Backhoe attachment not working

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ytr1903

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The Bradco 9HD operates off a Bobcat. Last fall the backhoe attachment worked perfectly. Now only the stabilizer arms operate correctly. Both of them will go up and down and will maintain their position overnight with the Bobcat's weight on them. No other functions operate, though. They all seem to want to operate and will move slightly and then will stop their movement. It seems as if there is not enough pressure in the system. I'm guessing that the stabilizer arms don't need very much pressure and that is why they are working.There is hydraulic fluid coming out of what looks like a relief tube/overflow tube down to the ground, when the hydraulics are turned on from the bobcat. I checked and cleaned the inline filter, but there was no apparent clogging in the filter, and it made no difference in the performance of the backhoe. When I turn on the hydraulics of the Bobcat, I can see the hydraulic hoses jump, just as I can see the hoses move as I operate the the backhoe controls. The bobcat itself works perfectly and I have no reason to believe that it is not producing enough hydraulic pressure. My skills with hydraulics are in their infancy and any suggestions as to what the problem may be would be appreciated. Tom
 

Tazza

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This may sound silly, but are you sure the flow is in the rite direction? Oil flow in the opposite direction could do what you describe....
 
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ytr1903

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This may sound silly, but are you sure the flow is in the rite direction? Oil flow in the opposite direction could do what you describe....
Tazza, That is not silly question, but I don't know how the flow would be in the wrong direction. Nothing has changed since last fall. It is the same Bobcat and the same backhoe. The couplers are the same also. Maybe I am missing something, but how could the flow be reversed when no other variables have changed? At least, no variable that I am aware of. Is there a way to reverse the flow of oil in a 743 without being aware of it? Thanks for your reply! I have been reading on the internet, since I posted the question. (I know that a little knowledge is dangerous) The problem seems to be pointing more and more in the direction of the backhoe's pressure relief valve. If this valve was malfunctioning and allowing fluid through the system at lower pressure, I would think that the unit would not operate properly. Is this a reasonable possibility? Tom
 

Tazza

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Tazza, That is not silly question, but I don't know how the flow would be in the wrong direction. Nothing has changed since last fall. It is the same Bobcat and the same backhoe. The couplers are the same also. Maybe I am missing something, but how could the flow be reversed when no other variables have changed? At least, no variable that I am aware of. Is there a way to reverse the flow of oil in a 743 without being aware of it? Thanks for your reply! I have been reading on the internet, since I posted the question. (I know that a little knowledge is dangerous) The problem seems to be pointing more and more in the direction of the backhoe's pressure relief valve. If this valve was malfunctioning and allowing fluid through the system at lower pressure, I would think that the unit would not operate properly. Is this a reasonable possibility? Tom
Try getting someone to sit in the seat of the bobcat and hold the right stick to the left to reverse flow, it will not lock in though but this is just to test. If it functions normally its a flow problem. As you said nothing has changed i doubt it is the cause though....
You did say the stabilizer legs still worked normally so the relief should be ok... When you put the legs down, does it lift the front of the loader up off the ground? or does it have little power?
The control block may have a relief valve that indeed could have something stuck to prevent you getting pressure. It will look like a plug but usually with what looks like a bolt hanging out the end. They are very simple, they use a poppet and spring to regulate pressure. The higher the pressure the more load on the spring against a plug, when the pressure exceeds what the spring can hold it opens up to allow the oil to flow back to the return line. Very simple! but a small piece of O-ring can hold this valve open.
See how you go, hopefully its a simple answer..... These systems really aren't that complicated and you will learn a lot trouble shooting one.
 
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ytr1903

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Try getting someone to sit in the seat of the bobcat and hold the right stick to the left to reverse flow, it will not lock in though but this is just to test. If it functions normally its a flow problem. As you said nothing has changed i doubt it is the cause though....
You did say the stabilizer legs still worked normally so the relief should be ok... When you put the legs down, does it lift the front of the loader up off the ground? or does it have little power?
The control block may have a relief valve that indeed could have something stuck to prevent you getting pressure. It will look like a plug but usually with what looks like a bolt hanging out the end. They are very simple, they use a poppet and spring to regulate pressure. The higher the pressure the more load on the spring against a plug, when the pressure exceeds what the spring can hold it opens up to allow the oil to flow back to the return line. Very simple! but a small piece of O-ring can hold this valve open.
See how you go, hopefully its a simple answer..... These systems really aren't that complicated and you will learn a lot trouble shooting one.
Tazza, thanks so much for your prompt replies. I will be out of town until the weekend, but I can tell you that the backhoe is paramount in my mind. I will try your suggestion of moving the stick to the left and report back on Monday. Thanks again, Tom
 

TriHonu

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Tazza, thanks so much for your prompt replies. I will be out of town until the weekend, but I can tell you that the backhoe is paramount in my mind. I will try your suggestion of moving the stick to the left and report back on Monday. Thanks again, Tom
If you have hydraulic fluid coming out that small hose you need to do some more checking. I have a Bradco 609 old model and my neighbor has a 609 new model.
The old model has a knob on the plastic cover in front of your knees that is a system pressure relief. You open it to drain a small amount of fluid from the hoe so you can attach the couplers to the loader after it has been sitting.
My neighbor has the new model that also has a valve in the same position that is a swing speed adjustment. The swing speed knob allows you to slow down the swing speed.
If you turn on continuous flow in the loader and fluid is coming out of that small hose you either need to close the pressure relief or the swing speed hose is blown.
Tazza is also correct to tell you to check the direction of flow. If the flow is reversed my hoe acts like what you describe. The control valve is designed to flow in one direction only.
 

skidsteer.ca

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If you have hydraulic fluid coming out that small hose you need to do some more checking. I have a Bradco 609 old model and my neighbor has a 609 new model.
The old model has a knob on the plastic cover in front of your knees that is a system pressure relief. You open it to drain a small amount of fluid from the hoe so you can attach the couplers to the loader after it has been sitting.
My neighbor has the new model that also has a valve in the same position that is a swing speed adjustment. The swing speed knob allows you to slow down the swing speed.
If you turn on continuous flow in the loader and fluid is coming out of that small hose you either need to close the pressure relief or the swing speed hose is blown.
Tazza is also correct to tell you to check the direction of flow. If the flow is reversed my hoe acts like what you describe. The control valve is designed to flow in one direction only.
It could also be a falty relief valve. Are the levers for the outriggers on a separate valve body from the rest of the hoe controls. Each valve body would have its own relief, even a common valve body might have separate relief for the boom and the out riggers?
Just a thought
Ken
 
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ytr1903

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It could also be a falty relief valve. Are the levers for the outriggers on a separate valve body from the rest of the hoe controls. Each valve body would have its own relief, even a common valve body might have separate relief for the boom and the out riggers?
Just a thought
Ken
To all, I am here to confess my sins and stupidity. As Tazza originally pointed out I reversed the flow to the backhoe and it started working correctly. I have had this 743 for ten years and never did anything with it but move dirt until I got the backhoe last year. The auxiliary hydraulics just weren't used at all. I guess that last year I was moving the lever in the correct position and didn't even realize the difference. I am 59 years old, so can I chalk this up to a "senior moment"? Thanks all for your help. Tom
 

Tazza

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To all, I am here to confess my sins and stupidity. As Tazza originally pointed out I reversed the flow to the backhoe and it started working correctly. I have had this 743 for ten years and never did anything with it but move dirt until I got the backhoe last year. The auxiliary hydraulics just weren't used at all. I guess that last year I was moving the lever in the correct position and didn't even realize the difference. I am 59 years old, so can I chalk this up to a "senior moment"? Thanks all for your help. Tom
LOL glad it was something simple.
 

skidsteer.ca

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To all, I am here to confess my sins and stupidity. As Tazza originally pointed out I reversed the flow to the backhoe and it started working correctly. I have had this 743 for ten years and never did anything with it but move dirt until I got the backhoe last year. The auxiliary hydraulics just weren't used at all. I guess that last year I was moving the lever in the correct position and didn't even realize the difference. I am 59 years old, so can I chalk this up to a "senior moment"? Thanks all for your help. Tom
Tom
Your not the first or the last that will need to "go to confession"
Always be glad when it comes as a simple fix.
Ken
 

Tractor guy

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Oct 26, 2022
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I got it from came up and installed it on my bobcat. I watched him operate it the other night. I tried today and the same as you....wrong direction! Thank you, guys! Working great! But I am 68....lol
 
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