Finally, Hydraulic Backhoe Stabilizer Locks, Lift and Lock,

[DonnieP]

I believe Paul might have something. He's saying if you try and lower the stabilizer then the fluid in the rod end has no where to go the pressure will be greatly increased. In attached pic. Say you put 2000 psi on 4 sq. in. that gives 8000# force on piston. On the rod side you have the 8000# and 2 sq. in. that will give 4000 psi. Am I missing something?

 

[WaxMan]

I believe Paul might have something. He's saying if you try and lower the stabilizer then the fluid in the rod end has no where to go the pressure will be greatly increased. In attached pic. Say you put 2000 psi on 4 sq. in. that gives 8000# force on piston. On the rod side you have the 8000# and 2 sq. in. that will give 4000 psi. Am I missing something? View attachment 382613

I see your drawing but the piston would be fully retracted when the fluid tries to go into it. Would it still be 4 to 2 if the body has so little room compared to the rod side.

What would it be using your same picture but the green rod is all the way at the bottom.

 

[DonnieP]

It's the area of the piston that does the work, not the volume of the chamber. The volume of the chamber determines how fast the piston will move. The effective area of the rod end is the area of the piston minus the area of the rod. That's what causes the difference.

 

[WaxMan]

It's the area of the piston that does the work, not the volume of the chamber. The volume of the chamber determines how fast the piston will move. The effective area of the rod end is the area of the piston minus the area of the rod. That's what causes the difference.

So on a fel piston there is more power pushing the rod out (dumping the bucket) then pushing the rod back in as in (curling the bucket)?
It's still the same diameter piston either way.
I'm not being smart, I just don't know. Thats why I'm asking.

 

[rScotty]

So on a fel piston there is more power pushing the rod out (dumping the bucket) then pushing the rod back in as in (curling the bucket)?

YES, that's correct.

It's still the same diameter piston either way.

Yes, the piston is still the same diameter on both sides, but the only effective part of the moving piston is the area of the piston that is perpendicular to the direction of motion. Donnie is correct when he said that on the rod side you subtract the area of the rod from the area of the piston.
BTW, the directional FORCE that the fluid applies to the piston is simply the hydraulic pressure in pounds per square inch multiplied by the area of the piston head in square inches.
Of course inside the cylinder the hydraulic pressure is the same in all directions..... but the only thing that is moving much is the piston and so it the movement of the piston that is doing our useful work.


I'm not being smart, I just don't know. Thats why I'm asking.

I'd call that being smart.
luck, rScotty

 

[J_J]

If the shutoff valve is in the base end, there is no fluid flow. Valve relief will activate if he tries to use the outrigger.

A relief valve across the cyl will relieve at the set pressure.

 

[Gary Fowler]

I believe Paul might have something. He's saying if you try and lower the stabilizer then the fluid in the rod end has no where to go the pressure will be greatly increased. In attached pic. Say you put 2000 psi on 4 sq. in. that gives 8000# force on piston. On the rod side you have the 8000# and 2 sq. in. that will give 4000 psi. Am I missing something? View attachment 382613

Yes, you still only have 2000# per square inch. If you have a cylinder that is 4 sq inched in area, you might have 8000# of thrust, but you would still only have 2000# or pressure. You guys are confusing hydraulic oil PSI with force exerting on the cylinder. That force is on the cylinder each time you use it or at least enough force to raise what ever the cylinder is attached to.

You cant get more PSI into the cylinder than the relieve valve setting OR the pumps max capacity which ever is greater. Blocking in a line will only see the relieve valve pressure. This is how I tested my tractors pump pressure, removed one of the lines on the stabilizer which was the same size and thread as the gauge, screwed in my gauge and held the lever down to see how high the pressure would go. It stopped at 2000 PSI, a little low but I haven't adjusted the RV setting yet.

 

[GMIslander]

Backhoe Stabilizers Bleed Down, Why didn't I think of this, before.

I think Kioti may have stolen your idea only difference being is that the spring is on the inside and the hole on the outrigger end of the strap is elongated so it automatically disengages when you retract the outrigger slightly.

 

[WaxMan]

What I'm going to do shortly is put a gauge between the line and the shut off valve. Run the backhoe with the riggers all the down to lifting the tractor off the ground to sa far as they go.
Then with the outrigger up and valve off I will dead head it and see what I have.
I will be back with the results and pictures.

 

[kennyd]

Waxman, your projects are always well thought out and executed, but I gotta say this seems (to me anyway) to be a overly complicated way of just keeping the stabs up, a simple chain or strap between the two will do that same thing, and not be at risk for damage if you use you backhoe in harsh environments.