Here's a component that has been mentioned at various threads and folks have asked what kind of project is it to repair, the simple joystick control valve. From excavators to skidsteers, variations of this type pilot oil control valve are used on many machines nowdays, and the most common problem they have is leaking oil from the spool pistons at the top of the valve. It's typically just a tiny u-cup seal for the pistons causing the leak, replacing that seal is the challenge. I've repaired them inside the cab with hoses still attached, and disconnected from the hoses as well. I prefer to disconnect from the hoses and cap or plug the hoses so the valve components can be drained of oil and cleaned. Also, much more comfortable rebuilding while standing at a workbench than fighting one inside a cab. My helper removed this one from a Case 9050B excavator because it was working all wacky, it was obvious someone had been inside this unit and had done something wrong. After he disassembled it, it became clear to me the former shade tree wrench had not paid proper attention to what they had disassembled and had not performed correct re-assembly, which I thought would benefit others as to what I found inside the unit, and to caution anyone who attempts to take one of these apart to note or mark the orientation of the valve mounting and every piece as to where it came from. I've repaired a couple of pilot valves, but I don't recall one being quite as specific inside as this one. This may not be that unusual though, so note how you take one apart. This is a pic of the re-assembled unit, as I didn't have a pic of the unit when it was removed. You can clamp the body in a vise, put a wrench in the flats on the actuator disk, and screw the universal joint out that holds the retainer plate on the top of valve assembly. I have seen the u-joint installed with Loctite, making it all but impossible to remove it without destroying it, well, sacrificial part then, replace the u-joint. Once you get the u-joint popped loose, work very carefully unscrewing it, those brass piston guides have springs underneath them, if you were to simply remove the u-joint and retainer plate, the resistance of the o-ring seal of the piston guides would let go and parts would fly. Slowly screw the u-joint bolt out a bit, lift the retainer plate, and start working the brass guides up out of the chambers until the o-ring is unseated. Once they are unseated, hold down on the retainer plate and remove the u-joint, then you can gently lift plate off of the guides. Here's what you'll see when you get the plate off and the piston guides out. This is the spools and springs removed. The springs at top and bottom are the same, the spring to the right is different, and so is the one to the left. Also, the spring retainer disks on the spools, two of them are thick, two of them are thinner. Even the springs on the spools held in place by the retainer disks are different size. Differences don't stop there, the actuator pistons, the hole on the inside of them that the spool head fits into, two of the pistons have a 3/8" deep hole, the other two have a 7/16" deep hole. Hey, 1/16" makes a difference in how a unit like this operates. So the delima is, what part is supposed to go where? Fortunately for me, the Case parts diagram was a cross section view with excellent detail, even the parts list page noted which part went in which port, such as the thin and thick spring retainer disks. If it had been an exploded view, probably been bad. The one thing I couldn't determine was the main springs, the parts page told what spring went in what port by part number, but I had no way of knowing which spring was which part number, had to order new springs just to get the part number of each spring.
Now that I have it sorted out how to assemble the unit proper, it's time to put it back together. First though, we need to discuss the leak that is common with these units. Replace the o-rings on the outside of the brass piston guides, and the seal that's in the bore of the piston guides. It's typically a small u-cup seal, or an o-ring with a backup ring. Very simple to fix a leaky valve once you get in there. The challenge to put these things back together is the springs trying to force the piston guides back out, you have to hold them set in the valve body until you can fit the retainer plate. It's nearly impossible to push all four spools/pistons into the unit using the retainer plate to force downward as you have to align each spool with the bore it fits into. You pretty much have to fit each spool/piston unit in one at a time and hold that unit in the valve body. There are various methods to do this, maybe some others here will post some ideas, but this method has been fairly easy and effective for me. Clamp the valve body in a vise. I take some thin/workable tie wire, twist a loop in one end and fit it around the outside flange of brass piston guide. I used a 3/4" socket sitting on the face of the brass piston guide to push the spool/guide assembly into the bore of the valve by hand. Once I push it home and hold it there, slack up the wire and tie it to fittings on bottom of valve. This keeps the spring from pushing the assembled unit back out. Make sure you have everything pulled taught, and have a good tie off on the underside. This is after all the units are installed and held in place with wire. Fit the retainer plate. Then screw in the u-joint bolt, stop short of fully tightening it, leave room to nip the wires and pull them out with some pliers. Now you can lock down the u-joint bolt. Check for proper contact of actuator plate on top of pistons, it can't be pushing any of the pistons down, nor do you want a gap between actuator plate and pistons. If adjustment is needed, put your wrench on the flats on the actuator plate, and another wrench on the joystick lever nut on top acting as a jamb nut. Pop the nut loose, typically RH threads, then turn the actuator plate CW or CCW to obtain proper adjustment. Lock down top nut, you're done.
Great Pictures and text ATCO! It's tough repairing someone else's repair. And it's a sickening feeling when you realize to late that you should have marked those pieces you just pulled out.
I have done the same thing with ordering new springs that i mixed up or was unsure of due to another persons repair.
I have had the same problem with the springs and had no parts drawing to relate to. I figured the weakest spring went on outside since that was the weakest way to push the handle. The next was to the inside and the heaviest springs were fore and aft. It seemed to work the last time I did one. Also I've never had those things pop out on me. Usually I've had to use plier and a rag to pull the spools from the bores. Nice job ATCO!
Atco, this forum wouldn't be the same without you! Merry Christmas everyone
I thought the same thing about the springs John C. This was the left joystick, the strongest springs were fore and aft as you noted, stick extend/retract, which is the motion your arm has the most strength. Next lighter spring is swing right, which is a motion your arm still has some strength. The weakest spring, much weaker, was swing left, which motion your arm has the least strength. Seems there's some ergonomic design with these type configurations. I've done this repair on the Hitatchi valves on 100's and 120's, same thing as you described, have to pluck the piston guides out, and setting them back isn't much of a chore either. This valve...it had some SPRING to it, took a good bit of hold down pressure to hold the stiff springs while fitting the retainer wire. Merry Christmas to you as well watglen. Wouldn't be the same? Bah ha ha haha Hey, we got ourselves a "Shop" section on the forum for Christmas, so I'm gonna post some shop stuff here.
I have rebuilt pilot controllers for deere and hitachi. I would always order new Brass piston guides and piston (as an assembly) and install. I agree with Atco, better to remove pilot controller from machine then repair.
Atco, I guess i broke the #1 rule and lost track of which spring goes where. i have 2 different types of spings for inside the plungers and 2 different ones for outside the plungers.
Oh my BLconst, that doesn't look good. Unless you have very good parts diagrams, it's difficult to determine exactly where the components go, and they have to go in the correct orientation. What machine is it on? We'll do what we can to help you re-assemble it, but it's difficult for us on this end. One thing you can do, if all other plans fail, is to take the opposite side joystick off and very carefully take it apart, probably needs seals anyway. The other joystick should be assembled in the same manner, just the opposite right hand/left hand orientation.
Its a cat 287b. drive stick (left). See if this pic clears it up. the large springs #6, i know where those go. My confusion is the little ones. Thank you for any help. I can take apart the right hand stick, but will it be the same since its a skid steer not an excavator?
Lee-online might be able to help you out with that one BLconst, he works at a Cat house.
Cat 287b left drive joystick. trying to figure out if the tight spring goes with the loose spring or the loose with tight. or the tight with tight and which one is forward/reverse and which pair is left right
What about the 4 large diameter springs, are they all the same size?
Yes sir, the large spring #6 are all the same.
Well, I'll take a wag at it, but keep in mind, it's only a best guess. The stiff springs pair up, and the weak springs pair up. The two stiff spring sets go in the for and aft motion, the two weak spring sets go in the left/right motion of joystick handle.
Thank you. Im gonna give it a try.
I don't supose one could disassemble the opposite side and see how that side is paired up? Not to boubt atco's wisdom and experience, but.. I believe in a dozer the lighter springs are fore and aft, and the stif are in the side to side motions to help keep you driving in a straight line.
You could be right stumpjumper, I really can't say one way or the other, just doing like you and noodling through possibilities. Consider this possibility though. When operating a dozer, you do make turns and changes in directions. With skid loaders, you are typically making constant turns and turnarounds. So it's possible that it would be oriented with the stiff springs for and aft, the direction your arm has the most strength, and the weak springs left and right, the direction your arm muscles are weaker to prevent arm fatigue from making constant turns. Just a complete guess on my part.
Well got 'er back together. Seemed to be okay. delay is gone but now machine has a left side weakness, goes forward and back fine, when i rotate full left or full right only the right track is turning. i swithched springs and plungers around and did not make a difference. Maybe ball resolver? maybe drive motor? I did notice that the ball resolver and the case for the plungers have updated, changed, part numbers. maybe time to dump the 1300 on new joystick complete, such a shame after a 500 sealkit!
Wow, that's a bummer! Wish I could tell you what to do, just don't know with that one.
Hello, I'm trying to change the seals on the pilot controls of a Cat 267B skidsteer. Having trouble finding the seals and o rings, cat parts doesn't break anything down past the actual plunger kit (289-8451). Wondering if I can use a generic U-seal & oring for this application, or is there a part number for the actual seals and orings from cat? Thanks for any help. Jason
I am also looking for seals for a cat 236 skid steer. Where has anyone found them? Thanks Romer
I am also looking for seals for a cat 236 skid steer. Where has anyone found them? Thanks Romer
Thanks for this post Willie!! I noticed just the other day that the control on one of our 690e's is starting to leak pretty good.Good,useful info here!
I've looked through the prior threads and knew willie59 would have one up for me to read, my hitachi ex100 has had problems twice now with the pilot control for the arm control, the arm goes out and locks there under a load, the last time it came out of it on its own, this time its not, its in the pilot control valve, we got it narrowed down to that, now my question is, do we need to rebuild it or is there something lodged or stuck in it that just needs to be cleaned out? If so what, someone told me to take it off and blow it out with air, is this a good idea or not? I noticed yesterday that there is a height difference of the plungers, the one that controls the arm out, which is the direction its stuck now, is a lot lower under the plate. Now my second question is, why did it clear up and work fine the last time, which was about 7 years ago, so its had a lot of hours put on it since then?
If that, in fact, is the case, the plunger that controls arm out does not come up to the same level as the other three plungers, definitely sounds like you have a problem there. Just what's causing the problem, how it can come and go, hard to say. Could be a broken spring, could be the retainer C-clip is awry, could be a fragment lost in there that occasionally hits the right spot and causes the control spool to stick. Sounds to me like it's time to take that PPC control valve apart. Very important, as you take it apart, mark orientation of all components, including how PPC valve is mounted in console. Do not mix up where parts came from as springs are different and plungers are different. Aside from paying close attention to disassembly, PPC control valves aren't that bad to service, it's a bigger PITA simply removing them from the console.
Great post!
My rebuild seal kit is supposed to be in tomorrow, so we'll see how things go, I didn't have time today to tear it apart to see whats inside it and how things look, but I'll find out tomorrow and post the results here so others know how it turned out, thanks willie59 for the input and taking the time to respond, also excellent thread on a detailed description of how to tear the valve apart, otherwise I'd end up like most, with a pile of parts and no idea where things go back in the right sequence.
I hope it all works out well for ya Randy88.
It was a two hour drive to the shop, so I took the valve along to make sure I had all the parts I needed, they took it apart and found the one spool that controls the arm was stuck down, we dismantled the whole valve assembly and the only thing we could come up with was there had to be something like grit or debris that locked it down, once we got it apart we couldn't find a thing wrong, no broken springs, nothing, so we cleaned it all up and put a few new seals in it and put it back together, got it home put the valve back into the machine, willie is absolutely right, the worst part is getting it out of the machine and back in again. We've run it all afternoon and it works flawlessly. Thanks for the informative thread willie and taking the time to help me out, your description was spot on for the disassembly and reassembly process, the pictures were a major benefit.
That is awesome news Randy88, good to hear you got it sorted out. The tolerances of those spools in the bores are so close, it only takes a small fragment of something in there to muck them up. Once you disassemle the unit and clean it, likely the problem won't come back again. Be sure and check the filter in your pilot system.
If there are issues in pilot joysticks.i.e. bypass worn spools,bad or missing seals what effect can this have at the main vave bank? I have a Valmet 646 forwarder with Mannsmann Rexroth joysticks.Lots of vibration and noise right at sticks.Used to only happen on very hot days and even then it was intermittent now it is almost constant. Functions are ok although a little slow/weak. All pressures are ok and pump is new as is filter(s) and oil. Dealer does not show any rebuild parts except for a seal kit.Someone has suggested switching sticks as the left one does not seem to be as bad as the right one,which is used more. Thanks,Leeroy
Welcome to the forum leeroyjd. :usa Are you saying pilot pump was replaced? If so, did the original go to pieces inside? What was the condition of the pilot system filter when you changed it? I suppose it's possible to switch the left and right joystick, never tried it myself. Keep in mind, most joystick PPC valves have certain configurations of springs inside, switching left and right might give a different feel in the wrists.
Thanks for the welcome and reply! There is no pilot pump- just a main pump on this machine.The main pump was fine internally.Shaft sheared off when trannsmission went. As far as switching right to left I'm hoping this will confirm it is the joysticks that are the problem. I'm guessing just a seal kit will not help. If there is a lot of bypass within joysticks will this cause a noticeable change in oil temp?
Well leeroyjd, I must admit I really don't know anything about the workings of a Valmet 646, but if the joystick controls are actually pilot operated control valves, pilot systems typically don't work at full system pressure, they typically operate in a range of 300 to 500 PSI. If that's the case with this machine, there has to be some form of pressure regulating valve that not only maintains this pilot system pressure, but also prohibits pilot system from experiencing full system pressure. Have you actually tested the pilot system pressure to make sure it's within specified range? As for seal kit, most any PPC valve that I've worked on doesn't have any seals internally, the seals are only external, to keep oil leaking out of valve at spools and such. As for bypassing oil, any hyd component that lets considerable amount of oil under pressure bypass around it (typically from component wear), the result is oil going through a restricted passage, which does in fact heat up oil. However, if you're experiencing considerable heating of oil in reservoir, I would tend to think the problem isn't caused by faults in pilot system as it's a relatively low pressure system, would take quite a while to heat oil in reservoir, rather I would suspect something wrong in main working system hyd circuits would be causing the heat problem. Excessive heat at reservoir is an indicator of a problem somewhere.
leeroyjd, there is a spring and ball, or spring and tiny valve, under an allen socket plug (about #6 boss) usually on one end of your main valve banks that regulate pilot pressure, remove and check for debris and broken parts. i have never worked on a 646 my experience is with timbco/valmet, and cat forestry without pilot pumps....theironoricle
That would be the pressure reducing valve you are talking about,right? I have checked that and actually replaced spring and spool.I think this may be similar to Timbco/Valmet hydraulic set ups. Pilot pressure is reulated by pressure reducing valve on end section of main valve bank.Pilot pressure is 550,right where it should be.I understand what you are saying about bypass in joysticks would not be enough to heat up the whole reservoir,but could it cause spools not to open fully on main bank or something similar? The seal kit made no difference and I only got half way through switching right to left before calling it a day.
I noticed that one of the lines,pilot or tank(forgot) was dry when I took lines off.Does this indicate anything?The machine had been running right before I took lines off bottom of joystick.
I don´t usually remove them from the consoles. Had one customer calling me after he dismantled his PPC and put it back in the machine, swing right, left and stick in worked but not stick out. He had mixed the T line with port 4 witch is the stick out. Bummer! About mounting the brass guides and the retainer plate, i don´t recall ever having problem pushing the retaining plate down.
Hey Romer, Did you find the parts you were looking for? Bob
Just curious if anyone knows where to get a pilot seal kit besides through OEM? Or should I just go ahead and get OEM. The machine is a Hitachi EX 300 lc-3. Thanks for any help. And by the way Willie59 thanks for your efforts and time in this thread...extremely helpful !!:drinkup
Willie, Just wanted to thank you for a great help! I installed all new bushings, o rings and pistons on the right hand pilot vale on a Tak TL140. man! There is a grunch of oil in that beast. I found out by leaving the return line to tank unplugged. ugh! It took many days to de oil the entire machine below the floor boards. The bilges are now clean The Kawasaki folks are very good to deal with directly for the overhaul kits on the 48 series pilot valves. Again, many thanks, the left one has a slight leak , so it is next. best regards, Jim Yancy aka Chief Jim Pedro, Ohio [email protected] PS I did a simplified rewire for the Auxiliary hydraulic circuits. What is the best area to post that ?
Glad the info was helpful. :drinkup As for the rewire of the aux, well, that's a good question, not sure if it would be best in the CTL loader section or the shop talk section. I suppose it's your choice.
Great write up Willie I'm about to attempt the same repair now after reading your tutorial, Would you mind confirming that I'm after part numbers 11 & 12 in the following link http://komatsupartsbook.com/#?k=!0!1!3738!22!67 Thanks for any advice mate, I did post this in the compact excavators section but can't seem to get any replies Cheers John
Yep, I viewed the diagram at the link you posted, #11 and #12 are the seals you need. Remember, when you disassemble the unit, be sure and note which spring/spool set came from which hole, don't switch the location of those parts or mix them up.
Excellent, Thanks Willie I ended up buying the parts from the place below, Seals were $1.80 instead of $20 and they reckon they are OEM http://yueboda.en.alibaba.com/ I took a bit of a chance as you could only pay by bank transfer or Western Union Time will tell Thanks again
Got my parts today and did one side in the machine, Pretty simple job really after reading the instruction I wouldn't even have attempted it before reading this, so thanks to willie59 and the forum for the great advice It's great to do the DIY and learn from it as well
Good to hear you got it sorted out purnong. :drinkup
I went to do this on a 246 cat skidsteere and they did not have the parts brake down for the seals. Wanted me to buy the whole thing. Looked up a cat 315 and seals spear to be the same. $20 insted of $1200
All sorted mate I can't believe how much more responsive the machine is now, it just seems to work a lot more smoothly I had gotten used to it as every valve has been leaking since I got it, Definitely a job well worth doing
How did that work out? I have a 5FZ07755 226 with the so called non repairable left joystick valve. Was hoping to do the same thing.
Willie, Here is the location for getting the 48 series seals. Nice folks. Hope it helps someone. Best regards, Jim. Matt Bol Senior Applications Engineer Kawasaki Precision Machinery (U.S.A.), Inc. 3838 Broadmoor Grand Rapids, MI 49512 Ph. 616.975.3114 Fx. 616.975.3103
So far it works fine. They look identical.
I picked up a set of inners for my 3AW 315. Fit perfect for $20! Thanks
Wow, it's one thing to help folks re-seal a PPC valve (as opposed to having a dealer/shop do it for bucks), but for you guys to find a seal that works in various PPC valves (as opposed to replacing the whole valve 'cause it don't break down in the parts book)...Bonus! :drinkup
I have a cat 236b2 that I am replacing the pilot gp valve. The old one that I took off was not hooked up properly, does anyone know how to determine which hose goes where on the joystick? I've found all the schematics to hook up to the pump but cannot find anything on how they hook up to joystick.