Variable Flow Open Center Delivers Constant Efficiency

Variable Flow Open Center Delivers Constant Efficiency - Backhoe - Motion Systems Group

As hydraulic systems on construction equipment continue to evolve, the goal of increasing simplicity, reliability and productivity remains the same. Parker Variable Flow Open-Center (VFO) takes a big step towards realizing these objectives.

Typical hydraulic system layouts

The most common hydraulic systems on mobile equipment are based on two designs: an open-center valve technology with fixed displacement pumps or load-sensing (LS) valve technology with variable or fixed displacement pumps. Both of these arrangements have their benefits. The open-center system, for example, is simple, cost-effective and provides the operator with a less jarring operation.

Variable flow open-center

VFO innovatively employs a variable displacement pump controlled by an open-center type valve. The result: VFO integrates the advantages of the current technologies (simplicity, cost-effectiveness, smooth operation) with the energy efficiency of piston pumps.

Variable Flow Open Center delivers constant efficiency graph

VFO in brief

The distinct value of the variable flow open-center system can be seen from several perspectives:

Simplicity: There are no compensators and shuttle networks (open-center valve technology).

Reliability: In general, less complexity means more dependability (open-center valve technology).

Productivity: The system optimizes the energy balance of variable-pump technology.

Applicability: It can work with any valve control type without the need for electronics.

Parker is a global leader in motion and control technologies and a pioneer in the variable flow open-center system.

For in-depth details on our VFO, download the white paper.  And for additional construction equipment content from Parker, visit www.parker.com/buildingbetterlives


Variable Flow Open Center Delivers Constant Efficiency Germano FranzoniArticle contributed by Germano Franzoni, Ph.D., senior systems engineer, Parker Hannifin, Global Mobile Systems.





Related, helpful content for you:

Hydraulic Technologies and Key Markets

Load Sensing Valve Improves Heavy Duty Machine Productivity and Fuel Savings

Electronic Control Systems for Heavy-Duty Vehicle Implements


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Comments for Variable Flow Open Center Delivers Constant Efficiency

Brian Martineau
I just bought a new mini excavator (Volvo ec60e) with this type of hydraulic system and am trying to gain an understanding of it's working principle. I own tractors with either OC or CCLS systems but nothing with VFO systems. Some of the other excavators I considered buying had CCLS systems and I was curious of the advantages/disadvantages of this VFO system in excavator applications. I only have 250hrs on it so far but it does seem to work excellent. Thanks for the informative article. Brian
Dr. German Franzoni
Brian, Thank you for reading our post and your comment. VFO allows you to combine the efficiency of a piston pump system with the operator's feel and controllability of an open center valve. Open center technology gives a smoother, less stiff control feeling, compared to Load Sensing technology, which is commonly used with variable displacement piston pumps. Open center valves are much easier to service, if needed, and contain fewer parts so they are also more cost-effective.

FYI, unfortunately the model you indicate, the Volvo mini excavator ec60e, does not have a Parker VFO system.

Also if you are interested in the technical information around the VFO, please download the White Paper highlighted in the above blog post.

Best Regards,
Dr. Franzoni

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