1. INTRODUCTION

With the worst of the economic downturn left behind, India is set firmly on the path of

growth. Growth is characterized by expansion. Expansion means more factories and

warehouses. From real estate, retail and hotel industries to shipping, aviation and steel,

capacity expansions are ongoing phenomena and thus there is a boom in the market for

material handling equipment. The Material Handling Equipment (MHE) industry has a

wide array of products on offer to the industry depending on the needs of the particular

industry. As the name suggests this sector deals with equipments that relate to the

movement, storage, control and protection of materials, goods and products throughout

the process of manufacturing, distribution, consumption and disposal. Material handling

sector is a critical intermediary in the economy of a country today. MHE may not

directly contribute towards production of goods but it brings about efficiency in

handling, transport and storage of goods. In fact, the MHE industry practically

complements the manufacturing industry by ensuring smooth and efficient distribution

of goods. Thus it is a vital aspect and hence the role of MHE in any set-up cannot be

overlooked. The size of the Indian MHE industry was estimated at around Rs 5,000

crore in 2009 and projected to grow at 20% year-on-year over the next five years, in

keeping with overall economic growth. The reason of this growth being drivers—

domestic production and foreign trade. Since MHE is closely associated to the country’s

imports and exports, its importance to the logistics industry cannot be denied. The

global demand for material handling products was estimated grows 5 percent annually

by 2012. It was also predicted that growth in the nondurable goods sectors will outpace

the large durable goods manufacturing market, and that advanced/ automated products

will grow the fastest.

Material handling cannot be avoided in logistics, but can certainly be reduced to

minimum levels. The productivity potential of logistics can be exploited by selecting the

right type of handling equipment. The selection of material handling equipment cannot

be done in isolation, without considering the storage system. Investment in the material

handling system will basher waste if it is not compatible to the warehouse layout plan.

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The layout will create obstacles for free movement of equipment and goods, resulting in

poor equipment productivity. Recent trends indicate preference for automated system

with higher logistics productivity to enhance the effectiveness of human energy in

material movement. Everyone wants more control. The more control you have, the

better you perform. Similarly good material handling systems give you control on

productivity. Distribution, manufacturing, and warehousing are the areas where material

handling plays a major role. To do these things well, you need control of processes, of

equipment, of personnel, of space and also of time. In fact material handling systems

power today’s efficient distribution and manufacturing facilities. It is the secret weapon

in logistics operations for improving system productivity. Enhancing customer service

and speeding up throughputs. By gaining control of your warehouse, you gain control of

your profitability. Effective material handling systems create savings that helps directly

to improve your bottom line. If your business relies heavily on manufacturing,

warehousing, storage or distribution, the potential savings are perhaps your greatest

opportunity. If your suffer from damaged products, slow pick rates, a lack of space,

disorganization, or bottlenecks, don’t think throwing more people at it will solve the

problem—that’s short term help at best, and you’ll be stuck with ongoing costs which

you cannot eliminate. In the last several years material handling has become a new,

complex, and rapidly evolving science. For moving material in and out of warehouse

many types of equipment and system are in use, depending on the type of products and

volume to be handled. The equipment is used, in loading and unloading operations, for

movement of goods over short distances. The handling of material in warehouse is

restricted to unitized forms, which require smaller size equipment. However, for bulk

handling of material at logistics nodes such as shipyards, ports and airports different

type of equipment is used.

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1.1 PURPOSE OF THE PROJECT

A cargo lift system is used for transporting goods between ground level and a raised

handling position. Cargo lift system for trucks and trails is a hydraulic system attached

at the back of a truck for making loading and unloading fast and easy. It is highly

pointed out that the cost material handling involves 40% to 50% of total production

cost. Therefore considerable attention must be taken in the material handling. Improved

material handling system not only save time and cost reduction but also ensure the

following:

Reduction in accidents.

Greater job satisfaction.

Reduction in inventory or & work in progress.

Increasing production.

Saving time.

1.2 GUIDE LINES FOR BASIC HANDLING

1. Standardise equipment by using equipment that can be deployed as many areas as

possible.

2. Maximise continuous flow rather than intermittent or one-way flow.

3. Focus on handling rather than stationary

4. Minimise ratio of dead-weight to payload of handling equipment and not wasting

unnecessary capacity of equipment.

5. Use gravity flow if possible rather than trigger on electricity.

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1.3 TYPES OF MATERIAL HANDLING EQUIPMENT

Transport Equipment:

- Conveyors

- Cranes

- Industrial Trucks

Positioning Equipment:

- Hoist

- Rotary Index Table

- Lift/ Tilt/ Table

- Balancer

- Ball Transfer Table

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- Parts Feeder

- Air Film Device

UnitLoadFormationEquipment:

Pallets

-Inter-modalContainers

-Bins/Basket/Racks

-Cartons

- Bulk Load containers

StorageEquipment:

-Racks

-AutomaticStorage/RetrievalSystems(AS/RS

-StackingFrame

-StorageCarousel

- Mezzanine

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IdentificationandControlEquipment:

-Bar-Coding

-ElectronicDataInterchange(EDI)/Internet

-Radio-FrequencyTag.

-MagneticStrip

-MachineVision

- Portable Data Terminal

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1.4 LIFTING DEVICES

Column lifts

Column lifts are often mechanical, although they can be hydraulic or pneumatic. They

run on 'tracks' fitted to the rear of the vehicle. From the tracks, a folding platform

extends, which can be taken up and down.

Column lifts have the advantage of being able to lift to a higher level than the load bed

(and are therefore suitable for loads over more than one level in the truck. They are

usually the easiest of the lift types to fit, as they require little structural work.

The disadvantages of column lifts include that the platform is only usually able to

operate at a 90° angle from the track, meaning that on uneven surfaces, the lift will not

meet the ground properly.

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Cantilever lifts

The cantilever lift is the type first developed by Zepro. They operate only on a hydraulic

or pneumatic system. The system works by a set of rams attached to the chassis of the

vehicle. These rams are on hinges, allowing them to move angle as they expand or

contract. By using the rams in sequence, the working platform can either be tilted, or

raised and lowered.

Cantilever lifts have the advantage of being able to tilt, which means they can often

form a ramp arrangement, which may be more appropriate for some applications. It also

means that it can be easier to load or unload on uneven ground.

On truck away lifts, the ramp can be folded away under the load bed of the vehicle,

leaving the option of it not being used when at a loading ramp, and giving access and

egress for operatives without the need to operate the lift.

Tuck away lift

Tuck Away Lifts are special lifts adapted for at the side of truck or semi

trailer, to enable easier loading and unloading of heavy loads or small

pallets through the side door of the truck.

More suitable for loading and unloading in congested areas.

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Passenger lift

To facilitate movement of Wheel Chaired Person this lifts are used.

Tail lift

These Types are Lifts are light in construction and suitable for Vans for

City Distribution Both under Chassis and On Chassis Installation

Possible Because Of Compact Design; even On Chassis Installations

keep the passage free for movement.

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1.5 CARGO LIFT SYSTEM

A cargo lift system is used for transporting goods between ground level and a raised

handling position .Cargo lift system for trucks and trails is attached at the back of a

truck for making loading and unloading fast and easy. Cargo lift systems are widely

used in manufacturing industries for minimizing lead time and increasing the

productivity of the plant. Cargo lift system minimizes the wear and tear of products

during handling and transportation. IT is kind of cantilever lift.

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2. OPERATING PRINCIPLE

Pascal's Principle and Hydraulics:

Pascal's law states that when there is an increase in pressure at any point in a confined

fluid, there is an equal increase at every other point in the container.

A container, as shown below, contains a fluid. There is an increase in pressure as the

length of the column of liquid increases, due to the increased mass of the fluid above.

For example, in the figure below, P3 would be the highest value of the three pressure

readings, because it has the highest level of fluid above it.

If the above container had an increase in overall pressure, that same added pressure

would affect each of the gauges (and the liquid throughout) the same. For example P1,

P2, P3 were originally 1, 3, 5 units of pressure, and 5 units of pressure were added to

the system; the new readings would be 6, 8, and 10.

Applied to a more complex system below, such as a hydraulic car lift, Pascal's law

allows forces to be multiplied. The cylinder on the left shows a cross-section area of 1

square inch, while the cylinder on the right shows a cross-section area of 10 square

inches. The cylinder on the left has a weight (force) on 1 pound acting downward on the

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piston, which lowers the fluid 10 inches. As a result of this force, the piston on the right

lifts a 10 pound weight a distance of 1 inch.

The 1 pound load on the 1 square inch area causes an increase in pressure on the fluid in

the system. This pressure is distributed equally throughout and acts on every square

inch of the 10 square inch area of the large piston. As a result, the larger piston lifts up a

10 pound weight. The larger the cross-section area of the second piston, the larger the

mechanical advantage, and the more weight it lifts.

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3. WORKING PRINCIPLE

In hydraulic cargo lift, Pascal's law allows forces to be multiplied. The larger the cross-

section area of the second piston, the larger the mechanical advantage, and the more

weight it lifts.

The formulas that relate to this are shown below:

P1 = P2 (since the pressures are equal throughout).

Since pressure equals force per unit area, then it follows that

F1/A1 = F2/A2

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It can be shown by substitution that the values shown above are correct,

1 pound / 1 square inches = 10 pounds / 10 square inches

Because the volume of fluid pushed down on the left side equals the volume of fluid

that is lifted up on the right side, the following formula is also true.

V1 = V2

By substitution,

A1 D1 = A2 D2

A = cross sectional area

D = the distance moved

or

A1/A2= D2/D1

This system can be thought of as a simple machine (lever), since force is multiplied.

The mechanical advantage can be found by rearranging terms in the above equation to

Mechanical Advantage (IMA) = D1/D2 = A2/A1

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4. COMPONENTS DESCRIPTION

4.1 HYDRAULIC CYLINDER

An hydraulic cylinder operates through pressurized fluid (usually oil), which gives the

hydraulic cylinder force. The cylinder's driving force is the piston, which is attached to

a piston rod that is enclosed in the cylinder's barrel. The bottom of the barrel is closed

off by the cylinder cap and the top is closed off by the head. The head contains a round

hole, which allows the piston rod to come out of the barrel. The inside of the barrel

contains the oil, and the hydraulic pressure that the oil creates acts on the piston rod,

causing it to move back and forth in a linear fashion. One end of the piston is attached

to the object or machine it is responsible for moving. As the hydraulic pressure of the

oil moves the piston rod, the piston rod moves the piston, which in turn moves the

object.

There are two main types of hydraulic cylinders: the tie rod cylinder and the welded

body cylinder. The tie rod hydraulic cylinder contains threaded steel rods attached to

either end of the cylinder barrel. These threaded steel rods are extremely strong and

make the tie rod cylinder useful in heavy-duty industrial applications. A welded body

cylinder has no steel rods. Instead, the top end of the barrel is welded directly to the

object that it is designed to move. Because it has no steel rods, a welded body cylinder

is much smaller than a tie rod cylinder and is used in smaller machinery. The welded

body cylinder is the main hydraulic cylinder used in construction machinery. There are

other types of specialized hydraulic cylinders, including the telescoping cylinder that

allows the piston rod to retract into the barrel. Specialized hydraulic cylinders are

primarily used in custom machinery and specialized industrial equipment.

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Parts of a hydraulic cylinder:-

A hydraulic cylinder consists of the following parts:

Cylinder barrel

The cylinder barrel is mostly a seamless thick walled forged pipe that must be machined

internally. The cylinder barrel is ground and/or honed internally.

Cylinder Bottom or Cap

In most hydraulic cylinders, the barrel and the bottom portion are welded together. This

can damage the inside of the barrel if done poorly. Therefore some cylinder designs

have a screwed or flanged connection from the cylinder end cap to the barrel. (See

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"Tie Rod Cylinders" below) In this type the barrel can be disassembled and repaired in

future.

Cylinder Head

The cylinder head is sometimes connected to the barrel with a sort of a simple lock (for

simple cylinders). In general however the connection is screwed or flanged. Flange

connections are the best, but also the most expensive. A flange has to be welded to the

pipe before machining. The advantage is that the connection is bolted and always

simple to remove. For larger cylinder sizes, the disconnection of a screw with a

diameter of 300 to 600 mm is a huge problem as well as the alignment during mounting.

Piston

The piston is a short, cylinder-shaped metal component that separates the two sides of

the cylinder barrel internally. The piston is usually machined with grooves to fit

elastomeric or metal seals. These seals are often O-rings, U-cups or cast iron rings.

They prevent the pressurized hydraulic oil from passing by the piston to the chamber on

the opposite side. This difference in pressure between the two sides of the piston causes

the cylinder to extend and retract. Piston seals vary in design and material according to

the pressure and temperature requirements that the cylinder will see in service.

Generally speaking, elastomeric seals made from nitrile rubber or other materials are

best in lower temperature environments while seals made of Viton are better for higher

temperatures. The best seals for high temperature are cast iron piston rings.

Piston Rod

The piston rod is typically a hard chrome-plated piece of cold-rolled steel which

attaches to the piston and extends from the cylinder through the rod-end head. In double

rod-end cylinders, the actuator has a rod extending from both sides of the piston and out

both ends of the barrel. The piston rod connects the hydraulic actuator to the machine

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component doing the work. This connection can be in the form of a machine thread or a

mounting attachment such as a rod-clevis or rod-eye. These mounting attachments can

be threaded or welded to the piston rod or, in some cases, they are a machined part of

the rod-end.

Rod gland

The cylinder head is fitted with seals to prevent the pressurized oil from leaking past the

interface between the rod and the head. This area is called the rod gland. It often has

another seal called a rod wiper which prevents contaminants from entering the cylinder

when the extended rod retracts back into the cylinder. The rod gland also has a rod wear

ring. This wear ring acts as a linear bearing to support the weight of the piston rod and

guides it as it passes back and forth through the rod gland. In some cases, especially in

small hydraulic cylinders, the rod gland and the rod wear ring are made from a single

integral machined part.

Other parts

Cushions

A hydraulic cylinder should be used for pushing and pulling only. No bending moments

or side loads should be transmitted to the piston rod or the cylinder. For this reason, the

ideal connection of a hydraulic cylinder is a single clevis with a spherical ball bearing.

This allows the hydraulic actuator to move and allow for any misalignment between the

actuator and the load it is pushing.

Hydraulic Cylinder Designs

There are primarily two styles of hydraulic cylinder construction used in industry: tie

rod style cylinders and welded body style cylinders.

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Tie Rod Cylinders

Tie rod style hydraulic cylinders use high strength threaded steel rods to hold the two

end caps to the cylinder barrel. This method of construction is most often seen in

industrial factory applications. Small bore cylinders usually have 4 tie rods, while large

bore cylinders may require as many as 16 or 20 tie rods in order to retain the end caps

under the tremendous forces produced. Tie rod style cylinders can be completely

disassembled for service and repair.

The National Fluid Power Association (NFPA) has standardized the dimensions of

hydraulic tie rod cylinders. This enables cylinders from different manufacturers to

interchange within the same mountings.

Welded Body Cylinders

Welded body cylinders have no tie rods. The barrel is welded directly to the end caps.

The ports are welded to the barrel. The front rod gland is usually threaded into or bolted

to the cylinder barrel. This allows the piston rod assembly and the rod seals to be

removed for serviceA Cut Away of a Welded Body Hydraulic Cylinder showing the

internal components

Welded body cylinders have a number of advantages over tie rod style cylinders.

Welded cylinders have a narrower body and often a shorter overall length enabling them

to fit better into the tight confines of machinery. Welded cylinders do not suffer from

failure due to tie rod stretch at high pressures and long strokes. The welded design also

lends itself to customization. Special features are easily added to the cylinder body.

These may include special ports, custom mounts, valve manifolds, and so on.

The smooth outer body of welded cylinders also enables the design of multi-stage

telescopic cylinders.

Welded body hydraulic cylinders dominate the mobile hydraulic equipment market such

as construction equipment (excavators, bulldozers, and road graders) and material

handling equipment (forklift trucks, telehandlers, and lift-gates). They are also used in

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heavy industry such as cranes, oil rigs, and large off-road vehicles in above-ground

mining.

Piston rod construction

The piston rod of a hydraulic cylinder operates both inside and outside the barrel, and

consequently both in and out of the hydraulic fluid and surrounding atmosphere.

Metallic coatings

Smooth and hard surfaces are desirable on the outer diameter of the piston rod and slide

rings for proper sealing. Corrosion resistance is also advantageous. A chromium layer

may often be applied on the outer surfaces of these parts. However, chromium layers

may be porous, thereby attracting moisture and eventually causing oxidation. In harsh

marine environments, the steel is often treated with both a nickel layer and a chromium

layer. Often 40 to 150 micrometer thick layers are applied. Sometimes solid stainless

steel rods are used. High quality stainless steel such as AISI 316 may be used for low

stress applications. Other stainless steels such as AISI 431 may also be used where there

are higher stresses, but lower corrosion concerns.

Ceramic coatings

Due to shortcomings of metallic materials, ceramic coatings were developed. Initially

ceramic protection schemes seemed ideal, but porosity was higher than projected.

Recently the corrosion resistant semi ceramic Lunac 2+ coatings were introduced.

These hard coatings are non porous and do not suffer from high brittleness.

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Lengths

Piston rods are generally available in lengths which are cut to suit the application. As

the common rods have a soft or mild steel core, their ends can be welded or machined

for a screw thread.

Special hydraulic cylinders

Telescopic cylinder

The length of a hydraulic cylinder is the total of the stroke, the thickness of the piston,

the thickness of bottom and head and the length of the connections. Often this length

does not fit in the machine. In that case the piston rod is also used as a piston barrel and

a second piston rod is used. These kinds of cylinders are called telescopic cylinders. If

we call a normal rod cylinder single stage, telescopic cylinders are multi-stage units of

two, three, four, five or more stages. In general telescopic cylinders are much more

expensive than normal cylinders. Most telescopic cylinders are single acting (push).

Double acting telescopic cylinders must be specially designed and manufactured.

Plunger cylinder

A hydraulic cylinder without a piston or with a piston without seals is called a plunger

cylinder. A plunger cylinder can only be used as a pushing cylinder; the maximum force

is piston rod area multiplied by pressure. This means that a plunger cylinder in general

has a relatively thick piston rod.

Differential cylinder

A differential cylinder acts like a normal cylinder when pulling. If the cylinder however

has to push, the oil from the piston rod side of the cylinder is not returned to the

reservoir, but goes to the bottom side of the cylinder. In such a way, the cylinder goes

much faster, but the maximum force the cylinder can give is like a plunger cylinder. A

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differential cylinder can be manufactured like a normal cylinder, and only a special

control is added.

Rephrasing cylinder

Rephrasing cylinders are two or more cylinders plumbed in series or parallel, with the

bores and rods sized such that all rods extend and/or retract equally when flow is

directed to the first, or last, cylinder within the system.

In "parallel" applications, the bore and rod sizes are always the same, and the cylinders

are always used in pairs. In "series" applications, the bore and rod sizes are always

different, and two or more cylinders may be used. In these applications, the bores and

rods are sized such that all rods extend or retract equally when flow is applied to the

first or last cylinder within the system.

This hydraulic synchronization of rod positions eliminates the need for a flow divider in

the hydraulic system, or any type of mechanical connection between the cylinder rods to

achieve synchronization.

Position sensing "smart" hydraulic cylinder

Position sensing hydraulic cylinders eliminate the need for a hollow cylinder rod.

Instead, an external sensing “bar” using Hall-Effect technology senses the position of

the cylinder’s piston. This is accomplished by the placement of a permanent magnet

within the piston. The magnet propagates a magnetic field through the steel wall of the

cylinder, providing a locating signal to the sensor.

4.2 HYDRAULIC FLUID

Introduction to fluid power

Fluid power is a term which was created to include the generation, control, and

application of smooth, effective power  of pumped or compressed fluids (either liquids

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or gases) when this power is used to provide force and motion to mechanisms. This

force and motion may be in the form of pushing, pulling, rotating, regulating, or driving.

Fluid power includes hydraulics, which involves liquids, and pneumatics, which

involves gases. Liquids and gases are similar in many respects.  The differences are

pointed out  in  the appropriate  areas  of this  manual. This  manual  presents  many  of

the  fundamental concepts  in the fields  of  hydraulics  and pneumatics. It  is  intended

as  a  basic reference for all personnel of the Navy whose duties and responsibilities

require  them  to have  a  knowledge of the fundamentals of  fluid  power.

Consequently, emphasis is placed primarily on the theory of operation of typical fluid

power systems and components that have applications in naval equipment. Many

applications of fluid power are presented in this manual to illustrate the functions and

operation   of   different   systems   and   components. However, these are only

representative of the many applications of fluid power in naval equipment. Individual

training manuals for each rate provide information concerning the application of fluid

power to specific equipment for which the rating is responsible.

Force in liquids

The study of liquids is divided into two main parts: liquids at rest (hydrostatics) and

liquids in motion (hydraulics). The effects of liquids at rest can often be expressed by

simple formulas. The effects of liquids in motion are more difficult to express due to

frictional   and   other factors whose actions cannot be expressed by simple

mathematics. we learned  that  liquids  have a definite volume  but  take  the  shape  of

their containing vessel.  There are two additional characteristics we must explore prior

to proceeding. Liquids are almost   incompressible.   For example, if a pressure of 100

pounds per square inch  (psi)  is  applied  to  a  given  volume  of  water that is at

atmospheric pressure, the volume will decrease  by  only  0.03  percent.  It would  take

a force of approximately 32 tons  to  reduce   its volume by 10 percent; however, when

this force is removed, the water immediately returns to its original  volume.  Other

liquids behave  in  about the same manner as water. Another  characteristic  of  a  liquid

is  the tendency  to  keep  its  free surface  level. If  the surface  is   not   level, liquids

will   flow   in   the direction  which will  tend  to  make  the   surface level. LIQUIDS

AT  REST In  studying  fluids  at  rest,  we are  concerned  with  the  transmission  of

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force  and the  factors  which  affect  the  forces  in liquids. Additionally,   pressure   in

and   on   liquids   and factors   affecting   pressure   are of great importance.

Functions and properties

The primary function of a hydraulic fluid is to convey power. In use, however, there are other

important functions of hydraulic fluid such as protection of the hydraulic machine

components. The table below lists the major functions of a hydraulic fluid and the properties

of a fluid that affect its ability to perform that function:

Function Property

Medium for power transfer and

control

Low compressibility (high bulk modulus)

Fast air release

Low foaming tendency

Low volatility

Medium for heat transfer Good thermal capacity and conductivity

Sealing Medium Adequate viscosity and viscosity index

Shear stability

Lubricant Viscosity for film maintenance

Low temperature fluidity

Thermal and oxidative stability

Hydrolytic stability / water tolerance

Cleanliness and filterability

Demulsibility

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Antiwear characteristics

Corrosion control

Pump efficiency

Proper viscosity to minimize internal

leakage

High viscosity index

Special function

Fire resistance

Friction modifications

Radiation resistance

Environmental impact Low toxicity when new or decomposed

Biodegradability

Functioning life Material compatibility

The different types of hydraulic fluids

Hydraulic fluids are a large group of liquids made of many kinds of chemicals. They are

used in automobile transmissions, power steering, forklift trucks, brakes, tractors,

industrial machinery, all forms of plant machinery etc.

There are many types of hydraulic fluids, of which the most common would be mineral

oil, polyaphaolefin and organophosphate ester. Others are based on glycol esters and

ethers, castor oil, or silicone.

Environmentally sensitive applications (e.g. farm tractors and marine dredging) may

benefit from using biodegradable hydraulic fluids based upon rapeseed (Canola)

vegetable oil when there is the risk of an oil spill from a ruptured oil line.

Brake fluid is a subtype of hydraulic fluid with high boiling point and low freezing

point.

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Some hydraulic fluids have a bland, oily smell and others have no smell; some will burn

and some will not burn. Certain hydraulic fluids are produced from crude oil and others

are manufactured by many companies.

Because industrial hydraulic systems operate at thousands of PSI and temperatures

reaching several hundred degrees Fahrenheit, severe injuries and death can result from

component failures and care must always be taken when performing maintenance on

hydraulics.

4.3 RELIEF VALVE

The relief valve (RV) is a type of valve used to control or limit the pressure in a system

or vessel which can build up by a process upset, instrument or equipment failure, or fire.

The pressure is relieved by allowing the pressurised fluid to flow from an auxiliary

passage out of the system. The relief valve is designed or set to open at a predetermined

set pressure to protect pressure vessels and other equipment from being subjected to

pressures that exceed their design limits. When the set pressure is exceeded, the relief

valve becomes the "path of least resistance” as the valve is forced open and a portion of

the fluid is diverted through the auxiliary route. The diverted fluid (liquid, gas or liquid-

gas mixture) is usually routed through a piping system known as a flare header or relief

header to a central, elevated gas flare where it is usually burned and the

resulting combustion gases are released to the atmosphere. As the fluid is diverted, the

pressure inside the vessel will drop. Once it reaches the valve's reseating pressure, the

valve will close. The blow down is usually stated as a percentage of set pressure and

refers to how much the pressure needs to drop before the valve reseats. The blow down

can vary from roughly 2-20%, and some valves have adjustable blow downs.

In high-pressure gas systems, it is recommended that the outlet of the relief valve is in

the open air. In systems where the outlet is connected to piping, the opening of a relief

valve will give a pressure build up in the piping system downstream of the relief valve.

This often means that the relief valve will not re-seat once the set pressure is reached.

For these systems often so called "differential" relief valves are used. This means that

the pressure is only working on an area that is much smaller than the openings area of

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the valve. If the valve is opened the pressure has to decrease enormously before the

valve closes and also the outlet pressure of the valve can easily keep the valve open.

Another consideration is that if other relief valves are connected to the outlet pipe

system, they may open as the pressure in exhaust pipe system increases. This may cause

undesired operation.

In some cases, a so-called bypass valve acts as a relief valve by being used to return all

or part of the fluid discharged by a pump or gas compressor back to either a storage

reservoir or the inlet of the pump or gas compressor. This is done to protect the pump or

gas compressor and any associated equipment from excessive pressure. The bypass

valve and bypass path can be internal (an integral part of the pump or compressor) or

external (installed as a component in the fluid path). Many fire engines have such relief

valves to prevent the over pressurization of fire hoses.

In other cases, equipment must be protected against being subjected to an

internal vacuum (i.e., low pressure) that is lower than the equipment can withstand. In

such cases, vacuum relief valves are used to open at a predetermined low pressure limit

and to admit air or an inert gas into the equipment so as control the amount of vacuum.

4.4 CHAIR FRAME

It is the main support structure of our project. It provides support to hydraulic system

and other components of cargo lift system. It is made of cast iron consisting total of

eight pipes.

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4.5 SUPPORT FRAME

It encapsulates the hydraulic piston cylinder assembly and provides support to the

lifting plate such that it remains intact. It is made of cast iron. There are two support

frames for covering hydraulic assembly completely (left and right).

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4.6 RADIAL ARM

Basically the main function of radial arm is to provide simultaneous motion in two

perpendicular directions. There are two radial arms provided to connect the base plate to

support frame. It is made of cast iron. Radial arm helps to maintain the base plate in

horizontal position.

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4.7 LIFTING ARM

It connects the base plate to hydraulic piston. It is the main part which transmit the

hydraulic force develop by hydraulic assembly to base plate which lift the load in

accordance to the force developed.

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4.8 BASE PLATE

Both lifting arm and radial arm are attached to base plate. The main function of the base

plate is that it supports the load which is to be lifted. Base plate is a firm support made

up of cast iron and wood, the load which is to be raised or lowered is placed on it.

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5. SPECIFICATIONS

1. Chair frame – 8 pipes – 300*380*295(in mm).

2. Trail body – 300*450*165(in mm).

3. Base plate – 300*160(in mm).

4. Hydraulic unit ---

(a) Piston stroke length – 60 mm.

(b) Lifting height range – min 110 – max 190 (in mm).

(c) Load lifting capacity – 2 ton.

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6. CALCULATIONS

Lifting force calculation:

• Plift=W/A

• Plift=Lifting Pressure (Pressure Gauge in N/mm2)

• W=Weight Lift (N)

• A=Hydraulic Cylinder Area (mm2)

• Ppump=Pump Pressure (N/mm2)

• Ppump> Plift

• (Ppump - Plift)=Hydraulic Fluid Circulate Pressure (N/mm2)

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7. ADVANTAGES

The following are the merits or advantages of scientific material handling:

Reduction in labour cost: 

A proper system of material handling after loading and unloading of material reduces

the labour cost.

Reduction in transport cost: 

Improved material handling eliminates unnecessary movement of materials which

reduces transportation cost.

Less accident:

Due to scientific handling of materials there would be less chances of accident and

reduces cost of production.

Reduction of investment in equipments: 

An efficient material handling system ensures standardization of equipments. This

results reduction in cost of operation, repair maintenance and storage cost etc.

Better working conditions:

Scientific material handling provides better lay out of the store which results better

working condition for the employees. It increases the productivity of the organization.

Job satisfaction:

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Worker may be satisfied as the materials handed over scientifically. It leads to less

tiring and leads to greater job satisfaction.

Better customer service:

Material handling ensures timely production by reducing cost and providing qualitative

product to the ultimate consumers.

Smooth flow of materials:

The materials are quickly transported from one place to the other through the process of

scientific material handling.

Increases profit:

Reduction of cost, better working condition, job satisfaction etc. leads to higher

productivity and much profit.

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8. DISADVANTAGES

1. Mobile equipment may increase per-unit cost.

2. Scheduling activities becomes key challenge.

3. Arrivals of material and equipment are critical.

4. Storage space can be a problem.

5. Coordination requires narrow management span.

6. Accounting, purchasing, and inventory control functions are very complex.

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9. APPLICATIONS

1. Raw materials from receiving to the warehouse.

2. Parts from the warehouse to the assembly line.

3. Work in process through manufacturing cells.

4. packaged goods from palletizer to stretch wrapper.

5. palletized goods from the stretch wrapper to storage/shipping.

6. Finished goods from the warehouse to shipping.

7. Finished goods into trailers (trailer loading AGV) for shipping.

8. Man Lift

9. Brick Clamp

10. Car Lifting

11. Grab

12. Clamshell Bucket

13. Car Lifting

14. Pallet Lifting Fork.

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10. MATERIAL HANDLING EQUIPMENTS: RATIONAL USE

Now companies Mitsubishi Heavy Industry ltd, Technical Review Vol.40 No.1 (Feb

2003) think that the future material handling will be as described below. So they will be

positively developing technologies in open markets.

• More demands for environmental protection and safety since engines and power

electronics are the key components for environmental protection; they will place

importance on development of technologies for these key components. Regarding

safety, companies will adopt electronic control method to ensure safety.

• Rational “use” of vehicles concept that material handling vehicles should be

"exclusively used" for certain specified economic purposes are spreading among

customers. From the viewpoint of this concept, it is needed that the maintenance cost

should be reduced, and the vehicle operation conditions should be properly managed in

order to improve the efficiency in material handling. Besides the prolonging

maintenance intervals and proving-manufactured parts (recycled parts) for maintenance

at low prices, it becomes important to further develop the information technology (IT)

for material handling, such as collection and management of vehicle operation data,

upgrade of failure diagnosis technology, and preventive maintenance based on

reliability analysis. The vehicle related data accumulated will be very useful for

providing the better services in the future. For example, such data will be used for

proposal of optimum maintenance plans and of upgraded services.

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11. NEW GENERATION METERIAL HANDLING SYSTEM

The new-generation material handling system are highly automated system based on

latest technologies, provided with flexibility capable of changing its own structure or

function in response to changes from manufacturing systems, and autonomous functions

to enhance system reliability. Such system is defined as “MMHS - Metamorphic

Material Handling System”.

MMHS Project was the fifth international R&D project in IMS program, and its was to

contribute to industries, optimize life cycle of equipment, produce a system most suited

to the global environment, and respect humanity through research and development

activities. MMHS project perform research and development activities focusing on the

following four Points.

• Life cycle optimization

• Environmentally conscious manufacturing

• User-friendliness

• Contribution to global industry productivity

Subjects and objectives of MMHS project conceived from this viewpoint were as

follows.

• Responsive: Responsive to changes that may take place in manufacturing

technology and environment, type of product or material to be handled, work schedule

and load.

• Flexible: Capable of transforming itself and altering its function to meet any change

in handling requirements.

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• Autonomous: Able to make decisions on its own (to enhance system availability).

• Highly automatic: Incorporated with next-generation automation technology

• Multi-functional: Having such functions as assembling, packaging and

disassembling, besides transporting.

• Modularized: Composed of various modules, each with a distinct function; e.g.

Planning module, basic module, tool-setting module, communication module, capable

Of associating or dissociating one another to organize themselves into configurations

required

• Multi-level: Designed into multi-level sub-systems so as to be capable of

cooperating

Other independent material-handling equipment including AGVs and mobile robots

• Compatible: Capable of adapting itself to other existing material-handling systems

12. FUTURE IMPROVEMENT

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Present –Manual hand operated cargo lift system with no automatic control.

Future-Automatic control of fluid high capacity lifting system with the integration of following systems in our design,

1. Hydraulic pump

2. Motor

3. Control valve

4. Hydraulic fluid tank

5. Piping’s

6. Direction valve

7. Filters

8. Double acting hydraulic cylinder.

13. SUMMARY

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The material handling is important activity in the logistics system. The speed of the

material flow across the supply chain depends on the type of the material handling

equipment and the sophistication in the system. In the logistics operation the material

handling system is designed in and around the warehouse. Commonly, the following

material handling operations are performed in the warehouse, unloading the incoming

material from transport equipment, moving the unloaded material to the assigned

storage place, lift the material from its storage place during order picking, move the

material for inspection and packing, and load the packages on to the transport vehicle.

These operations are performed using manual, mechanized or computerized controlled

material handling equipment. The mechanized system shifts the fatigue to machine and

brings effectiveness to human efforts. The selection of the appropriate system depends

on the factors such as volumes to be handled, speed in handling, product characteristics

(weight, size, shape) and nature of the product (hazardous, perishable, crushable). The

prime consideration before going in for mechanized material handling the layout of

the warehouse. The investment in the material handling system will be sheer waste if it

is not compatible to the warehouse layout plan. The layout will create the obstacles for

the free movement of equipment and the goods. The mechanized equipment requires the

space for the free movement across the warehouse. They should have the accessibility to

storage area for material loading and unloading during storage and retrieval. In the

mechanized version the variety of equipment are used for the specific application. The

range covers common types are wheeled trolleys, forklift trucks, conveyors, cranes,

towlines and carousal etc. The more sophisticated systems such as robotics, automatic

storage & retrieval and automatic guided vehicles systems are used in semi or fully

automatic warehouses for speedy material movement.

14. REFERENCES

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1. Material handling industry of America (MHIA).

2. Material handling system and terminology by Edward Frazelle.

3. Reinventing the warehouse: world class distribution logistics.

4. Plant layout and material handling by Fred E. Meyers.

5. www.google.com, www.wikipedia.com, www.youtube.com .

6. College-Industry Council on Material Handling Education (CICMHE).

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