Hydraulic System Fundamentals

7/28/2019 Hydraulic System Fundamentals

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Chapter 3

Hydraulic System Fundamentals

Hydraulic Principles • HydraulicSystem Pressure Supplements •

Hydraulic Means of Transmission •

Fluid Power System Diagrams



Chapter 3 — Hydraulic System Fundamentals

Liquid takes the shape of any container it is in, but

only as much volume as it can fill.




In a hydraulic system, liquid can transmit energy

because it is almost completely incompressible.




Pascal’s law can be applied during the transmission

of energy in a hydraulic system.




Laminar flow is

preferred in fluid

power systems over

turbulent flow

because it is moreefficient and loses

less energy.




Volume is the three-dimensional space of an object

measured in cubic units.




Fluids that are thick

and flow with difficulty

have high viscosity,

while liquids that are

thin and flow easilyhave low viscosity.




A Saybolt viscometer is a test instrument used to

measure fluid viscosity.




A flow meter is a meter that is used to measure the

flow of fluid (in gpm) within a system.




Resistance to fluid flow generates friction and the

resulting energy is converted into heat.




Fluids follow the path of

least resistance, thus the

cylinder with the least

amount of load on it

extends first.




Velocity is the speed

of fluid flow through a

hydraulic line in feet

per second.




The velocity of a fluid

increases at any

restriction in the piping or

component if the flow

rate remains the same inthe system.




A relief valve sets the

maximum operating

pressure in a

hydraulic system.




When there is too much

resistance, pressure

increases until the

weakest point in the

system fails and bursts.




Accumulators are categorized as mechanical or

gas charged.




A force multiplication system allows the force applied

on one cylinder to be increased on another cylinder.




An intensifier converts

low-pressure, high-flow

hydraulic fluid to high-

pressure, low-flow

hydraulic fluid.




A hydraulic power unit is

a self-contained unit that

contains all the

equipment required to

create fluid flow.




A custom-designed

power unit is often

housed in a separate

facility known as a pump-

room or pumphouse.




The two types of pipes

that are used in hydraulic

system applications are

black and stainless steel.




The three common

pipe schedules that

are used in fluid

power applications

are schedule 40,schedule 80, and

schedule 160.




Piping is typically welded to flanges, with the flanges

bolted together.




The two types of pipe

threaders are handheld

pipe threaders and pipe-

threading machines.




Male pipe threads are

cut at the ends of a

pipe to ensure a

proper connection

with the pipe fitting.




Leave a couple of the end pipe threads free from pipe

thread sealant to ensure that it does not contaminate

the system.




A flared fitting is

connected to tubing in

which the end is

spread outward.




A flared fitting is

tightened by using a

torque wrench or by

turning the fitting nut

while observingwitness marks.




Flareless tube compression fittings create a seal witha ferrule.




Tubing is typically bent to reduce strain from vibrationand to compensate for thermal expansion that is

caused by heated liquid.




Hoses are fabricatedin layers for use in

high-pressure

hydraulic systems.




Two types of connectionfittings for hoses are

threaded fittings and

quick-disconnect fittings.




Hoses are installed to avoid excessively shortlengths, sharp bends, and twists.




A pictorial diagram is a graphic representationthat shows how devices interconnect in a fluid

power system.




A cutaway diagram shows the internal details of components and the path of fluid flow.




A schematic diagramuses standardized

lines and shapes with

interconnecting lines to

represent the functionof each component in

a system.




The differentlines used in

schematic

diagrams are

standardized torepresent

various types of

working pipes.

Hydraulic System Fundamentals

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