1. COMBUSTION CHAMBER

Internal combustion engines can contain any number of combustion chambers (cylinders),

with numbers between one and twelve being common, though as many as 36 (Lycoming

R-7755) have been used.

Having more cylinders in an engine yields two potential benefits: first, the engine can have a

larger displacement with smaller individual reciprocating masses, that is, the mass of each

piston can be less thus making a smoother-running engine since the engine tends to vibrate as

a result of the pistons moving up and down. Doubling the number of the same size cylinders

will double the torque and power. The downside to having more pistons is that the engine

will tend to weigh more and generate more internal friction as the greater number of pistons

rub against the inside of their cylinders. This tends to decrease fuel efficiency and robs the

engine of some of its power. For high-performance gasoline engines using current materials

and technology, such as the engines found in modern automobiles, there seems to be a point

around 10 or 12 cylinders after which the addition of cylinders becomes an overall detriment

to performance and efficiency.

2. IGNITION SYSTEM

The ignition system of an internal combustion engines depends on the type of engine and the

fuel

used. Petrol engines are typically ignited by a precisely timed spark, and diesel engines by

compression heating. Historically, outside flame and hot-tube systems were used, see hot

bulb engine.

2.1 Spark

In a spark ignition engine, a mixture is ignited by an electric spark from a spark plug — the

timing of which is very precisely controlled. Almost all gasoline engines are of this type.

Diesel engines timing is precisely controlled by the pressure pump and injector. The normal

plug distance between the spark plug is 1mm apart, and the voltage is 3000v at normal

atmospheric conditions.

2.2 Compression

Ignition occurs as the temperature of the fuel/air mixture is taken over its autoignition

temperature, due to heat generated by the compression of the air during the compression

stroke. The vast majority of compression ignition engines are diesels in which the fuel is

mixed with the air after the air has reached ignition temperature. In this case, the timing

comes from the fuel injection system. Very small model engines for which simplicity and

light weight is more important than fuel costs use easily ignited fuels (a mixture of kerosene,

ether, and lubricant) and adjustable compression to control ignition timing for starting and

running.

2.3 Ignition timing

For reciprocating engines, the point in the cycle at which the fuel-oxidizer mixture is

ignited has a direct effect on the efficiency and output of the ICE. The thermodynamics of

the idealized Carnot heat enginetells us that an ICE is most efficient if most of the burning

takes place at a high temperature, resulting from compression — near top dead center. The

speed of the flame front is directly affected by the compression ratio, fuel mixture

temperature, and octane rating or cetane number of the fuel. Leaner mixtures and lower

mixture pressures burn more slowly requiring more advanced ignition timing. It is

important to have combustion spread by a thermal flame front (deflagration), not by a

shock wave.

Combustion propagation by a shock wave is called detonation and, in engines, is also

known as pinging or Engine knocking.

So at least in gasoline-burning engines, ignition timing is largely a compromise between a

later "retarded" spark — which gives greater efficiency with high octane fuel — and an

earlier "advanced" spark that avoids detonation with the fuel used. For this reason, high-

performance diesel automobile proponents, such as Gale Banks, believe that

There’s only so far you can go with an air-throttled engine on 91-octane gasoline. In other

words, it is the fuel, gasoline, that has become the limiting factor While turbocharging has

been applied to both

gasoline and diesel engines, only limited boost can be added to a gasoline engine before the

fuel octane level again becomes a problem. With a diesel, boost pressure is essentially

unlimited. It is literally possible

to run as much boost as the engine will physically stand before breaking apart.

Consequently, engine designers have come to realize that diesels are capable of

substantially more power and torque than any comparably sized gasoline engine.[1]

2.4 Fuel systems

Fuels burn faster and more efficiently when they present a large surface area to the oxygen in air. Liquid fuels must be atomized to create a fuel-air mixture, traditionally this was done with a

carburetor in petrol engines and with fuel injection in diesel engines. Most modern petrol

engines now use fuel injection too — though the technology is quite different. While diesel

must be injected at an exact point in that engine cycle, no such precision is needed in a petrol

engine. However, the lack of lubricity in petrol means that the injectors themselves must be

more sophisticated.

2.5 Carburetor

Simpler reciprocating engines continue to use a carburetor to supply fuel into the cylinder.

Although carburetor technology in automobiles reached a very high degree of sophistication

and precision, from the mid-1980s it lost out on cost and flexibility to fuel injection. Simple

forms of carburetor remain in widespread use in small engines such as lawn mowers and

more sophisticated forms are still used in small motorcycles.

2.6 Fuel injection

Larger gasoline engines used in automobiles have mostly moved to fuel injection systems

(see Gasoline Direct Injection). Diesel engines have always used fuel injection system

because the timing of the injection initiates and controls the combustion.

Autogas engines use either fuel injection systems or open- or closed-loop carburetors.

3. Fuel pump

Most internal combustion engines now require a fuel pump. Diesel engines use an all-

mechanical precision pump system that delivers a timed injection direct into the combustion

chamber, hence requiring a high delivery pressure to overcome the pressure of the

combustion chamber. Petrol fuel injection delivers into the inlet tract at atmospheric pressure

(or below) and timing is not involved, these pumps are normally driven electrically. Gas

turbine and rocket engines use electrical systems.

Other internal combustion engines like jet engines and rocket engines employ various

methods of fuel delivery including impinging jets, gas/liquid shear, preburners and

others.

Oxidiser-Air inlet system

Some engines such as solid rockets have oxidisers already within the combustion

chamber but in most cases for combustion to occur, a continuous supply of oxidiser must

be supplied to the combustion chamber.

Animated cut through diagram of a typical fuel injector, a device used to deliver fuel to the internal combustion

engine.

Naturally aspirated engines

When air is used with piston engines it can simply suck it in as the piston increases the

volume of the chamber. However, this gives a maximum of 1 atmosphere of pressure

difference across the inlet valves, and at high engine speeds the resulting airflow can limit

potential output.

Superchargers and turbochargers[edit]

A supercharger is a "forced induction" system which uses a compressor powered by the shaft

of the engine which forces air through the valves of the engine to achieve higher flow. When

these systems are employed the maximum absolute pressure at the inlet valve is typically

around 2 times atmospheric pressure or more. Turbochargers are another type of forced induction system which has its compressor powered by a gas turbine running off the exhaust gases from the engine.

Turbochargers and superchargers are particularly useful at high altitudes and they are

frequently used in aircraft engines.

Duct jet engines use the same basic system, but eschew the piston engine, and replace it

with a burner instead.

Liquids

In liquid rocket engines, the oxidiser comes in the form of a liquid and needs to be delivered

at high pressure (typically 10-230 bar or 1–23 MPa) to the combustion chamber. This is

normally achieved by the use of a centrifugal pump powered by a gas turbine — a

configuration known as a turbopump, but it can also be pressure fed.

A cutaway of a turbocharger

Parts

For a four-stroke engine, key parts of the engine include the crankshaft (purple), connecting rod (orange), one or more camshafts (red and blue), and valves. For a two-stroke engine, there may simply

be an exhaust outlet and fuel inlet instead of a valve system. In both types of engines there

are one or more cylinders (grey and green), and for each cylinder there is a spark plug

(darker-grey, gasoline engines only),

a piston (yellow), and a crankpin (purple). A single sweep of the cylinder by the piston in

an upward or downward motion is known as a stroke. The downward stroke that occurs

directly after the air-fuel mix passes from the carburetor or fuel injector to the cylinder

(where it is ignited) is also known as a power stroke.

A Wankel engine has a triangular rotor that orbits in an epitrochoidal (figure 8 shape)

chamber around an eccentric shaft. The four phases of operation (intake, compression,

power, and exhaust) take place in what is effectively a moving, variable-volume chamber.

Valves

All four-stroke internal combustion engines employ valves to control the admittance of fuel

and air into the combustion chamber. Two-stroke engines use ports in the cylinder bore,

covered and uncovered by the piston, though there have been variations such as exhaust

valves.

Piston engine valves

In piston engines, the valves are grouped into 'inlet valves' which admit the entrance of fuel

and air and 'outlet valves' which allow the exhaust gases to escape. Each valve opens once

per cycle and the ones that are subject to extreme accelerations are held closed by springs that

are typically opened by rods running on a camshaftrotating with the engines' crankshaft.

Control valves

Continuous combustion engines—as well as piston engines—usually have valves that

open and close to admit the fuel and/or air at the startup and shutdown. Some valves

feather to adjust the flow to control power or engine speed as well.

Exhaust systems

An illustration of several key components in a typical four-strokeengine.

Internal combustion engines have to effectively manage the exhaust of the cooled combustion gas from the engine. The exhaust system frequently contains devices to control both chemical and noise pollution. In

addition, for cyclic combustion engines the exhaust system is frequently tuned to improve emptying of

the combustion chamber. The majority of exhausts also have systems to prevent heat from reaching

places which would encounter damage from it such as heat-sensitive components, often referred to as

Exhaust Heat Management.

For jet propulsion internal combustion engines, the 'exhaust system' takes the form of a high

velocity nozzle, which generates thrust for the engine and forms a colimated jet of gas that gives the

engine its name.

Most reciprocating internal combustion engines end up turning a shaft. This means that the linear motion of a piston must be converted into rotation. This is typically achieved by a crankshaft.

Flywheels

The flywheel is a disk or wheel attached to the crank, forming an inertial mass that stores rotational

energy. In engines with only a single cylinder the flywheel is essential to carry energy over from the

power stroke into a subsequent compression stroke. Flywheels are present in most reciprocating engines

to smooth out the power delivery over each rotation of the crank and in most automotive engines also

mount a gear ring for a starter. The rotational inertia of the flywheel also allows a much slower minimum

unloaded speed and also improves the smoothness at idle. The flywheel may also perform a part of the

balancing of the system and so by itself be out of balance, although most engines will use a neutral

balance for the flywheel, enabling it to be balanced in a separate operation. The flywheel is also used as a

mounting for the clutch or a torque converter in most automotive applications.

UNIT -2 HYDRAULIC SYSTEM

1. LUBRICATION SYSTEM

Lubricating systems are used to introduce oil, grease and other lubricants to moving machine

parts. The lubricants reduce friction between parts, and therefore increase the longevity of all

components. Without lubrication, most machines would overheat or suffer extreme damage.

There are several different types of automatic lubrication systems including:

Single Line Parallel systems.

Dual Line Parallel systems.

Single Point Automatics.

Single Line Progressive systems (or Series Progressive)

Single Line Resistance.

Oil Mist and Air-Oil systems.

Oil re-circulating.

Chain lube systems.

Exhaust manifold with ceramic plasma-sprayed system

A crankshaft for a 4-cylinder engine

1.1 Mist lubrication system:

Mist lubrication system is a very simple type of lubrication. In this system, the small quantity

of lubricating oil (usually 2 to 3%) is mixed with the fuel (preferably gasoline). The oil and

fuel mixture is introduced through the carburetor. The gasoline vaporized and oil in the form

of mist enters the cylinder via the crank base. The droplets of oil strike the crank base. The

droplets of oil strike the crank base, lubricate the main and connecting rod bearings and the

rest of the oil lubricates the piston, piston rings and cylinder.

The system is preferred in two stroke engines where crank base lubrication is not required. In

a two- stroke engine, the charge is partially compressed in a crank base, so it is not possible

to have the oil in the crank base.

This system is simple, low cost and maintenance free because it does not require any oil pump, filter,

etc. However, it has certain serious disadvantages. Therefore, it is not popular among the

lubrication system. Its disadvantages are the following:

1. During combustion in the engine, some lubricating oil also burnt and it

causes heavy exhaust and forms deposits on the piston crown, exhaust port

and exhaust system.

2. Since the lubricating oil comes in contact with acidic vapours produced during

the combustion, it gets contaminated and may result in the corrosion of the

bearings surface.

3. When the vehicle is moving downhill, the throttle is almost closed, and the

engine suffers lack of lubrication as supply of fuel is less. It is a very serious

drawback of this system.

4. There is no control over the supply of lubricating oil to the engine. In normal

operating conditions, the two-stroke engines are always over-oiled. Thus

consumption of oil is also more.

5. This system requires thorough mixing of oil and fuel prior to admission into the

engine. It requires either separate mixing or use of some additives.

1.2. Wet-sump lubrication system:

In the wet-sump lubrication system, the bottom of the crank case contains an oil pan or sump

that serves as oil supply, oil storage tank and oil cooler. The oil dripping from the cylinders,

bearings and other parts, fall under gravity back into the sump, from where it is picked up by

pump and recirculated through

the engine lubrication system. There are three varieties in wet-sump lubrication system. They are: 1. Splash lubrication system

2. Splash and pressure system and

3. Pressurized lubrication system.

2.1 Splash lubrication System:

Splash lubrication system is used on small, stationary four-stroke engines. In this system, the

cap of the big end bearing on the connecting rod is provided with a scoop which strikes and

dips into the oil- filled through at every revolution of the crank shaft and oil is splashed all

over the interior of crank case into the piston and over the exposed portion of the cylinder is

shown in the figure below.

A hole is drilled through the connecting rod cap through which the oil passes to the bearing

surface. Oil pockets are provided to catch the splashed oil over all the main bearings and also

the cam shaft bearings. From these pockets oil passes to the bearings through drilled hole. The

surplus oil dripping from the cylinder flows back to the oil sump in the crank case.

2.2 Splash and pressure lubrication system:

Splash and pressure lubrication system is combination of splash and pressure system as shown

in below figure. In this system, the lubricating oil is supplied by a pump under pressure to

main and cam shaft bearings In pressurized lubrication system, the lubricating oil is supplied

by a pump under pressure to all parts requiring lubrication as shown in below figure. The oil

under the pressure is supplied to main bearings of the crank shaft and camshaft. Holes drilled

through the main crank shaft bearings journals, communicate oil to big end bearing and small

end bearings through the hole drilled in the connecting rod. a pressure gauge is provided to

confirm the circulation of oil to various parts.

Splash and pressure lubrication system is combination of splash and pressure system as shown in

below figure. In this system, the lubricating oil is supplied by a pump under pressure to main and

cam shaft bearings. the oil is also directed in the form of spray from nozzle or splashed by a scoop

or dipper on the big end to lubricate bearings at the big end of the connecting rod, crank pin,

gudgeon pin, piston rings and cylinder.

1.3 Pressurized lubrication system:

In pressurized lubrication system, the lubricating oil is supplied by a pump under pressure to

all parts requiring lubrication as shown in below figure. The oil under the pressure is supplied

to main bearings of the crank shaft and camshaft. Holes drilled through the main crank shaft

bearings journals, communicate oil to big end bearing and small end bearings through the

hole drilled in the connecting rod. a pressure gauge is provided to confirm the circulation of

oil to various parts.

This system provides sufficient lubrication to all parts and is favoured by

most of the engine manufacturers. This is used in most heavy duty and

high-speed engines.

1.4 . Dry-sump lubrication system:

In dry-sump lubrication system, the oil supply is carried from an external tank.

The oil from the sump is pumped by means of a scavenging pump through filters

to the external storage tank. the oi from the storage tank is pumped to engine

cylinder through and oil cooler. The oil pressure may vary from 3 to 8 bar.

The dry-sump lubrication system is generally used for heavy-duty engines.

UNIT – 3 SPECIAL PURPOSE VECHILE

1. BULLDOZER

A bulldozer is a crawler (continuous tracked tractor) equipped with a substantial metal plate

(known as a blade) used to push large quantities of soil, sand, rubble, or other such material

during construction or conversion work and typically equipped at the rear with a claw-

like device (known as a ripper) to loosen densely compacted materials.

Bulldozers can be found on a wide range of sites, mines and quarries, military

bases, heavy industry factories, engineering projects and farms.

The term "bulldozer" correctly refers only to a tractor (usually tracked) fitted with a dozer

blade.

Typically, bulldozers are large and powerful tracked heavy equipment. The tracks give them

excellent ground holding capability and mobility through very rough terrain. Wide tracks

help distribute the bulldozer's weight over a large area (decreasing ground pressure), thus

preventing it from sinking

in sandy or muddy ground. Extra wide tracks are known as swamp tracks or LGP (low

ground pressure) tracks. Bulldozers have transmission systems designed to take advantage of

the track system and provide excellent tractive force.

1.1 Blade

The bulldozer blade is a heavy metal plate on the front of the tractor, used to push objects, and shove sand, soil, debris, and sometimes snow. Dozer blades usually come in three varieties:

1. A straight blade ("S blade") which is short and has no lateral curve and no side wings

and can be used for fine grading.

2. A universal blade ("U blade") which is tall and very curved, and has large side wings

to carry more material.

3. An "S-U" (semi-U) combination blade which is shorter, has less curvature, and

smaller side wings. This blade is typically used for pushing piles of large rocks,

such as at a quarry.

Blades can be fitted straight across the frame, or at an angle, sometimes using additional 'tilt

cylinders' to vary the angle while moving. The bottom edge of the blade can be sharpened,

e.g. to cut tree stumps.

Sometimes a bulldozer is used to push another piece of earth moving equipment known as a

"scraper". The towed Fresno Scraper, invented in 1883 by James Porteous, was the first

design to enable this to

Bulldozer blade

Komatsu bulldozer pushing up to 7m3 with semi-U tilt dozer

be done economically, removing the soil from the cut and depositing it elsewhere on

shallow ground (fill). Many dozer blades have a reinforced center section with this purpose

in mind, and are called "bull blades".

In military use, dozer blades are fixed on combat engineering vehicles and can optionally be

fitted on other vehicles, such as artillery tractors such as the Type 73 or M8 Tractor. Dozer

blades can also be mounted on main battle tanks, where it can be used to clear antitank

obstacles, mines, and dig improvised shelters. Combat applications for dozer blades include

clearing battlefield obstacles and preparing fire positions.[1]

1.3 Ripper

The ripper is the long claw-like device on the back of the bulldozer. Rippers can come as a single (single shank/giant ripper) or in groups of two or more (multi shank rippers). Usually, a

single shank is preferred for heavy ripping. The ripper shank is fitted with a replaceable

tungsten steel alloy tip, referred to as a 'boot'. Ripping rock breaks the ground surface rock or

pavement into small rubble easy to handle and transport, which can then be removed so

grading can take place. With agricultural ripping, a farmer breaks up rocky or very hard earth

(such as podzol hardpan), which is otherwise unploughable, in order to farm it. For example,

much of the best land in the California wine country consists of old lava flows. The grower

shatters the lava with heavy bulldozers so surface crops or trees can be planted. Some

bulldozers are equipped with a less common rear attachment referred to as a stumpbuster,

which is a single spike that protrudes horizontally and can be raised to get it (mostly) out of

the way. A stumpbuster is used to split a tree stump. A bulldozer with a stumpbuster is used

for landclearing operations, and is often equipped with a brush-rake blade.

2. FIRE VEHICLE ENGINE

A fire engine (also known in some territories as a fire truck or fire appliance) is a vehicle

designed primarily for firefighting operations. The terms "fire engine" and "fire truck" are

often used interchangeably; however in some fire departments/fire services they refer to

separate and specific types of vehicle.

The primary purposes of a fire engine include transporting firefighters to an incident scene,

providing water with which to fight a fire, and carrying other equipment needed by

firefighters. Specialized apparatus are used to provide hazardous materials mitigation and

technical rescue. A typical modern fire engine will carry tools for a wide range of

firefighting tasks, with common equipment including a pump, a water tank, hoses, ground

ladders, hand tools, self-contained breathing apparatuses, BLS (basic life support)

equipment, and first aid kits.

Many fire vehicles are based on standard vehicle models (although some parts may be

upgraded to cope with the demands of the vehicles' usage). They are normally fitted with

audible and visual warnings, as well as communication equipment such as two-way radios

and mobile computer technology.

Multi-shank ripper

The standard fire engine is an apparatus designed primarily for firefighting operations. The

primary purpose of the engine is transporting firefighters to the scene, providing a limited

supply of water with which to fight the fire, and carrying tools, equipment, and hoses needed

by the firefighters. The tools carried on the fire engine will vary greatly based on many

factors including the size of the department and what sort of terrain the department must

handle. For example, departments located near large bodies of water or rivers are likely to

have some sort of water rescue equipment. Standard tools found on nearly all fire engines

include ladders, hydraulic rescue tools (often referred to as the jaws of

life), floodlights, fire hose, fire extinguishers, self-contained breathing apparatus, and thermal

imaging cameras.[1]

The exact layout of what is carried on an engine is decided by the needs of the department.

For example, fire departments located in metropolitan areas will carry equipment to mitigate

hazardous materials and effect technical rescues, while departments that operate in the

wildland-urban interface will need the gear to deal with brush fires.

Some fire engines have a fixed deluge gun, also known as a master stream, which directs a heavy stream of water to wherever the operator points it. An additional feature of engines are their

preconnected hose lines, commonly referred to as preconnects.[2] The preconnects are

attached to the engine's onboard water supply and allow firefighters to quickly mount an

aggressive attack on the fire as soon as they arrive on scene.[2] When the onboard water

supply runs out, the engine is connected to more permanent sources such as fire hydrants or

water tenders and can also use natural sources such as rivers or reservoirs by drafting water. A turntable ladder (TL) is perhaps the best-known form of special purpose aerial apparatus, and is used for forcible entry, ventilation, search and rescue, and to gain access to fires occurring

at height using a large telescopic ladder, where conventional ladders carried on

conventional appliances might not reach. The name is derived from the fact that the large

ladder is mounted on a turntable on the back of a truck chassis, allowing it to pivot around a

stable base. To increase its length, the ladder

is telescopic. Modern telescopic ladders are either hydraulic or pneumatic. These mechanical

features allow the use of ladders which are longer, sturdier, and more stable. They may also

have pre-attached hoses or other equipment.

An example of an engine, which can be identified in part by the pump panel on the side.

Compartments in the rear hold essential tools for different types of emergency calls, and the apparatus

often holds a reserve of water as well. This truck contains about 1,000 gallons of water.

Aerial apparatus

Quint 13 belonging to Fort Lauderdale

Tiller-truck of the Los Angeles Fire Departmentmanufactured by American LaFrance

A ladder can also be mounted behind the cab. This is sometimes called "mid-ship" and the

arrangement allows a lower travel height for the truck, and also can be more stable in

certain conditions.

The key functions of a turntable ladder are:

1. Allowing access or egress of firefighters and fire victims at height

2. Providing a high-level water point for firefighting (elevated master stream)

3. Providing a platform from which tasks such as ventilation or overhaul can be executed

While the traditional characteristic of a fire appliance was a lack of water pumping or storage,

many modern TLs have a water pumping function built in (and some have their own on-board

supply reservoir), and may have a pre-piped waterway running the length of the ladder which

directs a stream of water to the firefighters at the top. In some cases, there may also be a

monitor at the top of the ladder for ease of use. Other appliances may simply have a track-

way which will hold a manually-run hose reel securely, and prevent it from falling to the

ground.

In the United States, some turntable ladders with additional functions such as an onboard

pump, a water tank, fire hose, aerial ladder and multiple ground ladders, are known as quad

or quint engines, indicating the number of functions they perform.[3]

The highest TL in the world is the Magirus M68L. With the range of 68

meters.[4] Tiller truck[edit]

In the United States, a tiller truck, also known as a tractor-drawn aerial, tiller ladder, or hook-

and- ladder truck, is a specialized turntable ladder mounted on a semi-trailer truck. Unlike a

commercial semi, the trailer and tractor are permanently combined and special tools are

required to separate them. It has two drivers, with separate steering wheels for front and rear

wheels.[5]

One of the main features of the tiller-truck is its enhanced maneuverability.[6] The

independent steering of the front and back wheels allow the tiller to make much sharper

turns, which is particularly helpful on narrow streets and in apartment complexes with maze-

like roads.[5] An additional feature of the tiller-truck is that its overall length, over 50 feet (15

m) for most models, allows for additional storage of tools and equipment.[6] The extreme

length gives compartment capacities that range between 500 and 650 cubic feet (14 and 18

m3) in the trailer with an additional 40 and 60 cubic feet (1.1 and 1.7 m3) in the cab.[6]

Several aerial apparatuses in use at a fire in Los Angeles

Some departments elect to use tiller-quints (see quint below), which are tiller trucks that have

the added feature of being fitted with an on-board water tank.[6] These are particularly useful

for smaller departments that do not have enough personnel to staff both an engine company

and a truck company.

3. CRANE

A crane is a type of machine, generally equipped with a hoist rope, wire ropes or chains, and

sheaves, that can be used both to lift and lower materials and to move them horizontally. It is

mainly used for lifting heavy things and transporting them to other places. The device uses

one or more simple machines to create mechanical advantage and thus move loads beyond

the normal capability of a human. Cranes are commonly employed in the transport industry

for the loading and unloading of freight, in the construction industry for the movement of

materials, and in the manufacturing industry for the assembling of heavy equipment.

The first known construction cranes were invented by the Ancient Greeks and were powered

by men or beasts of burden, such as donkeys. These cranes were used for the construction of

tall buildings. Larger cranes were later developed, employing the use of human treadwheels,

permitting the lifting of heavier weights. In the High Middle Ages, harbour cranes were

introduced to load and unload ships and assist with their construction – some were built into

stone towers for extra strength and stability. The earliest cranes were constructed from wood,

but cast iron, iron and steel took over with the coming of the Industrial Revolution.

For many centuries, power was supplied by the physical exertion of men or animals,

although hoists in watermills and windmills could be driven by the harnessed natural power.

The first 'mechanical' power was provided by steam engines, the earliest steam crane being

introduced in the 18th or 19th century, with many remaining in use well into the late 20th

century.[1] Modern cranes usually

use internal combustion engines or electric motors and hydraulic systems to provide a

much greater lifting capability than was previously possible, although manual cranes are

still utilized where the provision of power would be uneconomic.

Cranes exist in an enormous variety of forms – each tailored to a specific use. Sizes range

from the smallest jib cranes, used inside workshops, to the tallest tower cranes, used for

constructing high buildings. Mini-cranes are also used for constructing high buildings, in

order to facilitate constructions by reaching tight spaces. Finally, we can find larger

floating cranes, generally used to build oil rigs and salvage sunken ships.

Some lifting machines do not strictly fit the above definition of a crane, but are generally

known as cranes, such as stacker cranes and loader cranes.

Q-1 What is bulldozer ?

Q-2 Define various types of engine parts.

Q-3 Define lubrication system.

Q-4 Define sump type.

Q-5 Define crane with various parts.