Feed Roller pressure

wade284jm · Apr 30, 2016

I am new to hydraulics in this way. I understand the basics involving push and pull but pressure is something I've never looked into. I'm building a processing head for my crawler. It has a 12" hydraulic shear on the bottom, powered by 2-5" bore 8" stroke pistons. Above that is where i loose confidence. I have 2-12" feed wheels powered by 2 hydraulic motors on arms controlled by 2 cylinders.This is my question..and it may be stupid. These 2 rollers clamp down on the tree and roll it through the delimbing knives like any processor. As the tree gets thinner at the top, what do i need to do to have the feed rollers keep a constant pressure on the tree automatically. I just want to be able to hit a button for the rollers to close and hit it again to open, but have the arms close as the tree stem slims down. Does this make any sense? Any insight would be appreciated.
Thanks
Wade

wade284jm · Apr 30, 2016

Anyone?

bigdeano · Apr 30, 2016

Seems like you'd just need an adjustable pressure relief valve so you can adjust the clamping force. Just keep pressure on the cylinders and they will follow the size of the tree with constant clamping force.

wade284jm · Apr 30, 2016

Thanks bigdeano. So if i have a 12v solenoid activated valve which turns on when i press a button. And i have a relief valve after that that is set for Xpsi. It should keep those arm cylinders pushing at constant Xpsi. Now will there be alot of heat created in the system with the relief valve bypasing all that fluid, or should i be alright?

bigdeano · May 1, 2016

Maybe I replied without giving it enough thought. That function will be used a lot, so you're right a lot of heat will be generated. Are you going to use open center hydraulic system? Maybe a separate small pump for that function to minimize heat would be the easiest way. Or a hydraulic accumulator could be used to maintain the pressure without constant flow. Lots of possibilities. Any chance of looking at a commercial unit to see how they do it?