Boom Cylinder Hydraulic Lines

[TexasTimbers]

1997 Daewoo DSL 601 I do have the manuals, but I cannot understand the hydraulic schematic, it's greek to me. I had my boom cylinders repaired (new rods and a barrel I bent them) and failed to note how the lines were removed. But I am not sure it matters. When the ends of the rods are disconnected from the top of boom, the rods are pushed out no matter what direction I call for. When I replaced them last year I had them going in {i]opposite[/i] directions at one point! Let me just ask it this way. When both cylinders are pinned at the back end, with all the hoses hooked up *properly*, but both working ends of the cylinders are not yet pinned to the top of the boom, should the rods obey the inputs just as if they were pinned? Do they behave differently in any combination? Of course, my thought was that they shoul dboth operate in the same direction as the input calls for, and operate in the same direction simultaneously. But I can't get them to do that no matter what combination I use to hook the hoses up. And I can't tell from the "lay" of the hoses, you know, how they hang from the memory built into the rubber from how they were hooked up so long, because they are so close together on each boom you really cant tell how they were hooked up. Stumped.

 

[TriHonu]

When both cylinders are pinned at the back end, with all the hoses hooked up *properly*, but both working ends of the cylinders are not yet pinned to the top of the boom, should the rods obey the inputs just as if they were pinned? - Yes
If you only disconnected the hoses at the two boom cylinders you should only have 4 hoses disconnected, two on each side. Is this correct?
When you start the loader is there any hydraulic fluid coming out of any of these hoses? There shouldn't be any fluid under pressure coming out of the lines. If you do, you probably have a control valve leaking or stuck.
Get a helper. Have them stand to one side and watch the hoses on that side. You start the loader and operate the boom lift control just enough for fluid to come out of the hose. That hose should be connected to the cylinder port that supplies the base of the cylinder. The other line on that side connects to the port that supplies the rod end of the cylinder. Do the same thing on the other side.
There are three ways to hook up the cylinders:
1. If you connect one side correct and one side incorrect when you try to raise the boom one side will be trying to push the boom up and the other side will be trying to pull the boom down.
2. If you hook up both sides incorrect and try to raise the boom it will pull down and when you try to lower the boom it will raise up.
3. Both sides hooked up correct it will work properly.

 

[TexasTimbers]

When both cylinders are pinned at the back end, with all the hoses hooked up *properly*, but both working ends of the cylinders are not yet pinned to the top of the boom, should the rods obey the inputs just as if they were pinned? - Yes
If you only disconnected the hoses at the two boom cylinders you should only have 4 hoses disconnected, two on each side. Is this correct?
When you start the loader is there any hydraulic fluid coming out of any of these hoses? There shouldn't be any fluid under pressure coming out of the lines. If you do, you probably have a control valve leaking or stuck.
Get a helper. Have them stand to one side and watch the hoses on that side. You start the loader and operate the boom lift control just enough for fluid to come out of the hose. That hose should be connected to the cylinder port that supplies the base of the cylinder. The other line on that side connects to the port that supplies the rod end of the cylinder. Do the same thing on the other side.
There are three ways to hook up the cylinders:
1. If you connect one side correct and one side incorrect when you try to raise the boom one side will be trying to push the boom up and the other side will be trying to pull the boom down.
2. If you hook up both sides incorrect and try to raise the boom it will pull down and when you try to lower the boom it will raise up.
3. Both sides hooked up correct it will work properly.

Great description of the process and it makes perfect sense. I didn't know that there shouldn't be any fluid coming out while running and disconnected either. I'll be able to do this tomorrow evening. I'll let you know how I fare. Thanks for the response this forum is an excellent resource for us DIYers. Kevin.

 

[Fishfiles]

Great description of the process and it makes perfect sense. I didn't know that there shouldn't be any fluid coming out while running and disconnected either. I'll be able to do this tomorrow evening. I'll let you know how I fare. Thanks for the response this forum is an excellent resource for us DIYers. Kevin.

I have found that not all machines have no flow to the hoses , while running with the controll valve in neutral position , some will flow pretty good when cranked up with hoses disconected , depends on how it's plumbed, seems especially true when a lift (boom ) cylinder has a holding valve on it --------- don't really know what you are trying to do , with both boom cylinders disconnected from machine on the rod side they both will not allways act the same , one may all the way retract or extend before the other side reacts , one may be faster than the other , wen pressure is applied to the cylinders it will act differently

 

[jerry]

Since you had the cylinders off you may get odd movement and no movement then all of a sudden it will go due to air in the lines and cylinders yet.

 

[TexasTimbers]

Since you had the cylinders off you may get odd movement and no movement then all of a sudden it will go due to air in the lines and cylinders yet.

I've tried every combination with the two hoses that connect to each cylinder, that are possible and I get the same general result: the cylinders are conflicting each other to the point that they twist the boom assembly to the point that I'm afraid something will fail.
I can get the rods to move in unison by using one combination, and I can swap a pair of hoses on one cylinder and get them to move opposite of each other, but no matter what combination I hook them up, when I pin both rods to the boom frame there is no forecasting what will happen other than it isn't going to be right. You can feel and hear the pressure building immediately and if I were to keep moving the pedal something would fail.
This last go around, no matter which input I gave the pedal, the boom assembly moved up, but of course was all twisted and threatening to bend a rod or bust a weld or blow a seal at least. I am out of ideas.
It shouldn't matter which side the cylinders are mounted right? I mean, they are exactly identical in every way.

 

[Fishfiles]

I've tried every combination with the two hoses that connect to each cylinder, that are possible and I get the same general result: the cylinders are conflicting each other to the point that they twist the boom assembly to the point that I'm afraid something will fail.
I can get the rods to move in unison by using one combination, and I can swap a pair of hoses on one cylinder and get them to move opposite of each other, but no matter what combination I hook them up, when I pin both rods to the boom frame there is no forecasting what will happen other than it isn't going to be right. You can feel and hear the pressure building immediately and if I were to keep moving the pedal something would fail.
This last go around, no matter which input I gave the pedal, the boom assembly moved up, but of course was all twisted and threatening to bend a rod or bust a weld or blow a seal at least. I am out of ideas.
It shouldn't matter which side the cylinders are mounted right? I mean, they are exactly identical in every way.

Are there holding valves on the cylinders , they woud be manifold block mounted to the base end of the tube which acts as a saftey device to prevent boom from dropped if a hydraulic oil blow out occured , --- there could also be restricter / orifice valves in the plumbing , it will look like a fitting and have a plastic (usually) which is in there to slow down the down side movement , have seen these cause problems ----------could be the nut holding the piston to the rod loosened up ---------how did this all start , did you disassemble the cylinders for repairs , or did the problem start it all

 

[TriHonu]

I've tried every combination with the two hoses that connect to each cylinder, that are possible and I get the same general result: the cylinders are conflicting each other to the point that they twist the boom assembly to the point that I'm afraid something will fail.
I can get the rods to move in unison by using one combination, and I can swap a pair of hoses on one cylinder and get them to move opposite of each other, but no matter what combination I hook them up, when I pin both rods to the boom frame there is no forecasting what will happen other than it isn't going to be right. You can feel and hear the pressure building immediately and if I were to keep moving the pedal something would fail.
This last go around, no matter which input I gave the pedal, the boom assembly moved up, but of course was all twisted and threatening to bend a rod or bust a weld or blow a seal at least. I am out of ideas.
It shouldn't matter which side the cylinders are mounted right? I mean, they are exactly identical in every way.

Texas Timbers - "I can get the rods to move in unison by using one combination"
I take it when they are in unison the controls are reversed ie the raise control lowers the boom? If so what happens when you swap the hoses on the right and then swap the hoses on the left?