clod h
Member
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- south lincs farmer
what is the difference of these two systems thank in advance for your reply
Actually that's not quite correct.Open centre the pressure is always at the valve spool(meaning alway pressure in the system). Closed the system will go to a standby pressure(meaning an idle, and then stroke up when needed).
Actually that's not quite correct.
Open centre hydraulics have a pump that outputs a constant flow at a given speed. The output is usually measured in terms of cc/rev.
The oil circulates around a circuit, hence any valves in the loop need to be "open" when in the neutral position.
When a valve is operated to divert oil, the pressure then rises to meet the resistance.
Closed centre hydraulics operate by supplying full pressure to all the valves in the system, but vary the flow rate. If there is no demand, the pump does not circulate oil around and back to tank. This reduces oil temperature, pump wear, and fuel consumption.
In closed centre hydraulics there is a load sensing pipe back to the pump. When the valve is opened to divert oil, the pressure in the circuit drops. The pressure drop causes the pump to increase output flow, meeting demand.
It was a very simple way of explaining the difference. To get the point across.
Open centre the pressure is always at the valve spool(meaning alway pressure in the system). Closed the system will go to a standby pressure(meaning an idle, and then stroke up when needed).
Actually that's not quite correct.
Open centre hydraulics have a pump that outputs a constant flow at a given speed. The output is usually measured in terms of cc/rev.
The oil circulates around a circuit, hence any valves in the loop need to be "open" when in the neutral position.
When a valve is operated to divert oil, the pressure then rises to meet the resistance.
Closed centre hydraulics operate by supplying full pressure to all the valves in the system, but vary the flow rate. If there is no demand, the pump does not circulate oil around and back to tank. This reduces oil temperature, pump wear, and fuel consumption.
In closed centre hydraulics there is a load sensing pipe back to the pump. When the valve is opened to divert oil, the pressure in the circuit drops. The pressure drop causes the pump to increase output flow, meeting demand.
There is a difference in closed center ( up to 50 series John Deere's were closed center) and closed center load sensing, the original closed center works without the load sensing line and pumps on pressure drop anywhere in the system whereas the CCLS pumps on demand sensed by the load sensing line to give power beyond capabilities
In technical terms, it's all been very neatly explained in the posts above. In practical terms either system is pitched at different ends of the market. CC is invariably CCLS these days - it's found on the higher output systems where it can justify its cost premium and additional complexity by being (a) more fuel efficient (b) increasing the service intervals on oil/filters and other components (c) delivering better performance right across the rev range of the engine driving it.what is the difference of these two systems thank in advance for your reply
While there are still lots working, it should be noted that production of tractors with the JD radial piston pumps, with their very simple and limited closed centre system, ceased over 20 years ago.
Are you trying to justify posting factually inaccurate information once again?
No. But by what i can see is the op wants a simple explanation. Maybe not something he cant remember. Or something ripped from a 101 of hydraulics text book.
Presumably he wants to know the truth, not complete bulls**t that would make him a laughing stock if repeated to people that have a modicum of knowledge. Your information is completely false and misleading, full stop.No. But by what i can see is the op wants a simple explanation. Maybe not something he cant remember. Or something ripped from a 101 of hydraulics text book.
Whatever the OP wanted, it certainly wasn't information that is completely opposite to the facts!
I note once more that when the accuracy of your posts is questioned, your go to response is still an attempt to insult. In this instance to suggest every post with factually accurate information is some form of plagiarism.
I would respectfully request that you desist from posting inflammatory and insulting comments when anybody on here questions your views, or corrects the factually inaccurate nonsense you often post.