Regenerative Log-splitter Bi-Directional Circuit

[N8ghz]

I agree too now. This is a hard concept to get a grasp on. I had ignored the rod/bore ratio, as I can't really alter what I have. I added some calcs to my excel spreadsheet to figure ratios. To achieve near 2:1 I would need a 4x24x2.75 or so rod. And with an oversize rod, normal retract would be alot faster anyway. I attended a Bunyan festival last weekend, and saw a few processors that had 5" cylinders with 3.5" rods...they would have a good return speed with the pumps they used.

I now think that my experiment would be an exercise in futility with the cyl. I have.

 

[J_J]

What about the chance of using an accumulator to add to the volume of fluid going to the retract stroke.

If you had 5 GPM pump, and a full 1 gal accumulator and used them both to retract the cyl, what would be the outcome.

 

[N8ghz]

I have a bottle of nitrogen around here somewhere....might keep an eye out for an accumulator...projects,projects,projects....

Thanks for all input.

 

[oldnslo]

Accumulators are a bit difficult to apply on a free moving system like retracting a splitter. They want to dump all of their flow instantly. They also require some time to charge or fill with oil. I would be concerned about this since the charge time could / would add to your cycle time.

Roy

 

[J_J]

About the accumulator, would not a controlled release provide the right speed. The hose on the base end would have to be large enough for the increased velocity caused by the accumulator. The accumulator could charge up in the dead time/or neutral time.

 

[SPYDERLK]

I agree too now. This is a hard concept to get a grasp on. I had ignored the rod/bore ratio, as I can't really alter what I have. I added some calcs to my excel spreadsheet to figure ratios. To achieve near 2:1 I would need a 4x24x2.75 or so rod. And with an oversize rod, normal retract would be alot faster anyway. I attended a Bunyan festival last weekend, and saw a few processors that had 5" cylinders with 3.5" rods...they would have a good return speed with the pumps they used.

I now think that my experiment would be an exercise in futility with the cyl. I have.

Well, I dont. You have 3.14 times whatever pressure your system runs as your net extension force. Thats thousands of pounds to push an unloaded ram. All you really need is a valve between A and B that when activated closes off the B port to the main valve while simultaneously linking the AB lines going to the cylinder. Your engine will work hard sure, but the ram will move quickly as is your goal.
larry

 

[glastron23]

if you are trying to increase retract speed it would be a lot cheaper and less trial and error to just have a hydraulic shop build you a cylinder with a really big rod, we have some corner cranes with a 6 inch cylinder with a 5.5 rod. We only need the extend to have power, the retract is for stowing only.
To try and build a system that has regen on retract is a waste of time and energy. If people like Sun hydraulics, Prince and others can't get it then it's a lost cause.
Sun Hydraulics - Standard Valve Package

 

[glastron23]

Spyderlk.. if you close off the B port on the valve and then hook it to the A/B hoses from the cylinder together, how is the oil from the pump going to get to the rod side of the cylinder??

 

[oldnslo]

Well, I dont. You have 3.14 times whatever pressure your system runs as your net extension force. Thats thousands of pounds to push an unloaded ram. All you really need is a valve between A and B that when activated closes off the B port to the main valve while simultaneously linking the AB lines going to the cylinder. Your engine will work hard sure, but the ram will move quickly as is your goal.
larry

Larry,
problem with regen is that the rod end area of the cylinder is 9.42 square inches. So if there is 100 PSI in line loss from the rod end port to the cap end port it will require 3 x times that much pressure or 300 PSi pump pressure to extend. He only has 1000 PSI available and using 300 PSI in loss through the extra valves, hoses, etc may not be unreasonable. I never said it wouldn't work, just may not work as expected.

Roy

 

[SPYDERLK]

Spyderlk.. if you close off the B port on the valve and then hook it to the A/B hoses from the cylinder together, how is the oil from the pump going to get to the rod side of the cylinder??

This is only for extension. As you extend, oil is exiting from the rod side of the cyl. You essentially are connecting both cyl ports to "A" and applying the same pressure to both ends. The piston end has more area so the cyl trys to extend. If this extension encounters low resistance it extends. The fluid forced out of the rod end has nowhere to go but over to the piston end. This added fluid increases ram speed a lot. The cyl quickly moves toward its maximum volume condition [extends]. No fluid has to return to sump during this move so the B port is blocked by the same valve that simultaneously connects the cyl ends. After quick extension to the point it needs to do work this valve is put back to its normal position returning the system to standard operation.
larry