## Class Details

- Class Name:
- Hydraulic Principles and System Design 391
- Difficulty:
- Advanced
- Number of Lessons:
- 16

## Class Outline

- Basic Hydraulic System Design
- Effective Piston Area
- Cylinder Actuator Output Force
- Cylinder Bore Diameter
- Piston Stroke Length
- Pump Flow Rate and Cylinder Speed
- Cylinder Calculations Review
- Pump Flow Rate and Motor Speed
- Hydraulic Motor Output Force
- Prime Mover Horsepower
- Hydraulic Motor Calculations Review
- Conductor Sizing
- Conductor Pressure Ratings
- Filtration Requirements
- Conductor and Filtration Review
- Environmental and Safety Considerations

## Objectives

- Describe a basic hydraulic system.
- Explain how to determine effective piston area.
- Explain how to calculate a cylinder actuator's theoretical output force.
- Describe considerations when selecting cylinder bore diameter.
- Explain how to match cylinder stroke length to a load.
- Explain how to determine the pump flow rate needed for a specific cylinder speed.
- Determine the pump flow rate needed for a specific motor speed.
- Determine a hydraulic motor's theoretical torque.
- Determine the prime mover horsepower needed to drive a pump.
- Describe factors involved in sizing a conductor.
- Describe how to select conductors based on pressure ratings.
- Describe filter selection criteria.
- Describe environmental and safety considerations involved in hydraulic system design.

## Job Roles

## Certifications

## Glossary

Vocabulary Term | Definition |
---|---|

bar | A metric unit of measurement that may be used to measure pressure. One bar is equal to 100,000 pascals. |

beta ratio | A filter rating that indicates a filter's ability to remove particles of a specific size or smaller at a constant flow rate. Beta ratio is calculated during a multipass test by counting particles upstream and downstream of the filter. |

bore | The interior of a cylindrical object. The bore of a cylinder actuator contains the movable elements within the cylinder barrel. |

burst pressure | A rating that indicates the pressure at which a conductor fails during a pressure rating test. Burst pressure is higher than the working pressure. |

cap end | A closure on one end of a cylinder actuator that covers the bore area to protect interior elements from damage. The cap end of a cylinder actuator is opposite the rod end. |

clearance | A specified amount of space or distance between two objects or areas. Clearance between the hydraulic cylinder and machine components is necessary. |

computer-aided design | CAD. A computer software program that aids in the design and drawing of a part, process, or building. Computer-aided design programs allow designers to evaluate how components can be used in a particular system. |

conductors | A passive fluid system component that conveys fluid through a hydraulic system. Conductors include pipes, tubes, and hoses. |

contamination | The presence of any foreign material in a hydraulic or pneumatic fluid that has a negative effect on the fluid system. Contamination may be material or a form of energy. |

control valves | An active fluid system component that controls the flow rate, direction, and pressure of fluid as it moves through a fluid system. Control valves are placed strategically throughout a system. |

cylinder actuator | A fluid power actuator that directs force in a straight line. Cylinder actuators include a movable piston and rod that reciprocate in response to fluid pressure. |

diameter | The distance from one edge of a circle that passes through the center to the opposite edge. The diameters of the piston and rod in a cylinder actuator affect its force output. |

effective piston area | The surface of the piston at the cap end or rod end of a cylinder actuator. The effective piston area depends on whether the cylinder exerts force during extension or retraction. |

emergency cut-off valve | A safety device that halts all fluid action immediately. An emergency cut-off valve is located between the pump and the master valve. |

factor of safety | A ratio of a component's absolute strength compared to the theoretical applied load it will experience. A factor of safety indicates the reliability of a component. |

filters | A fluid conditioning device that removes solid contaminants from hydraulic fluid. Filters may be classified by micron rating, beta ratio, and filtration efficiency. |

filtration efficiency | A filter rating that indicates the amount of particles of a given size a filter is able to trap. Filtration efficiency is calculated using the beta ratio and is expressed as a percentage. |

flow rate | The total volume of fluid that moves through a hydraulic system or individual component in a given amount of time. Flow rate is expressed in gallons per minute (gpm) or liters per minute (lpm). |

formulas | A representation of a known mathematical equation using numbers, letters, and variables. Formulas for fluid power systems include calculations for flow rate, pressure, and horsepower. |

friction | The resistance to motion between two components that are in contact with each other. Friction can alter a cylinder actuator's theoretical output force. |

horsepower | hp. A unit of power used to describe motor strength. One horsepower equals 746 watts. |

hp | Horsepower. A unit of power used to describe motor strength. One hp equals 746 watts. |

hydraulic fluid | A thick liquid, typically oil, that flows through a hydraulic system to transmit power. Hydraulic fluid is stored in the reservoir in a hydraulic system. |

hydraulic motor | An actuator that rotates to convert hydraulic energy into mechanical power. A hydraulic motor can rotate continuously. |

hydraulic pump | A mechanical power source that creates fluid flow and pushes fluid through a hydraulic system. A hydraulic pump receives energy from a prime mover, such as an electric motor or engine. |

hydraulic safety valve | A safety device that relieves pressure in a hydraulic system. A hydraulic safety valve is used in conjunction with a rotating cylinder and a check valve. |

inch-pounds | in-lb. A unit in the English system used to measure torque. The inch-pound's International System of Units equivalent is the newton-meter. |

injection injury | A small puncture of the skin or body tissue caused by high-pressure fluid. Injection injuries usually occur while operating or inspecting pressurized hydraulic equipment. |

inlet strainers | A coarse surface-type filter installed on a hydraulic pump inlet line to filter fluid entering the pump. An inlet strainer has a micron rating of 75 or higher. |

inner diameter | ID. The interior surface of a hole or cylindrical feature. The inner diameter of a conductor hose is a critical measurement when sizing conductors for a fluid system. |

job specifications | A document containing the essential components of a job or function. Job specifications include a summary of the work to be performed, the primary duties, and the minimum qualifications needed to perform the essential functions of the job. |

linear actuator | A fluid power actuator that directs force in a straight line. Linear actuators are at the end of a hydraulic circuit and include single- and double-acting cylinders. |

load | The force or pressure placed on a system or component. The load in a hydraulic system is pressurized fluid. |

manifolds | A conductor in a fluid system that provides multiple connection ports. Manifolds reduce the number of separate fittings and connections in a fluid system. |

MAWP | Maximum allowable working pressure. A pressure rating that indicates the highest pressure a component can experience during operation in order to overcome the resistance of the applied load. MAWP may be referred to as the working pressure. |

maximum allowable working pressure | MAWP. A pressure rating that indicates the highest pressure a component can experience during operation in order to overcome the resistance of the applied load. Maximum allowable working pressure may be referred to as the working pressure. |

mechanical efficiency | An efficiency rating that describes the amount of energy loss in a hydraulic component. Mechanical efficiency decreases due to friction between mechanical and fluid components. |

micron ratings | A filter rating that indicates the largest size particle that can pass through the filter. Micron ratings are based on a filter's pore size. |

microns | µ. A metric unit of measurement equal to one thousandth of a millimeter. Microns are often used to measure particles and pore sizes of hydraulic filters. |

motor displacement | The volume of fluid a motor requires for one complete rotation of its output shaft. Motor displacement is measured in cubic inches or cubic centimeters. |

multipass test | A test that measures filter performance under controlled operating conditions and at the filter's specified flow rate. A multipass test evaluates if a filter can achieve the cleanliness rate needed for the system. |

newton-meters | N-m. A unit in the International System of Units used to measure torque. The newton-meter's English equivalent is the inch-pound. |

nominal size | The stated dimensions or ideal dimensions of a part. Nominal size is different from the actual size of a part. |

nomograph | A graph containing parallel scales gradated for different variables so that when a straight line connects values of any two scales, the related value is indicated. Nomographs assist in estimating data that normally would require calculations. |

operating pressure | The pressure at which a system normally runs. The operating pressure of a fluid system may be used when specifying the capabilities of fluid system components. |

outer diameter | OD. The exterior diameter of a cylindrical or round feature. The outer diameter of a conductor tube is a critical measurement when selecting a conductor for a fluid system. |

output shaft | A shaft that rotates to transmit torque. An output shaft is mechanically linked to a motor or actuator. |

pi | A mathematical constant that relates the diameter of a circle to its circumference. Pi equals 3.14 when used to calculate the area or circumference of a circle. |

pounds per square inch | psi. An English unit used to measure pressure. Pounds per square inch units are used to express the pressure requirements for a hydraulic system or a hydraulic system component. |

pressure | The force exerted on a fluid or object per unit area. Fluid pressure may be expressed using pounds per square inch (psi) or bar units. |

pressure drops | The difference in pressure measurements between any two points of a system or component. A pressure drop occurs when force acts on a fluid as it flows through a hydraulic system component. |

pressure gages | An instrument that measures fluid pressure. Pressure gages in a fluid system are installed throughout conductor lines to indicate pressure levels. |

pressure ratings | An indication of the amount of pressure a fluid conductor can withstand. Pressure ratings generally depend on a conductor's wall thickness. |

prime mover | The component in a hydraulic system that provides mechanical energy to power the hydraulic pump. Prime movers for hydraulic systems include electric motors and internal combustion engines. |

psi | Pounds per square inch. An English unit used to measure pressure. The psi unit is used to express the pressure requirements for a hydraulic system or a hydraulic system component. |

pull force | The force a cylinder exerts upon retraction. Pull force occurs when pressure acts on the rod end of a cylinder. |

push force | The force a cylinder exerts upon extension. Push force occurs when pressure is introduced to the cap end of a cylinder. |

radius | The distance from the center to the edge of a circle. Twice the length of a circle's radius equals its diameter. |

rod end | The portion of a cylinder actuator containing the piston rod that extends out of the barrel. The rod end of a cylinder actuator is opposite the cap end. |

rotary actuator | An actuator that rotates in fixed degrees to convert fluid energy into mechanical power at the end of a hydraulic circuit. A rotary actuator develops rotational force. |

schedule number | A number that describes the thickness of a pipe wall. Schedule 40 is the most common metal pipe size. |

square | The product of a number multiplied by itself. Square numbers may be used to calculate the area of a circle. |

square centimeters | cm². A metric unit of measurement that is equal to a square with sides that are one centimeter long. Square centimeters are found by multiplying the square's length and height. |

square inches | in.² A unit of area measurement that is equal to a square with sides that are one inch long. Square inches are found by multiplying the square's length and height. |

stroke | The length of travel of a piston rod when it moves into or out of a cylinder. Stroke length is adjustable in some cylinder actuators. |

theoretical output force | The rated push or pull an object exerts. The theoretical output force of a cylinder actuator depends on the effective piston area and the supplied fluid pressure. |

theoretical torque | The amount of rotational force produced at the output shaft of a motor, assuming 100% operating efficiency for the motor. Theoretical torque may be expressed in inch-pounds or newton-meters. |

torque | A twisting or turning force that produces rotation. Torque is produced in a rotary actuator as a result of the pressure drop across the motor. |

volume | The amount of space contained within a three-dimensional shape. Volume may be measured in cubic inches or cubic meters. |

wall thickness | A value that indicates the thickness of the wall of a conductor. Wall thickness may remain unchanged as outside diameter and inside diameter change. |

working pressure | A pressure rating that indicates the highest pressure a component can experience during operation in order to overcome the resistance of the applied load. Working pressure may be referred to as the maximum allowable working pressure, or MAWP. |

working pressure | A pressure rating that indicates the highest pressure a component can experience during operation in order to overcome the resistance of the applied load. Working pressure may be referred to as the maximum allowable working pressure. |