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Basic Engineering
In ye olde days, 1325 AD to be more precise, an engineer was defined as "a constructor of military
engines". Back then engineering was divided into two categories: Military Engineering and Civil
Engineering. The former involved the construction of fortifications and military engines, the latter
concerned non-military projects, for example bridge building. This definition is now obsolete, as
engineering has broadened to include a myriad of disciplines.
The exact origin of the word 'engineering' comes from the era when hum applied themselves to skilful
inventions. Man evolving further in the world invented devices such as the pulley, the wheel and levers.
The word engineer has its root in the word engine, which comes from the Latin word ingenium, which
me "innate quality particularly of mental power". And thus the word engineer emerged as a person who
creates nifty and practical inventions.
Today an engineer is described as someone who has acquired and is applying their scientific and
technical knowledge to designing, analysing and building useful, helpful and functional works. This
would involve structures, machines and apparatus, manufacturing processes as well as forecasting their
behaviour in particular environmental conditions. This is all accomplished with functionality, operational
economics and safety to life and property forefront in mind.
Engineering is a broad discipline with many subdisciplines dedicated to various fields of study with
regards to particular types of technologies or products.
Engineers may begin their career being trained in a specific discipline, but because of the engineering
jobs they take-on, they often become multi-disciplined having worked in a variety of different fields.
The field of engineering has traditionally been divided into the following engineering job categories:
- Aerospace Engineering
- Chemical Engineering
- Civil Engineering
- Electrical Engineering and,
- Mechanical Engineering.
However, since the human race has been swiftly advancing with regards to technology, new branches of
engineering are being developed. Engineering jobs can now also be found in the following fields:
Although all these fields may be defined differently, there is generally a great overlap, particularly in the
fields of physics, chemistry and mathematics.
Engineering jobs usually entail applying physics and mathematics to problems in order to discover viable
solutions or to make improvements. Where a number of different solutions are available, engineers
evaluate these options and the required outcome in order to identify the best route to follow.
The earliest recorded civil engineer was an Egyptian known as Imhotep. It is believed that Imhotep
designed and built the great pyramid of Djoser, also known as the Step Pyramid. Imhotep was one of
Pharaoh Djoser's officials and it is possible that he was the first person to make use of columns in
architecture. The Step Pyramid was built in Egypt in about the time period 2630 - 2611 BC and can be
found at Saqqara.
Imhotep would probably be absolutely fascinated with the leaps and bounds engineering has taken in
the last 4000 years - although he might have a few secrets to share himself!
What is engineering? Is it an art, a skill or a just a regular profession?
Either way, history taught us that through engineering, mankind is continuously breaking its inborn limits. Engineering determined leaders and nations to set up ambitious goals and to eventually surpass them. These successful results were achieved through sacrifice & hard work and they are now standing as real symbols of determination and progress.
Here are 12 of the greatest engineering projects man has ever created, that completely changed our perspective over the world:
- The Great Pyramids of Giza, Egypt
The three pyramids famous worldwide are located in Egypt, on the outskirts of Cairo. Egyptologists say that these amazing pieces of architecture are approximately 4,500 years old and they are currently considered the oldest monuments constructed in dressed masonry.
The Great Pyramid, the complex’s largest structure, is 756 feet long and 450 feet high. For three millenniums, it was the highest structure in the world. 2,300,000 blocks of stone, each averaging 2 ½ tons in weight were used to raise this fascinating piece of architecture. Although the methods of constructions are still uncertain, it is strongly believed that stones used in construction were quarried in the surrounding areas and then dragged on special created sledges and ramps. Egyptologists estimate that approximately 200,000 people participated in the construction of the Great Pyramid, a record that was achieved only once in our known history.
- The Great Wall of China
This is the longest railway in the world, connecting Moscow with Vladivostok, in the Russian Far East, at the Sea of Japan. It was built in record time from 1891 to 1916, under the rule of Tsar Nicholas II. The Tr -Siberian Railway is 5,753 miles (9,259 kilometers) long, spanning over seven time zones. A train trip from Moscow to Vladivostok now takes eight days to complete.
The design of the route took ten years, since this railway was vital for Siberia’s economical development. Still, the project ignored many of the existing cities that demanded tr port and many major Siberian cities remained unconnected. The workers involved in the project were mainly Russian soldiers and convicted laborers. The electrification of the line started in 1929 and finalized 80 years later. The construction of the line boosted the Siberian agriculture and its benefits continue to affect the Russian economy: 30% of the country’s exports travel on this line.
- The Panama Canal
The Panama Canal is a 48 mile (77 kilometers) long ship canal that connects the Atlantic and the Pacific Oce. The canal was built from 1904 to 1914 and it was one of the most difficult engineering projects ever pioneered. The opening of the canal had a tremendous impact upon shipping between the two oce , since all the boats en route from one ocean to the other did not have to route around the notorious Cape Horn anymore, America’s southernmost point.
Besides excavating immense volumes of earth, the project involved a serious upgrade of the Panama railway system, so that heavy-duty locomotives and railroad cars could be used to improve the efficiency of the work. During the construction period, the process of moving the land become so well-organized, that at one point 160 loaded dirt trains were used daily – that is one train leaving about every one and a half minutes of the day. More than 60,000,000 pounds (roughly 27,215,500 kilograms) of dynamite was used when constructing the canal. Since its inauguration, a total of 815,000 vessels have passed through the canal, making it one of the leading areas on Earth in terms of naval traffic.
- The Hoover Dam, Arizona/Nevada, USA
Once known as Boulder Dam, The Hoover Dam is a concrete arch-gravity dam built on the Colorado River, between 1931 and 1936. The dam is a marvel of engineering, given that never before such a huge concrete structure was built in such a torrid environment. Its generators continue to provide power for three states: Nevada, Arizona and California and more than 1 million people visit the dam each year.
The colossal structure is 726 feet (221 meters) high and 1,244 feet (379 meters) long at the top. Also, it is 660 feet (200 meters) thick at the base, narrowing up to 45 feet (14 meters) at the top. For its erection, a new model city was built in the desert, near the dam site (eventually known as Boulder City, Nevada) and a railway was constructed to connect Las Vegas with the new town. Preparations also included the creation of four diversion tunnels, in order to redirect the Colorado River from the construction site. Each tunnel was 56 feet (17 meters) in diameter and their combined length reached 3 miles (5 kilometers). A total of 3,250,000 cubic yards (2,480,000 cubic meters) of concrete and 16,
people were used to build the Hoover Dam, the most ambitious infrastructure project in the period of the Great Depression.
- Burj Khalifa, Dubai, UAE
This is currently the tallest man-made structure ever built, measuring 2,717 feet (828 meters). The tower’s chief architect was Adrian Smith, while the chief structural engineer position was occupied by Bill Baker. The cost of the whole project raised up to US $1,5 billion and the skyscraper was officially opened on January 4th, 2010. Burj Khalifa has 163 habitable floors, summing a floor area of 3,331,100 sq feet (309,473 sq meters). The tower has a Y-shaped design, to maximize outward views and inward natural light. The base structure consists of three elements arranged around a central core. For better stability, setbacks occur as the tower reaches toward the sky, creating 27 terraces. The core element emerges into a 4,000 tonnes steel spire, which also houses communications equipment.
A new structural system was developed by the architects and the engineers for the extraordinary height of the tower. The so-called buttressed core is formed by a hexagonal core reinforced by three buttresses that form the Y-shape. Moreover, architects rotated the building 120 degrees from its original position, in order to reduce stress from the existing winds.
- The Channel Tunnel, France/England
The Channel Tunnel is a 31.4 miles (50.5 kilometers) undersea tunnel that connects Folkestone, in the United Kingdom with Coquelles, in Northern France. The tunnel reaches up to 250 ft (75 meters) deep, and seven years after its opening it still possesses the largest underwater portion of any tunnel in the world: 23.5 miles (37.9 kilometers). It is now used by high-speed Eurostar passenger trains, Eurotunnel Shuttle vehicle tr port and freight trains.
The tunnel consists of three bores: two 25 feet (7.6 meter) diameter rain tunnels, 94 feet (30 meters) apart, with a 16 feet (4.8 meter) diameter service tunnel in between. Special tunnel boring machines or “moles” were used to dig the tunnels. Works started concomitantly on the French and on the British sides and a total of eleven such pieces of equipment were used. Taking in consideration special geology studies, the moles start cutting through the chalk marl layer. Special impermeability and pressure problems need to be addressed during the construction process, so that engineers designed a linking system between the tunnels that manages the pressure changes with the train movement. The construction of the tunnel brought Europe closer to Britain and standing as a proof, since its opening, the Channel Tunnel has been crossed by 17 million people.
- K ai Airport, Osaka, Japan
Civil Engineering
It is difficult to determine the history of emergence and beginning of civil engineering, however, that the history of civil engineering is a mirror of the history of human beings on this earth. Man used the old shelter caves to protect themselves of weather and harsh environment, and used a tree trunk to cross the river, which being the demonstration of ancient age civil engineering.
Civil Engineering has been an aspect of life since the beginnings of human existence. The earliest practices of Civil engg may have commenced between 4000 and 2000 BC in Ancient Egypt and Mesopotamia (Ancient Iraq) when hum started to abandon a nomadic existence, thus causing a need for the construction of shelter. During this time, tr portation became increasingly important leading to the development of the wheel and sailing.
Until modern times there was no clear distinction between civil engg and architecture, and the term engineer and architect were mainly geographical variations referring to the same person, often used interchangeably. The construction of Pyramids in Egypt (circa 2700-2500 BC) might be considered the first instances of large structure constructions.
Around 2550 BC, Imhotep, the first documented engineer, built a famous stepped pyramid for King Djoser located at Saqqara Necropolis. With simple tools and mathematics he created a monument that stands to this day. His greatest contribution to engineering was his discovery of the art of building with shaped stones. Those who followed him carried engineering to remarkable heights using skill and imagination.
Ancient historic civil engineering constructions include the Qanat water management system (the oldest older than 3000 years and longer than 71 km,) the Parthenon by Iktinos in Ancient Greece (447-438 BC), the Appian Way by Roman engineers (c. 312 BC), the Great Wall of China by General Meng T’ien under orders from Ch’in Emperor Shih Huang Ti (c. 220 BC) and the stupas constructed in ancient Sri Lanka like the Jetavanaramaya and the extensive irrigation works in Anuradhapura. The Rom developed civil structures throughout their empire, including especially aqueducts, insulae, harbours, bridges, dams and roads.
Other remarkable historical structures are Sennacherib's Aqueduct at Jerwan built in 691 BC; Li Ping's irrigation projects in China (around 220 BC); Julius Caesar's Bridge over the Rhine River built in 55 BC, numerous bridges built by other Rom in and around Rome(e.g. the pons Fabricius); Pont du Gard (Roman Aqueduct, Nimes, France) built in 19 BC; the extensive system of highways the Rom built to facilitate trading and (more importantly) fast manoeuvring of legions; extensive irrigation system constructed by the Hohokam Indi , Salt River, AZ around 600 AD; first dykes defending against high water in Friesland, The Netherlands around 1000 AD; El Camino Real - The Royal Road, Eastern Branch, TX and Western Branch, NM (1500s AD).
Machu Picchu, Peru, built at around 1450, at the height of the Inca Empire is considered an engineering marvel. It was built in the Andes Mountains assisted by some of history’s most ingenious water resource engineers. The people of Machu Picchu built a mountain top city with running water, drainage systems, food production and stone structures so advanced that they endured for over 500years.
A treatise on Architecture, Book called Vitruvius' De Archiectura, was published at 1AD in Rome and survived to give us a look at engineering education in ancient times. It was probably written around 15 BC by the Roman architect Vitruvius and dedicated to his patron, the emperor Caesar Augustus, as a guide for building projects.
Throughout ancient and medieval history most architectural design and construction was carried out by artis , such as stonemasons and carpenters, rising to the role of master builder. Knowledge was retained
in guilds and seldom supplanted by advances. Structures, roads and infrastructure that existed were repetitive, and increases in scale were incremental.
One of the earliest examples of a scientific approach to physical and mathematical problems applicable to civil engineering is the work of Archimedes in the 3rd century BC, including Archimedes Principle, which underpins our understanding of buoyancy, and practical solutions such as Archimedes’ screw. Brahmagupta, an Indian mathematician, used arithmetic in the 7th century AD, based on Hindu-Arabic numerals, for excavation (volume) computations.
Educational & Institutional history of civil engineering
In the 18th century, the term civil engineering was coined to incorporate all things civilian as opposed to military engineering. The first engineering school, The National School of Bridges and Highways, France, was opened in 1747. The first self-proclaimed civil engineer was John Smeaton who constructed the Eddystone Lighthouse. In 1771, Smeaton and some of his colleagues formed the Smeatonian Society of Civil Engineers, a group of leaders of the profession who met informally over dinner. Though there was evidence of some technical meetings, it was little more than a social society.
In 1818, world’s first engineering society, the Institution of Civil Engineers was founded in London, and in 1820 the eminent engineer Thomas Telford became its first president. The institution received a Royal Charter in 1828, formally recognizing civil engineering as a profession. Its charter defined civil engineering as: “Civil engineering is the application of physical and scientific principles, and its history is intricately linked to advances in understanding of physics and mathematics throughout history. Because civil engineering is a wide ranging profession, including several separate specialized sub-disciplines, its history is linked to knowledge of structures, material science, geography, geology, soil, hydrology, environment, mechanics and other fields.”
The first private college to teach Civil Engineering in the United States was Norwich University founded in 1819 by Captain Alden Partridge. The first degree in Civil Engineering in the United States was awarded by Rensselaer Polytechnic Institute in 1835. The first such degree to be awarded to a woman was granted by Cornell University to Nora Stanton Blatch in 1905.
Facts
All the mechanical engineering systems are studied with the help of thermodynamics. Hence it is very important for the mechanical engineers.
There are three laws of the thermodynamics.
First Law: Energy can be neither created nor destroyed. It can only change forms.In any process in an isolated system, the total energy remains the same.
Second Law: When two isolated systems in separate but nearby regions of space, each in thermodynamic equilibrium in itself, but not in equilibrium with each other at first, are at some time allowed to interact, breaking the isolation that separates the two systems, and they exchange matter or energy, they will eventually reach a mutual thermodynamic equilibrium. The sum of the entropies of the initial, isolated systems is less than or equal to the entropy of the final exchanging systems. In the process of reaching a new thermodynamic equilibrium, entropy has increased, or at least has not decreased.
. The entropy of the universe increases over time and moves towards a maximum value. . The heat addition and rejection processes in Otto cycle are of constant volume, whereas in Brayton cycle, they are of constant pressure.
-Otto cycle is the ideal cycle for spark ignition engines. -Brayton cycle is the ideal cycle for gas power turbines.
. scrap the excess lube oil from the cylinder walls. there by preventing oil from entering combustion zone. . DTSI stands for Digital Twin Spark Plug Ignition. The vehicles with DTSI Technology use 2 spark plugs which are controlled by digital circuit. It results in efficient combustion of air fuel mixture.
- Digital - Since the spark generation will be initiated by a microchip.
- Twin - Since two spark plugs will be used.
- Spark ignition - Since the ignition will be done via a spark. . The point at which the fracture energy passes below a pre-determined point for a standard Impact tests. DBTT is important since, once a material is cooled below the DBTT, it has a much greater tendency to shatter on impact instead of bending or deforming. . All the mechanical engineering systems are studied with the help of thermodynamics. Hence it is very important for the mechanical engineers. . P11 the chromium molybdenum composition that is 1% ofchromium and 1/4% of molybdenum
P12 the chromium molybdenum composition that is 1% ofchromium and 2% of molybdenum
. Generally, journal bearings have higher friction force, consume higher energy and release more heat, but they have larger contact surface, so normally used in low speed high load applications. In anti friction bearings friction is less. One object just rolls over each other.
. Engineering is application of science. Technology shows various methods of Engineering. A bridge can be made by using beams to bear the load,by an arc or by hanging in a cable; all shows different technology but comes under civil engineering and science applied is laws of force/load distribution. . Wet bulb temperature is measured in a wet bulb thermometer by covering the bulb with a wick and wetting it with water. It corresponds to the dew point temperature and relative humidity. . Advantages
- Complete combustion
- Fuel saving
- Homogenous combustion
Disadvantages
- As complete combustion is occurring ,more heat liberated,not advised for long journey, engine will be over heated
- Installation is difficult
- Reduce engine life efficiency . The rated speed tells us about the maximum speed which can be achieved by a vehicle or some other machine but the economical speed me the speed limit at which the machine works efficiently with least consumption of fuel.eg-in normal bikes(not racing),the max.speed limit shown on speedometer is upto 120 kmph but companies always advice their customers to drive such bikes at around 60 kmph to have maximum mileage. . Powder technology is one of the ways of making bearing material. In this method metals like bronze, Al, Fe are mixed and compressed to make an alloy.
. Strength is capability over a short length of time and Stamina is the ability to keep going continuously. . Hydrostatics is the study of fluid bodies that are
- At rest
- Moving sufficiently slowly so there is no relative motion between adjacent parts of the body
For hydrostatic situations
- There are no shear stresses
- There are only pressure forces that act perpendicular to any surface.
It’s a closed loop hydraulic systems. It comprises of motor and pump. Here pump supplies energy to motor and motor gives return energy to pump supply.
. A cotter joint is used to connect rigidly two co-axial rods or bars which are subjected to axial tensile or compressive forces. Here shaft is locked in place by a smaller pin that passes through the side of the lug and partly or completely through the shaft itself. This locking pin is named as cotter. . Discharge pressure prevented by a pressurized spike cushion. Here the system employs a pressurized cushion of air and a two o-ring piston, which permanently separates this air cushion from the water system. When the valve closes and the water flow is suddenly stopped, the pressure spike pushes the piston up the arrester chamber against the pressurized cushion of air. The air cushion in the arrester reacts instantly, absorbing the pressure spike that causes water hammer. . Strainer for coarse size, Filter is more accurate than Strainer. . In 180 degree angle the Top ring, Second ring and Oil ring are fixed. Position the ring approximately 1 inch gap below the neck. . To build a Very high pressure and the temperature for a boiler feed water pump and it discharge high pressure water to the boiler.
And to provide the required Net Positive Suction Head (NPSH) for the BFW pump and to serve as a storage tank to ensure a continuous supply of feed water during rapid changes in BFP.
. 1 ton refrigeration me 210 kJ/min extracts heat from thesystem.
. HEAT AND MECHANICAL WORK ARE MUTUALLY CONVERTABLE. ENERGY CAN BE CREATED NOR BE
DISTROYED BUT IT CAN BETR FERED FROM ONE FORM TO ANOTHER FORM.
. It gets bigger. . Centrifugal pump is a kinetic device. The centrifugal pump uses the centrifugal force to push out the fluid. So the liquid entering the pump receives kinetic energy from the rotating impeller. The centrifugal action of the impeller accelerates the liquid to a high velocity, tr ferring mechanical (rotational) energy to the liquid. So it discharges the liquid in high rate. It is given in the following formulae:
Centrifugal force F= (M*V^2 )/R.
Where,
M-Mass
V-Velocity
R-Radius
. Cavitation me bubbles are forming in the liquid.
· To avoid Cavitation, we have to increase the Pump size to One or Two Inch;
To increase the pressure of the Suction Head, or
· Decrease the Pump Speed.
. The formation of cavities (or bubbles) is induced by flow separation, or non-uniform flow velocities, inside a pump casing. In centrifugal pumps the eye of the pump impeller is smaller than the flow area of
. Differential mechanism . Natural gas (Gasoline)… at 20 Celsius . Divide the shaft diameter size by 5, it will give last two digit of the bearing no. and according to type of load we have to choose the type of bearing and that will give prior number of the bearing. . Improving the surface finish by Polishing & providing residual stress by Shot peening. . No, It will not work, as the Compression ratio of Petrol engine is 6 to 10 & that of Diesel engine is 15 to 22. Thus on such high compression, gasoline gets highly compressed & it may blast. . When a material is compressed in one direction, it usuallytends to expand in the other two directions perpendicular tothe direction of compression. This phenomenon is called thePoisson effect. Poisson’s ratio is a measure of the Poisson effect.
For rubber = 0.
For steel = 0.
For wood < 0.
Thus Poisson’s ratio is higher in RUBBER.
On the basis of Indian standards fits can mainly be categorized into three groups:
Clearance Fit: These types of fits are characterized by the occurrence of a clearance between the two mating parts. The difference between the minimum size of the hole and the maximum size of the shaft is called the minimum clearance, the difference between the maximum size of the hole and the minimum size of the shaft is known as maximum clearance. Interference Fit: In these types of fits the size of the mating parts are predefined so that interference between them always occurs. The tolerance zone of the hole is completely below the tolerance zone of
the shaft.
Tr ition Fit: As the name suggests these type of fit has its mating parts sized limited to allow either clearance or interference. The tolerance zone of the hole and the shaft overlaps in case of such fits.
For a shaft designated as 40 H8/f7, calculate the tolerances.
Given: Shaft designation = 40 H8/f The shaft designation 40 H8/f 7 me that the basic size is 40 mm and the tolerance grade for the hole is 8 ( i. e. I T 8) and for the shaft is 7 ( i. e. I T 7). Since 40 mm lies in the diameter steps of 30 to 50 mm, therefore the geometric mean diameter, D = Square root of (30 x 50) = 38.73 mm We know that standard tolerance unit, i = 0.45 x Cube root of (D) + 0.001 D i = 0.45 × 3.38 + 0.03873 = 1.559 73 or 1.56 microns i = 1.56 × 0.001 = 0.001 56 mm ...(1 micron = 0.001 mm) The standard tolerance for the hole of grade 8 (IT8) = 25 i = 25 × 0.001 56 = 0.039 mm The standard tolerance for the shaft of grade 7 (IT7) = 16 i = 16 × 0.001 56 = 0.025 mm
The factor of safety is used in designing a machine component. Prior to selecting the correct factor of safety certain points must be taken into consideration such as:
The properties of the material used for the machine and the changes in its intrinsic properties over the time period of service. The accuracy and authenticity of test results to the actual machine parts. The applied load reliability. The limit of stresses (localized). The loss of property and life in case of failures. The limit of initial stresses at the time period of manufacture. The extent to which the assumptions can be simplified.
The factor of safety also depends on numerous other considerations such as the material, the method of manufacturing , the various types of stress, the part shapes etc.
Heat treatment can be defined as a combination of processes or operations in which the heating and cooling of a metal or alloy is done in order to obtain desirable characteristics without changing the compositions. Some of the motives or purpose of heat treatment are as follows:
In order to improve the hardness of metals. For the softening of the metal. In order to improve the machinability of the metal. To change the grain size. To provide better resistance to heat, corrosion, wear etc.
The main theories of failure of a member subjected to bi-axial stress are as follows:
Maximum principal stress theory ( Rankine’s theory): This theory states that failure occurs at a point in member where the maximum principal or normal stress in a bi-axial system reaches the maximum strength in a simple tension test. Maximum shear stress theory ( Guest’s or Tresca’s theory): This theory states that failure occurs when the biaxial stress reaches a value equal to the shear stress at yield point in a simple tension test. Maximum principal strain theory ( Saint Venant theory): This theory states that failure occurs when bi- axial stress reaches the limiting value of strain. Maximum strain energy theory ( Haigh’s theory): This theory states that failure occurs when strain energy per unit volume of the stress system reaches the limiting strain energy point. Maximum distortion energy theory ( Hencky and Von Mises theory): This theory states that failure occurs when strain energy per unit volume reaches the limiting distortion energy.
- What happens if gasoline is used in a Diesel engine?Diesel engine will work?
No, It will not work,as the Compression ratio of Petrol engine is 6 to 10 & that of Diesel engine is 15 to
- Thus on such high compression, gasoline gets highly compressed & it may blast.
Differential mechanism
Engine specifications are different in different manufactures like as Bore Diameter(CC), Ignition timing.Also the exhaust passage take more responsible for sound.
ds=dQ/TEntropy is inversely proportional to the temperature so.as temp. increases,entropy decreases.
746.2Watt
Divide the shaft diameter size by 5, it will give last two digitof the bearing no. and according to type of load we have tochose the type of bearing and that will give prior no. ofthe bearing.
Rear wheel sprocket works under the principle of ratchet and pawl.
Octane No.- Octane number is defined as the percentage, by volume, of iso octane in the mixture of iso octane and h-heptane. It is the measure of rating of SI engine.
Cetane No.- Cetane number is defined as the percentage, by volume, of n-cetane in the mixture of n- cetane and alpha methyl naphthalene. It is the measure of rating of CI engine.
A turbine rotor is supported by two radial bearings, one on each end of the steam cylinder. These bearings must be accurately aligned to maintain the close clearance between the shaft and the shaft seals, and between the rotor and the casing. If excessive bearing wear lowers the he rotor, great harm can be done to the turbine.
Two independent governors are needed for safe turbine operation. One is an over speed or emergency trip that shuts off the steam at 10 percent above running speed (maximum speed). The second, or main governor, usually controls speed at a constant rate; however, many applications have variable speed control.
As the turbine speeds up, the weights are moved outward by centrifugal force, causing linkage to open a pilot valve that admits and releases oil on either side of a piston or on one side of a spring-loaded piston. The movement of the piston controls the steam valves.
It is the speed at which the machine vibrates most violently. It is due to many causes, such as imbalance or harmonic vibrations set up by the entire machine. To minimize damage, the turbine should be hurried through the known critical speed as rapidly as possible. (Caution, be sure the vibration is caused by critical speed and not by some other trouble).
An auxiliary pump is provided to maintain oil pressure. Some auxiliary pumps are turned by a hand crank; others are motor-driven. This pump is used when the integral pump is running too slowly to provide pressure, as when starting or securing a medium-sized turbine.
In larger units, lube oil cools the bearings by carrying off heat to the oil coolers. Lube oil in some turbines also acts as a hydraulic fluid to operate the governor speed-control system.
You should keep the cooling water circulating for about 15 mill or more so that the condenser has a chance to cool down gradually and evenly. Be sure to have cooling water flowing through the condenser
