My Craning/Digging Switch is not working, I suspect the solenoid might be bad. But... What I would like to know is: (1) What direction is the oil flowing with the switch on or off? (2) What is it doing? Without taking everything apart I can't figure out what's going on here. The hammer switch does work when I put power to it. This is all the book says about it. Thanks! Blue
Anyone on the forum have a B.H.S. Degree? Bachelor of Hose Science. You probably need some kind of degree to understand this mess.
Bueller?… Bueller?… Bueller?… Bueller?… …Anyone?… Anyone?… Anyone seen this before?
As a guess, there's a two stage counterbalance valve connected to the boom cylinders, and when you select "craning" the solenoid valve pressurizes a port on the counterbalance valve telling it to operate at a higher counter pressure, giving finer control. But that's just a SWAG given the limited information I could be way off.
Hey lantraxco thanks for taking a shot at this. So by counterbalance that means the solenoid valve is letting a certain amount pressure on the opposite side of whatever cylinder is being moved? Limited information? What more do you need? Maybe I should mention this machine is a Dynahoe 1900 backhoe. Anything else?
Pretty rare bird, need a hydraulic schematic.... probably written on parchment if you ever find one...
This is the best quality I can get for a pic. I tried it 3 different ways and they all look like crap. I think actual parchment would be better. I have the parts manual if you need individual diagrams. Below is a pdf. much better. View attachment IMG_0007.pdf View attachment IMG_0009.pdf
Only thing I know now is that it's not what I suggested previously. Next guess is that it's a load sensing system and the solenoid valve connects the pump sense line directly to the pressure side, putting the pump in high pressure standby all the time, or something similar. Is part# 110 on the image 0007 a shuttle block?
Hey lantraxco, the book describes it as a shuttle valve (whatever that means). And according to the second pic in the first post, I think there is two of them connected together. I found this in the back of the book. They call it a "rear auxiliary hydraulic circuit". Thanks for your help, this means a lot!
It's looking more and more like a load sensing pump system, the shuttle valves are to allow whichever system, loader, backhoe, or auxiliary has the highest pressure demand to feed back to the pump while excluding the other two. The regulator on the pump always tries to keep pressure at the pump outlet higher than the load signal pressure coming back from the valves. It would seem to me that the solenoid valve selects whether to send the load signal from the spools in the backhoe valve to the pump regulator which is normal digging, "load sense" operation, or connects directly to the pump pressure line coming into the backhoe valve bank, effectively making the pump run constantly at it's maximum or "standby" pressure. Connecting a pressure guage anywhere you can tap pump pressure should tell you what's happening. Some people do jigsaw puzzles or crosswords or whatnot, I like puzzles like this the best! LOL
OK, riddle me this Batman... Looking at the 0007 pdf. 217 and 225 are return lines that go to the in tank filter. 217 gushes oil from idle to full RPM and only has hose clamps on it. 9, 15, 18 and 21 are the main feed lines for the loader and backhoe. 186 and 189 are return lines that connect to 191,193, 224 and 225 104, 105 and 108 are load sensing lines from 112 and 116 threw the shuttle valve 110 The more I look at this schematic the more I understand what's happening here. But there are a few things I can't figure out. Q1 Do the main feed lines have full line pressure all the time or does the load sensing line send pressure when the valves are being used? I'm familiar with how a bypass valve works, like on my log splitter you can move the lever to fully extend the cylinder, hold it there, and the hydraulic pressure just bypasses without killing the engine. But not so with my backhoe! If I extend or retract any cylinder and hold it there for more than one second, it will kill the engine. After studying this schematic I found what's called a filter, number 11 that I was not aware of. I assume it's a screen filter. Keep in mind when I bought this backhoe there was no filter in the hydraulic tank and there was ground up chunks of rubber and debris throughout the oil system. Q2 Everything does work at a seemingly normal speed, but I am just wondering (and I don't see how) if this number 11 filter is partially clogged, could that be why my engine is dying? Actually I'm thinking it might be blown out. If that's even possible. I did have a fuel issue (clogged supply line) that was resolved and it did help out quite a bit, but I'm still having a problem with the engine dying. If you could explain how this pressure sensing line works in the system maybe I can figure out what the problem might be or if you think you know by all means explain away, please!
Okay, I think you have all the lines sorted correctly. Line 217 is coming from the cooler, and since it looks like #142 is a steering pump that's probably why you're seeing constant flow there. Q1: A load sense system working properly will usually have 250-300 psi on the main pressure lines with no work being done. When you activate any function logic valves (shuttles or checks) inside the valve banks will connect the high pressure side of the spool to the pump regulator. The pump regulator will stroke up the pump providing more flow, it's always trying to keep the pump outlet pressure higher than the load sense line, so if your boom cylinder for example needs 1,000 psi to lift the load, the pump will give you 1,200 to 1,300 psi at it's outlet, always staying ahead of the load, up to it's maximum flow. That filter would appear to be a high pressure filter, you might want to check it, it's probably sintered bronze or the like. Or it may be missing? If it was plugged you would get slow or no movement from any loader or backhoe function. Q2: When you hit the end of stroke on a cylinder, the load sense line will be feeding that pressure back to the pump regulator and the pump pressure will climb to it's maximum setting. If the engine is dying I can think of three possibilities: 1) the engine lacks power. 2) There is an internal leak or weak relief valve somewhere in the system that is bypassing oil, and when you deadhead a function the pump is trying to keep up at max pressure and overloads the engine. 3) The high pressure setting on the pump is too high or it's not destroking fast enough to unload demand off the engine. E) All of the above. Do they break down individual parts for the loader and backhoe valve banks? If so do they show relief valves in those valve banks? Any relief valve in the system should open at a higher pressure than the max pump pressure setting. Any idea what the pressure spec is for your machine?
You are correct sir! 142 is a pump for the steering and brakes. But the 217 line is 1.5” in diameter and its a solid stream at idle. I can see it with the filter housing cap off. I couldn’t go much above idle without getting oil everywhere but I did notice if you move the loader or backhoe that stream starts to go down and 225 goes up. Have fun with these descriptions for 00007pdf---------- View attachment IMG_0000.compressed.pdf Main hydraulic pump--------------- View attachment IMG_0001.pdf Loader valve------------------------ View attachment IMG_0002.pdf Backhoe valve---------------------- View attachment IMG_0003.compressed.pdf Pressures from operator manual-- View attachment IMG_0004.pdf
Very interesting... verifies that it is a load sense system with a separate pressure limiter control. What is kinda unique in my experience is that it appears the piston pump has a gear supercharger pump. That's why you're seeing so much oil flow on the 217 line, the gear pump is pushing just a bit more than maximum flow all the time and the unused oil passes out through probably a check valve into the pump case and back to tank. When you use piston pump flow to move any loader or backhoe function, the excess charge flow is diminished by the same amount being pumped to the work function and that flow returns via the 225 line until it gets hot at which point it flows through the cooler and will again return via the 217. Follow that? LOL. Lots of relief valves, main relief is in the inlet end of the backhoe valve stack. You need to start by getting some gauges and checking/setting the main relief and pump limiter, and then the individual port relief valves. The load sense has an adjustment as well but I don't see anything about that listed.
You're the man! Very interesting indeed! I totally follow what you're saying and it's good to finally make sense of this thing. I will definitely hook up some gauges to a couple cylinders and see what's going on there. Once I see what the pressure is I won't be afraid to give the engine more RPMs. Detroit engines like to be run at high speeds but I didn't want to go to high and blow a line or cylinder seals. Altho I did run it much higher than I should have a couple times but the engine still died. I was thinking a stuck relief valve was the culprit, that it wouldn't let the pressure relieve into bypass. I imagine the relief valve for the pump would be somewhere on the control unit number 64, but I'm not seeing it on the breakdown. I can see relief valves on some of the separate components like: The main backhoe valve number 4 Backhoe bucket section number 22 and maybe 27 The dipper stick section number 22 and 23 Boom section number 21 and 22 But I'm not seeing a main one for the loader valves Except for the loader bucket section number 20 like you said, Lots of relief valves Do you see a relief valve anywhere here? Not that I want start adjusting pressures but to inspect a sticking or damaged valve. Just wondering, who's the slightly scruffy and generally grumpy Dr. Don? Nice equipment!
Since it's essentially a closed center system, pressure is the same at the loader valve, backhoe valve, and aux valve, the main line from the pump is just teed, so the one relief valve #4 in the backhoe valve is the main system relief for everything and it's just there for safety, if the pump regulator control is working properly that relief should never open. The reliefs in the individual sections only work to allow the cylinders to move if external force makes the pressure high enough to pop the port relief open, OR when you activate that particular function and the relief opens at a lower pressure than the pump setting. There are no main relief valves in the pump that I can see, only high pressure control and load sense settings. Without the factory procedure I wouldn't mess with the pump settings unless it's the last resort to get it working properly. In your first picture the test port should be charge pressure from the gear pump The second picture is the load sense block, at that test port you should have near zero pressure with no functions activated I believe. If you put a gauge on it, make sure the gauge is good for a minimum of 3,500 psi, 5,000 would be safer. If you have high pressure on this port all the time, you are most likely stuck in "Crane" mode woud be my guess. According to the pressure chart in IMG_0004 the pump should max out at 3,000 psi, the system relief (#4) opens at 3,500 in case of a pressure spike or control malfunction. The port reliefs are all higher than 3,000 except it seems the loader bucket function. Steering and brakes are on a separate pump so we can probably ignore those. In an open center system like you're familiar with oil flows all the time and only varies with rpm. When using a work function if pressure exceeds the relief setting, the relief valve opens and dumps oil back to tank. The engine will load down, as it will be pushing all that oil at the relief setting. The way a closed center system works, rather than letting oil flow back to tank across a relief, the control on the piston pump will sense the pressure and destroke the pump to a point where balance is achieved, pressure will max out to the set pressure and the pump will only pump enough oil to make up for whatever minimal internal leakage occurs in the system. At this point essentially no oil is flowing in the high pressure part of the sytem. Basically if you are digging or say lifting a load with the front bucket, when load exceeds the set pressure the cylinders will just stop and you may hear a slight growling noise from the pump in standby, or no change in sound at all. Since basically no oil is being pumped, the engine will not load down. Horsepower is pressure times flow, so no flow=no horsepower. Re: Dr. Don, that's an old joke I should probably take off the website... to answer your question, he's just tired old guy foolishly hanging onto some duct taped dreams.
Like I said, your the man! I'll order a gauge tomorrow and while I'm waiting for it to get here I'll check out that filter. This closed center system is rather interesting, I'll have to study up on it. I thought Dr. Don might be you, but either way some of the best things are held together with duct tape. Hey lantraxco, you helped me out in a big way, THANKS!! God bless!!! Blue
NOT what I expected! 1st, I thought the filter would be gone. 2nd, if there was one it would be packed full of junk. ( BTW the element was in the other way, not like the pic.) I can clean this one but I would like to find a new element if I can. I can't find any information on the inner web with the part number, but I have one place to call Monday. Pall Corporation World Headquarters in NY. UNLESS someone has a better idea. You know, if the engineers would have moved this thing back 12" it would make servicing it MUCH easer. Oh well, on to pressure checks...
That's ugly, I wouldn't put that back in if there's any other way....
I concur. That element is ugly, but it did clean up pretty good. At this point I don't have the time to get involved with another plumbing job. 1st pressure check I put a gauge on the loader lift cylinder and it revealed some interesting results. The system operating pressure is supposed to be 3,000 psi. But at full speed, 2,700 RPM, the engine dies before it reaches 3,000 psi. I can hold the pressure at 2,800 psi, the engine is loaded down but keeps running. If I try to go more the engine will die even if I move the lever in the opposite direction. Once the engine starts to die off it keeps dropping until it does die. It's like what you said in post #13, "it's not destroking fast enough to unload demand off the engine". Further testing showed some different results. I put the gauge on the load sensing test port at the pump and I can operate the backhoe up to 3,000 psi. The engine still dies off but I can release the lever and it will pick up rpm's again and keep running. The loader acts like it's sticking somehow. All 3 functions do the same thing. (it has a side dump loader bucket) The other test pore at the pump has zero pressure. It must be the charge pump #62. I assume it would have pressure if the return filters were clogged. I need to buy another gauge and more hydraulic oil (still working on the leaking cylinders) to better see whats going on. As far as the engine goes, the whole machine seems to be under powered. Or there is still a fuel problem, like a clogged injector or something.
Probably need to run the overhead on the engine to get it up to snuff if you haven't, and you may have some stuck rings on the pistons since it set for so long. Just for giggles try one of the stabilizer valves, they're in the loader stack but they don't have port relief valves. The load sense circuit in the loader valve bank may not be draining off as fast as the backhoe valve, it's hard to say without knowing how they operate internally. The good news is it sounds like the pump is basically operating as it should.
Ok, I am seeing more and more why Dynahoe went out of business. From buying components that are obsolete in a few years and replacements cost a small fortune. That Grit Stop filter made by PULL is a good part number but I can’t buy the element only, I have to buy the whole assembly. And if they think I’m going to fork out $1,250.00 for that thing, they are completely off their rocker! I can get a better system from Donaldson, plumbed and everything for half that price. Still working on doing more pressure tests. Readjusting the top end is a good idea. I'll put it on my things to do list. And it would be nice to know the compression.
Yeah, Pall always was extremely spendy, but it makes no sense you can't get a replacement element. Donaldson or Parker will have high pressure filters that will work for sure. If you pull the injectors for any reason, like checking compression... take them to a fuel injection shop or a Detroit dealer and have them tested, one thing I forgot is they tend to gum up when they sit for a long time. On that note, I had a 6-71 that one injector actually froze at about two thirds throttle, and when they do that all the injectors follow as the rack can't pull them back to idle. Sure was happy the air shutoff mostly worked and letting the clutch out in third gear killed it.
Didn't make me giggle. Just as you suspected it killed the engine the same way. I'm wondering if this shuttle valve could be hanging up. It seems strange that both the backhoe and loader valves are connected to the same block and that they react completely different.
I doubt it's the shuttle, though odd things sometimes happen. Some load sense pumps have an orifice to bleed a bit of oil which helps the response time when the pressure starts to drop, no way to know if your pump is like that or not. What you're observing may be no more than the internal differences in the two valve stacks, the backhoe valve it seems drops the load sense pressure off quickly as the spools return to center, the loader valve apparently is much slower. Some valves use internal shuttles or "resolver" valves to provide the sense pressure, some use just a gang of check valves and they don't allow return flow so pressure stays up until it bleeds off elsewhere, for example through that orifice in the pump I mentioned. There may be somewhere in the system that's bypassing oil internally, o-rings on the relief valve or like that. One other possibility is still that the main relief is opening before the compensator destrokes the pump, find that main relief in the end of the backhoe valve, remove the acorn nut if still present, mark the position of the screw, loosen the lock nut and turn it in one half turn, tighten the lock nut. Try your backhoe valve again and watch the pressure guage, see if you can get past 3,000 but DO NOT allow it to exceed 3,500 please, I don't want to be responsible for some hose blowing up in your face. If your load sense pressure goes above about 3,200 psi the pump compensator is not working correctly and needs to be adjusted. If you achieve a higher pressure before the engine pulls down that's a clue. If you're deadheading a cylinder (assuming it's not leaking internally a lot) and the pump gets to it's set pressure you should hear the load come off and the engine run free as the pump destrokes, it will hold max pressure with zero flow so there's almost no load on the engine at that point.
Bull's-eye!!! Pressure started out at about 2,800 psi. I turned the relief valve in 1/2 turn and the pressure went up 200 psi but no difference. Tried a full turn and the pressure went up another 200 psi but still no difference on the engine load. Finally I turned it in a total of 1 1/2 turns and EUREKA! The pump destrokes at 3,400 psi and the load comes off the engine. I even tried the loader and outriggers and the engine no longer dies! Even at 1,300 rpm I can hold any lever fully open and the pressure goes to 3,400 and the engine keeps running with almost no load at all. My question now is where is the pump compensator adjustment? Is it #107 in post #16? Now my biggest problem is rebuilding the cylinders. Which is coming along ok. I just rebuilt the left outrigger cylinder and welded and rebored the main bore on the outrigger arm. Lantraxco you saved me a ton of aggravation!!! Let me send you a gift card. PM me your info and what kind of card you would like.
Hey that's great! You will probably want to leave that relief valve set where it is then. Your pump doesn't exactly match the parts diagrams, but I think #107 sets the load sense pressure. What does your gauge show with everything in neutral, like 250 psi or so? Probably don't want to be on the load sense port for this reading as it may drop to zero with no functions being used. I haven't seen a setting for it, but usually this will be somewhere between 150 and 400 psi...... You might try turning it a quarter turn out and see what happens both in neutral and with a function stalled. The pump parts diagram shows the inner block to be the control which I assume to mean pressure limiter. They show two adjusting screws, #77 and #89, I *Think* #77 would be the pressure adjustment. Looks like it's under a cap in that four bolt end cover behind #107. Same deal, try backing it out a full turn and see if that doesn't put you close? I would buy 2,900 to 3,100 it's not that critical. I appreciate the offer, but no. I figure when the day comes the good lord punches my ticket I will need all the karma points I can possibly accumulate just to qualify for a spot sweeping floors in the magic carpet shop. This kind of problem is fun for me, and if I can help solve one it's a good day. And really that's what this board is all about, the sharing of knowledge, experience, a little wisdom, a little humor and kicking ideas around. We all gain from it, I learn something almost every day here. Cheers, :drinkup
I'll have to play around with it this weekend. I'm just thrilled it works like it does! It's like a new machine now. Ok well my offer stands until Sunday. I’ll give the money to my pastor. He can use it for his family or help out another family. I’ve heard of karma but the magic carpet shop, that’s a new one for me. These days people like to get offended by anything other than what they believe. I was never offended by what someone said how they get to their form of grater existence in the life beyond this one. Myself, I believe in grace. And getting to heaven can only be achieved through Jesus Christ. He went to the cross for the sins of the world and eternal life is for anyone who asks for it. He is the Lord of my life, I could be 6’ under ground but He kept me alive and each day is a blessing.
You'll never hear me argue the point, one of my biggest gripes is religions that insist I do the things they say are right and there's no other way. Good idea if you want to make a donation, passing on a helping hand. I make a lot of jokes, a defense mechanism sometimes that helps me avoid being serious. Sometimes on the "Black dog" days it keeps me just enough away from the razor thin edge I don't have to look into the abyss and perhaps lean forward into it. You know Jesus said "Love your neighbor" and I have a simplistic view of that. I don't need to love the whole world, that's too big a job for any man. All I have to do is love the person on either side of me, and if they do the same and so on and such like, the world will become a much better place. One neighbor at time. Cheers, Lanway
Well said Lanway. I have been following this post with interest with nothing to offer. I am glad you and Blueboy got it sorted out and got him on to other things. That really is what this forum is all about.
Long story short, I got the pressure down right around 3,100 psi. #77 was it!! But I didn't start there. Since it looked easer I tried #107 but it got things all out of whack. It did drop the pressure around 2,000 but if you hold the lever the pressure climbed to 3,400 and when you release the lever it would kill the engine. Before I started I marked the threads and nut with a paint stick, so it's back where it was. So on to #77. Wouldn't you know it, the screw was stuck from corrosion. I had to take the end cap off to tap on the screw from the inside and outside. Finally came loose but I thought I was going to brake my allen wrench. After I cleaned it all up I backed it out 1/2 turn. Kinda makes you think, the last two owners had this problem, hydraulics killing the engine, which is how I probably ended up with this machine. Goes to show, it pays to know someone in high places. And HE Lead me to Mr. Lanway. Lanway, God bless you!!! And my pastor said thanks for the 200 bucks. God bless everyone, Blue
Amen