That 3.4 GPM may well be all I can handle while I learn the operation of a backhoe. Once you start practicing on a new-to-you machine, reality gets real close and sometimes real ugly if you're not careful. So I hope to go slow but strong as I gain proficiency.
I'll have to cut away the mounting brackets and weld others into place because this pump, although smaller displacement, is physically larger in all dimensions other than body length. Also, the rotation is going to have to be reversed. Fortunately I was able to look up the instructions to do that and they're not too complicated. Yes, the "fun" never stops!
The new pump is installed after reversing the rotation and making room for the larger dimensions. Not as challenging as I expected once I got into it. I did use the restrictors I made up and it all seems to work the way I had hoped. I have yet to try digging with it but that will have to wait till tomorrow. I spent the day correcting a couple of control valves by switching the away and back hookups. There were also some seepage issues that needed correction. Careful use of Teflon Tape should take care of them. I say "careful use" because any tape that wraps beyond the threads winds up clogging valves downstream. Taking apart scroll valves is not my idea of a fun or relaxing afternoon.I picked up a new pump yesterday and took a look at the challenges I face installing it where I had the original pump. That is going to take some planning!!
I'm pulling this thread back up to get some feedback and ideas. First the positives: after changing out the tired and inconvenient vertical shaft engine the Sears/Craftsman GT18 that the backhoe is built on with a horizontal shaft 13hp as described in the thread titled "From vertical to horizontal - proposed engine swap?!" in the Build it Yourself forum, I have finally been able to do some digging with it. The ability to mount the hydraulic pump directly has vastly improved digging ability. The belt drive just kept on slipping no matter what I tried. The tough conditions of our soil following our summer of drought conditions has caused numerous weaknesses in my design and workmanship to show up as breakdowns one after another. No real biggie though because now the hoe is better and stronger for it!! The negative(s): the hydraulic cylinders all do not hold position. Some are older used salvaged from other implements but the new ones are also leaking down. The former I realize I will need to overhaul and I can do it over winter. The new ones I suspect something else is the cause - I allude to it in the sentences in bold in the above quote. Careful as I tried to be when I used the Teflon tape to stop seepage I may have messed up on one or a few! Can anyone advise me what I can expect and need to be wary of when I disassemble scroll valves? The scroll valves were purchased new but sat unused for almost ten years while I waited for funds to become available to finish the build. I don't think that should be a factor but I mention it in case it is. None of the hoses and connections are leaking so the leak-down is not from that. Anyone have experience/advice to share? Also other possibilities that would be responsible for this?
The drifting is occurring in the direction the resistance is pushing. For example: the stablizers keep dropping the wheels back on the ground. The boom cylinder drops the dipper and bucket till they drag along while I'm driving between the shed and dig site. those are the most annoying examples. The stablizers are the ones I will overhaul. The boom cylinder is new.
The pilot operated checks are something I have not heard of till now. Are they a solution for the boom cylinder as well and where can I find them?
