New adjustable priority flow control solutions leverage Sun's expertise

Adjustable Priority Flow Control Solutions

Sun solutions provide simple, efficient control of auxiliary hydraulic power to a range of mobile equipment attachments

Sun Hydraulics has developed a range of adjustable priority flow control solutions that have already found their way into applications in rock breaker hammer control. As a priority flow control circuit, it also offers much wider application in general attachment controls and in applications where priority flow control is required such as priority steering control and concrete mixing. It can also function as an unloading valve for fixed displacement pumps in applications requiring two or more functions operated by a single pump.

This Sun-based adjustable priority flow control solution provides several significant advantages:

  • High-quality, durable LH** valves made with all hardened parts
  • Significantly reduced pressure drops from Sun valves and cavities
  • Zinc-nickel coating for improved corrosion resistance
  • Wide range of options available for different applications
  • Solenoid-selectable pressure options
  • Manually adjustable XMD with electro-hydraulic flow control (FPFK)

These new circuits provide a simple, efficient way to supply auxiliary hydraulic power to attachments like rock breakers or hydraulic hammers attached to skid steers, backhoes or excavators.

Below are three adjustable priority flow control solutions that leverage Sun technologies for efficient control of mobile equipment attachments.


Adjustable orifice using the NF** needle valve

In this circuit, the priority flow control manifold divides the inlet flow of port P into a priority flow to port PP with the excess flow going to port PC.  The priority flow can easily be adjusted for specific applications using the NF** needle valve.

In operation, the LHDA bypass/restrictive priority modulating element will act as a pressure compensator to ensure that the flow to port PP will remain constant during pressure changes. This will ensure a very stable flow rate for a given needle valve setting to control hydraulic hammers or rock breakers.

With this design, the flow sharing is achieved with very low pressure losses across the needle valve and modulating element and is independent of the pressure at ports PP and PC.


Selectable priority flow with pressure-limiting option

In this design, when the FLeX Series DMBF-XNN three-way, two-position directional spool valve is energized, the priority flow control divides the inlet flow of port P into a priority flow to port PP with the remaining flow going to port PC. This allows the operator to switch the priority flow on and off easily. The priority flow to port PP can be adjusted using the NF** needle valve, and the pressure to that port can be adjusted with the relief valve.

When the DMBF is not energized, all the flow will be diverted from port PP at 100 psi (7 bar) to port PC. The system will reach maximum pressure at maximum flow.


Electro-proportional flow control using the FP** valve and XMD driver


This electro-hydraulic priority flow control manifold divides the inlet flow of port P into a priority flow to port A, with the excess flow going to port B.  It provides electro-proportional priority bypass flow control using the FPFK electro-proportional throttle valve with reverse flow check coupled with the XMD electro-hydraulic valve driver.

When the FPFK valve is given a proportional command signal, the output of the controlled priority port will start to increase proportionally to the signal provided. The LHDA acts as a pressure compensator to ensure that flow to port A remains constant during pressure changes. This will allow for very stable, continuous flow for a given command signal to control even the most demanding applications like hydraulic hammers and rock breakers.

The FPFK valve will provide optimal performance when combined with a factory-tuned XMD. Using the XMD driver in conjunction with the FPFK will give the user the ultimate in command control and ease of setting using the free XMD mobile app available for Apple and Android devices.

Save time and money and use our unique, factory-tuned, optimized electro-hydraulics right out of the box.


Sun Hydraulics has developed custom solutions for specific machine attachments based on these adjustable priority flow control circuits.  Later this year, we will be introducing a series of standard priority flow control circuits offering a range of flow rates and mounting options, reducing both your costs and your development time. To learn more about applying a Sun adjustable priority flow control solution in your application, contact us at SystemSolutions@SunHydraulics.com.