Download Class 1 Introduction - The University of Jordan

Mechatronics Outreach Day
Mohammad I. Kilani
Associate Professor & Head
Department of Mechatronics
The University of Jordan, Amman, Jordan
Education

Ph.D. Mechanical Engineering, Florida State University,
Tallahassee, Florida, USA. Dissertation Title "Development
of a surface micromachined spiral-channel viscous pump".

M.Eng. 1991, Mechanical Engineering, Carnegie Mellon
University, Pittsburgh, Pennsylvania, USA. M.Eng Project:
“Design for Assembly Analysis of Part Features and
Interactions”.

M.S. 1988, Mechanical Engineering, (Computer Integrated
Manufacturing) George Washington University,
Washington, D.C. USA. MS Thesis: “Force Control of
Robotic Manipulators”.

B.Eng. 1986, Mechanical Engineering, University of Jordan,
Amman, Jordan
Professional Careers

Associate Professor & Chair, Mechatronics
Engineering Department, The University of Jordan,
Amman, Jordan

Associate Professor, Mechanical Engineering
Department, King Faisal University, Al-Ahsa, Saudi
Arabia 2008 –2011

Assistant Professor, Mechanical Engineering
Department, The University of Jordan, Amman,
Jordan

Visiting Research Scientist, Institute of
Mictrotechnology, Braunschweig, Germany, through
DFG research scholarship, 2006

Training Leader and Facilitator: TUV Akademie
Middle East

Engineering Consultant, Nayzak Dies and Moulds
Mfg. Company
Midterm Exam:
Sunday 27-10-2013
12:00 – 1:00
Hydraulic Basic Principles

Hydraulics is the technology or study of
liquid pressure and flow. Liquids are
materials which pour and conform to the
shape of their container. Example are oil
and water at room temperature.

Stationary fluids provide no resistance to
shear stresses. This allows fluids to take
the shape of the container they are in,
and also leads to Pascal’s law, which
states that the pressure at any given point
in a fluid is the same in all directions.

Pressure applied to a confined fluid is
transmitted undiminished in all directions,
and acts with equal force on equal areas,
and at right angles to them.
Prove
Pascal’s
law
10 N per square cm
Pressure of 100 kPa
10 N Force
1 square cm
stopper
Multiplication of Force

Since liquid transmit the same amount of pressure in all
directions. The force transmitted to the output piston is
multiplied by a factor equal to the area ratio of the output piston
to the input piston
Multiplication of Force


Even though force is multiplied, the power or energy is not. In fact, the energy
or power input is usually larger than the obtained output.
The transmission ratio is defined as the velocity at the input to that at the
output in case of no leakage, and is a function of the geometry of the setup.
The ratio of the output force to the input force is usually less than the
transmission ratio due to frictional losses.
Introduction to Fluid Power
An Introductory Fluid Power System
Lifting and Lowering a Load
An Introductory Fluid Power System: Load Raising
Directional Control Valve in Load Lifting Position
An Introductory Fluid Power System: Load Lowering
Directional Control Valve in Load Lowering Position
An Introductory Fluid Power System: Locked Position
Directional Control Valve in Load Locked Position
An Introductory Fluid Power System:
Directional Control Valve
Four Way
Three Position
Manually (Lever) Operated
Spring Centered,
Directional Control Valve
An Introductory Fluid Power System: Symbolic Presentation
Fload
Operation of a Basic Hydraulic Circuit

When the directional
control valve lever is moved
upward, the pumped oil
flows through path P – B of
the to the lower part of the
cylinder.

Since the oil is under
pressure, it pushes up the
piston inside the cylinder,
causing the piston rod to
retract, and the load to be
raised. The oil in the upper
side of the piston is drained
back to the reservoir
through path A – T of the
directional control valve.
Operation of a Basic Hydraulic Circuit

When the directional
control valve lever is
centered, all four ports are
blocked and oil can not
escape from either side of
the cylinder. This stops the
movement of the piston
and causes the oil to flow
from the pump back to the
reservoir through the
pressure relief valve.

The pressure in the lower
end of the cylinder will be
at an intermediate level
due to the presence of the
load.
Operation of a Basic Hydraulic Circuit

When the directional
control valve lever is moved
toward the valve body, the
pumped oil flows through
the path P – A of the
directional control valve to
the upper end of the
cylinder. The oil pushes the
piston downward, which
lowers the attached load.

The oil in the lower end of
the cylinder of the piston is
drained back to the
reservoir through path B – T
of the directional control
valve.
An Introductory Fluid Power System: Engineering Issues
As an Engineer, what issues will you be
concerned about in the presented system
1 minute to write on a piece of paper!
An Introductory Fluid Power System: Basic Performance
1. How much load will the system be able to raise?
2. How fast does the load go up?
3. Is it possible to control lifting and lowering speeds? How?
An Introductory Fluid Power System:
Efficiency/Operating Cost Issues
1. How much power will I need for (i) raising the load, (ii) lowering the load,
and (iii) stopping the load?
1. What is the needed pressure at the pump outlet?
2. What is the pressure at the pump inlet?
2. Can I make the system more efficient, particularly during lowering and
stopping the load
An Introductory Fluid Power System: Safety Issues
1. Is the system safe enough?
2. What happens in case of hydraulic line rupture, pump failure, or
electrical power shutdown in the position shown?
An Introductory Fluid Power System:
Expansion Issues
1. Is it possible to give the cylinder a command position, and have it go to
that position automatically, without operator intervention?
2. Can I have two or more cylinders work in tandem?
3. Can I have two or more cylinders work in series?
Introduction to Fluid Power
Work and Power
How much power can a person produce?
What experiments would you perform to
estimate your own power production?
Work and Power

A person is required to lift a 50 N box a
distance of 2 m. The work done by this
person is given by:
Work = Force x Displacement
Work = 50 N x 2 m = 100 N.m (Joule)

If the person is asked to raise the box in 2
second. How much power is he producing?
Power is the time rate of doing work.
Power = Work/time
Power = 100 J/2 s = 50 J/s (Watt)

A person doing the same work in 1 seconds
produces 100 W of power
How much power can a
person produce?
Power Produced by a Weight Lifter

The Power produced by popular
weight lifters during the lift
process ranges between 2 – 2.5
kW
Weight Lifter
Disc Mass
(kg)
Force (N)
Lift Distance*
(m)
Lift Time
(s)
Power
(W)
Vakhonin
130
1275.3
2
1
2550.6
Fukuda
130
1275.3
2
1.3125
1943.3
Berger
140
1373.4
2
1.375
1997.7
Mryake
151
1481.31
2
1.5
1975.1
* Estimated
Power Produced By a Cyclist
Average power for the
first 30 seconds is 300 W
http://mapawatt.com/wp-content/uploads/2009/07/Hour-watts-power-output.jpg
Power Produced By a Horse
1 Horsepower = 745.6 W
Lifting a 70 kg man at 23 km/h up a 10 degree slope
Power Produced By an Automobile Engine
Power @ 6000 rpm
Make and Model
Engine
hp
kW
Toyota Corolla
1.8 L, 4-cylinder
132
98.4
Mercedes Benz C-Class
1.8 L, 4-cylinder
153
114.1
Toyota Camry
2.5 L , 4-cylinder
178
132.7
Lexus
3.5 L, 6-cylinder
306
228.1
Introduction to Fluid Power
Other Applications
Requiring Work and Power
Applications requiring work and power

Lift a load against gravity

Manufacturing processes: (metal
forming, cutting, punching, deep
drawing, cutting, turning, milling,
etc. involves applying a force for
a certain distance.

Changing the speed of an object

Moving objects against friction,
air drag, water drag: e.g., car,
ships, airplanes, etc.

Walking, speaking, etc.
How much power can a
person produce?
Introduction to Fluid Power
Power Conversion and
Power Transmissions
Forms of Power
Power Form
Potential Variable
Flow Variable
Mechanical Linear
Force (F)
Linear velocity (v)
Mechanical Rotational
Torque (T)
Angular Speed (ω)
Fluid
Pressure (P)
Flow Rate (Q)
Electrical
Voltage (V)
Electric Current (I)
Power Converters – Electromechanical
Txω
Fxv
Electric Generator
VxI
Mechanical to Electric
VxI
Electric Motor
Linear Electric Actuator
Electric to Mechanical
Txω
Fxv
Power Converters – Hydromechanical
Txω
Fxv
Pump
PxQ
Mechanical to Fluid
PxQ
Rotary Actuator
Linear Actuator
Fluid to Mechanical
Txω
Fxv
Power Transmitters – Direct Power Transmission
Ti x ωi
Fi x vi
Power Transmitter
Why would we perform power transmission?
Give Some Examples on power transmission devices
To x ωo
Fo x vo
Reasons for Power Transmission


Manipulation of the values
of the potential – flow
variable, e.g. when the
potential variable at the
load (torque or force) is not
compatible with the source
(too high or too low)
Load is placed at a location
different from that of the
source. Need to
“Transport” power from
the source location to the
load location
Power
Transmitter
Ti x ωi
Fi x vi
To x ωo
Fo x vo
Direct Power Transmission
Ti x ωi
Fi x vi
Power Transmitter
Direct (Mechanical)
Examples:
1.
Mechanical Linkages: (Levers, mechanisms, etc.)
2.
Pulleys and Ropes
3.
Sprockets and Chains
4.
Gear Boxes
5.
Belt Drives
To x ωo
Fo x vo
Indirect Power Transmitters
(Back – to – Back Converter)
Ti x ωi
Fi x vi
To x ωo
Fo x vo
Electric
Power
Converter
Hydraulic
Pneumatic
Power
Converter
Power Transmission Methods


Direct (Mechanical)

Gear trains and shafts

Levers and linkages

Ropes and Pulleys

Chains and Sprockets

Belt Drives
Power
Transmitter
Ti x ω i
Fi x vi
Indirect (Back to Back)

Electric
(Generators – Transformers – Motors)

Hydraulic
(Pump – Hydraulic motor or hydraulic actuator)

Pneumatic
(Compressor – Pneumatic cylinder)
To x ωo
Fo x vo
Transmission Ratio

We define the speed magnification ratio,
for a power transmitter as the ratio of
the output speed to the input speed.
rS  o i

rS  vo vi
Linear Power
Transmitter
Fi x vi
Fo x vo
If the power transmission system is
ideal, the output power is equal to the
input power (no losses), then
Toωo  Ti ωi
Fo vo  Fi vi
To rS ωi  Ti ωi
Fo rS vi  Fi vi
rS  Ti To
rS  Fi Fo
Rotational Power
Transmitter
Ti x ωi
To x ωo
Transmission Ratio



In a number of power transmission systems, a
definite relationship exists between the input
motion and the output motion. This
relationship is maintained by a set of
constraints provided in the transmission
system.
Example constraints in mechanical power
transmission systems include the constant
distance between any two points in a rigid
body, the equal displacement of the two pitch
points on the pitch circles of two gears in
mesh, and the constant length of ropes and
chain sprockets in rope-pulleys and chainsprocket drives.
In hydraulic power transmission systems, input
– output motion constraint is provided by the
incompressibility of the hydraulic fluid in the
system and the conservation of mass principle
Fo
Fi
O
A
B
di
do
vi d i  vo d o  
r  vi vo  d i d o
vo  vi r
Transmission Ratio


If the arm of the lever mechanism is
treated as a rigid body, the constant
distance constraint means that the
angular displacement (Δϴ) is the same
for all lines in the body. This means that
the angular speed (ω = dϴ/dt) is the
same for all points in the lever.
We define the transmission ratio as the
ratio of input speed to output speed.
This ratio is sometimes called the speed
reduction ratio.
vi d i  vo d o  
r  vi vo  d i d o
vo  vi r
Fo
Fi
O
A
B
di
do
Transmission Ratio

If no power losses exist (no friction),
the output power produced by the
lever is equal to the input power.
Therefore, we have
Fo ,idealvo  Fi vi
Fo
Fi
A
Fo ,ideal vi r   Fi vi
The mechanical advantage or the force
amplification ratio is the ratio of the
ideal output force to the input force.
In an ideal transmitter with no power
loss, the mechanical advantage is
equal to the speed reduction ratio.
r  To ,ideal Ti r  Fo ,ideal Fi
B
di
Fo ,ideal  rFi

O
To ,idealωo  Ti ωi
rTi ωo  Ti ωi
r  ωi ωo
do
Fovo ideal  Fi vi
rFi vo  Fi vi
r  vi vo
Transmission Ratio
Toωo ideal  Tiωi
rTi ωo  Ti ωi
r  ωi ωo

Fovo ideal  Fi vi
rFi vo  Fi vi
r  vi vo
For an ideal transmission system,
the torque (force) amplification
ratio is equal to the speed
reduction ratio. This ratio is
called the transmission ratio and
it is completely defined by the
geometry of the system.
Linear Power
Transmitter
Fi x vi
Fo x vo
Rotational Power
Transmitter
Ti x ωi
To x ωo
Transmission Ratio
Linear Power
Transmitter
Fo x vo
Fi x vi
M
o
0
Fi d i  Fo d o
Fo
r  Fo Fi  d i d o
Fi
O
di
do
vi d i  vo d o  
r  vi vo  d i d o
Transmission Ratio
Rotational Power
Transmitter
To x vo
Ti x vi
M
A
0
Ti  FC ri
M
B
0
To  FC ro
Ti ri  To ro  FC
To Ti  ro ri  r
FC
ro
To
ri
A
B
Ti
FC
i ri  o ro  v
i o  ro ri  r
Overall Efficiency

The overall efficiency is defined is the ratio
of the power produced by the system to the
power delivered to the system
P T
overall  o  o o
Pi Tii

Power
Transmitter
Ti x ωi
For an ideal power transmission systems
with no frictional losses, Ti and To are
related by To = rTi . If the system is also a
non-slipping mechanical system or a nonleaking converter, the following relation
hold.
overall 
Po rTi i r 

1
Pi
Tii
To x ωo
To ,ideal  rTi
Ti ,ideal  To r
mech 
To
To,ideal

To
rTi
To  rTi
o  i r
Mechanical Efficiency

When frictional losses exist the
torque produced by the transmitter is
less than that of an ideal frictionless
transmitter, (To < rTi). The mechanical
efficiency is defined as the ratio of
the output torque produced by the
system to the torque produced by an
ideal frictionless transmitter for the
same torque input.
mech 

To
To ,ideal
T
T
 o  i ,ideal
rTi
Ti
The mechanical efficiency is also the
ratio between the ideal input torque
needed by a frictionless system to the
actual input torque needed by the
system to produce the same torque
output.
Power
Transmitter
Ti x ωi
To ,ideal  rTi
Ti ,ideal  To r
To x ωo
Volumetric Efficiency

For non-slipping mechanical
transmitters (gear trains, levers,
pulleys and chain-sprocket), the
speed ratio relation, ωo = ωi /r,
holds regardless of frictional loss.
This relation is also valid for nonleaking back-to-back converters
based on mass/current
conservation. When the systems
have slippage or leakage, the
output speed is reduced. The
volumetric Efficiency is defined as:
vol 

o

 o  i ,ideal
o,ideal i r
i
Power
Transmitter
Ti x ωi
o,ideal  i r
i ,ideal  o r
To x ωo
Efficiency Relationships

The overall efficiency may be written in terms
of the mechanical efficiency and the
volumetric efficiency by utilizing the
relationships
o,ideal  i r
To,ideal  rTi
i  ro,ideal
Ti  To,ideal r
overall 
Po Too
Too


Pi Tii To ,ideal r ro ,ideal 
 To  o 

  mech  vol
overall  



 To ,ideal  o ,ideal 
Power
Transmitter
Ti x ωi
To x ωo
Introduction to Fluid Power
Power Transmission Comparison Factor
What factors will you
consider when
comparing the
different methods of
power transmission?
Power
Transmitter
Ti x ω i
To x ωo
Comparison Factors: Transmission Distance

Effect on initial cost
(capital)

Effect on running cost
(transmission efficiency )
Power
Transmitter
Ti x ω i
To x ωo
Comparison Factors: Transmission Ratio



What is the effect of
increased transmission
ratio on initial cost
(capital)?
What is the effect of
increased transmission
ratio on running cost
(transmission efficiency)?
Is there a practical limit
on the maximum
transmission ratio
provided that may be
provided by the system?
Power
Transmitter
Ti x ω i
To x ωo
Comparison Factors: Outlet speed variation

Does the system allow
the outlet speed to be
varied?

Is output speed variation
continuous or in discrete
steps

What is the effect on
initial cost

What is the effect on
running cost
(transmission efficiency)
Power
Transmitter
Ti x ωi
To x ωo
Comparison Factors: Outlet torque or force variation

How does the system
respond to variations in
the outlet load?

Will the system stall if
the load is increased
beyond a certain level?
Power
Transmitter
Ti x ωi
To x ωo
Comparison Factors: Distribution



Does the system allow the
outlet power to be
distributed among a number
of terminals?
Does it have the flexibility to
allow control of the amount
of power delivered at each
terminal, either
continuously, or in discrete
steps
What is the effect of
distribution on initial cost
and on running cost
(transmission efficiency )
T1 x ω1
Power
Transmitter
Txω
Fxv
T2 x ω2
Tn x ωn
Comparison Factors: Leakage


How much leakage does the
system has? Is it leak free?
T1 x ω1
Effect on power cost and
material cost
Power
Transmitter
overall  mech vol
vol
Qactual

Qideal
vol 
Qideal  Qleakage
Qideal
vol  1  Qleakage Qideal 
Txω
Fxv
T2 x ω2
Tn x ωn
Comparison Factors: Noise

How much noise does the
system produce
T1 x ω1
Power
Transmitter
Txω
Fxv
T2 x ω2
Tn x ωn
Comparison Factors: Safety

How safe is the system?

What happens in case of
overload?

What happens in case of
tube rupture, mechanical
failure?
T1 x ω1
Power
Transmitter
Txω
Fxv
T2 x ω2
Tn x ωn
Advantages of Fluid Power

High Transmission Ratio:
A fluid power system can
multiply forces simply and
efficiently several thousands of
times in a compact setup.

Simplicity, compactness and
light weight
Fluid power systems use fewer
number of moving parts than
comparable mechanical or
electrical systems. Thus they
are simpler to maintain and
operate. This also increases
reliability and allows
compactness and light weight
of the system.
1 square cm
cylinder
Advantages of Fluid Power

Constant Force or Torque:
Fluid power systems are capable of
providing constant force or torque
regardless of speed changes.

Ease and Accuracy of Control:
By the use of simple control valves
operated by manually or
electrically, the operator of a fluid
power system can readily start,
stop, speed up and slow down
desired equipment.

Safety:
A consequence of simplicity,
overloads can be easily controlled
by relief valves
1 square cm
cylinder
Advantages of Fluid Power

Flexibility:
Unlike mechanical methods of
power transmission where the
relative position of the engine
and the work site must remain
relatively constant, the flexibility
of hydraulic lines allow power be
moved flexibly wherever needed.

Economy:
This is the natural result of the
previous factors, particularly
simplicity and compactness.
Fluid power systems provide an
relatively low cost method for
power transmission. Also, power
and frictional losses are
comparatively small.
Drawbacks of Fluid Power Systems





Fluid power systems have some drawbacks.
Hydraulic systems suffer from messy oil, and
leakage which is impossible to eliminate
completely.
Hydraulic lines can burst resulting in possible
injury or fire.
Hydraulics and pneumatic systems employ
pumps or compressors, which tend to
generate noise.
For short distance transmission, hydraulic and
pneumatic power transmission systems are
usually less efficient than mechanical
transmission systems. They are, however,
typically more efficient than electrical power
transmission systems.
For long distamce transmission, electrical
power comes first, followed by hydraiulic.
Comparison of individual factors for power transmission methods


The commonly used power
transmission methods in the
industry are electric,
mechanical, pneumatic and
hydraulic.
These methods may be
compared with respect to
energy production, storage
transportation and cost,
leakage and environmental
effects, ability to generate
linear, angular and rotary
motion, ability to provide linear
and rotary thrusts,
controllability, handling and
noise
Advantages of Fluid Power

Compared to electrical and
mechanical power transmission,
fluid power transmission offers
versatility and manageability
advantages allowing it to be an
economic and efficient candidate
for a number of application.

Industry is moving toward
automating its operation in order
to increase productivity, accuracy
and consistency. Fluid power will
be an essential element in
industrial automation for the
foreseen future.
What is Fluid Power
Aviation is an industry that
relies heavily on hydraulics.
Aircraft hydraulic systems are lightweight and compact, yet powerful
enough to move the control surfaces of the wings of the largest planes.
Components of a Basic Hydraulic Circuit

A hydraulic circuit is a path for oil or hydraulic fluid to flow through a set of basic
components. These components are:







The reservoir or an oil tank that hold the oil.
The pump that pushes the oil and increases its pressure.
An electric motor or other power source to drive the pump
The directional control valve, which controls the direction of oil flow to the cylinder.
The hydraulic cylinder which converts fluid energy into linear mechanical energy.
The relief valve, which limits the system pressure to a safe level by allowing oil to flow
directly from the pump back to the reservoir when the pressure at the pump output reaches
a certain level.
The piping which carry oil from one location to another
Components of a Basic Pneumatic Circuit

A hydraulic circuit is a path for oil
or hydraulic fluid to flow through a
set of basic components. These
components are:






An Air Tank that stores a given
volume of compressed air.
A compressor that compresses
the air coming from atmosphere
An electric motor or other prime
mover to drive the compressor.
The directional control valve,
which controls the direction of oil
flow to the cylinder.
The pneumatic cylinder which
converts fluid energy into linear
mechanical energy.
The relief valve, which limits the
system pressure to a safe level by
allowing oil to flow directly from
the pump back to the reservoir
when the pressure at the pump
output reaches a certain level
Introduction to Fluid Power
Example Pneumatic Circuits
Direct Control of a Single Acting Cylinder – Extension
List of equipment
01 Air service unit (filter with
water separator, pressure
regulator and pressure
gauge) with 3/2 directional
control ball valve
02 Distributor, 6-fold
03 Single-acting cylinder
06 3/2 directional control valve
with manually operated
push-button
21 Pressure gauge
Direct Control of a Single Acting Cylinder – Extension



The piston rod of the
single-acting cylinder
extends when the button
of the directional control
valve is pushed. The rod
remains extended as long
as the button is pushed.
The piston retracts when
the button is released
The active pressure of the
cylinder appears on the
pressure gauge.
Direct Control of a Single Acting Cylinder – Retraction
List of equipment
01 Air service unit (filter
with water separator,
pressure regulator and
pressure gauge) with
3/2 directional control
ball valve
02 Distributor, 6-fold
03 Single-acting cylinder
07 3/2 directional control
valve with manually
operated push-button
Direct Control of a Single Acting Cylinder – Retraction



The default position of
the piston rod of the
single-acting cylinder is
extension when the
compressed air supply is
switched on.
When the push button
of the directional control
valve is actuated, the
piston retracts and
remain retracted.
The piston returns to its
extended position when
the pushbutton is
released
Direct Control of a Single Acting Cylinder – Retraction
Introduction to Fluid Power
Video
Direct Control of a Single Acting Cylinder
Retraction
Introduction to Fluid Power
Projects
(5 points)
Video Recording of your Lab Experiments
Introduction to Fluid Power
Example
Spiral Pump Video
Introduction to Fluid Power
Power Transmission Comparison Tables
Energy Source
Electrical
Mechanical
Hydraulic
Pneumatic
Usually relies on
regional power grid
tied to site
consideration (hydro,
fossil fuel, or power
plants)
Stationary or mobile
electric motor or
internal combustion
engine. Some units
manually operated.
Motor selected based
on power and torque
requirements.
Stationary or mobile
pump plant, electric
motor drive, rarely
internal combustion
engine driving
generator and motor.
Minimum duty units
also manually
operated. Pump type
selected based on
required pressure and
capacity
Stationary or mobile
air compressor plant,
electric motor or
internal combustion
engine drive.
Compressor selected
based on pressure and
capacity. Air for
compressor available
everywhere with
unlimited supply.
Energy Storage
Electrical
Mechanical
Hydraulic
Pneumatic
Highly difficult and
elaborate to store.
Minimal quantities
may be stored using
batteries of fuel cells
Possible to store
intermediate amounts
of power by a
flywheel.
Limited storage
capability by
accumulators and
compressed air as an
auxiliary medium.
Economical only for
small quantities
Large quantities can
be stored economically
by compressed air
cylinders.
Energy Transportation
Electrical
Mechanical
Hydraulic
Pneumatic
Easily transported over
unlimited distances
Transportation
possible efficiently
over limited distances
through an axle.
Frictional losses
reduce efficiency for
large distances
Can be transported
through piping up to
distances of about 100
meters without loss of
pressure
Readily transportable
through piping up to
distances of about
1000 meters without
loss of pressure.
Energy Transmission
Electrical
Mechanical
Hydraulic
Pneumatic
Ac voltages and
currents can be easily
transmitted by a
transformer
Geared transmissions
allow torque – speed
manipulation with high
efficiency
Piston – cylinder
arrangements allow
efficient transmission
of flow rate and
pressure heads.
Piston – cylinder
arrangements allow
efficient transmission
of flow rate and
pressure heads.
Leakage
Electrical
Mechanical
Hydraulic
Pneumatic
No loss of energy
without conductive
paths or parts. Lethal
accident risk at high
voltages.
Loss of energy
possible due to friction
for long transportation
paths. Accident risk
due to moving
mechanical parts.
Loss of energy and
substantial effect on
environment due to
leaking hydraulic fluid
with accident risks
Piston – cylinder
arrangements allow
efficient transmission
of flow rate and
pressure heads.
Effect of Environment
Electrical
Mechanical
Hydraulic
Pneumatic
Insensitive to
temperature variations
in normal range.
Additional protective
measures are required
in fire or explosionhazard areas.
Temperature
fluctuations may affect
performance. Special
treatment necessary in
corrosive or humid
environments
Sensitive to variations
in temperature. Fire
hazards entailed with
oil leakage.
Compressed air is
insensitive to
temperature
fluctuations. No fire
or explosion hazard.
Risk of icing at low
ambient temperature,
high humidity and high
flow velocities.
Linear Motion
Electrical
Mechanical
Hydraulic
Pneumatic
Short travel only with
solenoids or linear
motors.
Rack and pinion, lead
screw and nut, and
other mechanical
linkages provide wide
selection of linear
motions
Convenient with
cylinders. Well
amenable to control in
slow speed range.
Convenient with
cylinders. Strokes up
to 2000 mm. High
acceleration and
deceleration. Speeds
Rotary Motion
Electrical
Mechanical
Hydraulic
Pneumatic
Best efficiency by
rotary drives or
motors.
Best efficiency by
rotary drives or
motors. Internal
combustion engines
also readily provide
rotary motion
Hydraulic motors of
various types. Smaller
speed range than air
motors, but better
control in slow speed
range
Air motors of various
types. Wide range of
speed up to 500,000
rpm, and higher.
Simple reversal of
rotation.
Angular Motion
Electrical
Mechanical
Hydraulic
Pneumatic
Translated from rotary
motion through
mechanical linkage.
Translated from rotary
motion through
mechanical linkage.
Conveniently obtained
with cylinders or
swivel actuators, up to
360 degrees and
more.
Conveniently obtained
with cylinders or
swivel actuators, up to
360 degrees and
more.
Linear Thrust
Electrical
Mechanical
Hydraulic
Pneumatic
Mechanical linkage
needed for energy
transmission. Rack
and pinion may result
in poor efficiency.
Rack and pinion, lead
screw and nut, and
other mechanical
linkages provide wide
selection of linear
motions with
intermediate linear
thrust. Difficult
overload protection
High forces available
due to high pressure.
Overload protection by
relief valves.
Continuous energy
consumption for
holding forces.
Narrow range of force
due to low pressure.
Overload protection up
to standstill. No
energy consumption
for holding force.
Economical for thrusts
from 1 N to 50 kN.
Rotary Thrust
Electrical
Mechanical
Hydraulic
Pneumatic
Minimum torque at
standstill. Cannot be
overloaded, small
range of force
Force multiplication by
geared transmission
Full torque even at
standstill, but less
efficiency. Overload
protection by relief
valve. Wide range of
torques.
Full torque even at
standstill without
energy consumption.
Overload protection
without drawbacks.
Narrow range of force.
Controllability
Electrical
Mechanical
Hydraulic
Pneumatic
Limited means of
control. Highly
elaborate.
Limited means of
control. Highly
elaborate.
Thrust conveniently
controlled through
pressure reducing
valves over a wide
range. Speed control
very good and precise
in low range.
Thrust conveniently
controlled through
pressure reducing
valves in range 1:10
dependent on load.
Speed conveniently
controlled through
restrictor valves or
quick exhaust valves,
poor reduction in low
range.
Noise
Electrical
Mechanical
Hydraulic
Pneumatic
Loud actuation noise
of contactors,
otherwise within limits
of workshop noise.
Within limits of
workshop noise.
Noise can be reduced
or eliminated by
proper lubrication and
design.
Pump noise at high
pressure. Noise
conducted through
rigid piping
Exhaust noise
unpleasant but can be
greatly reduced by
installing silencers.