solid state laser (SSL)

LASER -Light Amplification by Stimulated Emission of Radiation

Main components of a Laser

1 Active medium,
2 Excitation source/pump
3 Reflecting mirrors/ resonator

Solid State Lasers

•Ruby Laser: the first laser
•Nd: YAG & Nd: Glass Lasers
•Tunable Solid State Lasers
•Alexandrite Laser
•Ti: Sapphire Laser
•Colour Center Lasers
•Fiber Lasers

Main properties of a Laser

Coherence: from phase correlation

Directionality
High intensity: results from directionality
Monochromaticity: results in high temporal coherence
Short pulse duration

Types of Lasers

Several ways to  classify lasers

Mode of operation:

ContinuousWave(CW)orPulsed

Active medium:- 

1 Solid lasers-

2 Gas lasers-

3 Liquid lasers

4 Semiconductor lasers

Classification may be done on basis of other parameters

1  Gain of the laser medium

2  Power delivered by laser

3  Efficiency or

4  Applications

Solid State Laser

1 For historical reasons, solid-state lasers are lasers in which active ions in crystal or glass host materials are optically pumped to create a population inversion.

2 Other types of lasers that employ solid-state gain media are semiconductor lasers and optical fiber lasers and amplifiers. Since these lasers employ very specialized technologies and design principles, they are usually treated separately from conventional bulk solid-state lasers.

3 Semiconductor or diode lasers are mostly electrically pumped (though in principle, optical pumping may be possible with some) Are versatile and provide a large range of average and peak power, pulse width, pulse repetition rate, and wavelength

The flexibility of solid-state lasers stems from the fact that:

• The size and shape of the active material can be chosen to achieve a particular performance
• Different active materials can be selected with different gain, energy storage, and wavelength properties
• Output energy can be increased by adding amplifiers
• A large number of passive and active components are available to shape the spectral, temporal and spatial profile of the output beam

Solid State Laser: requirements

Requirements for Host material:

•Should not absorb light at laser wavelength

•Must possess sharp fluorescent lines, strong absorption bands, and high quantum efficiency

•Crystal should have good thermal conductivity

Problems with Host material:

o Most of excitation energy ends up as heat rather than light

o Excess heat damages the laser crystal

Active centresare ions from:Chromium (Cr), Neodymium (Nd), Titanium (Ti), Cerium (Ce), Erbium (Er), Holmium (Ho) and Cobalt (Co)

Chromium is active centre in Ruby and Alexandrite lasers

Neodymium is active centre in commonly used Nd: YAG laserSolid State Laser: requirements

Representative Solid State Laser

1 Ruby Laser

2 Nd:YAG Laser

3 Nd:Glass Laser

Tunable Solid State Lasers

•Alexandrite Laser

•Titanium-Sapphire Laser

•Colour-Centre Laser

Fiber Lasers

•Erbium in a Glass host

Ruby Laser: the first laser

Ruby laser rod:

A synthetic pink Ruby crystal (Al2O3doped with Cr3+ions)

Cr3+ions concentration: 0.05%, ==Approx 1.6*10^25ions per cubic meter.Ruby Laser: the first laser

The Al2O3(sapphire) host is hard, with high thermal conductivity, and transition metals can readily be incorporated substitutionally for the Al

•Active Centres(Cr3+ions) have a set of three energy

•Aluminum & Oxygen ions are inert

•Ruby crystal as cylindrical rod (4cm length 0.5 cm in diameter)

•Helical photographic flash lamp filled with Xenon.

Laser Weapon Melts Test Drone

The Compact Laser Weapons System features four main parts that help it turn plain old energy into a deadly force: It has a battery, a chiller that keeps the system from getting too hot, a 2-kilowatt laser and a "beam director" that points the laser light at the intended target.

Engineers designed the system to be lighter and more compact than its big cousin, the High Energy Laser Mobile Demonstrator (HEL MD), by redesigning the beam director. The first prototype of the Compact Laser Weapons System is 40 percent lighter than the vehicle-mounted HEL MD system, said Neal, who noted that this lower weight makes the portable laser gun easier to move around than the HEL MD.and also allows the motors that control the compact system's beam director to function quickly.

Both the HEL MD and the smaller laser weapon can be operated by one person, but the main advantage of the Compact Laser Weapons System is that it can be used just about anywhere. While the bigger system features a more powerful, 10-kW laser, it's fixed to the top of a vehicle, so it can only go where the vehicle goes.

"Think of it like a welding torch being put on a target, but from many hundreds of meters away," Isaac Neal, a Boeing engineer, said in a video about the new weapons system that was posted on the defense contractor's website.

In a recent test, the laser, which is compact enough to carry around in a suitcase, was able to locate, aim and fire at a small drone flying above a testing facility in Point Mugu, California. The laser gun acts quickly (it took just 15 seconds for it to shoot the test drone out of the sky) and discreetly, according to Neal. Speedy reaction times can be important in battles when every second counts.

                                                              Gauges

• Gauges are inspection tool of rigid design, without a scale,which serves to check the dimensions of         manufacturing parts.

• Gauge do not indicate the actual value of the inspected part of the component.

• They are used to determine whether the part is made within the specified limit.

                                        Classification of Plain Gauge

• Plain gauges are used for checking plain (unthreaded) holes and shafts. Gauges are classified:

• According to their type :

(a) Standard gauges- made as an exact copy of opposed(mating)part

(b) Limit gauges- made to the limits of the dimensions

• According to their purposes :

(a) Workshop Gauge: To Check Dimension after manufacture

(b) Inspection Gauge: To check part before final acceptance

(d) Purchase Inspection Gauge: To check part of other factory

(c) Reference or master gauges: To check the dimension of gauge

                               Classification of Plain Gauge

• According to the form of the tested surface :

(a) Plug gauges for checking holes.

(b) Snap and ring gauges for checking shafts

According to their design :

(a) Single limit and double limit gauges

(b) Single ended and double ended gauges,

(c) Fixed and adjustable gauges

                                                  Limit Gauge

• Limit gauges are made to the limits of the dimensions of the part to be tested. There are two limit of dimensions, so we need two limit gauge.

• ‘Go gauge’ should pass through or over a part while ‘Not Go gauge’should not pass through or over the part.

Effects of Alloying Elements

•Carbon•The basic metal, iron, is alloyed with carbon to make steel and has the effect of increasing the hardness and strength by heat treatment but the addition of carbon enables a wide range of hardness and strength.

•Manganese•Manganese is added to steel to improve hot working properties and increase strength, toughness and hardenability.

•Molybdenum

           Molybdenum, when added to chromium-nickel austenitic steels, improves resistance to pitting corrosion especially by chlorides and sulphur chemicals.
•When added to low alloy steels, molybdenum improves high temperature strengths and hardness.• When added to chromium steels it greatly diminishes the tendency of steels to decay in service or in heat treatment.

•Titanium•The main use of titanium as an alloying element in steel is for carbide stabilisation.
•It combines with carbon to form titanium carbides, which are quite stable and hard to dissolve in steel, this tends to minimise the occurrence of inter-granular corrosion.

•Phosphorus•Phosphorus is usually added with sulphur to improve machinability in low alloy steels, phosphorus, in small amounts, aids strength and corrosion resistance.• Phosphorus additions are known to increase the tendency to cracking during welding.

•Sulphur•When added in small amounts sulphur improves machinability .

•Silicon•Silicon is used as a deoxidising (killing) agent in the melting of steel, as a result, most steels contain a small percentage of silicon. Silicon contributes to hardening of the ferritic phase in steels and for this reason silicon killed steels are somewhat harder and stiffer than aluminium killed steels.

TORQUE CONVERTER AND

TRANSMISSION HYDRAULIC SYSTEM

The torque converter housing is the oil sump for the torque converter and transmission oil supply. A four-section torque converter and transmission pump is located at the rear of the torque converter.

The four sections (from rear to front) are:

1. Transmission lube

2. Transmission charging

3. Torque converter charging

4. Transmission scavenge

The transmission lube pump section pulls oil from the end of the manifold that is supplied by the cooler return line. All of the oil going to this section of the pump comes from the cooler return line. Oil flows from the transmission lube section of the pump to the transfer gears. Transmission lube oil flows through the transfer gears and the transmission to cool and lubricate the internal components.

The transmission charging pump section pulls oil from the end of the manifold that is supplied from the sump in the converter housing. All of the oil to this pump section comes from the sump.

A small amount of oil from the transmission charging pump section flows through a priming bleed orifice to the outlet of the lube pump section. Most of the oil flows through the transmission charging filter.

From the filter, transmission charging oil flows in the following

two directions:

1. Transmission charging oil flows to the torque converter lockup clutch valve located on top of the torque converter.

2. Transmission charging oil also flows to the transmission control valves located on top of the transmission. Oil that is not used to actuate the clutches flows back to the converter housing and joins with

flow from the converter charging pump section at the inlet relief valve.

The torque converter charging pump section pulls oil from the middle of the manifold in the torque converter housing. Oil is supplied both from the cooler return line and from the sump. Oil flows from the torque converter charging pump section through the torque converter

charging filter to the torque converter inlet relief valve. Transmission charging oil joins with the torque converter charging oil at the inlet relief valve. The charging oil flows through the torque converter, the outlet relief valve, the

torque converter outlet screen, and the power train oil coolers. The oil flows through the coolers and returns to the torque converter housing.

Final drive

Planetary final drive has full floating axle shafts and a plug in differential carrier assembly

Lubrication System

The engine oil pump draws oil from the oil pan through a screen. The engine also has a scavenge pump at the rear of the engine to transfer oil from the rear of the oil pan to the main sump. Oil flows from the pump through an engine oil cooler bypass valve to the engine oil cooler. The bypass valve for the engine oil cooler permits oil flow to the system during cold starts when the oil is thick or if the cooler is plugged. Oil flows from the engine oil cooler to the oil filters. The

oil flows through the filters and enters the engine cylinder block to clean, cool, and lubricate the internal components and the turbochargers. Some trucks are equipped with an engine oil renewal system. Engine oil flows from the engine block to an engine oil renewal system manifold. A small amount of oil flows from the engine

oil renewal system manifold into the return side of the fuel pressure regulator. The engine oil returns to the fuel tank with the return fuel.

SHOVEL

This is the oldest excavation equipment of the world. This equipment can be classified  in the following way

 (a) Electric shovel

 (b) Hydraulic shovel.

The main useful component of the machine is the BUCKET, which digs in the soil or earth or mineral or ore body of any project. The component is attached to a member known as DIPPER STICK. This again moves forwarded and backward,which is regarded as CRWDING  with the help pinions  driven by pinion shaft. The bucket can be lifted up and down by hoist rope. This hoist rope is operated by hoist drum, which again driven by hoist shaft.

The bucket and the dipper stick along with the pinions are mounted on another member known as BOOM, which pinned to super structure at one end and held by rope pulley arrangement on the top. The whole of the unit as described   is mounted on platform through roller race.This makes the super structure capable of rotating about a vertical axis This rotation of the super structure about vertical axis is known as SWINGING .

The roller race  is placed on a big gear known as BULL GEAR, which is again mounted on an unit known as UNDER CARRIAGE unit. The under carriage unit  consists of two crawler mechanism, which are actually resting on the ground. The crawler unit is made of endless chain, which is driven by sprockets.  These   sprockets are driven by a shaft taking power from engine or motor. The endless chain consists of a No. of shoe members pin joined with each other and mounted over roller ring and driven wheel. These rings, the wheels  and the sprockets are held in a frame. Two frames of the two crawler mechanism are joined by other frame members. The assembly of the whole unit is regarded as under carriage unit.

ELECTRIC SHOVEL

INTRODUCTION:- The descriptions as stated remain the same for Diesel and Electric shovel. The only difference is that in Diesel shovel the various mechanisms such as crowd mechanism, swing mechanism, hoist mechanism and travel mechanism  are driven by Diesel engine through clutch, chain and sprocket, rope pulley and different liver mechanism While in Electric

shovel the same mechanism are driven by electric motor through clutch, gear box and related equipment. So different mechanisms are provided with  different motors, except that swing and propel mechanism are driven by the same motor with the restriction that both swing and travel activities  can’t be allowed to take place simultaneously. All these motors are D.C. motor, who draw power from D.C. generators, who in turn is driven an A.C synchronous motor. In fact all the D.C. generators and the synchronous motor are mounted on a common shaft joined by flexible coupling. This combination of motor and generator is called MOTOR GENERATOR (M.G.) set of Ward Leonard system.In the combine shaft one excitor  unit is mounted, which is mainly to control the electric current in the D.C. generator.

APPLICATION :- Power shovels are used at surface metal and nonmetal mines for overburden removal and for ore loading. Many different sizes of shovels may be used. depending on the type of operation and application.

Block Diagram

Accidents relating to shovel operation most often result from slips and falls, becoming caught in or struck by moving mechanisms, and standing or walking near the machine while it is in operation. Slips and falls occur most often during maintenance,' repair, or cleanup, and when mounting and dismounting the machine. Miners are most often struck by moving mechanisms during greasing or oiling, or when performing maintenance or repair. Injuries to persons standing or walking near the machine often occur when the person is in the area and the shovel operator is unaware of their location.

The basic job steps included in this module are:

1. Conduct walk-around inspection of shovel and  work area.

2. Mount and dismount.

3. Conduct on-board inspection.

4.  General operation.

5.  Shutdown procedure.

6.  Perform repairs and maintenance.

.

HYDRAULIC SHOVEL

INTRODUCTION:- It will describe PC-650 But the mechanisms are driven by hydraulic motor  ,which in turn are driven by hydraulicpumps. These pumps are driven by either electric motor or Diesel engine.The operation of different mechanismsare done  by reciprocating piston-cylinder arrangement, while travel and swing activities are done by hydraulic traction motor. Now in this shovel no rope pulley arrangement is used. Hence this is also regarded as Non- Rope shovel. This  type of shovel is very compact and take less space in comparison with similar capacity of other variety shovels. General view of hydraulic shovel .

PC-650 MAINTENANCE IN DIFFERENT PREVENTIVE RESPECT:- Preventive maintenance is the activities to be followed at a particular interval period. They are nothing but certain check list to be followed as suggested by the manufacturer(s) in their literature during the supply of the equipment. Those need to be followed strictly.

250 hours maintenance :-radiator ,oil cooling fan , tension pully bearing ,  swing machinery case , final drive , fuel filter element.

500 hours maintenance:- fuel filter , swing machinery case, final drive case left/right .

1000 hours maintenance:- fuel filter , swing machinery case, final drive case left/right .

2000 hours maintenance :- hydraulic oil change , power take off (PTO) oil, swing pinion check.

ENGINE MAINTENANCE :- :- In open cast project engines are the main source of power for open cast machineries. High horse power diesel engines are used principally. Maintenance of these engines plays a very vital role for successful operation and achievement of an open cast project. It increases the availability, utilization of the machines as a whole. To understand the maintenance procedure for these engines, the constructional aspect of the engines need to discussed. The engine specifications of these machines are slightly different than those of other.

Lubrication System

The engine oil pump draws oil from the oil pan through a screen. The engine also has a scavenge pump at the rear of the engine to transfer oil from the rear of the oil pan to the main sump. Oil flows from the pump through an engine oil cooler bypass valve to the engine oil cooler. The bypass valve for the engine oil cooler permits oil flow to the system during cold starts when the oil is thick or if the cooler is plugged. Oil flows from the engine oil cooler to the oil filters. The

oil flows through the filters and enters the engine cylinder block to clean, cool, and lubricate the internal components and the turbochargers. Some trucks are equipped with an engine oil renewal system. Engine oil flows from the engine block to an engine oil renewal system manifold. A small amount of oil flows from the engine

oil renewal system manifold into the return side of the fuel pressure regulator. The engine oil returns to the fuel tank with the return fuel.

The following safe job procedures wil help minimize incidents which may cause injuries and adversely affect production:

Required and/or recommended personal protective equipment:

 Hard hat, safety shoes, safety glasses with side shields, gloves,

 clothing appropriate for weather conditions, hearing protection