HydraForce Insider Blog

5 Ways You Can Apply Spool-Type Logic Valves

Posted by David Price on Wed, Mar 09, 2011 @ 15:03 PM

Someone recently joked with me that I’ve never created a circuit that didn’t have at least one Logic Valve in it. HydraForce model numbers for these valves begin with the prefixes EP, EPFR and EV. Typically, these valves are piloted-closed, vented-open, or used as pressure compensators or regulators. I use them often because they are versatile, and they have low pressure-rise and pressure-drop characteristics.

On our catalog pages for these valves, we describe them as: “hydraulic directional element, with multifunction potential when used with other directional, pressure, or flow control devices.” Talk about a vague (albeit true) statement. So, to demystify this situation a little, I started to think about all the different ways spool-type logic valves can be used in integrated circuits. I’ve sketched up some generic circuits that show different ways in which we use spool type logic valves:

Bypass Compensator

Bypass Compensator

Maintains a constant pressure drop
(EP spring value) across a fixed or variable
orifice, thus maintaining proper flow rate
regardless of changing load pressures.

Bypass Compensator
with Pressure-Compensated

Bypass Compensator with Pressure Compensated Bleed-Off

Built-in flow regulator bleeds-off trapped
pressure in sense line. Bleed-off is
pressure-compensated, making a
proportional circuit more accurate and controllable.

Bypass Compensator
with Boost Circuit

Bypass Compensator with Boost Circuit

Allows for a low unloading-pressure drop
while boosting the compensator value
only when needed to perform the work.


Accumulator Charging Circuit

Accumulator Charging Circuit

Works with a UP10-31 valve to unload
a fixed-displacement pump at a low
unloading-pressure drop. The EV valve
can be sized to handle any flow while
cycling to keep a predetermined range
of pressure in the accumulator.


       High-Flow Sequence Valve

High Flow Sequence Valve

Most sequence valves have limited
flow capabilities. However, a high-flow
circuit can be accomplished by using a
large EV valve along with a small RV valve.

Do you have another Vented Spool-Type Logic Element Application?
Do you have any questions about any of the circuits I describe here?
Shoot me an email if you’d like to share your application or ask a question.

About the Author:

Scott Parker is a Senior Application Engineer at HydraForce.
He’s been developing Hydraulic Systems for 20 years. Contact Scott

Tags: cartridge valves, pressure control valve, logic valves, pressure compensators, Bypass Pressure Compensator, Sequence Valve, Accumulator Charging Circuit, cartridge