Mini Dozer - Project near complete

[workinprogress]

There was a few earlier threads about mini dozers. I am nearing completion of my project. Basically I took a riding mower with a bad rear axle and built a subframe for it. The sub frame consists of the tracks and hydraulic motor mounts. In the tractor frame I mounted a zturn pump/control unit. The first couple test runs seem fine but I have issue with the rear chain drive tension. Basically the chains from the hydraulic motors to the track jump off. Hope to get it solved this weekend. I will post some additional pictures.

 

[larryccf]

can't tell from the photo, do you have a chain tensioner on the slack side of the chain?

 

[JB4310]

That thing is awsome, I want one.

JB.

 

[workinprogress]

The hydraulic motors are mounted on a slide so I can tighten the chain up. The Chain is tight when under light use but when I push things the chain loosens up. I think the entire back bracket is flexing and the pillow blocks mounting the track sprockets move slightly. My current thought is to put another pillow block onto the 1 inch shaft so that there is support on the other side of the drive sprocket.

I also added a photo of the sub frame without the track.

 

[ultrarunner]

I think every dozer I operate has additional rollers to guide and take up track slack...

Awesome project and very cool!

 

[workinprogress]

Yes that is my plan to add additional roller to the track. I just haven't found the right wheels/roller at the right price yet. I am able to put some good tension on the track so in the short term it seems to work ok. The chain I keep throwing is from the hydraulic motor (small sprocket) to the drive sprocket off of the tracks axle.

 

[workinprogress]

Here is the hydraulic pump/control and the linkage to the two control levers. The seat and rear fenders are off the tractor. The pump is driven by a belt and it uses the existing belt tensioner system on the tractor.

 

[porky69]

For adjusting the motors up/down do you have a mechanical adjuster(push or pull bolt) or just the slotted motor mounts? Looking at the picture it would be easy to simply drill a hole in the flat below the motor and put a nut and bolt in the hole with the bolt head against the motor housing and the nut against the plate and use this to help hold the motors position.

I would think that if there is no mechanical means of forcefully adjusting/holding the motors position as soon as you put a sizable load on the motor it would simply move the motor down in its mounts.

 

[EddieWalker]

That's very creative!!!

I'm impressed with your fabrication skills. Just creating your own tracks must have been quite the challenge.

How does it handle? Do you have many hours driving it around?

Eddie

 

[workinprogress]

The motors are just on plate with slotted holes and there is not any mechanical tensioners. I was concerned about that so have been watching it but it doesn't appear they have moved. During the initial setting I put a prey bar below the motor to put tension on the chain as I tighten the mounting bolts up. I do think a bolt or mechanical adjuster would make putting tension on them much easier. It seems the pillow blocks on the track chain have move slightly so hopefully a third pillow block on the drive axle will keep that from moving.

 

[workinprogress]

I have less than an hour on the unit so the bugs are still being worked out. The track design was borrowed from an earlier posting so it just took lots and lots of time to cut, drill, weld, weld, weld the track together.

Each motor/track is independent (forward and reverse and speed) of each other so it will turn right around or you can run one track faster than the other for a slow turn. The tracks do make a mess in my gravel driveway. Currently the rear is heavier than the front but after the drive system bugs are worked out I plan on building a front blade which hopefully will help improve the balance.

 

[ultrarunner]

I have one chain driven vehicle... it's a 7 hp 1905 Oldsmobile and the drive chain is rather massive as are the sprockets... I think the combination allows for more and deeper contact... and it's only 7 horsepower.

Good move on independent track control... there are times I wish my Cat was set-up this way.

 

[Ductape]

I like it !!!!!

 

[Willl]

Love your tracks, awesome job.

Redo your motor to drive axle framing thickness by 2. Gota be some major flex going on under there.

 

[mjncad]

I like your use of rebar on the track shoes. Excellent work!

 

[hammerdwn20]

what did you use for the track chain? Pitch and length? What size are your drive sprockets and where did you get them? thanks

 

[workinprogress]

The chain is 100 pitch and each side is 10ft in length. The just watched ebay for a good price. The track sprockets as well as the hydraulic pump/control and most of the other sprockets came from Surplus Center. The track sprockets (OD around 9 inches) were ones with an odd hub (2517 taper hub) so it took awhile to find the hubs at a fair price. Surplus center doesn't have any more of these sprockets.

 

[GuglioLS]

Awesome mini dozer build! I am super impressed. Very "simple" but clever and effective design. No doubt it's got to be a blast to drive around. I would have loved to seen the do-do eating grin on your face during the first test drive. I know I had a hard time keeping a straight face first time on my crawler. Perhaps consider adding a few mini track rollers between the large front and rear sprockets? 3 or so on the bottom and one in the center at the top. Doing that would reduce strain / tension on the tracks when crawling over uneven surfaces such as rocks, mounds and valleys and overall track tension could be reduced without sacrificing the chance of the track chain coming off. Just an idea to kick around and something to consider for the future.

Your Definitely going to have to add a blade up front and or even a rake in the back to "cover up your tracks" hehehe

I'll take two!

Larry

 

[JoelD]

You are going to have to find a way to really stiffen things up if you want to stop that chain from coming off. My thought would be one of a couple of approaches and there are much better engineers on here than me.

First, don't fight the tension fight and give some slack to the chain, then use a spring tensioner to keep the chain taught enough. Up at the drive motors you could put chain guides, this way, whether spinning forward or back the chain could not skip off the sprocket. You'd need to do something similar on the drive sprocket at the track.

I think you have two alternatives if you are going with chain drive, A - Have everything so stiff that the sprockets stay aligned no matter what you are pushing, pulling nor how twisted up you have the machine.

Or B - Provide for movement.

Another option, which may be a little more foregiving would be belt drive, deep V don't slip for nothing (or even two), but a lot easier, in my opinion, to keep on the pulleys (with guides).

Awsome build, I bet you are as good at welding as you've ever been.

Joel

 

[IslandTractor]

I am impressed. What a great project and beautifully done. I love the tracks.