Mini Dozer - Project near complete

David Devuono · Nov 18, 2009

When I built my tracked wheel barrow I had not end of chain problems until I added a tentioner. It does not so much as add pressure to the chain as it allows the chain to wrap around the drive gear more. My chain would ride up on the drive gear and then jump a tooth with a loud crack. I am also collecting pieces for a mini dozer\dump cart. Thanks for the ideas.

Danno1 · Nov 18, 2009

wldrbob said:
how about some uhmw plastic and just make sliders on each side of your center chain no wories about bogie wheels then just like a skidoo slider inside the track. 2.5 or 3 ft sliders would fit just nice and that stuff takes forever to wear out and it stays slipery

+1

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David Devuono · Nov 22, 2009

My plan is to build a small dozer with a dump bed. Problem is I can't take all day to drive from my sand pit to the end of the road. I would really like to see a short video. What size pump and what Horse Power motor? How fast will it go flat out? Will it spin one track forward and the other in reverse at the same time or will it stall out or do it very slowly. I don't want to by two motors so need to get one big enough. I would be happy with 5mph (8kmph). Ready though a lengthy build on Machine builders network, the fellow had to enclose the drive chains with covers as small rocks caused chain problems.

Renze · Nov 22, 2009

David Devuono, why not buy a Honda motorised wheelbarrow with rubber tracks ?? it already has a dumpbed. All you need to add is a dozer blade and a decent operators seat so you dont have to walk behind them.

About the track sliders, if you make them run on the chain rollers there is even less friction.

wldrbob · Nov 22, 2009

hi there would be less friction on the track rollers but i dont think they would stay in place on hard turns and rough ground on each side would keep the track level to....bob

workinprogress · Nov 22, 2009

Took longer than I thought but I have things back together at least until the boggie wheels I ordered come in. I straighten the bent angle iron and welded 1.5x1.5 angler 1/4 thick on top of the part that bent. I also placed a third pillow block on. Once everything was put together I took a piece of flat stock long enough to between the drive sprocket like a straight edge. I made slight ajustments on the sprocket alignment so the flat stock have good contact with the sprockets. The resulted in about a 1/8 inch adjustment on one side and close to 1/4 inch on the other. I took a test run into the woods and looked for something to pull. The drive chain never came our in close to 20 minutes of playing. I put a chain onto a big flat rock and tried to drag it. The ground was soft and I couldn't get the rock to move (not sure I should expect the machine to move it) but I did dig some nice holes with the tracks. Gave up on the rock and drove back to the wood shed. Not sure the boggie wheels will be here before thanksgiving but will post pictures then.

Answers to a few questions Posted:
Speed - Currently the dozer zips along around 2.5 mph. With the boggie order I also have additional sprocket to try and gain a little more speed. Currently 3.4 to 1 ratio will try 2.4 to 1. Good site to check gear ratios and RPM to speed. Baum Hydraulics Corp :: Spec Calculator

Controls - The track are indepent of each other. One can go forward and the other reverse. At the current gear ratio there seems to be little impact to the gas motor.

Other specs: Pump/control - 0.43 CI for each motor. Hydralic motor 6.0CI, and unit is running off a 12.5 HP kawaski motor. Even at 1/4 throttle I can run one motor forward and one reverse. Drive Gear reduction - 3.4:1. In version 1.0 I ran 1.93 CI hydraulic motors, they had good speed but did bog down.

Questions: For those people suggesting direct drive with the upper (CAT type) drive design any thoughts how much sprocket contact do I need. I looked at things might be able to sneak a small drive sprocket right on the track but with the current track length and configuration I would only have 1/3 or so of the sprocket in contact with the track chain contact. Would that be enough?

Thanks for all the suggestions. I still need to work on the drive chain spring tensioners but wanted to get the boggie wheels on first.

PILOON · Nov 22, 2009

For idlers you could use smaller (same pitched) sprockets, say 3 per side and mount them between some serious enough flat stock (3/8 X 2-3") with only the teeth protruding.
Then you could attach to the upper track structure with perhaps some side bracing to keep them centered.
This way you'd always have good ground contact without streatching your track chains.

Otherwise real fun project, wish I were doing it.

Mace Canute · Nov 22, 2009

The recommended minimum wrap angle of the smallest sprocket in the drive is 120°. The wrap angle can be reduced to 90°, if good chain tension adjustment is maintained. If chain tension is not closely maintained with less than 120° wrap, the chain can jump teeth, resulting in damage to the chain and/or the sprocket. Also, the usual recommendation is a minimum of six teeth engagement.