accumulator

A hydraulic component used to store hydraulic fluid. Accumulators are designed to increase or relieve pressure in the system.

actual flow rate

The flow rate that a pump delivers during operation. Volumetric efficiency compares the theoretical flow rate with the actual flow rate.

actual operating horsepower

The amount of horsepower a hydraulic component delivers during operation. When compared to the theoretical operating horsepower, actual operating horsepower can describe mechanical efficiency.

actuator

A component such as a cylinder, motor, or rotary actuator that directly helps convert hydraulic energy into mechanical energy.

Aweighted decibel scale

A decibel scale that reflects the exclusion of frequencies that humans do not normally hear.

bar

A unit of pressure equal to 100,000 pascals.

burst pressure

The pressure rating that indicates the pressure at which a component failed during a pressure rating test.

capacity

A hydraulic variable that indicates the volume of fluid a component can contain.

centimeters per minute

In the metric or SI system, the number of centimeters that a hydraulic component such as a piston actuator travels in one minute. Centimeters per minute is abbreviated cpm.

component noise

Noise caused by the normal operation of a hydraulic component.

conductor

A component such as a pipe, tube, or hose that conveys liquids throughout a hydraulic system.

cubic centimeters per revolution

A metric unit of measurement that describes the displacement of a hydraulic component.

cubic inches per revolution

An English unit of measurement that describes the displacement of a hydraulic component.

cycle

One complete revolution or rotation of a rotary hydraulic component, or one complete extension and retraction of a linear hydraulic component.

decibel

A unit of measurement that describes the intensity of a sound wave.

directly proportional

A constant ratio between two values in which one value changes in the same way as the other. For example, if value A increases, value B increases. If value A decreases, value B decreases.

displacement

A hydraulic power variable that indicates how much fluid is moved by a hydraulic pump in one cycle. Displacement is measured in cubic inches per revolution or cubic centimeters per revolution.

efficiency

The amount of power output by a fluid power system compared to the amount of power input.

flow rate

A hydraulic power variable that describes how much fluid is being moved and how much work is being performed. Flow rate is usually measured in gallons per minute (gpm) or liters per minute (lpm).

fluid noise

Noise caused by pressure surges in a hydraulic system.

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.

footpound

A measurement of force indicating the amount of energy needed to move one pound a distance of one foot.

force

The push or pull that gives energy to an object.

force multiplication

The exponential increase in available power usually associated with tools and power transmission systems.

frequency

The number of sound wave oscillations or vibrations in a unit of time. Measured in Hertz (HZ), high frequencies involve more wave cycles than low frequencies in the same amount of time.

gallons per minute

A unit of measurement that indicates the flow capabilities of a hydraulic component. Gallons per minute is abbreviated gpm.

horsepower

A unit of power used to describe the strength of a hydraulic component. One horsepower equals 746 watts.

hydraulic horsepower

A hydraulic variable that describes the power provided by a hydraulic system. HHP is directly proportional to flow rate and pressure and inversely proportional to the efficiency of a system.

hydraulic power

Power derived from the motion and pressure of a liquid, such as water or oil.

hydraulic power variable

A characteristic of a hydraulic system or component that can be measured and quantified.

inches per minute

In the English system, the number of linear inches that a hydraulic component such as a piston actuator travels in one minute. Inches per minute is abbreviated ipm.

inlet port

The opening on the side of a pump through which fluid is drawn into the pump.

input horsepower

The power required to operate a pump.

inversely proportional

A constant ratio between two values in which one value changes in the opposite way as the other. For example, if value A increases, value B decreases. If value A decreases, value B increases.

laminar flow

A desirable type of fluid flow in which fluid moves smoothly in individual layers or streams.

linear motion

Motion that takes place along a straight line.

maximum flow

A hydraulic power variable that indicates how much fluid volume a component can move in a given time.

mechanical efficiency

The theoretical operating horsepower compared to the operating horsepower. Mechanical horsepower describes the amount of energy loss in a hydraulic component.

mechanical power

Power created by the force and motion of physical components.

Newtonmeter

In the metric system, the unit used to measure power and torque, abbreviated as Nm.

newtons per square meter

A unit of pressure. A newton per square meter is also known as a pascal, which is derived from the International System of Units (SI).

noise

Any unwanted sound. Noise at high decibels is a hearing hazard.

overall efficiency

A variable that describes all energy losses in a hydraulic system. Overall efficiency is determined by multiplying volumetric efficiency by mechanical efficiency and dividing by 100.

peak value

The point at which horsepower and torque are highest. As speeds increase after the peak values, horsepower and torque decrease.

pounds per square inch

A unit of pressure. Pounds per square inch is abbreviated psi.

power

The rate of doing work in a specified period of time.

power input

The power required to run a prime mover, usually expressed in kilowatts or horsepower at a maximum pressure and speed.

pressure

The amount of force applied upon an object. Pressure is calculated by dividing force by an area.

pressure rating

An indication of the amount of pressure a fluid conductor can withstand.

prime mover

The component of a hydraulic system that powers the main pump.

productivity rate

The amount of work performed in a particular time.

pump

A mechanical device used to move liquids in a hydraulic system.

revolutions per minute

A unit of measurement that indicates the number of revolutions a hydraulic component makes in one minute. Revolutions per minute is abbreviated rpm.

rotary motion

Motion that takes place around a point. Rotary motion is circular.

speed

The amount of distance an object travels in a given period of time. Speed is used to measure both linear and rotational movement.

suction capability

An indication of the amount of fluid a pump can draw in. Suction capability determines the flow rate of a pump.

theoretical flow rate

The flow rate that a pump is rated to deliver during operation. Volumetric efficiency compares the theoretical flow rate with the actual flow rate.

theoretical operating horsepower

The amount of horsepower a hydraulic component is capable of delivering. When compared to the actual operating horsepower, theoretical operating horsepower can describe mechanical efficiency.

throttle

A control used to vary the speed of a mechanical device such as an engine.

torque

The force exerted in rotation.

turbulent flow

An undesirable type of fluid flow in which fluid moves roughly and erratically.

valve

A mechanical device that regulates the flow of liquid in a hydraulic system.

vane pump

A hydraulic pump that uses a flat protrusion to trap and move liquid through a hydraulic system.

vibration noise

Noise caused by the vibration of components in a hydraulic system.

viscosity

A hydraulic fluid's resistance to flow. As temperature increases, viscosity decreases.

volume

A hydraulic power variable that describes both the quantity of fluid and the capacity of a component.

volumetric efficiency

The theoretical flow rate compared to the actual flow rate. Volumetric efficiency describes the amount of leakage, or losses in volume, in a hydraulic component.

watt

A unit used to measure power. 746 watts is equal to one horsepower.

work

The result of force applied to an object over a distance.

working pressure

The pressure rating that indicates the maximum pressure a conductor should experience in service.
