656 Hydraulics Question

the definition has to do with the excess flow from the pump circuit during the time when no hydraulics are being used. open center lets the excess flow return to the reservoir. closed center has no return to the reservoir. with open center, the pump runs constantly at the same output whether you use the oil or not. closed center has built in valves to change the pump output so that when the oil deadheads the pump will reduce its output to almost nothing, and when you actuate a device the pump will adjust and give up to full output.

there are returns to the reservoir from hydraulic valves and the 3 pt lift cylinder, the lack of a return has only to do with when you are not using/activating the hitch or valves.

hard to keep it simple so hope this helps a little. there are better explanations out there and illustrations too.

karl f

The main hyd. pump goes into and tees off the bottom of the flow divider valve and then goes to the loader/hoe valves before going to the resevoir.

Or does open and close refer to the pump itself? Mine just has two rotating gears just like and internal oil pump of an engine with nothing stopping the output of oil. Seems like I've looked at a parts diagram at caseih or maybe it was cessna for some other type of pump which has some type of valves attached to the pump itself at the output area. Can you clarify that? Thanks.

karl f