Mine mechanisation 1

Mine Mechanisation - I
P Bharath kumar

PRIME MOVER
• Prime mover is a machine or component that converts energy
from an energy source into motive power
• Machine- Dumper Prime mover-Engine

PRIME MOVER
• Machine- Manriding Chair Lift Prime mover-electrical motor

IC Engines
• The internal combustion (IC) engine has been the dominant
prime mover in our society since its invention.
• Its purpose is to generate mechanical power from the chemical
energy contained in the fuel and released through combustion
of the fuel inside the engine. It is this specific point, that fuel is
burned inside the work-producing part of the engine, that gives
IC engines their name.

IC Engines
•C – crankshaft
•E – exhaust camshaft
•I – inlet camshaft
•P – piston
•R – connecting rod
•S – spark plug
•V – valves. red: exhaust, blue: intake.
•W – cooling water jacket

Pneumatic Power
• Pneumatics is the science and technology of pressurized air—using piped,
compressed air (or a similar gas, such as nitrogen) to transmit force and
energy.
• Pneumatic machines need five basic components to make, store, control, move, and use compressed air:
1. A compressor—makes air.
2. A reservoir (or receiver)—stores air.
3. One or more valves—control air.
4. A circuit—moves air between the other components.
5. An actuator or motor—uses air to do something.

Pneumatic power- Advantages
• One of the reasons why a pneumatic system is commonly used in industrial equipment is
that it is intrinsically safe. It does not derive power or energy from electricity; hence, a
pneumatic system will not produce sparks that could ignite gases and cause fires or
explosions. Mining equipment, and other similar hazardous working environments
benefit from using pneumatic systems.
• Atmospheric air is abundant and readily available, which makes the power source an
infinite resource.
• A pneumatic system purges compressed air, automatically keeping the instrument clean
and free from contaminants that can damage or prevent the system from working.
• A pneumatic system is easy to maintain and easy to use.
• Pneumatic systems are suitable for working environments exposed to radiation and high
temperature, which makes pneumatics immune to most elements present in nature.
• A pneumatic system can also use other types of compressed gases. This is beneficial for
applications where natural gas is the power source. Compressed natural gas may be used
as an alternative power source for pneumatic instruments.

Pneumatic power- Disadvantages
• A pneumatic device is sensitive to extreme changes in
temperature as well as vibration.
• Compressed air is more expensive than electricity
• It is essential to ensure that there are no leaks in a pneumatic
system because compressed air escaping leads to energy loss.
• Pneumatic systems are known for making a loud noise. As a
solution, you can install a silencer in every dump line.
• Installation cost increases when the instrument requires
speciality pipes.
• Pneumatic systems are not upgradable to become compatible
with smart electronics

Hydraulic Power
• Hydraulic power, also called Fluid Power, power transmitted by the
controlled circulation of pressurized fluid, usually a water-soluble oil or
water–glycol mixture, to a motor that converts it into a mechanical output
capable of doing work on a load.
• Synthetic or mineral based incompressible oil is also used as power
transmitting medium.
• A hydraulic system is a drive technology where a fluid is used to move the energy
from e.g. an electric motor to an actuator, such as a hydraulic cylinder. The fluid is
theoretically uncompressible and the fluid path can be flexible in the same way as
an electric cable.

Hydraulic Power – applications in mining.

Hydraulic Power - Pumps
• The power source, or prime mover, associated with most hydraulic power units is
the motor, which is generally selected based on its speed, torque level, and
power capacity.
• The motor runs the Pump, which develops the pressure in hydraulic system.
• Types of Pumps used are i) electrical powered, ii) diesel powered.

Hydraulic Power –Controlling system (valves)
• There are different types of valves are used in hydraulic systems.
• 1. Pressure release valve: Pressure control valves Pressure control valves on the
hydraulic power units with pressure relief valve, sequence valve, relief valve, are
pressure relay-based. Almost each hydraulic power unit comes complete with a
relief valve.

2. Directional control valve:
Directional control valves are used to control the direction and movement of
hydraulic fluid through a system. They are often referred to as switching valves, and
come in three main categories: hydraulic check valves, directional spool valves and
poppet valves that make up the different types of control valves.

• 3. Flow control valves:
• The purpose of flow control in a hydraulic system is to regulate speed.
• The speed control of the actuator is carried out by the control of the flow rate of
the fluid to the actuator.

Hydraulic Power – Actuators (Hydraulic Cylinders)
• A hydraulic cylinder (also called a linear hydraulic motor) is a mechanical actuator
that is used to give a unidirectional force through a unidirectional stroke.

Hydraulic Power – Actuators (Hydraulic Cylinders)
• Types of hydraulic actuators:
• i) single acting actuator ii)double acting actuator.

Hydraulic Power – Advantages
• A hydraulic system is an efficient transmitter of power for many reasons. Firstly,
its simple levers and push buttons make it easy to start, stop, accelerate and
decelerate.
• This also allows for control accuracy. Also, because it is such a fluid system,
without any cumbersome gears, pulleys or levers, it easily copes with a huge
weight range.
• It provides a constant force, regardless of changes in speed. For the most part,
hydraulic systems are simple, safe and economical because they use fewer
moving parts compared to mechanical and electrical systems, which makes them
easier to maintain.
• Hydraulic systems are safe to use in chemical plants and mines because they do
not cause sparks.

Hydraulic Power – Disadvantages
• Hydraulic systems also have some drawbacks.
• Handling hydraulic fluids is messy, and it can be difficult to totally get rid of leaks
in a hydraulic system. If hydraulic fluid leaks in hot areas, it may catch fire.
• If hydraulic lines burst, they can cause serious injuries.
• Take care when handling hydraulic fluids, as too much exposure can lead to
health issues. Hydraulic fluids are also corrosive, but some types are less so than
others.
• For example, two main types of brake fluid are available for hydraulic mountain
bikes, DOT fluid and mineral oil. Due to its non-corrosive properties, mineral oil is
less likely to destroy a bike's paintwork.
• To keep your hydraulic system in its prime, periodically check hydraulic systems
for leaks, lubricate when necessary, and change filters and seals as required.
• More prone to accumulate the impurities due to the wearing of the different
parts.

ELEMENTS OF MECHANICAL POWER
TRANSMISSION
• What is Mechanical power transmission?
• Mechanical power transmission is the transfer of energy from where
it’s generated to a place where it is used to perform work using
simple machines, linkages and mechanical power transmission
elements.
• Why do we need mechanical power transmission?
• There are many ways to generate power but sometimes its impossible
to generate power where it’s needed or in the right form or direction
or magnitude. Hence electrical & mechanical power transmissions are
vital for any engineering product design.

TRANSMISSION
• Mechanical power transmission and its elements are used for the
following reasons;
1. Generated power or energy can be converted into a useful form
2. Physical constraints limit the power generation at the place where
its used hence it can be transferred from source to a place where it
is needed
3. It can be used to change direction and magnitude such as speed or
torque
4. It can be used to change the type of energy i.e. rotational to linear
and vice versa

TRANSMISSION
• Types of Mechanical power transmission elements
1. Shafts & Couplings
2. Power screws
3. Gears & Gear trains
4. Brakes & Clutches
5. Belts, Ropes & Pulleys
6. Chains & sprockets

Definition
Couplings provide a means of linking shafts or transmitting
drive from a driver unit (e.g. electric motor or gearbox) to a
driven unit (e.g. a pump).
As within the name, a coupling couples together in 2 halves, the
source of the power in whatever form it may come in, and the
driven application.
There are numerous types of coupling, each type which is suited
to is own application; we are now going to look into this.

Industrial Coupling Application

Coupling Facts
• Take up misalignment of the shafts.
• Allow for expansion of the shafts caused by heating.
• Permit disengagement of the shafts at low speeds or at rest.
• Slip when overload occurs to protect both driven and driver units.
• Prevent overloading of the driver unit during start up.
• Prevent or reduce vibrations in a shaft system.
• Allow machinery or sections of shafting to be removed for maintenance.

Coupling Drive in Action
This animation shows a motor driving an application, connected
together via a coupling.
http://www.youtube.com/watch?v=MXAsKFnCqUE

Coupling Types & Applications
• Bellows Type
• Flanged
• Sleeved
• Universal Joint
• Pin and Bush
• Rubber Tyre Type
• Spider Type
• Gear Type
• Spring / Bibby
• Chain Type

Bellows Coupling
• Is flexible coupling
• For angular, offset & parallel
• High torsional stiffness
• Suitable for drives associated with instruments
• High quality or translation of motion
• Service life affected by load reversal applications &
• When driving loads incrementally

Flanged Coupling
• Is rigid coupling
• Connects 2 shafts in line
• Used to transmit high loads
• Employed to connect to large turbines,
power drives & other large applications
• Do not tolerate misalignment
• Require accurate setting up

Sleeved Coupling
• Also known as muff coupling
• Fits snugly over the mating shafts
• Can utilise a keyway
• Secured tightly via taper pins or screws
• Coupling closes as it is tightened
• Used when lack of space prohibits a flange coupling

Sleeved Coupling
Also available in a non-
Compressing figuration

Universal Joint Coupling
• Classed as solid coupling
• Comes with a flexible joint
• Connects to shaft via a pin
• Can fit into a keyway on each shaft end
• Flexes via adjoing piece between both halves
• Can transmit drive / drive of angle up to 52 degrees
• Used in car drives, covered with a seal known as a ‘boot’
https://www.youtube.com/watch?v=TgzesZuArCo

Universal Joint Coupling Parts

Double Universal Joint Coupling
• A double Cardan joint consists of two universal joints mounted
back to back with a center yoke; the center yoke replaces the
intermediate shaft.

Pin and Bush Coupling
• Classed as a solid coupling
• Comes as 2 half flanges
• Usually joined to each shaft via a keyway
• Each half is attached via fitted pins into hole
• Can have upward of 3 driving pins
• Bushes made from soft material such as rubber
• When fitting, correct side has to be fitted to drive half
• Come with manufacturers instructions for correct fitting

Rubber Tyre Coupling
• Also known as Fenner Coupling
• Comes as 2 flanges with keyway
• Flanges fit onto either side of ‘tyre’
• Tyre is made from rubber
• Coupling can tolerate slight misalignment
• Secured together via cap headed bolts
• Used when vibration or torsional load is present
• Rubber can perish over time, especially in high temperatures

Spider / Jaw Coupling
• Used in lighter applications
• Can reduce vibration
• 2 halves separated by a flexible insert
• Insert is usually made from a rubber
type material
• Material resistant to heat, chemicals
• Insert or ‘spider’ is replaceable part

Gear Coupling
• Classed as solid coupling
• Used for heavy applications such as
heavy industry drives
• Do not tolerate misalignment
• Require precise setting up
• Requires regular lubrication

Spring / Bibby Coupling
• Classed as flexible coupling
• 2 flanged with spring at centre
• Excellent for absorbing any shock loading &
reducing any vibration
• May require lubrication
• Requires accurate setting up and alignment
• Used for cement mills, conveyors, cranes, marine auxiliaries

Chain Coupling
• 2 sprockets accommodating a duplex chain
• Fitted to shaft via key drive
• Minor misalignment can be tolerated
• The coupling assembly is usually lubricated
• Limitation with speeds used
• A cover normally is fitted over chain
• Disconnection of coupling halves by removing chain

Chain Coupling in Casing
This will guarantee keeping
lubrication inside and
contamination outside

What is Clutch?
• The Clutch is a mechanical device used to connect or
disconnect the driven shaft from the driving shaft at the
will of the operator while power is transmitted from driving
to driven shaft.
• Clutch is mounted between driving and driven shaft and
power is transmitted from one shaft to the another shaft
which is required to be started and stopped frequently.
• In general, clutch is the mechanical device which connects
engine with the transmission (gear box).

Bolted to
Crank
(friction disk) splined to transmission
Input shaft
(throw-out
bearing T/O
bearing) allows
to push on
rotating clutch
fingers
Bolted to flywheel -
Applies the spring force to
clamp the friction disk to
the flywheel
(clutch fork) pushes
T/O bearing to
release rotating
Pilot bushing or bearing in
center of flywheel or
crankshaft, supports the end of
input shaft

Classification of clutch
Types
of
Clutche
s
Positiv
e
Clutch
Frictio
n
Clutch
Plate Or
Disc
Clutch
Single
plate
clutch
Multiplate
Clutch
Cone
Clutch
Centrifug
al
Clutch

Positive Clutch
• In this type of clutch, the engaging clutch
surfaces interlock to produce rigid joint they are
suitable for situations requiring simple & rapid
disconnection, although they must be
connected while shaft are stationary &
unloaded.
• The jaw may be square jaw type or spiral jaw
type.

Positive Clutch
Advantages
Disadvantag
es
• Simple • Must be
connected
• No heat
generated
• No slip
• Compa
ct
• Low
cost
whe
n
shaft is
unloaded

Friction Clutch
• Friction Clutches work on the basis of the
frictional forces developed between the two or
more surfaces in contact. Friction clutches are
usually over the jaw clutches due to their better
performance. There is a slip in friction clutch.
 The major types of friction clutches are
I. Single Plate Clutch
II. Multi Plate Clutch
III. Cone Clutch
IV. Centrifugal Clutch

Single Plate Friction Clutch
• A single plate friction clutch consisting of two
flanges. One flange is rigidly keyed in to the
driving shaft, while the other if free to move
along the driven shaft due to spliced
connection. The actuating force is provided by
a spring.

• T
orque transmitted by single plate clutch
is obtained as follows :
R1 = External radius of clutch
plate R2 = Internal radius of
clutch plate r = Small
elemental ring of radius

Multi Plate Friction Clutch
• A multi-plate clutch is a type of clutch in which the multiple clutch plates are used to
make frictional contact with the flywheel of the engine in order to transmit power
between the engine shaft and the transmission shaft of an automobile vehicle.
• A multi-plate clutch is used in automobiles and in machinery where high torque
output is required.
• Please refer the video for understanding the mechanism
• https://youtu.be/TcYsV063lk8

Explodedview ofmulti-plate
clutch

• Cone clutches are friction clutches. They are
simple in construction and are easy to disengage.
However, the driving and driven shafts must be
perfectly coaxial for efficient functioning of the
clutch.
• This requirement is more critical for cone clutch
compared to single plate friction clutch. A cone
clutch consists of two working surfaces, viz., inner
CONE CLUTCH

• The outer cone is fastened to the driving shaft
and the inner cone is free to slide axially on the
driven (output) shaft due to splines.
• A spring provides the necessary axial force to
the inner cone to press against the outer cone,
thus engaging the clutch. A contact lever is
used to disengage the clutch.

• The
inne
r
cone
surfac
e
with friction
material.
Du
e
to
wedgin
g
is
line
d
actio
n
between the
conical working surfaces, there is considerable
normal pressure and friction force with a small
engaging force.
• The semi cone angle a is kept greater than a
certain value to avoid self-engagement;
otherwise disengagement of clutch would be
difficult. This is kept around 12.50.

1. Cones: female cone (green), male
cone(blue)
2. Shaft: male cone is sliding on
splines
3. Friction material
4.Spring: brings the male cone back
after using the clutch control
5. Clutch control: separating both
cones
by pressing
6.Rotating direction: both
direction of the axis are possible

Centrifugal Clutch
• The centrifugal clutch permits the drive motor to
start, warm up and accelerate to the operating
speed without load. Then the clutch is
automatically engaged and the driven
equipment is smoothly brought up to the
operating speed.

BRAKES
• Brakes are mechanical devices which absorb the kinetic energy of the
system & convert it into any other form of energy(generally heat) in
order to stop a moving system.
• It is a mechanical device which produces frictional resistance against
moving machine member, in order to slow down the motion of
machine.
• We generally see them mounted on the end of the shafts & axles of
vehicles.
• The energy absorbed by brakes is released to surrounding in form of
heat.

BRAKES - TYPES
BRAKES
Mechanical
Block Brake / Shoe
brake
Single Block Brake
Double Block Brake
Band Brake
Internal or External
expanding shoe
brake
Electrical
Hydraulic
Pneumatic

Mechanical Brake – Single Block Brake
• Single block brake: A single block is consists of a block which is
pressed against the rim of revolving brake wheel drum.

Mechanical Brake – Double Block Brake
• It consist of two brake blocks at the opposite ends of the wheel.
• These shoes apply force to both the sides of wheel and reduces the
Unbalanced force on the shaft.
• This spring pull the upper end of the brake arms
together and Brake is applied.
• When a force is applied to the bell crank level , the
spring is Compressed and the brake is released.

Mechanical Brake – Band Brake
• A band brake consists of a flexible steel band lined with friction material, which
wrap to the brake drum. When an upward force is applied to the lever end, the
lever turns about the fulcrum pin and tightens the band on the drum and hence
the brakes are applied.
• The friction between the band and the drum provides the braking force.

Mechanical Brake – Interna expanding Shoe Brake
• An internal expanding shoe brake consists of two shoes.
• The outer surface of the shoes are covered with friction
material.
• Each shoe is pivoted at one end about a fixed fulcrum
and other end rests against cam. When the cam is
operated, the shoe are pushed outwards against
brake drum.
• The friction between the shoes and the drum
produces the braking torque.

Mechanical Brake – Disc Brake
• Disc brakes are different from drum brakes in that the drum is replaced by a
circular metal disc and the brake shoe are replaced by a caliper which supports a
pair of friction pads , one on each side of the disc.
• These pads are forced inward by the operating force and also retard the disc.

Mechanical Brake – Band and Block Brake
• The working of band & block brake is pretty much similar to band brakes except that
they contain blocks between the band & drum. The blocks maybe wooden or any other
friction lined material.
• More the number of blocks, more is the braking force & thus higher retardation.

Electrical Brakes
• Electrical braking process is depended on the flux and torque directions.
• It is generally used in braking of the electrical motors or electrical powered vehicles.
• Some types of electrical braking systems are:
1. Regenerative Braking.
2. Plugging type braking.
3. Dynamic braking.

Hydraulic Breaking System
• Hydraulic brakes are basically a system where brake fluids are used to operate braking
mechanism i.e to generate pressure on brake pads & thus to push them towards drum
or discs. The brake fluids are generally contain glycol ethers or diethylene glycol.

Pneumatic Breaking System
• As the word speaks for itself, it operates via. Air. Braking system maintain a high
pressure air inside it and moment driver applies brake, pressure in the line starts
dropping. This results in applying of brakes on wheels.

Power Transmission
1. Belt drive
2. Chain Drive
3. Gear Drive

Belt Drive
• One of the most common devices, belt drives are used to transmit motion from one
shaft to another with the help of a thin inextensible band that runs over two pulleys.
It is basically a looped strip of flexible material that mechanically link the rotating
shafts.
• There are various kind of belt drives available in the market such as flat belt, V-belt,
rope drive, and timing belt. It is important to select the right kind of belt drive,
depending upon:
i. Power to be transmitted
ii. Direction of belt motion
iii. Shaft’s velocity and Velocity ratio
iv. Service conditions
v. Distance between shafts, and space available
• Irrespective of the type of belt drive you are using, this technology offers a smooth
and effective transmission of power between shafts even if they are at a
considerable distance. This technology is used when you need to transmit rotary
motion between two parallel shafts. They are the cheapest method of power
transmission.

Chain Drive
• Chain drives come with an endless series of chain links with a net of toothed
sprockets. Unlike belt drives, there is no slip in chain technology. However,
they are mostly suited for small centre distances, usually up to 3 metre. In
some special circumstances, chain drives can even cover a distance of up to 8
meter.
• This technology is used for performing three basic functions. These are:
i. Transmitting power: They can transfer power (speed and torque) from one
component to another by means of a linked chain and sprockets. Chain
drives can transfer a large amount of torque even within a compact space.
ii. Conveying materials: They can move, carry, slide, push, and pull various
materials by attaching buckets, frames, pockets, or meshes to the chains.
They are often used for turning rollers to move a conveyor belt.
iii. Timing purposes: Many industries use them to synchronize or time
movements.

Gear Drive
• In the world of mechanical power transmission, gear drives have a very
special and prominent place. This is the most preferred technology when
you need to transmit considerable power over a short distance with a
constant velocity ratio. The mechanism of gear drives is quite simple –
the teeth, which are cut on the blanks of the gear wheel, mesh with
each other to transmit power. To avoid slipping, the projections on one
disc mesh with the recesses on other disc in gear drives.
• This technology uses different types of gears for power transmission. In
fact, it can transmit power not only between parallel shafts, but also
between non-parallel, co-planar, and intersecting etc. shafts.

Mine mechanisation 1

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