ck30 BH connecting hydraulic lines

KiotiJohn · May 21, 2006

( I've found that I have stored pressure on the BH lines preventing them from being reinserted. So, if I understand this correctly, have the machine off when disconnecting the lines? )
By ALL means have the tractor turned off.

You get the backhoe disconnected and move the tractor out where it will clear, turn it off and then relieve all the pressure in the lines. How could you relieve the pressure in the lines if the tractor is still running and producing more pressure? Once you disconnect the hoses, there is no where for the fluid (pressure) to return to, so the pressure can't be relieved.

You actaully returning the fluid to the reservoir when you move the controls around, taking the fluid pressure out of the lines. That can't happen with the tractor running.
John

KiotiJohn · May 21, 2006

( I've found that I have stored pressure on the BH lines preventing them from being reinserted. So, if I understand this correctly, have the machine off when disconnecting the lines? )
By ALL means have the tractor turned off.

You get the backhoe disconnected and move the tractor out where it will clear, turn it off and then relieve all the pressure in the lines. How could you relieve the pressure in the lines if the tractor is still running and producing more pressure? Once you disconnect the hoses, there is no where for the fluid (pressure) to return to, so the pressure can't be relieved.

You actaully returning the fluid to the reservoir when you move the controls around, taking the fluid pressure out of the lines. That can't happen with the tractor running.
John

IslandTractor · May 22, 2006

Even with the tractor shut off the pressure in hydraulic lines can persist even for weeks. Case in point: I removed my QA grapple while tractor was shut off. Two weeks later I came back to reattach it and found one of the male QCs on the grapple side was still pressurized. I only figured that out after talking to a dealer who gave me the hint of covering the pin with a cloth then tapping it with a hammer. Worked instantly.

IslandTractor · May 22, 2006

Even with the tractor shut off the pressure in hydraulic lines can persist even for weeks. Case in point: I removed my QA grapple while tractor was shut off. Two weeks later I came back to reattach it and found one of the male QCs on the grapple side was still pressurized. I only figured that out after talking to a dealer who gave me the hint of covering the pin with a cloth then tapping it with a hammer. Worked instantly.

HODAK · May 22, 2006

I don't think hitting that fitting with a hammer is something that should be done on a regular basis. If the tractor is shut off and you move all the controls around for a specific attachment, the pump pressure is gone. Now, if the cylinders move into a position causing pressure build up once disconnected, that's different. You just need to find a spot where the cylinders are in a relaxed state, then shut off,(operate the controls), and disconnect. Maybe your grapple was opened at the time of disconnect and then the build up of pressure was from gravity trying to close it? Again, the hammer job should not be commom practice. I believe that someone also pointed out in another thread that the heat of the sun on cylinders and hoses can cause the oil to expand. It should be easy to get rid of the pump pressure in any case. Just my 2 cents.

HODAK · May 22, 2006

I don't think hitting that fitting with a hammer is something that should be done on a regular basis. If the tractor is shut off and you move all the controls around for a specific attachment, the pump pressure is gone. Now, if the cylinders move into a position causing pressure build up once disconnected, that's different. You just need to find a spot where the cylinders are in a relaxed state, then shut off,(operate the controls), and disconnect. Maybe your grapple was opened at the time of disconnect and then the build up of pressure was from gravity trying to close it? Again, the hammer job should not be commom practice. I believe that someone also pointed out in another thread that the heat of the sun on cylinders and hoses can cause the oil to expand. It should be easy to get rid of the pump pressure in any case. Just my 2 cents.

KiotiJohn · May 22, 2006

( Even with the tractor shut off the pressure in hydraulic lines can persist even for weeks. )
Not if you follow the procedure that I outlined. If you return the fluid to the reservoir after you turn the tractor off, there is no pressure. Where do you suppose this magic pressure that persists comes from? It comes from you not moving the handle around to relieve the pressure.

Relieving the pressure as you noted is a last resort solution.
John

KiotiJohn · May 22, 2006

( Even with the tractor shut off the pressure in hydraulic lines can persist even for weeks. )
Not if you follow the procedure that I outlined. If you return the fluid to the reservoir after you turn the tractor off, there is no pressure. Where do you suppose this magic pressure that persists comes from? It comes from you not moving the handle around to relieve the pressure.

Relieving the pressure as you noted is a last resort solution.
John

IslandTractor · May 22, 2006

Guys,

I understand the point about shutting the tractor off. I am just reporting my experience. I left the grapple in the closed position, shut off the tractor and disconnected. Two weeks later when I went to reattach it I was able to install one of the male QCs easily to either female but could not connect the other male to either female. I called the dealer who told me to cover the tip with a cloth and give it a bang. I did so and saw oil on the cloth. The hammer "tap" was not nearly hard enough to hurt the fitting but was more concentrated force than I could generate by pushing the fitting against a solid surface. One tap and the fitting hooked up just as easily as ever.

As John pointed out, if I had shut off the tractor then tried to open and close the grapple it might have avoided there being residual pressure. However, I am sure we all forget to do that sort of thing occasionally and tapping a cloth covered fitting seems to be a good solution to the problem when it arises. Obviously if it is the female side that is pressurized you'd need to indent the valve to release pressure.

IslandTractor · May 22, 2006

Guys,

I understand the point about shutting the tractor off. I am just reporting my experience. I left the grapple in the closed position, shut off the tractor and disconnected. Two weeks later when I went to reattach it I was able to install one of the male QCs easily to either female but could not connect the other male to either female. I called the dealer who told me to cover the tip with a cloth and give it a bang. I did so and saw oil on the cloth. The hammer "tap" was not nearly hard enough to hurt the fitting but was more concentrated force than I could generate by pushing the fitting against a solid surface. One tap and the fitting hooked up just as easily as ever.

As John pointed out, if I had shut off the tractor then tried to open and close the grapple it might have avoided there being residual pressure. However, I am sure we all forget to do that sort of thing occasionally and tapping a cloth covered fitting seems to be a good solution to the problem when it arises. Obviously if it is the female side that is pressurized you'd need to indent the valve to release pressure.