Working on this new to me Chinese tractor with front end loader. It has a 2 spool valve to operate the front loader with open center. Apparently from day one these valves don’t work very well, they act very jerky and have issues with “locking” in the motion of the handle. So I had disassembled it and made sure everything was clean and tight and it all looks good. If I understand it correctly, the multiple small grooves between the glands help to make it operate smoother. What’s the chance that if I enlarge those ever so slightly in the lathe that I could make it operate better. Worst case is I screw it up and have to junk it. I’m sorta at the point of buying a better valve, but it’s more time and money.
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Any hydraulic engineers or experts here?
- Thread starter gregs
- Start date
manwithtools
ALLIANCE MEMBER
I would not do that, it could cause port overlap so to speak. Better to get a new loader control valve, plenty on eBay or online. Try Surplus Center or even Tractor Supply. Another good source is Bailey Hydraulics.
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nadogail
Well-known member
Have you tried the dealer who serviced your tractor last.
There was no previous service by a dealer. And these little tractors are not really supported by much of a dealer network. But there is a pretty decent web support among owners and a few dealers that offer parts online. The valve is a "known issue" and it seems that people either deal with it or replace it with a better valve. Several of the online dealers have put together kits with all the necessary parts to change it, but that runs over $500. I have found a valve that should work and already have most of the parts needed to install and its about $300. To the best of my research I haven't found anyone that has tried to improve the existing valve. I don't know that its possible but thought about giving it a try. The valve overall works and doesn't leak, but doesn't operate smoothly and lacks the ability to feather it. Also you can hear the hydraulics "load" as it moves between ports and sorta "sticks". That's where my spool valve research led me to the grooves machined in the spool that are supposed to make it work better by allowing some oil bypass when it moves between ports. And that's about as much as I know. The current spools have some of these grooves but they are very fine and I am considering making them slightly larger from some different pictures of spools I have found online. Worse case I screw it up and have to buy the $300 valve, best case is that it makes it operate better and I can save $300.
Fav Onefour
Well-known member
Is there a pressure release or adjustment on the valve assembly? How about the hydraulic pump itself?
I'm no hydraulics pro, but we used that type of setup on old loaders. They were often mismatched for the tractor systems output. I bet that is partially the issue with this tractor.
The current grooves should be there to keep it from locking into a specific flow position. You can certainly try modification, but I don't see that allowing you to feather. It would put a lot of pressure on the O rings assuming you have that style.
I'm no hydraulics pro, but we used that type of setup on old loaders. They were often mismatched for the tractor systems output. I bet that is partially the issue with this tractor.
The current grooves should be there to keep it from locking into a specific flow position. You can certainly try modification, but I don't see that allowing you to feather. It would put a lot of pressure on the O rings assuming you have that style.
It’s an old style valve with o-rings on the top side where the spool sticks out. It does have a adjustable pressure relief valve built in. I tee’d in a hydraulic gauge so I could adjust it correctly and also monitor the system while getting everything figured out. Once that’s done I am going to remove the gauge and just use a plug in that hole. I have the max pressure set at about 2100psi at 2800rpm. The jerkiness of the valve is all the time either loaded or unloaded. You can watch the gauge sorta bounce as you are moving the handle. The bucket might be tilting and you hit a spot where the handle gets stiff and the pressure jumps 200-300psi.Is there a pressure release or adjustment on the valve assembly? How about the hydraulic pump itself?
I'm no hydraulics pro, but we used that type of setup on old loaders. They were often mismatched for the tractor systems output. I bet that is partially the issue with this tractor.
The current grooves should be there to keep it from locking into a specific flow position. You can certainly try modification, but I don't see that allowing you to feather. It would put a lot of pressure on the O rings assuming you have that style.
Garcky
Well-known member
Well, if it's a known problem and it has been going on from the start, you're probably going to end up replacing the valve, in the end. It all depends on how much hassle the current valve is costing you, I guess. If it were me, I'd just go ahead and replace it with something that is known to work. Maybe the valve you found and the necessary parts, or maybe that kit. That I don't know. Have you heard that the kit is working out for those who have bought it?There was no previous service by a dealer. And these little tractors are not really supported by much of a dealer network. But there is a pretty decent web support among owners and a few dealers that offer parts online. The valve is a "known issue" and it seems that people either deal with it or replace it with a better valve. Several of the online dealers have put together kits with all the necessary parts to change it, but that runs over $500. I have found a valve that should work and already have most of the parts needed to install and its about $300. To the best of my research I haven't found anyone that has tried to improve the existing valve. I don't know that its possible but thought about giving it a try. The valve overall works and doesn't leak, but doesn't operate smoothly and lacks the ability to feather it. Also you can hear the hydraulics "load" as it moves between ports and sorta "sticks". That's where my spool valve research led me to the grooves machined in the spool that are supposed to make it work better by allowing some oil bypass when it moves between ports. And that's about as much as I know. The current spools have some of these grooves but they are very fine and I am considering making them slightly larger from some different pictures of spools I have found online. Worse case I screw it up and have to buy the $300 valve, best case is that it makes it operate better and I can save $300.
Fav Onefour
Well-known member
Bummer.
You've expended the tricks I've used.
The gauge is an excellent tool to narrow it down to the pressure jumping around. That is a lot of change with a small twitch in the lever and no load. I sure wouldn't want to be painting the side of a barn from that bucket.
You've expended the tricks I've used.
The gauge is an excellent tool to narrow it down to the pressure jumping around. That is a lot of change with a small twitch in the lever and no load. I sure wouldn't want to be painting the side of a barn from that bucket.
What do you have to lose…..
With a little study, figure out which grooves move fluid through ports - stay away from those obviously.
When I’m in the situation of what do I have to lose, then it’s time to play (if I have time), might learn something.
With a little study, figure out which grooves move fluid through ports - stay away from those obviously.
When I’m in the situation of what do I have to lose, then it’s time to play (if I have time), might learn something.
That’s the plan.
What do you have to lose…..
With a little study, figure out which grooves move fluid through ports - stay away from those obviously.
When I’m in the situation of what do I have to lose, then it’s time to play (if I have time), might learn something.
So I pulled the spools out and took a closer look at them. The grooves measured about .012-.015 wide/deep and where actually slightly different between the 2 spools. Not knowing what the outcome might be and finding no practical information on how big they needed to be I used my best judgement and decided to double there size. So I ended up making them about .035 wide and about .020 deep. This made them look more like the pictures of other spools I found. Put it back together and found it helped some to make it less jerky but the valve for the lift still has a spot where it seems to hydraulically stick. I did make sure the spools moved freely in the tight bores. I don't know that I would call it a success but more of a learning experience. I have 3 dump trucks of dirt I need to move and spread, so I will see how it goes. I also thought about lengthening the lever as it is kinda short, maybe that would give some better control/leverage as the valves are somewhat stiff to operate. If I find that it aggravates me enough, then I will order a new valve.
So I ended up junking the valve. It took to much to try and operate the loader without wrecking something. A couple of times one spool stayed stuck in one position while lifting and I had to shut the tractor down. I ended up going with one of the European made valves as I wasnt going to try a new Chinese one. It works great! So much easier to operate and control.
I agree. I can’t tell you how many times I have worked on a failure analysis project and root cause is we didn’t know what we were doing on the front end so we just copied what has been done before without really understanding it. I’m cleaning up a big mess right now at work for this very reason. We have one engineer who self admittedly said he didn’t pay attention in college and he is not a gearhead type. How the heck people think this is going to work is beyond me…..Super nice guy, but he can’t do basic calculations. On top of that, he doesn’t want to get his derrière on the shop floor and learn…..a desk engineer. We need some desk engineers, but not at the manufacturing facility.IMHO it all goes back to the design dept of factory: Monkey see, monkey do but monkey no understand.
Knowledge does not equal understanding.
I was put in a position at my last company where I had a guy working for me that was in an engineering technician position who could not remotely perform in that role. There is a huge difference in knowledge and understanding. They are related but they are not the same thing. We have to be at the understanding level in a design/engineering/maintenance type role. To illustrate the point to him, I asked him what pi was. He said he had might have heard of it before, but couldn’t remember. So I told him what it was. 3.14. That is knowledge. Understanding is: a ratio of a circle’s circumference to its diameter. I said here’s what we’re going to do, we’re going to go around the office area and we are going to ask people. I’m going to make a prediction. Some folks are gonna say they don’t remember, some folks are gonna say it’s 3.14, and most of the engineers are going to tell you that it’s the ratio of the circle‘s circumference to its diameter no matter how big or small the circle is, that ratio is always the same. Roughly 22/7. Sure enough, it played out just like I expected it would. One is knowledge the other is understanding.
One thing I ask when interviewing an engineer is what their hobbies are. Maybe it’s nothing gearhead-ish. Fine. Then I take them on the shop floor and I start asking questions about basic things. If they are completely clueless about basic things, then they have to go into an entry-level position. I have interviewed people with years of experience that do not understand basic, mechanical components, nor basic engineering behind them. A mechanical engineer should know what a sprocket is, and which part of the tooth would have the highest stress. A mechanical engineer should know the difference between a pair of calipers and a micrometer. If you don’t understand the basics, I don’t know how in the heck you are going to design anything in a cost efficient reasonably reliable fashion. You have OJT to go through and my offer to you will reflect your understanding level, not necessarily your years of experience.
Education does not equal intelligence. They are not the same thing. But that’s a diatribe for another time…….
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andyvh1959
Well-known member
I've always said some people are so smart, they're stupid.
Kind of saying the difference between book smart and knowledge/understanding smart. When I worked at Pierce Fire Apparatus, our lead hydraulic engineer "only" had an associates degree in Mech Design. Yet he proved over and over that he knew, he understood, hydraulics and mechanical engineering. Years later he reported to an engineering PHD type. Then we coordinated the hyd plumbing on a new light weight aerial torque box the PHD guy designed. 1st time they load tested it off to the side of the truck, it permanently twisted/failed.
We have a PHD engineer at our Chicago mobile hydraulics lab, an Italian, who knows, understands SO well he got an engineering book published, and I've seen him wrenching a system out in the lab. I'd bet he can just listen to a running hydraulic system and figure out design issues.
When it comes to cheap copies made far off shore, obviously takes a lot more to make it work than just back engineering it. Even subtle clearances of 15 micron on spool valves can affect hydraulic feel and performance.
Kind of saying the difference between book smart and knowledge/understanding smart. When I worked at Pierce Fire Apparatus, our lead hydraulic engineer "only" had an associates degree in Mech Design. Yet he proved over and over that he knew, he understood, hydraulics and mechanical engineering. Years later he reported to an engineering PHD type. Then we coordinated the hyd plumbing on a new light weight aerial torque box the PHD guy designed. 1st time they load tested it off to the side of the truck, it permanently twisted/failed.
We have a PHD engineer at our Chicago mobile hydraulics lab, an Italian, who knows, understands SO well he got an engineering book published, and I've seen him wrenching a system out in the lab. I'd bet he can just listen to a running hydraulic system and figure out design issues.
When it comes to cheap copies made far off shore, obviously takes a lot more to make it work than just back engineering it. Even subtle clearances of 15 micron on spool valves can affect hydraulic feel and performance.