Actuators Lab
Eng\ Ahmed Sedky
Course contents
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Hydraulic system.
Pneumatic system.
Classic control.
PLC.
Hydraulic & Pneumatic systems
Power supply
section
• Hydraulic:
Pump
• Pneumatic:
Compressor
Directional
control valves
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2/2
3/2
4/2
4/3
Actuators
(Cylinders)
• Single acting.
• Double acting.
Hydraulic system
It means the generation of forces and motion using hydraulic fluids. The
hydraulic fluids represent the medium for power transmission.
Hydraulics range of applications for which can be used. A basic distinction is made
between:
• Stationary hydraulics
• Mobile hydraulics
Hydraulic system
Hydraulic system advantages:
• Transmission of large forces using small components, i.e. great power
intensity.
• Precise positioning
• Start-up under heavy load
• Even movements independent of load, since liquids are scarcely compressible
and flow control valves can be used
• Smooth operation and reversal
• Good control and regulation
• Favorable heat dissipation
Hydraulic system
Hydraulic system disadvantages:
• Pollution of the environment by waste oil (danger of fire or accidents)
• Sensitivity to dirt
• Danger resulting from excessive pressures (severed lines)
• Temperature dependence (change in viscosity)
• Unfavorable efficiency factor
Hydraulic system
Power supply section:
The power supply section provides the energy required by the hydraulic system.
The most important components in this section are:
1.
2.
3.
4.
5.
6.
7.
8.
drive
pump
pressure relief valve
coupling
reservoir
filter
cooler
heater
Hydraulic system
Power supply section circuit symbol:
The power supply section provides the energy required by the hydraulic system.
The most important components in this section are:
1.
2.
3.
4.
5.
6.
7.
8.
drive
pump
pressure relief valve
coupling
reservoir
filter
cooler
heater
Pneumatic system
Pneumatics is the discipline that deals with mechanical properties of gases such
as pressure and density, and applies the principles to use compressed gas as a
source of power to solve engineering problems.
Advantages of pneumatics:
Simplicity of Design And Control: Machines are easily designed using standard
cylinders & other components. Control is as easy as it is simple ON - OFF type
control.
Reliability: Pneumatic systems tend to have long operating lives and require very
little maintenance. Because gas is compressible, the equipment is less likely to
be damaged by shock.
Storage: Compressed Gas can be stored, allowing the use of machines when
electrical power is lost.
Safety: Very low chance of fire (compared to hydraulic oil).
Pneumatic system
Disadvantages of pneumatics:
• accurate speed control and position control is difficult and often requires
auxiliary systems.
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As we are limited to a typical air supply pressure of 8 bar, it is normally used
to move lighter loads.
Pneumatic system
Power supply section:
The power supply section provides the energy required by the pneumatic
system. The most important components in this section are:
•
•
•
•
•
•
•
drive
compressor
pressure relief valve
coupling
reservoir
filter
cooler and dryer
Pneumatic system
Power supply section circuit symbol:
The power supply section provides the energy required by the pneumatic
system. The most important components in this section are:
•
•
•
•
•
•
•
drive
compressor
pressure relief valve
coupling
reservoir
filter
cooler and dryer
Service unit
• Filter
• Lubricator
• Water separator
• Pressure regulator
• Pressure indicator
• Shuttle valve
• Outlet and inlet ports
Air Dryer
Air filter and water trap
Deliquescent dryer
Lubricator
Linear actuators
Single acting cylinder
Linear actuators
Double acting cylinder
Distributer or Manifold
Control Valves
Graphical symbol
Directional control valves
Method of actuation
- by solenoid
2/2 Way valve
3/2 Way valve
4/2 Way valve
4/3 Way valve
4/3 Way valve
Flow control valves
Graphical symbol
Non-Return Valves Or
Check Valves
Sectional diagram
Graphical symbol
Restriction Check Valves
Pressure valves
a) Pressure regulator valve
Sectional diagram
Graphical symbol
Pressure valves
b) Pressure relief valve
Sectional diagram
Graphical symbol
Classical Control
Circuit components
Auxiliary
Elements
Control
Elements
Protection
Elements
Wires
Relays /
Contactors
Fuses
Momentarily
Switches
Timers
Overload
Heaters
Latch
Switches
Counters
Circuit
Breaker
Indicators
Comparators
Classical Control
Relay basic design and operation
Classical Control
Advantages of relays:
• Relays can switch AC and DC
• Relays are better choice for switching large currents > 5A
• Relays can switch many contacts at once
Disadvantages of relays:
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Relays are bulkier for switching small currents
Relays cannot switch rapidly (except red relays)
Relays use more power due to the current flowing through the coil
The fact that they are mechanical. This means That they wear down
and have to be replaced every so often
Classical Control
Fuses
Why the use of fuses!?
• Current flow in a conductor always
generates heat due to resistance.
• The greater the current flow, the
hotter the conductor.
• Excess heat is damaging to electrical
components.
• These protective devices are designed
to keep the flow of current in a circuit
at a safe level to prevent the circuit
conductors from overheating.
Current & Temperature
Classical Control
Fuses basic design and operation
Fuses types
Classical Control
Overload relay
Why the use of overload relays!?
• It is possible for a motor to encounter an overload condition which does
not draw enough current to open the fuse or trip the circuit breaker. This
overload condition could easily cause enough heat to damage the motor.
Classical Control
Overload relay design and operation
ON
OFF
Classical Control
Circuit breaker basic design and operation
Manual reset type
Automated reset type
Classical Control
Relay Control
A-1) Self holding circuit (High Current)
Classical Control
Relay Control
A-2) Self holding circuit (Low Current)
Classical Control
Relay Control
B) Self holding circuit with On-Off switch
Classical Control
Relay Control
C) Self holding circuit with different On-Off switches
Classical Control
Disadvantages of classical control
• Hard wiring.
• Bad response “depending on low speed switching components”.
• Correcting wiring faults is tricky and hard especially in larger control
systems.
• High cost compared to other control ways.
• Components can be easily damaged.