I have to admit I'm a little perplexed again, I did a little digging around the yard and dug up a stump yesterday. I noticed the the swing was loosing a lot of power, it couldn't even push loose dirt with the side of the bucket. Thought the oil might be getting hot but after it cooled it was still weak. It might have been that way all the time, not sure, first time digging. But it seems to me that it was stronger before. The gauge on the test port from the pump shows 1,000 psi to the left and 1,400 to the right. Not sure what the set pressure is supposed to be because I don't see it here. HeavyEquipmentForums I turned in the left (red circle) screw 1/4 turn and didn't notice any difference and the right (green circle) a full turn and still no difference. Apparently they don't do anything for setting the pressure. I think they let the boom drift after releasing the lever. I don't see where the pressure adjustments are. Is there 1 or 2 and why 400 psi difference? I fixed the leak today, fitting was loose. As always, any help is appreciated.
I just did another test. The piston seals are not bypassing oil. There is one hose that connects the back of both cylinders together. Another hose T's off of it and returns to the top of the tank. (keeps air from building up) I unscrewed it from the tank and held the swing lever for about 30 seconds and at 1,000 psi, no oil...
Apparently an oversight in the book, but then the setting is not a port relief like the others. Those valves you're adjusting are indeed where you set the swing pressures, that valve block allows for slow deceleration when stopping your swing and also allows the bool to swing if the side force on the bucket gets too high. The possible reasons for the lack of pressure change when you adjust those screws would be either an internal issue in the cushion valve, or bad rod side piston seals in the swing cylinders. According to the plumbing diagram only the rod end of both swing cylinders is actually under pressure.
Looks like I beat you to the reply above. OK, then if I put a gauge on and deadhead the valve before the cushion valve, I should get full pump pressure? I backed out the right screw two turns and it stayed at 1,400 psi. :beatsme
Cushion valve needs some TLC... Guess I'll start with #2 and see what that thing is and work my way down to #20. Oh joy!
LOL, too close to call, but yeah, you beat me by seconds... So, did you try deadheading one hose off the control valve into a gauge? #2 says "Bleeder valve" like a brake bleeder for air... never seen that before on a counterbalance valve. Maybe try bleeding them? I dunno. Probably got a chunk of old seal stuck under one of the relief poppets?
Checking the control valve pressure will have to wait until tomorrow. For some reason I don't have a #12 plug for the test port, a bunch of caps but no plugs. The in line pressure reads the same, but I figured it would. I cracked open the bleeder valve and only fluid came out. For a shot in the dark I plugged the crane/dig valve. No difference. I turned the screws all the way in and out and still no pressure change. What exactly does the black box thing do? And any chance it could be the problem? The bottom lines come from the control valve, up to the load sensing line, back and down to the cushion valve, then to the cylinders.
Don't know what that is, didn't think it was connected to the cushion valve until you posted this picture. That short hose between the two tees at the top makes no sense to me at all. That block may be a crossport relief, which would explain a lot.
Can you get the information that is on the blue tag that is riveted to the black hose block ?
Thats what it looks like to me also, a crossover relief valve.
Deadheading the right swing control valve to a gauge shows 3,000 psi. And what is interesting is when swinging left the pump puts out 3,000 psi BUT there is very little power at the boom. With the bucket sitting on the ground the boom will not move. So at this point where would be the best place to start? The cushion valve still or the mystery black block? If it is a crossport relief, what is it supposed to do?
Take it off and throw it away? I don't get at all what it's there for. Nor the little hose that appears to be an open circuit between the two lines? I think Waterman was absorbed by Parker in their voracious buying spree, can't find any information out there anymore. Unless the original cushion valves was not working well and it's a redundant counterbalance valve? Looks too small for that though.
I thought about bypassing it to see what happens. I don't see it in the hydraulic schematic, it might be an add on for the auxiliary system (hammer) but I'm not seeing it there either. Ya, the connection between the two is a mystery. I thought that hose went to the load sensing line, but it does not. It goes to the suction side of the pump for the steering and brakes. I think it's going by by.
Looking at your picture again, it does seem to be piggy-backed on a similar valve.It also seems like its tapped into the one its sitting on. My guess is that the one behind it is defective so they just threw this one on top, but I don't understand why it would be tapped into the old one.
I took that block off and connected the control valve hose directly to the cushion valve. Now the swing has 3,000 psi and will move the machine! It swings hard and fast which might not be the best thing. I suppose I could get used to it but I think I need to look into it further. Looking at the guts in the block I could put a stronger spring in it or add more shims. Going by the different shims it looks like it's been adjusted once or twice before. Now I know how it works that short hose kinda makes sense. It dumps oil out the other side that's not being used. As mentioned by lantraxco And hookedondiesel the cushion valve might have some issues. The adjustment screws were all the way in and now their all the way out with no difference in pressure. I think I'll look inside the cushion valve and go from there. Another issue is the pump is not destroking. It's supposed to cut back at 3,200 psi like everything else, but the swing cylinders are not getting there. Could be the piston seals (higher pressure now) in both cylinders or the cushion valve is bypassing oil. Not that it matters now but I got the hoses crossed.The short hose between the two tees returns up by the tank before the filters, NOT the suction side of the power steering pump. Adjusting the pressure up or down in either the cushion valve or that black block would change the deceleration when stopping the swing. Right? What would be a good set pressure for the swing? I'm thinking about 2,000 psi.
I assume there's a twin to that cartridge on the other side? Does look like just a crossport relief. If the passages are straight through and that's just a crossport, I don't get the tees, hose, and drain to tank, unless there are some orifices or drilled passages to limit bypass flow. Looks like it's essentially just dumping off some flow to tank to give you a more mushy control for lack of a better way to say it. I don't know how the pump could exceed it's standby limit if it works on other functions, have you checked the load sense test port up at the pump? In the very first picture you posted, the two hoses on the left connected to the cushion valve go to the swing cylinders?
Disregard this gibberish! Sorry for the confusion!! After sleeping on it and waking up in the middle of the night to take a pee, I realized this does not work. I tried to make sense of it thinking that whoever put it on knew more than me. I was looking at one side only and thought it made sense. Both the cross hose and the return should have thrown up a red flag. I hate when that happens...
That's where I have the gauge. I was running under 1,500 rpm. I could run higher and see what it does. But at the same rpm all the other functions work. Which makes me think the oil is bypassing somewhere. Is that a correct assumption? When I deadheaded the control valve with a gauge it worked like everything else. It went to 3,200 psi and destroked. Yes
Okay, I think maybe I misunderstood, what pressure are you seeing at the pump when the swing cylinders are at the end of stroke? Oh, and do you still have that small bypass hose connected up?
Small hose and other crap is gone. Pretty much looks like the schematic now. View attachment IMG_0007.pdf
This is so much fun I took a half day off work. Let me see if I can further complicate things. A left cylinder B left control valve. C & C.5 right control valve. D right cylinder. Before this pic I deadheaded C.5 from the control valve (right swing) and pump destrokes at 3,200 psi. Both gauges, test port and pump. Good so far. I moved the boom lever left and oil gushed out of C. Now as pic shows I deadhead C, move the boom lever left, pump gauge instantly reads 3200 and pump destrokes and test port gauge from C takes about 2 seconds to reach 3200. And what is really interesting, the boom does not move an inch! Even with the bucket off the ground. After the pic I connect C.5 to the test port. Move boom lever right and both gauges read 2,900 psi and kills the engine. Even at 2,000 rpm the engine wants to die. If I move the lever left the pump gauge reads 2900 and the test port reads 0. All the hoses are hooked up correct, according to the casting on the cushion valve.
That all sounds right except the killing the engine bit, I'm going to say you need to unscrew those two cartridges and see if they're gummed up or what. Any time you have a relief that opens up below the pump setting, the pump is going to try to fill the hole with oil, which is the same as the original problem you had, right? Might just need to put some flow control valves between the control valve and the cushion valve, either just needle valves or compensated.
Another job well done thanks to the guys at HEF! It's not 100% but far better than it was. Actually the right swing is perfect. The left is workable. Lantraxco you were spot on as usual. I already had it tore apart and saw the poppets (#14) were really tight. After a little honing with a brake cylinder hone it was nice and smooth. The relief seat (#15) was ok, didn't need honed. I think the left problem is the steel ball is worn in the poppet that seals against the seat. I reassembled the cushion valve and hooked it all up. I had the adjustment screws turned in one turn. After I worked the air out, the left had a small groan and the right was worse. And as lantraxco said this was like my original problem (the engine dying) I thought to turn the right screw in 1/2 turn and then another 1/2 turn, that fixed it! The left needed more but I ran out of adjustment before it would stop groaning, It's in 3 more than the right. But if I gently apply pressure it doesn't groan. So now the swing has 3,200 psi, the pump destrokes and the engine keeps running. Ready, set, dig!! The flow control valve is an interesting idea. I'll have to sleep on it. Thanks, God bless! Blue
I did a little landscaping today and the machine works great! The only complaint I have is the boom swings really quick. If I keep the rpm under 1500 it's not that bad to manage but moving the boom and dipper at the same time bogs the engine. If I did what you said in this quote would that be a good fix? How would it react with the pump needing to destroke? But I suppose with more hours on the machine I could get used to it. The township paved my road and they decided to put a drain in my yard.
If you put a needle valve with check in each line from the control valve to the cushion valve, with metered flow outbound and the free flow checks opening inbound, you could control the top speed at least, and the load sense would be sensing the backpressure from the needle valve and destroke to keep the flow right. If you still need more sensitivity at the beginning of swing control, then you could install a straight needle valve with no check teed across the lines on the cushion valve side of the setup to bleed some oil across until the flow was high enough to start the boom swinging. Tune it the way you like it, not a perfect world but better I think. http://www.surpluscenter.com/Brands...CE-WFC-1200-INLINE-FLOW-CONTROL-9-7960-12.axd http://www.surpluscenter.com/Hydrau...PM-PRINCE-WNV-1200-NEEDLE-VALVE-9-7961-12.axd
Just a thought, the lever/spool that controls your swing etc may be of the "full" flow type, meaning you cannot control the flow with it like the newer ones. On mine, you push the lever a "little' and you get a slower speed of flow, push it all the way out and fast and you get what you describe.
That is how mine is too. I'm just trying to make it less sensitive. It could be why they hat that cockamamy set up on there before. I'm going to try the first suggestion Mr. Lanway posted in #25. Might take a week or so.
OK I gave this a try and it does slow the top speed down but it pulses. Holding the control valve wide open the boom moves like it speeds up, slows down, speeds up, slows down... It would take about 4-5 of those to get from one side to the other. I have the adjustment out only two hash marks from closed. What would happen if I put these between the cushion valve and the cylinder? I think this is what I need. It's impossible to know what you really need until you do it. I'm a little confused where this valve goes. It's on the side between the cushion valve and the cylinders? Basically a cross over between the two cylinders? Also does it need to be 3/4? Would 3/8 be ok? And one more thing, with these valves in place would it help to readjust the cushion valve? I think we are almost there. Thanks!
Are you metering in, or metering out? You want the metering to work on the oil going from the control valve to the cushion, not the oil coming out of the cushion. The check valve should open allowing free flow from the cushion valve back through the return side of the control valve. Yes, I would try backing the cushion valves off a bit, generally swing doesn't need full pressure and the needle valves will prevent the pump from throwing too much oil out. Also might experiment with opening the needles up another notch or two. I would try a straight needle valve connected across the where the two caps are now on the lines coming from the control valve, yeah 3/8 will probably be fine, you won't need much of a bleed to give you some fuzziness around neutral.
It is as you say. I will play around with the adjustments before I put the other valve in. I guess the bleed off doesn't matter which side of the cushion valve it's on.
Yes, it does matter, if you put it on the cylinder side of the cushion valve, your swing won't lock in neutral. If you put it on the cushion valve side of the other needles you may not have enough flow to make the swing work at times. YMMV
Don't know why I didn't see that. Just wasn't thinking I guess. Naturally if you put a hose between the two cylinders it's going to let the boom "free wheel". This is how the flow valve is mounted, control valve is attached on the bottom. I will order the needle valve Monday. Since I have some of the parts already from the not so original mickey mouse set up, why not. I didn't bother messing around with the settings yet, I'll do that when I get the other stuff. By the way I had to look up "YMMV". You were either telling me "You Make Me Vomit" or "Your Milage May Vary" or something like "what worked for me in the past, might not work for you". I think it's the last one. But no worries, I'm not against trying something different. Usually I can tell if it's within the right ball park.
LOL, yeah the latter... comes from the EPA mileage ratings on new vehicles, which are largely fantasy... the TV ads always ended with "Your Mileage May Vary" Flow valve looks correct, meter in toward the cylinder, check valve opens to allow free flow out. The cushion valve may not be working correctly either, though I would think if there was an issue it would be more pronounced in one direction than the other.
Perfect! Works like a dream! No more pulsing, nice and smooth. The needle valve is out 1/2 turn and the flow valves are out 1 turn. And the cushion valve screws are out all the way, it's the safest and doesn't loose any power. Since there is a "hole" the pump can't fill, the pump will never destroke at 3,200 psi. But the pressure does reach about 2,800 psi without killing the engine. It will start to bog down but it's only the swing, not a big deal. Thought I would throw this in here. The two reducer fittings that went beck to the tank had an insert in it so there wouldn't be a total loss in pressure. That might explain their madness of reason. I took them out for the needle valve. Thanks! Blue
Yep, they did the same thing with those orifices, a little bypass. I would have put the bypass on the other side of the twin flow controls, but if it works this way, great. Glad you got it where you like it!
What benefit would there be putting the bypass after the flow control valves? Only thing I can see is more oil would be flowing threw them. And you might have to open them up a little more. But yes, the operation is very smooth. I'll know for sure if the adjustments are where they need to be when I start moving dirt.
Maybe none. It's a balancing act, and yes you probably would have to open them up a bit, but probably close the bypass needle down a bit. The only benefit, assuming it still functioned comfortably after some tuning, would be that the pump would see less flow as the flow control needles would limit pump flow, the bypass would occur after the limiting action. If you like the way it works, I would just leave it be, as I have heard said before, let's not waste good in pursuit of perfect.