even then probably wouldn't last long if actually working it. Good enough for shows probably.

Yeah, the single axle won't give me the weight and hydro controls that I think will function better.

I want the front of the dozer to present the rear cover plate of an axle rather than a more fragile hydro (and oil filter) sticking out there. Otherwise I'd have to build an enclosure and skid plate out front to cover it up and protect it.

Motor over the drives may well look better, so that's still an option and may actually be required to tuck the axles under the hood so to speak. Either way, I still need to turn the engine around if I want the front face to be a rear axle cover. Since I'm now quite familiar with double drive belt arrangements, it might be the way I go. Direct drive presents the challenge of starting the engine with two hydros hooked up.

[sawdustdad]

Originally Posted by DRohacek

This project would be a good time to install a hydraulic caliper. The steering levers could be hooked to a pair of master cylinders from a motorcycle. This is a pretty cool configuration too. I don't think anyone has done one like this yet with the high mounted drive wheel

That's the look I am going for, though the high point would be tensioner, not drive.

I think the dual hydros give the best and most controllable positive drive method.

[Ambush]

My mistake. I had front and rear reversed on your sketch, now I get it.

With that arrangement you can still pulley down to the front most shaft, than a drive line between the two hydro's.

The larger bearing is at that end too, for sideloading.

[DRohacek]

Originally Posted by sawdustdad

Ground speed is a function of the rotational speed of the axle (RPMs) and the radius of the wheel or track circle.

Cut the radius in half (use a 10 inch sprocket with a 12 inch track diameter, which is about half of the 23 inch diameter tractor tires, should reduce max ground speed from 8 mph to 4 mph. What matters is the effective radius of the surface in contact with the ground if that makes sense.

Thank you. I think I get it. It makes sense to me now I think. So effectively it basically means it doesn’t matter if the drive wheel is inside a track or running directly on the ground. Speed is a function of the diameter of the drive wheel regardless.