Open or Closed Center?

[RFB]

Sirs,

I am configuring my next purchase (a MF 5400 series, either the 5465 or 5475).

I would like the highest hydraulic flow that is offered. It has the following capabilities:

"15 gpm (57 L/min) open center system, or upgrade to the 26 gpm (98 L/min) system that combines the flow from two separate pumps. Lock the 3-point hitch in place and deliver all 26 gpm to remotes. For jobs that require the highest level of hydraulic performance, select a closed center load-sensing (CCLS) hydraulic system that delivers 29 gpm (110 L/min) on demand."

What is the difference between the open and closed center system, and by going to the closed center system (29 gpm), would I lose any capability or function?

Thank you,

RFB

 

[art]

Why do you need so much hydraulic power?

Closed is better for running motors then open.

 

[J_J]

It will take about 45 HP to run the pumps at 26gpm, and 2500 psi.

 

[mmurphy]

TractorData.com Massey Ferguson 5475 tractor information
TractorData.com Massey Ferguson 5465 tractor information

Looks like you have all the horses required.
To say which is better, need to know what you will be using it for. Closed center has some high price components compared to open center, so if you are using it just here and there as a field tractor I would go open center. If using it as mainly for hydraulics continuous, I would op for closed center.:2cents:

 

[Redneck in training]

Open center is simpler. There is not pressure in the system until you move a spool to operate cylinder or motor.
Closed center is under constant pressure. It usually has a variable delivery pump controlled by a pressure controller. The advantage is you can operate all cylinders or motors in the same time.
Hope I am correct.

 

[RFB]

The intended use for the hydraulics was to be able to employ skid steer components as well as a hydraulic auger and a hydraulic snowblower.

The difference between the open and closed system is only 3 gpm so its not a huge difference.

Aside from the cost, are there any other negative attributes to a closed system versus the open type?

 

[AKKAMAAN]

Sirs,

I am configuring my next purchase (a MF 5400 series, either the 5465 or 5475).

I would like the highest hydraulic flow that is offered. It has the following capabilities:

"15 gpm (57 L/min) open center system, or upgrade to the 26 gpm (98 L/min) system that combines the flow from two separate pumps. Lock the 3-point hitch in place and deliver all 26 gpm to remotes. For jobs that require the highest level of hydraulic performance, select a closed center load-sensing (CCLS) hydraulic system that delivers 29 gpm (110 L/min) on demand."

What is the difference between the open and closed center system, and by going to the closed center system (29 gpm), would I lose any capability or function?

Thank you,

RFB

Your two fixed displacement pumps in parallell, Open Center, will give you max flow capacity as long as your directional valve is fully engaged (center closed), and Pressure relief valve stay closed....
If you prefere to throttle or feather the valve this Open Center system will give you lots of power losses, because flow is partly diverted to tank via the controlvalve.

A closed center, constant pressure system, usually require a variable displacement pump, that can disengage flow when there is no demand from control valve.
There are three different varies of this system,

• *Straight constant pressure system

• *Unloaded constant pressure system, with a lower pressure at stand-by, and allways max pressure on demand

• *Load sensing, unloaded constant pressure system, with a lower pressure at stand-by, and a pressure equal to load pressure and stand-by pressure added together

Now, there is also a Load sensing type of system using fixed displacement pumps, and a closed center valve of a special type. Flow through control valve will be on demand and the rest of pump flow will be diverted to tank via a load sensing relief valve or dump valve. See Josh Cosford's picture

 

[AKKAMAAN]

The intended use for the hydraulics was to be able to employ skid steer components as well as a hydraulic auger and a hydraulic snowblower.

The difference between the open and closed system is only 3 gpm so its not a huge difference.

Aside from the cost, are there any other negative attributes to a closed system versus the open type?

A closed center system is almost always to prefer...
pro's---
*additional valve adds easy in parallel, no struggling with power-beyond valves
*Usually much lower power losses than open center systems
*Easier to control simultaneously operated functions

con's---
*cost
*more complex design

""Open center, constant flow system>>pressure on demand, flow is already available at control valve
Closed center, constant pressure system>>flow on demand, pressure is already available at control valve""

 

[radman1]

I looked at the MF brochure, and the closed center is only available with a cabbed model. I have Case-IH Maxuum 125 Pro which is very close to the MF 5475. Mine is closed with 27 gpm. With closed center, your gpm will not vary with change in engine speed and the flow is consistent. Most closed center hydraulics in tractors of this size will allow variable flow control to each spool. It may be manual or electro-hydraulic. That is a nice feature if you want to control the movement of a cylinder or speed of a hydraulic motor. We use that a lot on our ag tractors. Can easily adjust the speed on raising implement, hydraulic top link, hydraulic motors on planter or sprayer ect.

If you plan on getting a FEL, then it often it is cheaper to order the tractor loader ready with joystick and some of the FEL brackets already on the tractor. With Case-IH it is a lot more $$ and time to add them later.

 

[radman1]

Why do you need so much hydraulic power?
QUOTE]

Depends on useage. Our big ag tractor with 245 hp has 59 gpm and our planter requires about 40 gpm running through mulitple valves if using all functions at once. Some planters require even more. That tractor has 5 rear hydualic outlets.

I have 27 gpm on my 125 hp tractor and can run skid steer equipment if I want. My sprayer requires about 15 gpm for the hydraulic motor and I also have hydraulic booms to raise/lower and fold. This tractor has 4 hydraulic outlets plus 3 other outlets for FEL and accessory outlet on FEL.