LW-6 Spool valve leak

[shvl73]

jezorek,
Click on the small red triangle in the lower left corner. That brings it to the attention of the moderators. Then just ask for it to be moved.
I'll bet one of the guys in the chinese forum has had that apart and can tell you what seals are involved.

 

[RonMar]

shvl73,

Attached is a photo of the valve body, The tip of the screw driver points to the crowd valve where it oozes. The other valve in the picture is for the curl cylinder. The plate I mentioned can be seen also. It is held down by two allen screws.

If the alen head screws were loose, I would think it more likeley to leak around the plate and not around the spool so they are probably adequately tightened. I would bet that there is an "O" ring for each spool under that plate as that is pretty much the standard way to seal a moveable spool.

I am not specifically familliar with that valve, but here is what I would do. There should be 4 allen head screws that hold down that plate. Two are in front shown in your picture and two are around the back. You will have to disassemble the joystick linkage to access them and disconnect the joystick from the ends of the spools to remove the plate. Once the linkage is clear, remove the 4 allen heads and lift off the plate.

As always when working with hydraulics, make sure that none of the cylinders is supporting any weight and cycle all the valves to make sure there is no pressure anywhere in the system. And of course wear eye protection.

Under that plate, I would imagine you will find an "O" ring around each spool setting down in a recess/step machined around the spool hole. It may have a thin flat washer setting on top of it. Carefully dig out that "O" ring. Sometimes if you lift the spool, the "O" ring will move up with the spool and you can get a fingernail or straightedge under it to roll it up the shaft. If there is a parts listing in your manual, it may give a part listing for the spool "O" ring that includes the metric dimensions. If not, take that "O" ring to a hydraulic shop or other parts supplier that has metric "O rings and try and match it up locally.

Once yo have a new ring, apply a little hyd oil to the new ring and roll/slide it back down the spool and reverse the steps to install the linkage. Keep things clean. Dust or crap in with the "O" ring will only cause it to leak and or fail sooner. Digital pics during the disassembly process can be handy when it comes time to re-assemble. Note the dimensions of the new "O" ring that works, or buy a few of them when you do. It is steel working against rubber and they will wear out eventually. That is also a trap point for dirt and dust which will accelerate the "O" ring drying out and the wear-out process.

These also sometimes fail if the valve is exposed to excessive backpressure. You might want to confirm that the return line leaving the valve back to the resovoir has no restrictions that might cause excessive pressure buildup.

Good Luck

 

[jezorek]

Ron,

Your description of the valve was essentially what I found and the procedure you outlined was what was required. I had a spares kit that came with the hoe and it included the proper O ring.

The machine is off the tractor so I can't test the valve for leaks. I'll post what I find when I hook it up. In the mean time, I am doing some maitenance/repair work to try and tighten the unit up. It is like a big marimba. Some of the pins are thirty thousanths or more undersize.

I wanted to get the bucket to curl more. When I moved the pin to the next hole I found that I could not screw in the retaing screw on the pin because they welded the tapped hole shut when a reenforcing plate was welded on. It never ends with this thing.

Thanks for your help.

Leigh

 

[RonMar]

You are welcome. If you still have a new(uninstalled/undistorted) "O" ring, I would take it in and try and match it locally for future reference.

I have a HW-03 that i picked up this fall. I will be doing some "tightening" on it also. Most of the boom and dipper pivots are pretty tight, but the biggest issue on mine is the pivot/swing pins. Right now it has individual top and bottom pivot pins and due to the slop in those pin-hole dimensions, the frame bounces quite a bit on that slop as you shift from push to pull. I plan on putting in a single pin here which will tighten things up considerably and smooth out the swing as well. I also added a return line filter to mine and a dessicant air breather/filter to help keep the oil clean and dry. From the dealer I got mine thru, the biggest problems they have seen are from dirt/crap in the oil causing valve problems.

I did get a really good deal on this unit. I was starting to plan my own, but once I started to add up all the time and parts to fabricate it, my wife pointed out my current backlog of projects and suggested that this might be a problem/need to throw money at(another good reason I married that woman) this one works acceptably well and the structure is pretty well built. I think it will serve me well with a few refinements.

 

[Wayne County Hose]

Leigh, if you have trouble locating a spare o-ring, you can mail it to me. I'll mail you back a few of the correct ones. I have over 2000 part #'s of o-rings including metric and Japanese sizes. BTW, send a self addressed envelope, I never charge for o-rings, it's not worth wasting the paper on.

 

[RonMar]

Leigh, if you have trouble locating a spare o-ring, you can mail it to me. I'll mail you back a few of the correct ones. I have over 2000 part #'s of o-rings including metric and Japanese sizes. BTW, send a self addressed envelope, I never charge for o-rings, it's not worth wasting the paper on.

Yea, I think a trip for "O" rings is about the only time I have walked out of a shop with exactly what I needed for less than a buck

 

[jezorek]

WCH- Thanks for your generous offer but I have all the O rings I need. ( I hope).

Ron- So far I have made one new pin for one of the swing pivots. The top and bottom bores on the boom were different diameters as was the eye of the cylinder. Fortunately they got progressively smaller. I can't wait to see what I am up against on the other side.
I too have two separate pins for the swing and would like to make this assembly more rigid. The issue for me is how to deal with the weight of parts without some sort of lifting device. Any ideas?
I would think that it would be best to try and line bore or ream this section and fit a single diameter pin. I am sure you will run into some varying diameters and egg shaped holes.

Leigh

 

[RonMar]

Yep, I am sure you are correct about what I will find, and it will probably get more out of shape the more I use it(mine is still relatively new). I havn't removed the pivot pins to measure yet, but I figure I can support the boom assembly well enough with the backhoe hydraulics and the bucket on the ground to allow me to pull one pin at a time to measure. The new pin will go in from top to bottom so I should be able to install the new pin that same way. Line boring would be nice, but I think I will have to settle for the closest fit I can manage. I sure hope the top hole isn't smaller than the bottom one. I could make a stepped pin to compensate if the bottom was smaller, but it might be difficult to put a pin in from the bottom if the top is smaller. I guess if I backed the pivot over a hole in the ground, even this would be possible...

Quite frankly, even a sloppy single pin would be worlds better than the current loose 2 pin arrangment. I was also looking at possibly welding a pin sleeve that the pin would pass thru between the upper and lower brackets to help cut down on any potential pin flex, but I don't have a lot of room to spare between the pivot cylinder rods and pin when at full swing.

 

[john_bud]

Often there is a Quad-ring in there and not an O-ring. An O will work, but the quad is better. If it is an O-ring, a quad will provide better sealing.

You probably have a metric size.

jb