So heres my deal....i bought an old case 1740 motor runs great but clutches and variable drive were beyond repair so i decided to hack into this skidsteer and learn while "retrofitting" ..... I got rid of the clutches and belt drive and "simply" drilled some holes added two hydraulic motors, lined up the chains, cut them to size, added "woodsplitter valves" and plumbed everything.........this worked~~half ass~~the woodsplitter valves just didnt control the flow as smooth as i thought it would.... So its back to the drawing board, i found a set of bobcat 743 pumps and im just wondering if i can get theese worked up to my 40hp case powerplant i think i can make everything work..... for starters what size is the hydro resivoir on the 743? i think my case will hold 20-25 gallons but im also gonna add a cooler so that should up me a gallon or so and if i need more i think i have an idea to add 5-10 more gallons of volume Second will my 40hp motor be enuf for the pump setup? not really sure how many hp th 743 had but i think i read 39 so i sould be good if not better Third i need to know if thier is an internal charge pump on the 743 pumps? Just hook up to my res and im good right? anyway ill let you guys chew on that and see if anyone is down for the ride bofore i waste too much of your time....... Thanks for any and all help
Anyone wanna help with a project most call crazy?
- Thread starter 619atv
- Start date
SkidRoe
Well-known member
- Joined
- Dec 10, 2009
- Messages
- 1,887
That is quite a project! Some quick points:
-engine power seems adequate
-you have plenty of reservoir
Bobcat bleeds pressure from the fixed displacement loader pump to charge the hydro pumps, rather than running a dedicated pump. The charge valve is typically in a manifold that forms the base for the hydraulic oil filter (that is the way it is on my 440b). If you have this piece, that will make your life easier.
Cheers - SR
-engine power seems adequate
-you have plenty of reservoir
Bobcat bleeds pressure from the fixed displacement loader pump to charge the hydro pumps, rather than running a dedicated pump. The charge valve is typically in a manifold that forms the base for the hydraulic oil filter (that is the way it is on my 440b). If you have this piece, that will make your life easier.
Cheers - SR
Hmm... my 743 (not "B" series) manual has a hydraulic schematic that shows different for the charge. I'm not saying it is certain to be correct (we all know how manuals can be!), but it shows all flow through the cooler going through the long spin-on hydraulic filter and then to the hydrostatic pump, where it is regulated down by a "charge pressure relief". I assume that flow originates from the fixed-volume (vane?) pump on the front of the pump assembly. The schematic shows the reservoir as being 3-1/2 gallons, and that seems right to me as a 5-gallon pail will refill if I have to drain the system to work on it. The stock Kubota diesel is 36 hp. Do you want me to scan that schematic to .pdf and post here?
Yes a schematic would be great.....ive searched and found a couple but im not sure they are correct....if you have one for a 743 im definatley interested..... so your whole resivoir is only 3 1/2 gallons?...that seems crazy small, in my readings i was under the impression you needed 1 gal per gpm pumped
I do not have the manifold you are talking about but i do work at a scrapyard and i see all kinds of hydraulic fittings, hoses, manifolds, pumps, ect......what does this manifold do? Does it simply split the flow or is there something special i should look for? Thanks for your help
![Pampers Sensitive Baby Wipes, Clinically Proven, Fragrance Free, Unscented, Water Based, Hypoallergenic, Multi-Use, Hand Wipes 336 Wipes Total (6X Flip-Top Packs) [Packaging May Vary]](https://m.media-amazon.com/images/I/41KLBHu9CAL._SL500_.jpg)
Well, first problem is that there doesn't seem to be an easy way to attach a file here! Email me and I'll send it to you direct. Is there anybody that can put it up here, for all to enjoy?
Yes, the stock reservoir is pretty small. I think size isn't critical as long as the cooler is adequate and the system leaks are minimal. The cooler has certainly seemed fine on mine, and when I spring a leak a VERY noticeable gush is only a gallon or so, plenty left in there... Even 1 qt/hr is quite obvious, and lets you work "a full shift". Let's talk about the port blocks more once you have the schematic to look at, but that "charge relief" appears to be in the pump assembly itself.
7LBSSMALLIE
Well-known member
why.?
Anything is possible, the only concern i would have is how much money you would sink into it
Tazza i guess if i had to answer why...i would say because i cannot afford a decent skid but i am a decent mechanic and i work at a scrapyard......i bought the skid for $3,000 and spent $900 on the 743 pumps.....(everything else was found at scrapyard or charged with bosses permission to company account) so for $4000 i will have a "decent" machine and will have learned alot about hydraulics....i guess i have ocd and i want to learn about the machines that i sit in and run every day and i am poor as a church mouse..... That being said i have read many of your post and would definately value any and all of your ideas....
Wait..... sorry tazza wasnt your question..... Why? but i would love your input... Bill i got your schematic and thank you it came through loud and proud.... Looks like the block that i dont have is a combiner of some type? it looks to merge the returns in some way and send them to the main pump?.
Is anybody able to post attachments here? I (or the OP) could email you that schematic so that we can all discuss the details, plus it would be available to others that search and come across this thread in the future.
Ok so pumps arrived today...not sure how to post a pic here but they look to be in good shape and still have some usable linkage parts on them I am going to give them a meticulous cleaning and was wondering if i should paint them? Ive heard it both ways that painting runs cooler or that it runs hotter....any opinions?
I don't think paint is going to make a measurable difference in temperature, as opposed to a bare as-cast stock finish. I assume you would not try to polish these to a "mirror finish" and keep them that way, correct? Paint it, you feel better about the job. I don't think it even makes a difference what color paint you use, the heat is being radiated primarily as infra-red.
And my resivoir is the body of the skid itself...does my hydro tank HAVE to be above the pump? Or will the pump pick it up from vaccuum?
Hmm... good question. The hydrostatic pumps don't really suck from the reservoir, they recirculate fluid to/from the wheel motors. I think they will be fine, even if the charge pressure isn't up until a few seconds after starting. I also think the vane pump for all the rest (including providing that charge pressure) will suck a bit, but I am sure glad my reservoir is up above it! how high will it have to lift? I'm sure that vane pump is a commercial item, get the manufacturer's name and P/N off of it and it should be easy to find out how much lift it can handle.
It would probably have to lift 8" i will check on the spec i just found a make and model #
Sounds like you have a good source of cheap parts.
You better take pictures of all of this, i'm interested to see how it turns out.
The most expensive part i can see may be the hydraulic hoses.
