My first wack at SketchUp

[redsox985]

Well, building off of my recent interest in tracked vehicles, I've begun making this model. It's a belt tensioner system with forward and reverse. It has a final drive ratio of about 8.5:1 between the motor sprocket and the big driver wheels in contact with the tracks. I didn't add much detail, yet hopefully, because, well, I don't know how to. Items like bearings are not added in but, with some understanding, their locations should be obvious. I've never used SketchUp or any CAD-like program before so go easy on me. The only real color I added was the red shocks and then the black solid pieces between the rollers. There is some coloration, SketchUp did that and I don't know why but it's going to stay until the final "paint job." There's a roll cage and hand controls to come, no brakes though, just reverse the tracks. The motor is a HF 11hp motor with the outer most dimensions given by HF. Do you see any major design flaws? I'm open to any suggestions. I've put way too much time into this already than I'd like to admit to but self teaching isn't the fastest. I can get you more specific dimensions if you want.
SketchUp file

 

[redsox985]

With some additions. I added a friction throttle control. Just remove the return spring from the throttle and then tighten the center nut to provide some resistance. Also rigged belt tensioner arms. Push down for forward lift up for reverse.
The updated SketchUp file

 

[Doc Sprocket]

Pretty cool. I've been meaning to try Sketchup, just never have the time.
Your interest in tracked vehicles has sparked my interest. However, I have some potentially very useful parts- Namely a hydraulic pump, 2 motors, and some miscellaneous bits. I don't know much about the parts as I kind of inherited them from a neighbor before he moved. I don't know, for example, if the two motors share specs.
At any rate, I was batting ideas around, and I like the hydro-drive thing...

As for your design, how is the countershaft driven- rubber wheels, or have you got some gears in mind?

Regarding the no brakes thing- Personally, I'd say install a brake for each side. I don't think belts will live very long serving as brakes. If the drive system is rotating one way, and the driven system (vehicle rolling) is counter-rotating, I'm sure this'll eat belts for breakfast.

 

[r97]

redsox, don't sweat the sketchup I've bean using it occasionally for a year and usually get frustrated with it be for i finish, lol. i would suggest making it a supported frame and adding some sort of a roll bar at the minimum, a good cage is highly suggested, i would suggest you get a bit more power but if you gear it low enough you can get past that, remember to use one of those hf 20 percent coupons! also why not just make the controls push lever forward for forward and pull lever back for backward.

 

[r97]

automatic dirt bike engine, deisel engine, or a rotary engine would fit this perfectly

 

[redsox985]

For simplicity reasons, forward and backwards is not as easy with the belt tensioner set up. I do agree with you now about the belts and brakes. As for the counter shaft, it's driven by 2 decent sized gears with equal teeth, or more on top for lower reverse speed. It's those two random touching wheels behind the motor. I don't have the know-how to make equally spaced teeth otherwise they would look like gears. I've given it enough color to tell whats what now. That guy with the 2/5ths scale mini sherman powered his with a 6.5hp motor and big time reduction. This is "sketched up" at about 8.5:1 with 11hp put into it.

 

[r97]

redsox,skip to about 4:00 that explains how to build a a simple belt tensioner system so forward input makes the track move forward and back input to make the track move backward
toystory listen to the beginning on his short discussion on hydraulic drive.
http://www.youtube.com/watch?v=BWHAfaC-pPg
redsox, heres how to make the gears,
http://www.youtube.com/watch?v=TDefnEKZhNI

 

[fowler]

i reckon hydrolic pump and hydro motor is the way to go with a desiel engine
but regardless U HAVE TO MAKE THIS
it will be cool to see the finished product

id be intrested in how u are going to make the tracks

 

[redsox985]

It would also be cool to have the cash to make one.

 

[r97]

fowler, watch beginning of 1st vid, he says hes had problems with hydro, if he has spent 3yrs making a tranny he prob made the best one. if you have the cash and preform maintenance hydro could turn out great, but i don't think redsox is interested in spending money on hydro if he is buying clone, but maybe not

 

[fowler]

dam i thought u were acctually going to make one

if i can work out tracks im going to make a hydrostatic one next year

 

[redsox985]

My final product for tonight at least. I could change it to incorporate the forward for forward method but just think of it as "flooring it." (mostly because I don't want to change this, TOO much work.) Now it's got a nice paint job. The frame is that shifty gray color, tracks black, rollers brown, springs/shocks red, solid pieces between rollers black, motor HF blue, seat yellow, axles white-ish gray, throttle lever green (for go), and pullies, gears, and sprockets are pink-ish.

 

[redsox985]

As T-man said, tracks are 18 wheeler tires with the side walls cut out. I'd assume multiple may need to be joined for my design because of length.

EDIT: The most recent SketchUp file

2nd EDIT: SketchUp is screwing with me. I'm scrolling my mouse wheel to try to zoom out and fit the entire screenshots on my screen. I'm clicking the wheel and holding shift to try to pan left and right. I'm trying to rotate the model in the pictures I've posted. I'm losing it. I'm tired. I'm rambling. I've gotta stop.

 

[r97]

sry but i think now that a full cage is too much a good solid above your head roll bar will work fine, base it off this
http://www.youtube.com/watch?v=NWiXIoINcb0
, and don't worry about changing stuff on sketch-up those models you made prob would've taken me all day!

 

[r97]

maybe a cage with a bit more simplistic desing

 

[redsox985]

I made the cage more "airy" but I was thinking, those tracks are heavy, that's big enough motor, I wanna be strapped tightly into a rock solid box if I roll this mother. And these SketchUp designs did take me all day. I made one more TINY change to the roll cage so that the front bars don't taper as they go up. It's not noticeable above but I just needed to fix it, SketchUp has stolen my life.

EDIT: It needs a floor. Someone wanna do it for me? Screw it, I'm putting a floor in my baby now. She's getting diamond plated.

 

[redsox985]

I'm done. I swear. (for tonight)

 

[fowler]

i have alot of experience with hydro motors as a farmer
i know they are quite high mantinence
i also know they have alot of power
and if they are set up right they are great

 

[r97]

redsox, make a cage like this http://www.youtube.com/watch?v=9E000sU8-Rc&feature=related(my preference, you do what you want)
fowler, ide love to see a hydro kart

 

[redsox985]

I wanna see that thing roll before I use his cage design. I know that's obviously an enormous engine as well as metal tracks but there's no test like "testing" it.