Hydraulic Terms H speaks to hydraulic phrases H and hydraulic glossary H which are words and phrases commonly used in the hydraulics industry.
Head Vertical distance measured between two stages in a liquid.
Heat Exchanger A device which transfers heat through a conducting wall from one fluid to another. (Typically to cool a system.)
High Pressure Lubrication This lubrication is required for high pressure systems. As pressures climb, the hydrodynamic fluid wedges between moving parts and has more of a tendency to break down.
Hi-Lo System A Hi-Lo system consists of two pumps, one high volume and one low volume. Both pump flows combine under low pressure to give a large rate of flow. Yet, when system pressure climbs above a certain value, the high volume pump is unloaded while the low volume pump does the work.
Horsepower The horsepower required to
drive a pump is dependent on both pressure and output in GPM. The higher the
pressure, or greater the volume, the more Horsepower (HP) required. As a rule
of thumb, a 1000 PSI (pounds per square inch) pump will require 1 Horsepower
(HP), for the first gallon per minute and 3/4 HP each gallon per minute after
that. Doubling the pressure or output volume will require 4 time the input
The math: Input HP= GPM x PSI / 1714
Hydraulic Actuator The piece of machinery that receives pressure from the energized fluid and then converts it to motion and mechanical force.
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Hydraulic Cylinders Hydraulic cylinders transform the pressure and oil flow in a hydraulic system into work or mechanical force. They are used where linear motion is required to move something. Cylinders are usually double-acting, that is, oil under pressure can be applied to either side of the piston to provide movement in either direction.
Single acting cylinders are sometimes used where the weight of the load is used to return the cylinder to the closed position.
Hydraulic Filters These filters remove dirt from the hydraulic fluid. Dirt interferes with three functions, transmission of energy by plugging small orifices in hydraulic components like pressure valves and flow control valves. Dirt particles interfere with liquid cooling by forming a sludge which makes heat transfer to reservoir walls difficult. The biggest problem with dirt is that it interferes with lubrication.
Hydraulic Fluid (Petroleum Base) A common hydraulic fluid consists of paraffinic and naphthalenic petroleum oils which are blended for characteristics that make it suitable for hydraulic system use. A well as acting as a medium for energy transmission it is also important as a lubricant.
Hydraulic Horsepower Hydraulic horsepower is the mechanical horsepower transmitted by the cylinder pr motor to the resisting object will also be the hydraulic horsepower requirement at the cylinder or motor.
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Hydraulic Hoses A relatively thick hose that transfers liquids to and from hydraulic pumps.
Hydraulic Motors Hydraulic motors are another important piece of the hydraulic system. However, instead of a cylinder (force moving linear) the motor uses hydraulic pressure to rotate. In terms of how it's built, a motor is like al pump. But, when it's operated oil enters the motor and turns the shaft. The speed of a hydraulic motor is dependent on the amount of oil supplied by the pump and the torque is dependent on the amount of pressure supplied.
Hydraulic Power Unit Any device used to create kinetic energy within a hydraulic system. Motors and manual energy are both sources of power in hydraulic power units.
Hydraulic Pumps Hydraulic pumps convert the mechanical energy transmitted by its prime mover whether electric or combustion. Pumping action is the same for all pumps as all pumps generate an increasing volume at the suction side and a decreasing volume at the pressure side.
Hydraulic Reservoirs The function of a hydraulic reservoir is to contain or store a system’s hydraulic fluid.
Hydraulic Shock When hydraulic working energy moving a cylinder’s piston runs into a dead end (as at the end of a cylinder’s stroke), the liquid inertia is changed into a concussion known as hydraulic shock. If a substantial amount of working energy is stopped, the shock may damage the cylinder.
Hydraulic Tester A device used to troubleshoot and check hydraulic powered system components.
Hydraulic Valve A device used to regulate water distribution in hydraulic applications.
Hydraulics The science dealing with the transmission of force through the medium of a contained fluid.
Hydrostatic Drive Hydraulic motors used in combination with various pumps is termed a hydrostatic drive. A hydrostatic drive can be either open loop or closed loop.
Hydrostatic Drive Closed Loop A closed loop hydrostatic drive has motor inlet connected to pump outlet and motor oulet connected to pump inlet. The closed loop schematic shows motor rotation in either direction with variable pump input which will vary motor speed and direction. Any leakage in the system is made up by the replenishing pump.
A small reservoir is used in this system since most of the system fluid is carried and stored in the system piping. Closed loop hydrostatic drives are compact.
Hydrostatic Drive Open Loop An open loop hydrostatic drive has the motor inlet connected to the pump outlet connected to tank. The motor rotation is stopped or reversed with a directional valve. The speed of the motor depends on pump flow rate and motor displacement.
Hydrostatic Transmission Combination of one or more hydraulic pumps and motors forming a unit.
Inertia Inertia is the reluctance of a body to change in its motion and is directly related to the quantity of matter in a body. The more mass or matter an object has the heavier it is and the harder it is to move.
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