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Hydraulic and Pneumatic Transmission


Hydraulic and Pneumatic Transmission First, let me introduce myself. I was a student thirty years ago. I attended Tongji university in 1977, graduated in 1981. – PowerPoint PPT presentation

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Title: Hydraulic and Pneumatic Transmission

Hydraulic and Pneumatic Transmission
First, let me introduce myself. I was a student
thirty years ago. I attended Tongji university in
1977, graduated in 1981. After that, I became an
engineer, working at electrical machine design in
Zhengzhou mechanical institute of pre pre
ministry of water resources and electricity. In
1985 I became a teacher of mechanical engineering
department, North China institute of water
conservancy and hydroelectric power. My main
lectures include Hydraulic and Pneumatic
Transmission, Hydrodynamic power Transmission,
Hydraulic Servo System, computer program design,
AutoCAD and so on, particully, I have 20-year
experince of Auto CAD utilization and development.
Now Im a professor and master supervisor.
My interests include fluid power, new product
development. I have presided over five scientific
and technical projects and joined many other
projects. I have designed a series of hydraulic
power station hoists. As a specialist, I
frequently attends various design appraisal
conferences. Im the author of over 20 papers.
Cooperating with others I have published two
books. In academy, I have made great
progress. I created a new coordinate
systemgeneralized torus coordinate system. I
established a differential equation. More
importantly, my research results refresh the
history of hydodynamic torque converter design
and deepen peoples design phylosophy.
Second, let me introduce the course.
Hydraulic and pneumatic transmission is modern
industry technology(as advanced military
technology during the world war), which is called
the blood of modern industry. Most sophisticated
mechanical movments is accomplished with the help
of fluid power. The course includes fluid
mechanics, hydraulic elements, hydraulic system
and pneumatic transmission. On the other hand,
the course deals with mechanism, structure and
control. Particularly, the hydraulic control is
the pyramid top of mechnical discipline.
It should be noted that it is difficut to
study the course. mystery?understanding?feelin
g comfortable?gain insight Bilingual
teaching Step by step, gradually,
more and more After completing the course,
you can make great progress in both knowledge and
English if you study hard.
Third, something is of particular importance
to you. If you are interested in master degree,
welcome to become my post graduates. Furthemore,
if you are interested in doctor degree, the
course will lay a solid foundation for your
Keep in mind that Learning is a journey of
discovery that never ends.
Remember that methematics, English and are
three fundamental stones that surport your
knowledge. Mathematics is the queen of
scince.Gauss Your future research results
will depends on your mathematic application.
Foreign language ia weapon of lifeMarx
Englis is the vector of important
information(80). Computer application is a
main approch of scientific research and
engineering application.
Chapter 1 Introduction to fluid power
Objectives The purpose of this chapter is to
describe 1. Operation of hydraulic systems.
2. Power elements, actuators, control
components and Ancillary components . 3.
fluid power diagram and symbols Upon completing
this chapter, you should be able to 1.
Explain the operation of the various types of
elements. 2. Identify the graphical symbols
used for elements. 3. Understand the
advantages and disadvantages of fluid power.
1.1 Transmission and transmission classification
1.1.1 Transmission
A whole machine consists of a prime mover, a
transmission section, a control section and an
end-use device(working machine).
The commonly used prime movers are electric
motors, gasoline engines and diesel engines.
1.1.2 classification
According to working media, the transmission
mechanism can be classified as mechanical
transmission, electric transmission and fluid
1.1 Transmission and transmission classification
Fluid power is that energy transmitted and
controlled by means of a pressurized fluid,
either liquid or gas.
The fluid transmission can be classified as
hydrostatics transmission, hydrodynamics
transmission, pneumatics transmission and
viscosity transmission.
Fluid power Hydraulic transmission
Hydrostatic transmission Hydrodynamic
1 Several words
2 History of fluid power
In the seventeen century, Pascal put forward
the principle of fluid power
In the eighteen century, the first press was
1.1 Transmission and transmission classification
Before electrical power was developed , fluid
power had being used to drive hydraulic
equipment such as cranes, presses, winches,
extruding machines, hydraulic jacks, shearing
machines, and riveting machines.
The modern era of fluid power is considered
to have begun in 1906 when a hydraulic system was
used for elevating and controlling guns on the
battleship USS Virginia.
During and after World War II the aviation
and aerospace industry provided the impetus for
many advances in fluid power technology .
Today fluid power is used extensively in
practically every branch of industry.
1.2 Theory of hydraulics and hydraulic system
1.2.1 Theory of hydraulics
Figure1.1 Principle of operation of grinding
machines hydraulic system 1-tank 2-filter
3,12,14-return line 4-pump 5-spring 6-steel
ball 7-relief valve 8,10-pressure line
9-manually actuated directional control valve
11,16-hand lever 13-throttle valve 15-direction
al valve 17-piston 18-cylinder 19-work table.
  • 1?2?4?9?13?15 ? 18(left)
  • 18(right)?15?1
  • The work table moves to right.

(b)1?2?4?9?13?15 ? 18(right) 18(left)?15?1
The work table moves to left.
(c)1?2?4?9?1 The work table stops. The
pump unloads
Valve 13throttle valve, which is used for speed
Valve 5relief valve, which is used to maintain
the system pressure constant.
1.2 Theory of hydraulics and hydraulic system
(1) A power component(pump) which forces the
liquid through the system, and converts
mechanical power to fluid power.
(2)Actuators (Cylinders or motors) which
convert fluid power to linear or rotary
mechanical power.
(3)Control components including valves,
which control the direction, pressure and rate of
flow. Directional valve 15 is a control
(4)Ancillary hydraulic components Filters,
regulators, pipes, reservoirs, etc.
1.2 Theory of hydraulics and hydraulic system
1.2.3 fluid power diagram and symbols
1.3 Advantage and disadvantage of fluid power
1.3.1 The advantages of fluid power
(1) High horsepower, low weight ratio.
Hydraulic components are compact and lightweight
(2)Easy, accurate controlling ,reversible,
infinitely variable speed and load control
completely automatic operations.
(3)Accurate position control for linear and
rotary elements, and variable speed control.
(4)Power linkage where kinematic linkage is
impractical, convenient method of power
transmission over long distance.
(5)Reduction of wear by the self-lubrication
action of the transmission medium.
1.3 Advantage and disadvantage of fluid power
(6) simplicity, safety, great flexibility,
reliability and economy.
(7) Standardization. The fluid power industry
has established design and performance standards
for hydraulic and pneumatic products.
1.3.2 Some of the major disadvantages of
hydraulic systems
(1) Impairment of system operation by
contamination (2) Hydraulic fluid leakage
(3) Fire hazards with flammable hydraulic fluids
(4) Hydraulic lines can burst, possibly
resulting in injuries to people due to high-speed
oil jets and flying pieces of metal, if proper
design is not implemented. (5) Adequate oil
filtration must be maintained
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