My LW-3 backhoe is weak on the cylinders that swing the backhoe back and forth. Everything else is just fine. The cylinders don't even have enough pressure to hold the arm still when you are driving it will swing back and forth. Does anybody have any ideas like I said all other operations seem to be fine.
Backhoe LW-3 backhoe week
- Thread starter birddog55
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bluechip
Veteran Member
You should have chains for holding the hoe while driving. Others have complained about week side to side. Do you get a lot of oil coimng out of the vents?
RonMar
Elite Member
How are you powering it hydrauically? Are you sure all the air is out of the system? The swinging side to side while driving would probably be more a function of mechanical and seal integrity as Bluechip mentioned. If the seals are good in the swing cylinders(no leaking fluid from the vents), and the setup is mechanically strong enough(not overpowering the cylinders), then the boom should be hydrauically locked when you are not working the boom swing lever. As mentioned, your hoe may be weak in this mechanical area as a matter of design.
A number of backhoes limit the available pressure to the swing cylinders to limit the possibility of pushing the tractor over with an agressive boom movement against an immovable obect. It is possible that the relief valves on this portion of the system are not set or functioning properly(leaking) and allowing the boom forces to overcome these safeties.
A number of backhoes limit the available pressure to the swing cylinders to limit the possibility of pushing the tractor over with an agressive boom movement against an immovable obect. It is possible that the relief valves on this portion of the system are not set or functioning properly(leaking) and allowing the boom forces to overcome these safeties.
Stimw
Elite Member
I have the YW-6 and I have the same problem. It doesn't hold position when digging. I have to move it back to where I want it. When trying to push dirt sideways with the bucket it has no power. When I drive it around my property I have to keep checking to make sure it hasn't shifted to the side.
My guess is the two cylinders are too small for what they have to do. But they should hold where I leave it.
I still like the Hoe, I'm having a lot of fun, Or a-a-a, getting a lot done with it!
My guess is the two cylinders are too small for what they have to do. But they should hold where I leave it.
I still like the Hoe, I'm having a lot of fun, Or a-a-a, getting a lot done with it!
RonMar
Elite Member
Thinking a bit more about it, if the weight of the structure was overpowering the cylinders. I think It would be forcing fluid past the piston seals and you would see fluid comming out of the vents on the swing cylinders(open port of a double acting cylinder in a single acting application) when you swing the boom completely one way or the other. For the structure to move, fluid has to move somewhere. If not past the seal in the cylinder(no fluid leaking from the vents), it has to be moveing somewhere else otherwise the cylinder or structure would be bending/breaking.
I would look into the relief mechanism or control valve that feeds the swing cylinders. Perhaps remove a line to a swing cylinder and install a pressure gauge to see how much pressure the control can supply to the swing cylinder before relieving. If the relief pressure was set too low, perhaps that is where the fluid is transfering allowing the boom to swing when driving. If there is a relief system on the swing cylinders, there should be a spec for it somewhere.
I would look into the relief mechanism or control valve that feeds the swing cylinders. Perhaps remove a line to a swing cylinder and install a pressure gauge to see how much pressure the control can supply to the swing cylinder before relieving. If the relief pressure was set too low, perhaps that is where the fluid is transfering allowing the boom to swing when driving. If there is a relief system on the swing cylinders, there should be a spec for it somewhere.
heartservant
New member
From my experience, it is nothing uncommon. Though if it continues, it will break the end off the cylinder. Someone on one of these site suggested the chains. They suggested that you install 2 chains. Attach the ends to the boom (back side) and the other ends to the feet. Then all you have to do is move the feet a little and they will tighten up the chains and hold boom in place when you are moving around. As soon as I get my boom cylinder rebuilt, I will see if it work. It sound like the right idea, though. ,,,James
My backhoe does the same thing.
The issue is that there is a non adjustable relief built into the swing valve.
This is in addition to the adjustable full system backhoe relief valve
If you take the spool section out of the valve, you will see two ball and spring "pop offs" Built into the spool. It is an interesting design, but it cannot hold much pressure. I wanted to redesign it but I have not had time.
I am going to see if the FEL valve uses the same spool. I have an extra FEL valve since I upgraded to the USA valve. If anyone gets to this let us know how it works.
John
The issue is that there is a non adjustable relief built into the swing valve.
This is in addition to the adjustable full system backhoe relief valve
If you take the spool section out of the valve, you will see two ball and spring "pop offs" Built into the spool. It is an interesting design, but it cannot hold much pressure. I wanted to redesign it but I have not had time.
I am going to see if the FEL valve uses the same spool. I have an extra FEL valve since I upgraded to the USA valve. If anyone gets to this let us know how it works.
John
Bob Rooks
Elite Member
One look and you can see that the swing cylinders were not designed nor intended to push or move dirt, nor to even hold the boom steady. Hence the two single acting cylinders and the separate relief valves. Bear in mind that these are NOT high-end backhoes, and any attempt to modify the hydraulics and/or geometry without engineering is really asking for it.
