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ClassAct SRS enabled.

In this presentation you will:

compare hydraulic components to schematic symbols

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In this presentation you will see some

hydraulic symbols and how they might

be used to represent hydraulic

components in a hydraulic circuit.

You will also look at basic hydraulic

components.

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Purpose of Hydraulic Symbols

Standard symbols are used in order

to make the drawing, designing and

understanding of these systemssimpler.

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Hydraulic systems often become

complex.

To draw the components and

circuit connections in thesesystems would be both time

consuming and complicated.

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Symbols are used to show:

However, hydraulic symbols do

not show:

Circuit connections

The diagram shows a simple

hydraulic circuit using standard

hydraulic symbols.

Component construction

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Direction of fluid flow

Component function

Port locations

System pressures

Component size

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Example Hydraulic Circuit

An example hydraulic circuit is shown below.

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Actuator

Fixed displacement

pump

Main hydraulic line

Reducing pressurecontrol valve

Four-way, three-position, center closed,

directional control valve

Single-ended,

double-acting cylinder

Vented reservoir Hydraulic drain line

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1

Hydraulic symbols do NOT show:

Question

A) Component function

B) Component construction

C) Direction of fluid flow

D) Circuit connections

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2

What does this symbol represent?

Question

A) Directional control valve

B) Double acting cylinder

C) Fixed displacement pump

D) Pressure control valve

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A hydraulic reservoir holds a

supply of hydraulic fluid that is not

under pressure.

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Hydraulic Reservoirs

When drawing a circuit using a hydraulic

reservoir, the following circuit symbol couldbe used.

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Hydraulic Pumps

Hydraulic fluid is pressurized by a

pump. Pumps may be hand operated

or driven by motors. The pump takes

fluid from the reservoir. As the pump

turns, fluid is pressurized and applied

to the hydraulics system.

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Shown below are symbols used to identify some typical hydraulic pumps.

Fixed displacement Variable displacement

non-compensated

Variable displacement

pressure-compensated

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Accumulators

Accumulators are pressure storage

reservoirs in which hydraulic fluid is

held under pressure by an external

force. The external force could be a

spring, a raised weight, or

compressed gas.

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Accumulator symbols are shown here:

Spring loaded Gas charged Weighted

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Hydraulic transmission lines are

used to distribute fluid to system

components.

Plastic hoses or pipes are usually

used in low / medium pressuresystems.

Copper or steel tubing is usually

used in high pressure systems.

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Hydraulic lines are joined to

components by connectors that

have tapered or regular threads.

Hoses, Tubing and Fittings

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Shown below are symbols used to identify some typical hydraulic

connection lines (pipes):

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Main hydraulic line

or shaft

Pilot line

(control)

Hydraulic

drain line

Enclosure

for components

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Hydraulic Valves

Directional valves: Determine the

direction of fluid flow. Operation can be

manual or automatic.

Flow control valves: Control the rate

of flow, through an opening. Usually

adjustable. May allow full flow in one

direction and restricted flow in the other.

Pressure control valves: Protect

system by setting a maximum

operating pressure.

The hydraulics system uses valves to control

fluid flow. Typical types of valves are:

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3

Which type of valve controls the rate of fluid flow through a hydraulic

system?

Question

A) Directional

B) Flow control

C) Pressure control

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Hydraulic Actuators

An actuator receives fluid power

and changes it into mechanical

motion. Motion may be linear or

reciprocating as produced by a

cylinder, or rotary as produced by

a hydraulic motor.

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The symbols used for cylinders

are shown:The symbol used for a hydraulic

motor is shown:

Positive displacement motor

Single-acting cylinder

Double-acting cylinder

Cylinder

Motor

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4

Rotary motion is produced by:

Question

A) Applying fluid power to the piston of a cylinder.

B) Removing fluid power from the piston of a cylinder.

C) Repeated operation of a cylinder's piston.

D) A hydraulic motor.

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Summary

You should now be aware of:

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Hydraulic Symbols

Basic Hydraulic Components