Download HYDRAULIC SYMBOLS TP 2015

Hydraulic Symbols
Basic Hydraulics
HYDR 1305
For system diagrams and component identification
Flow Lines and Connections
Main line
Single
Pilot line
Four way junction
Enclosure
Hydraulic components in box or cabinet
Flexible
line
Hose usually connecting
parts with relative movement
Reservoir
Junction
Single
Junction
Four way junction
Crossing
not connected
Functional Elements
Triangle
Direction of fluid flow
Spring
Tee
Closed path or port
Arrow
Long sloping arrow that
crosses another line
indicates adjustability
Arrows
Straight or sloping
path and flow direction
Equipment
Accumulator
Filter
Operator
Pressure Gauge
Solenoid Operator
Shown
Equipment
Electric Motor
Pump
Hydraulic motor
Isolating valve
M
Equipment
Check valve
Flow in one direction
FLOW
RESTRICTED FLOW
RESTRICTED FLOW
FREE FLOW
FREE FLOW
One way flow control valve
Flow control
valve
Adjustable
Non-adjustable
Actuators
Single acting spring return
cylinder
Single acting load return
cylinder
Double acting cylinder
Rotary actuator
Pressure Regulators

A pressure regulator symbol represents a normal state
with the spring holding the regulator valve open.

The dotted line represents the feedback, that opposes
the spring and can vary the flow through the valve from
full flow through shut off.
Non-Adjustable regulator
Adjustable regulator
Pressure Relief Valves

A pressure relief valve symbol represents a normal state
with the spring holding the valve closed

The dotted line represents feed-forward, this opposes
the spring and can lift the valve to allow flow.
Non-adjustable relief valve
Adjustable relief valve
Control Valve Symbols - Structure
• Boxes are used to indicate the number of valve
positions.
• The number of adjacent boxes indicate whether a valve
is a two position or three position valve.
• The boxes are two states of the same valve
1
2
TWO
POSITION
VALVE
1
2
3
THREE
POSITION
VALVE
• Arrows are used to indicate the direction of flow.
• A tee indicates that a port is blocked (no flow).
NO FLOW POSITION
FLOW POSITION
Control Valve Symbols - Structure
• The function of a valve may be given by a pair of
numerals separated by a stroke.
 Examples: 2/2, 3/2, 5/2, etc.
• The first numeral indicates the number of main ports.
 These are inlets and outlets.
• The second numeral indicates the number of physical
positions the valve can be placed in.
 Such as left or right, pushed in or pulled out for two positions,
and left / center / right for three position.
• A 3/2 valve therefore has 3 ports (normally these are
inlet, outlet, and exhaust) and 2 states (the normal
state and the operated state.
2/2
2 PORTS
2 POSITIONS
3/2
3 PORTS
2 POSITIONS
Control Valve Symbols - Structure
• The port connections are shown on only one of the
boxes to indicate the shelf state.
 The shelf state is the state that the valve would be in if it
were setting on the shelf with no fluid flow, not being
operated, not powered, etc.
 Below, shown in the shelf state; flow is from port 1 to port 2
and port 3 is blocked.
• If the control valve is made to change state, the blocks
are swapped.
 Flow is now from port 3 to 1 and now 2 is blocked.
OPERATED STATE
• FLOW P TO 1
• E IS BLOCKED
1
2 3
SHELF STATE
• FLOW 1 TO E
• P IS BLOCKED
Control Valve Symbols - Structure
• The control valve operator is shown against the box
that the valve will change state to when operated.
 This is a push button symbol:
• The "shelf state" (in this case caused by a spring) is
shown on the opposite box.
• If there is no spring than the control valve is operated
by pushing the button in and pulling the button out.
1
1
2 3
2 3
SHOWN IN SHELF STATE (WITH SPRING)
• PUSH BUTTON IN GOES TO LEFT
BLOCK STATE
• PUSH BUTTON RELEASED GOES
BACK TO SHELF STATE AS SHOWN
THERE IS NO SHELF STATE (NO SPRING)
• PUSH BUTTON PULLED AND PUSHED IN
CHANGES STATES RESPECTIVELY
• NOTE ON DIAGRAM INDICATES IF PUSHED
IN OR OUT FOR POSITION SHOWN.
Control Valve Symbols - Structure
• The valve symbol can be visualised as moving from one
state to another state with the port connections not
moving.
• The 3/2 control valve shown
is frequently used for a single
acting cylinder.
3/2 CONTROL VALVE
SHOWN IN ITS
TWO POSITIONS
2 3
2 3
1
E2 P3
1
E2
3P
1
E2 P3
1
E2
3P
1
E2 P3
Control Valve Symbols - Structure
• A 4/2 valve symbol is shown below.
• This valve could be used to operate two different pieces
of equipment at the same time from the same control
valve.
1
2
3
4
Control Valve Symbols - Structure
• A 5/2 valve symbol is shown below.
• The most frequent application is controlling a double
acting cylinder.
1
2
SHELF STATE
3 4 5
1
2
OPERATED STATE
3 4 5
Control Valve Symbols - Structure
• 5/3 control valves have a normal central position that is
set by springs or with a manual control such as a lever.
• The flow pattern in the center position varies with the
type.
5/3 VALVE
• Depending on the application,
1
2
there are three types that
may be used.
3 4 5
LEVER OPERATED - SHOWN IN CENTER
POSITION, ROCKS BACK AND FORTH
SOLENOID OPERATED – IF THE LEFT SOLENOID IS
ENERGIZED, THE BOX NEXT TO IT WILL BE THE
POSITION OF THE VALVE
Control Valve Symbols - Structure
All valves types shown in the
Shelf State Position

Type 1.

Type 2.

Type 3.
Control Valve Symbols - Structure
All valves types shown in the
Left State Position

Type 1.

Type 2.

Type 3.
Control Valve Symbols - Structure
All valves types shown in the
Shelf State Position

Type 1.

Type 2.

Type 3.
Control Valve Symbols - Structure
All valves types shown in the
Right State Position

Type 1.

Type 2.

Type 3.
Valve Operators
Manual
General manual
Lever
Push button
Pedal
Pull button
Treadle
Push/pull button
Rotary knob
Control Valve Symbols - Operators
Mechanical
Plunger
Pressure
Spring normally as
a return
Pilot
pressure
Roller
Differential
pressure
Uni-direction or
one way trip
Detent in 3
positions
Electrical
Solenoid direct
Solenoid pilot