| 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. |