What is the definition of "unloading valve"?
A pressure relief valve located near a pump in order to depressurize the pump when a critical pressure downstream has been reached.

Learn more about unloading valve in the class Basic Hydraulic Circuit Design 310 below.


Hydraulics and Pneumatics Training


Class Information
Tooling U 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:Basic Hydraulic Circuit Design 310
Description:This class provides an overview of basic hydraulic circuits and how they are designed to perform basic tasks.
Prerequisites: 570200  570220  570230 
Difficulty:Advanced
Number of Lessons:18
Language:English, Spanish

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Below are all the competencies and job programs that contain the class Basic Hydraulic Circuit Design 310. Job programs are our traditional class lists organized according to common job functions. Competencies are our latest job-specific curricula that help tie online learning to practical, hands-on tasks.

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Competencies


Class Outline
  • Objectives
  • Basic Hydraulic Circuits
  • Pump Circuits: High-Low
  • Valve Circuits: Pump Unloading
  • Valve Circuits: Sequencing Cylinders
  • Valve Circuits: Reciprocating Cylinders
  • Valve Circuits: Locking an Actuator
  • Valve Circuits: Meter-In and Meter-Out
  • Valve Circuits: Other Speed Control Circuits
  • Filter Circuits
  • Actuator Circuits: Single-Acting Cylinder
  • Actuator Circuits: Double-Acting Cylinder
  • Actuator Circuits: Synchronizing Cylinders
  • Pressure Circuits: Intensifiers
  • Pressure Circuits: Accumulators as Backup Power
  • Pressure Circuits: Accumulators for Leakage and Shock
  • Building a Basic Circuit
  • Summary
  
Class Objectives
  • Describe essential components of a basic hydraulic circuit.
  • Describe a basic High-Low circuit.
  • Describe the basic unloading circuit.
  • Describe the basic cylinder sequencing circuit.
  • Describe the basic reciprocating cylinder circuit.
  • Explain how to lock an actuator using pilot check valves.
  • Distinguish between a meter-in and meter-out circuit.
  • Distinguish between a bleed-off and a variable feed circuit.
  • Identify different types of filter circuits.
  • Describe a basic single-acting cylinder circuit.
  • Describe a basic double-acting cylinder circuit.
  • Describe a basic synchronizing circuit.
  • Describe a basic intensifier circuit.
  • Describe the uses of an accumulator as backup power.
  • Describe accumulator circuits for leakage and shock.
  • Describe the considerations for building a basic circuit.

Class Vocabulary

Vocabulary TermDefinition
accumulator A hydraulic component used to store hydraulic fluid and pressure. An acccumulator can be used as a backup power source, a leakage compensator, and a shock absorber.
bleed-off circuit A flow control configuration in which a valve directs flow back to the tank when actuated. The valve of the bleed-off circuit can be located anywhere along the main line.
booster A hydraulic component that converts low pressure from a large area of the booster into high pressure in a small area of the booster. Also called an intensifier, a booster is usually two different-sized cylinders connected by a common piston.
cam-operated Actuated by the distinct physical geometry of a cam, or a circular shape that converts rotational movement into linear movement. As the cam rotates, its shape actuates the valving mechanism of the valve.
double-acting cylinder A fluid power actuator that directs energy in two directions.
extension The movement of a single-acting cylinder characterized by fluid pushing on the piston and moving the rod outside of the cylinder housing. In a double-acting cylinder, extension occurs on each stroke and alternates between ends of the cylinder.
filter A screen used for limiting contamination by trapping very fine and fine particulate matter.
flow control valve A fluid component that controls the rate of fluid flow. Flow control valves make it possible to control other system variables like the speed of an actuator.
high-low circuit A hydraulic circuit powered at different times by a high-pressure, low-flow pump and a low-pressure, high-flow pump. This two-pump circuit configuration eliminates the need for a relatively expensive high-pressure, high-flow pump and also saves energy.
hydraulic intensifier A hydraulic component that converts low pressure from a large area of the intensifier into high pressure in a small area of the intensifier. Also called boosters, intensifiers are usually two different-sized cylinders connected by a common piston.
in parallel A circuit configuration in which fluid flows into the cap end of two or more side-by-side cylinders from the same source at the same time. Although the cylinders will move, it is impossible to synchronize them.
in series A circuit configuration in which cylinders are connected end-to-end. In this configuration, all cylinders are synchronized regardless of the load on any individual cylinder.
independent filter circuit A secondary fluid circuit intended solely for filtering the fluid for another circuit.
kidney loop filter A filter located on an independent circuit intended only for filtration. The kidney loop filter shares a common reservoir with the main circuit.
logic The unique configuration of a hydraulic circuit that involves placing components to perform work.
lunging A situation in which the actuator and the load are moving in the same direction. Lunging, or overrunning, often causes the actuator to jump.
meter-in circuit A flow control configuration in which the valve is located downstream of the pump and upstream of the actuator.
meter-out circuit A flow control configuration in which the valve is located downstream of the actuator.
pilot check valve A check valve that is direct-operated under normal circumstances and actuated by a pilot signal under circumstances that call for a valve override.
position The number of physical settings on a directional control valve. A three-position valve can be placed in three different physical settings with a control such as a lever.
pressure drop The difference between two pressure levels in a hydraulic circuit.
pressure line bleed-off filter A filter located on a secondary line connected to the main line at the outlet of the pump.
pressure line filter A filter located at the outlet of the pump.
reciprocation The back-and-forth extension and retraction of a hydraulic cylinder.
retraction The movement of a single-acting cylinder characterized by fluid exiting the cylinder and the rod moving into the cylinder housing. In a double-acting cylinder, retraction occurs on each stroke and alternates between ends of the cylinder.
return line filter A filter located on the return line just before the line enters the reservoir.
rod end The side of the piston that is attached to the rod.
sequence valve A pressure control valve that allows hydraulic fluid to flow into a secondary system after a critical pressure is reached.
single-acting cylinder A fluid power actuator that directs energy in one direction.
spring-centered Situated by a mechanism that keeps a directional control valve in the center locked position unless the valve is actuated into the first or third position.
suction line filter A filter located between the reservoir and the pump.
unloading valve A pressure relief valve located near a pump in order to depressurize the pump when a critical pressure downstream has been reached.
variable feed circuit A flow control configuration in which a cam-operated two-way valve and a meter-out flow control valve are located in parallel. This results in varying speeds at different parts of the circuit.
water hammer Shock in a hydraulic system that can cause damage to components if not addressed.
way A characteristic of a valve that indicates how a fluid can flow through it.