Open center vs. close center

[pmsmechanic]

I'm just here to learn something.

 

[SilentJ]

I have operated a Vermeer R23 rake for hours on JD tractors with CC hyd that the operating hoses were too hot to touch for any amount of time. I've also utilized a gravity flow grain box with hyd powered auger that hoses were too hot to disconnect bare handed. That amount of heat can't be good for o-rings & seals. I also was employed by a JD dealer from '66-'87 serving as the dealer service manager for the last 13 years.

You have a system with high capacity and youæ±*e choking it down for so,etching that doesn稚 need everything youæ±*e throwing at it.

About 120 degrees is where human hands say ç™»w! But most hydraulic components are not too disturbed until 160 or so.

 

[AKKAMAAN]

any good primers out there discussing the pros and cons of each system?
Open center = fixed displacement (for the most part) and closed center = variable displacement.

What is there beyond that? What can closed center do that open centered can't? Anything else out there?

These terms, open center and closed center, are not necessarily individually related to fixed or variable displacement pumps.
It is better to ask the question about "constant flow/variable pressure" versus "constant pressure/variable flow" versus "variable pressure/variable flow". (Don't confuse "closed center/open center" with "closed loop/open loop" or "closed cirquit/open cirquit")

Open center/closed center relates to the directional valve in neutral spool position. A directional valve that we use to distribute parts of or all of the hydraulic "power" available. We do that by "throttling" (diverting) parts of or all the flow. Power losses in form of heat is crucial in the discussion, but also the problems about how we can control the motions of the actuators.

So we have 3 different options to vary the output power to one or several actuators.
1. Vary pump pressure from a constant pump flow.
2. Vary pump flow from a constant pump pressure
3. Vary both pump flow and pump pressure

Start over the discussion from here by analyzing the difference in these three basic system principles and a lot "more hidden cards will be flipped on the table"....