Posted: 10 - February - 2007 at 08:55 | IP Logged

Thanks guys for all the suggestions, I will try to sit down and download one of these this weekend.  Not sure what I need but with anything new to me I just jump in and hope for the best. Have spent the last 25 years working on heavy trucks. With the introduction of electronics on trucks in the 80's, I have seen many changes that have caused some mechanics to seek other professions. I try to keep up but my brain is still set on mechanical mode.

ctimbs, Hey hows the progress comming,   would love to see more drawings.

Posted: 11 - February - 2007 at 12:48 | IP Logged

Ok,  Here is the in progres redesign of the tracks.  I know that there are some problems in the drawing the most noticeable is probably the open chain.  I need to move the tensioner so I can fit another link in and I wanted to get your opinions before I spend the time to make that adjustment.  I also changed from pillow blocks on the rollers to wheels with built in bearing (off of 800 lb casters).  The lines on the drive sprocket represent 120 degrees or 1/3 of the sprocket.

Posted: 11 - February - 2007 at 12:52 | IP Logged

The entire length of the track has been shortened however since the idler sprockets have been lowered to the ground the length of track in contact with the ground is almost the same. 

Posted: 11 - February - 2007 at 22:59 | IP Logged

I will throw in my opinion on the engine issue. A 16hp will probably quit when you turn. There is a lot of surface area being skidded on the ground, making it work real hard. Someone had posted a real well built self propelled ice shanty hear that was hydraulic that ran on 2 tracks and hydro motors. There is a video demo of it, and when the guy turned it on the ice it almost quit...on the ice.

At least a 25 hp, even bigger is the way to go. If you're gonna be raising the bucket as you're moving, that will drop down some, but not nothing like a 16 hp.

You deffinately have an excellent idea here, and are showing your deep and intent thought into it. Just hope to see it be as powerful and impressive as you. My bet is that you could find an engine on e-bay, or even one at a local small engine shop. Maybe think about a good used one that runs, or is worth rebuilding. These engines are a little pricy to rebuild, but by far much echeaper than a new one.

Like I said, this is just my opinion.

Posted: 12 - February - 2007 at 03:07 | IP Logged

definitely need the grooved bottom rollers.If you operate this machine without some type of track guidance,it'l come right off first time you turn.If you can at all,spend some time with a REAL track machine and drive it(or watch),try turning around and making some pivot turns..it'l show you just what we are talking about.The machine weight is borne by the bottom rollers,they need to have a ridge to keep the track under the track frame when you turn,if not,the machine will twist itself right offa its tracks.You'll also want some sheet metal guarding to deflect the dirt and rocks from falling down into your rollers,what I mean is guards below the drive spocket to deflect falling dirt from the tracks off each side of the track frame.Allow yourself some room for a bigger engine behind that seat,you'll need a 25hp at least..allow your drive motors to counterrotate with your steer valving,it'l take less energy that way to pivot turn than dragging tracks.This is a pretty ambitious project,hope ya got the PATIENCE, equip and facilities necessary!!

Posted: 12 - February - 2007 at 19:37 | IP Logged

I have to agree that a 16hp engine may be a bit undersized for your application.  The standard formula for determining how much hp it will take to run a pump is: 

HP required = Flowrate (GPM) X System Pressure (PSI) /1714  X % pump efficiency.

A standard gear pump is at best 90% efficient.  Most low speed high torque hydraulic motors need between 2000 and 3000 PSI to develop maximum torque.

You have a 2 section pump with each section capable of 10 GPM for a total of 20 GPM.

Given those operating parameters and using the formula it will take:

 31.5 HP to get the full 20 GPM @ 3000 PSI

 21 HP to get 20 GPM @ 2000 PSI

 15.7 HP to get 20GPM @ 1500 PSI

Most open center hydraulic valves have relief pressures adjustable from 1500 PSI to 200 PSI.  That means once the system reaches the "relief pressure" set in the control valve the relief opens and sends oil directly into the exhaust stream back to the reservoir.

If the relief pressures are set at the maximum you'll need at least 21 HP to get reasonable output from the pump and motors. 

Having said all this I'm using a 22 HP engine and a 25 GPM pump in My Cadtrac.  The maximum the pump can send to the wheel circuits (through 2 sections of a rotary flow divider) is 16 GPM.  That's further limited by using 1/2" and 3/8" diameter hoses.  With all the different restrictions the maximum I can run through the wheel motor circuit is about 12 GPM.

With only a maximum of 12 GPM @ 2000 PSI to the wheels there's enough power to make all 4 spin in a tough situation.  About the only time I run the machine at full throttle is traveling over long distances with an empty bucket.  Most of the time I run the engine at half throttle or less.  You can still develop reasonable pressure, and the lower flow rate keeps the speed down.  Most of the work I've done with it is moving piles of black dirt, crushed limestone, or sand, or plowing snow.  I don't do a lot of digging. 

Posted: 13 - February - 2007 at 08:59 | IP Logged

this guy has everything you need,motors,drive wheels,etc...he's parting out a Bobcat track machine

http://cgi.ebay.com/Bobcat-864-to-T-300-series-Drive-motors- also-T190-s_W0QQitemZ180083849482QQihZ008QQcategoryZ50908QQr dZ1QQcmdZViewItem

Posted: 14 - February - 2007 at 12:56 | IP Logged

I am not sure what size engine was used in the ice shanty but you guys are right he almost stalls the engine when he turns using those huge tracks. 

Just to compare designs

                                                    Ice Shanty || Current loader design

Track length (Ground Contact) 6' 10'' || 3' 6''

Track Width 12'' +or- || 7''

Track Area (Ground Contact) 1968 sq in || 588 sq in

Machine Length 6' 10'' || 5' 6''

Machine Width 5' || 3' 3''

Total machine weight (Dry/Empty) 1600 || ~1500

Est machine weight (Loaded) 2000-3000 || 1750-2200

So you can see that while my machine will have a similar final weight (I could see them adding alot of weight in supplies in the ice crawler) it will have far less surface area to skid.  Check out the video of the SVET46K in action and keep in mind that it is only using a 13HP honda to skid a 1300lb (empty) machine. 

http://www.mini-skid-steer.com/video.htm

I do agree that I need to make my grousers less extreem as the current grip will require alot of HP.  I am thinking about using 2'' X .24'' C chanel for grousers.

Posted: 14 - February - 2007 at 20:10 | IP Logged

New to this type of operation, but somewhat familiar with Tsubaki bucket elevators. Do you need a sprocket at either end of the track frame to keep the track on? Or would a smooth lipped wheel work as well? The drive sprocket needs teeth to engage the chain. Why do the other sprockets need teeth?

Bill