What is the definition of "spool valve"?
A valve that controls the direction of hydraulic fluid flow. A spool valve consists of cylindrical spools that alternately block and open channels in the hydraulic system.

Learn more about spool valve in the class Intro to Hydraulic Components 120 below.


Hydraulics and Pneumatics Training


Class Information
Tooling U-SME classes are offered at the beginner, intermediate, and advanced levels. The typical class consists of 12 to 25 lessons and will take approximately one hour to complete.
Class Name:Intro to Hydraulic Components 120
Description:This class presents an overview of basic hydraulic system components. Includes an Interactive Lab.
Prerequisites: none
Difficulty:Beginner
Number of Lessons:15
Language:English, Spanish
 
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Class Outline
  • Objectives
  • What Is Hydraulic Power?
  • Intro to Hydraulic Components
  • Hydraulic Fluids
  • Hydraulic Pump
  • Gear Pump
  • Vane Pump
  • Piston Pump
  • Hydraulic Fluid Conductors
  • Hydraulic Control
  • Hydraulic Actuators
  • Hydraulic Accumulators
  • Hydraulic Intensifiers
  • Heat Exchangers
  • Summary
  
Class Objectives
  • Define hydraulic power.
  • Identify the components that make hydraulic power possible.
  • Describe the properties of hydraulic fluids.
  • Describe a positive-displacement pump.
  • Identify a gear pump.
  • Identify vane pumps.
  • Identify a piston pump.
  • Describe the types of hydraulic fluid conductors.
  • Describe the function of control valves.
  • Describe hydraulic actuators.
  • Describe accumulators.
  • Describe hydraulic intensifiers.
  • Describe heat exchangers.

Class Vocabulary

Vocabulary TermDefinition
accumulator Hydraulic components used to store hydraulic fluid. Accumulators are designed to increase or relieve pressure in the system.
actuator The components such as cylinders, motors, and rotary actuators that directly help convert hydraulic energy into mechanical energy.
air-cooled heat exchanger A component in a hydraulic system that relieves excessive heat with cool air.
air-operated accumulator A component used to store hydraulic fluid. The air-operated accumulator increases and relieves pressure through the use of an inflatable bag. Also called a gas-loaded accumulator.
air-over-oil intensifier A hydraulic component that is powered by compressed air. Compressed air exerts force on a piston, which magnifies pressure as the hydraulic fluid escapes to smaller conductors and actuators.
atmospheric pressure The weight of the atmosphere. Atmospheric pressure refers to the amount of pressure exerted by the air.
balanced vane pump A hydraulic pump that consists of a rotor mounted in the center of an elliptical cavity. As the rotor spins, vanes trap and move hydraulic fluid.
ball valve A valve that uses a spherical obstruction to stop and start hydraulic flow. A ball valve is usually rotated 90° to open and close.
booster A hydraulic component that converts low pressure from a large linear actuator into high pressure in a small linear actuator. Also called intensifiers, boosters are usually two different-sized cylinders connected by a common piston.
cam A circular component of a piston pump that is mounted off-center and moves pistons when rotated.
centrifugal force A force directed outward and away from the center of a rotating object.
check valve A hydraulic control valve that allows fluid to flow in one direction. Check valves prevent backflow.
conductor The components such as pipes, tubes, and hoses that convey liquids throughout a hydraulic system.
control valve Mechanisms that control liquids in a hydraulic system. Control valves direct liquid movement and regulate the amount of pressure exerted in a hydraulic system.
corrosion resistance The ability of a hydraulic fluid to resist rust and deterioration within the components of a hydraulic system.
crescent pump A gear-within-gear pump that consists of an inner gear that is separated from the outer gear by a crescent-shaped component that provides both support and a seal.
cylinder A hydraulic actuator that helps convert hydraulic energy into mechanical energy.
dead-weight accumulator A component used to store hydraulic fluid. The dead-weight accumulator increases and relieves pressure through the use of a weighted vertical piston.
demulsibility The resistance of a hydraulic fluid to emulsification, or how well a hydraulic fluid resists mixing with water.
dirt tolerance An indication of the internal clearance of a hydraulic pump. Pumps with high dirt tolerance have the most clearance, are the least efficient, and allow the most backflow. Pumps with low dirt tolerance have the least amount of clearance, are the most efficient, and allow little to no backflow.
double-acting cylinder A hydraulic actuator that directs energy in both directions.
drive gear The gear in a gear pump that is attached to the driving mechanism. The drive gear turns the driven gear.
driven gear The gear in a gear pump that is rotated by the drive gear.
driving mechanism A component of a gear pump that rotates the driving gear.
flow control valve A type of valve consisting of a needle valve and a check valve placed in close proximity in a common body. Flow control valves regulate the flow of hydraulic fluid.
flow demand The amount of fluid movement in a hydraulic system that is required to perform a specific job or type of work.
fluid power Power derived from the motion and pressure of a fluid, such as water or air. Hydraulics and pneumatics are sources of fluid power.
force multiplication The exponential increase in available power usually associated with tools and power transmission systems.
four-way spool valve A spool valve that allows the reversal of hydraulic fluid flow. A four-way spool valve has five ports.
gas-loaded accumulator A component used to store hydraulic fluid. The gas-loaded accumulator increases and relieves pressure through the use of an inflatable bag. Also called an air-operated accumulator.
gate valve A valve that either allows or prohibits the flow of hydraulic fluid. The gate valve consists of a plate-like obstruction that is raised and lowered into place to control the flow of hydraulic fluid.
gear A circular toothed component that engages, rotates, and transmits power to another circular toothed component when rotated.
gear pump A hydraulic pump that uses meshed gears that rotate and move liquid through a hydraulic system.
gear-on-gear pump A hydraulic pump that creates pressure in a hydraulic system through the interaction of two toothed gears that are located adjacent to one another. One gear rotates and drives the other gear.
gear-within-gear pump A hydraulic pump that creates pressure in a hydraulic system through the interaction of two toothed gears that are located one inside of the other. A gear with external teeth rotates and drives the internal gear.
gerotor A gear-within-gear pump that consists of an inner gear with one less tooth than the outer gear.
globe valve A valve that adjusts the flow of hydraulic fluid between and including fully on and fully off. The globe valve consists of a circular plug and a tapered seat.
heat exchanger Hydraulic components that help relieve the excessive heat that builds up in a hydraulic system.
hose A type of hydraulic fluid conductor that joins other components usually in a non-linear fashion. Hose bends and flexes and is the most versatile hydraulic conductor.
hydraulic fluid A liquid such as oil or water that is used to generate power in a hydraulic system.
hydraulic intensifier A hydraulic component that converts low pressure from a large linear actuator into high pressure in a small linear actuator. Also called boosters, intensifiers are usually two different-sized cylinders connected by a common piston.
hydraulic motor A device which converts the energy from liquid flow into mechanical motion. A hydraulic motor is a type of fluid motor.
hydraulic power Power derived from the motion and pressure of a liquid, such as water or oil.
hydraulic pump A mechanical device used to move liquids in a hydraulic system.
intensifier Hydraulic components that convert the low pressure from a large linear actuator into high pressure in a small linear actuator. Intensifiers are usually two different-sized cylinders connected by a common piston.
linear actuator An actuator that directs force in a straight line. A cylinder is a linear actuator.
load The amount of force or pressure placed on a hydraulic system.
lubricity The property that diminishes friction and increases smoothness and slipperiness.
mechanical accumulator A hydraulic component that transfers mechanical energy to trapped fluids. Mechanical accumulators include dead-weight and spring-loaded accumulators.
mechanical power Energy created by the physical interaction of instruments or tools.
needle valve A valve that adjusts the flow of hydraulic fluid between and including fully on and fully off. The needle valve consists of a sharp conical obstruction that is extended or retracted to block or allow flow.
non-petroleum-based oil A hydraulic fluid that contains no petroleum. Non-petroleum based oils are ideal for hydraulic systems that are used near a fire hazard.
petroleum-based oil A hydraulic fluid developed from petroleum. Petroleum-based oils are the most common hydraulic fluids.
pipe A type of hydraulic fluid conductor that joins other components usually in a straight line and on a permanent basis.
piston A rod inside a cylinder that is moved by hydraulic pressure.
piston barrel A rotating cylindrical mechanism that houses the pistons in a piston pump.
piston pump A hydraulic pump that uses pistons driven by a rotating swash plate or cam to move fluid through a hydraulic system.
piston shoe The swiveling end portion of a piston that maintains contact with the swash plate in a piston pump.
positive-displacement pump A hydraulic pump that continues to discharge fluid as long as it is powered.
pounds per square inch A unit of pressure that measures the amount of load pressure per inch. Pounds per square inch is abbreviated psi.
pressure control valve An adjustable control valve that regulates pressure in a hydraulic system.
pressure-relief valve A non-adjustable control valve that regulates pressure in a hydraulic system.
prime mover The component of a hydraulic system that powers the main pump.
pump A mechanical device used to move liquids and gases.
rack-and-pinion actuator A hydraulic rotary actuator that directs energy in a circular motion through the use of a toothed piston that turns a toothed gear.
ratio-of-areas principle A physical law governing hydraulic intensifiers stating that a given pressure in a larger cylinder can be intensified by the same pressure exerted in a smaller cylinder. In general, the ratio of areas is inversely proportioned to the ratio of pressures, meaning the larger area has a smaller pressure and the smaller area has a larger pressure.
reciprocating motion Movement characterized by repeatable back-and-forth action.
reducing valve An adjustable control valve that regulates pressure in a particular zone of a hydraulic system.
relief valve A non-adjustable control valve that regulates pressure in a hydraulic system. When a critical pressure is exceeded, the relief valve releases.
revolutions per minute RPM. A unit of measurement that indicates the number of revolutions a pump component makes in one minute.
rotary actuator An actuator that directs force in a circular motion.
sequence valve A control valve that allows hydraulic fluid to flow into another area of the system once a critical pressure has been achieved.
shock load Sudden extreme pressure increases within a hydraulic system.
single-acting cylinder A hydraulic actuator that directs energy in one direction.
spool valve A valve that controls the direction of hydraulic fluid flow. A spool valve consists of cylindrical spools that alternately block and open channels in the hydraulic system.
spring-loaded accumulator A component used to store hydraulic fluid. The spring-loaded accumulator increases and relieves pressure through the use of a spring-loaded piston.
swash plate A flat, angled component of a piston pump that moves the pistons when rotated.
three-way spool valve A spool valve with three ports.
torque The force exerted in rotation.
tubing A type of hydraulic fluid conductor that joins other components usually in a non-linear fashion. Despite being stronger than pipe, tubing is easily bent.
unbalanced vane pump A hydraulic pump that consists of a rotor mounted off-center in a circular cavity. As the rotor spins, vanes trap and move hydraulic fluid.
vacuum The state of negative pressure. A hydraulic pump works by creating a vacuum in the closed hydraulic system.
vane A retractable spring-loaded mechanism that extends radially from the center of a pump rotor.
vane actuator A hydraulic rotary actuator that directs energy in a circular motion through the use of a pivoting mechanism.
vane pump A hydraulic pump that uses a flat protrusion to trap and move liquid through a hydraulic system.
variable-displacement pump A hydraulic pump that can be adjusted to increase or decreases the amount of liquid that is moved in one pump cycle.
viscosity A hydraulic fluid's resistance to flow. As temperature increases, viscosity decreases.
water-cooled heat exchanger A component in a hydraulic system that relieves excessive heat with cold water.
work The result of force applied to an object over a distance.