Two-position, two-way directional control valves can turn on and off separate components of systems that are powered by the same hydraulic power unit.
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Most directional control valves used in industrial applications have two, three, or four positions, but some can have five or six positions.
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Every manufacturer has a different coding system used for ordering their directional control valves.
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Three-position, four-way directional control valves can only control one direction of fluid flow at a time
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Internal arrows on a hydraulic schematic diagram can be either colored solid or outlined.
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On a three-position directional control valve, both sides of the spool have springs to center the spool for normal condition.
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An AND logic valve allows fluid flow out of the valve when pressure is present on input 1 and input 2.
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A shuttle valve is also known as an AND logic valve.
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Right angle check valves are installed mainly in hydraulic systems, rather than pneumatic systems.
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A shuttle valve operates differently than an OR logic valve.
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Pilot-pressure actuators are used when electronic control of a hydraulic system is desired.
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On schematic diagrams, pilot lines are indicated by dotted lines.
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Open-center position directional control valves are typically used in applications where there is only one cylinder in the hydraulic system.
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Manifold subplates reduce the amount of space and piping that a hydraulic system requires.
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Two- and three-way directional control valves only control one direction of fluid flow at a time.
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Two-position, two-way directional control valves are always normally closed (NC).
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When a directional control valve is in the closed-center or tandem-center position, the piston in a hydraulic cylinder can move.
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The spring pressure of the biasing spring in a direct-acting check valve is adjustable.
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Directional control valve actuators can be automated or manual but never a combination of both.
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Pilot pressure does not require electrical, mechanical, or manual actuation.
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A position is the number of piping ports in a directional control valve.
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Solenoid-actuated directional control valves are always double-solenoid actuated.
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A shuttle valve is a type of logic valve.
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The pressure point at which an automatic detent releases can be fixed or variable.
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Newly installed directional control valves typically have a schematic symbol printed or embossed on the valve body.
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List four common DCVs:
Open-center
Closed-center
Tandem-center
Float-center
List four DCV automated actuator control methods:
Spring
Pilot-pressure
Solenoid
Proportional
Briefly describe the two main applications that direct-acting check valves are used for in hydraulic systems:
Maintain pressure control
Used as a bypass to change fluid flow and pressure in one direction but not in the other.
Describe the main advantage of using a cartridge valve:
When a cartridge valve fails, the cartridge can be replaced without disconnecting the entire valve manifold from the system.