GC1700 series fast dump loader function??

[aczlan]

OK, I hesitate to jump into the middle of this, but i believe that “fast dump” and regenerative circuit” are one and the same.
As I understand it, these valves are very valuable on a woodsplitter, where the “retract” doesnt need to develop much pressure, but VOLUME is most important. The more VOLUME of oil entering a cylinder port, the faster that cylinder travels.
So, as I understand it, in RETRACT) the “regen” valve combines the normal oil flow from the pump to the retract port but simultaneously intercepts the “return” oil from the “push” side of the wood splitter (which would normally be returned to the resevoir) and directs it into the retract port. So now “retract” has its normal volume of oil, PLUS the intercepted (diverted) oil from the push side (which would normally be returned to the resevoir) and uses the combined flow to move the piston really fast, but pretty weak. Perfect for a wood splitter or loader bucket curl function, where you want speed but dont need the power (force).
Not very useful on most hydraulic circuits, but works great on these functions.
And I tend to agree that these valves could be more trouble than they’re worth, especially if they are not designed correctly. Then again, engeneered correctly, there might be some extra value in them.
I disagree that the dump cylinder can “suck air from the resevoir”, because said air would also need to be sucked thru the pump and valve in order to get into the cylinder.

Almost correct, but it only works on the extend movement of a hydraulic cylinder, the reason it works is because of the difference in displacement between the base end and the rod end of the cylinder due to the amount of the fluid displaced by the rod. As such when you apply hydraulic pressure to both sides of the cylinder with a tee between the lines, it will tend to extend (think of the surface area of a circle which would be the base end seal on the base end of the rod, and then compare it to the surface area of the circle that is attached to the rod where you only have area between the rod and the bore of the cylinder for the hydraulic pressure to push on).

Aaron Z

 

[atsah]

Almost correct, but it only works on the extend movement of a hydraulic cylinder, the reason it works is because of the difference in displacement between the base end and the rod end of the cylinder due to the amount of the fluid displaced by the rod. As such when you apply hydraulic pressure to both sides of the cylinder with a tee between the lines, it will tend to extend (think of the surface area of a circle which would be the base end seal on the base end of the rod, and then compare it to the surface area of the circle that is attached to the rod where you only have area between the rod and the bore of the cylinder for the hydraulic pressure to push on).

Aaron Z

Thanks for the education by the way..

 

[jeepcj7]

Interesting conversation.

For what its worth, dumping a GC loader bucket under power takes ~4 seconds and dumping in "fast dump" with a loaded bucket takes about ~3 seconds (a 25% reduction!!!).

For the 1 second time saving you also get the added bonus of reduced bucket cylinder cavitation and lots of TBN discussion