Dual Direction Gera Mechanisum

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DESIGN AND FABRICATION OF DUAL

DIRECTION GEAR MECHANISM FOR SHAPER

MACHINE

A PROJECT REPORT

Submitted by

D.GOPINATHAN (41707114006)

B.RAGULGANDHI (41707114036)

In partial fulfillment for the award of the degree

Of

BACHELOR OF ENGINEERING

In

SRI ANDAL ALAGAR COLLEGE OF ENGINEERING

ANNA UNIVERSITY CHENNAI: CHENNAI 600 025

APRIL 2010

ANNA UNIVERSITY CHENNAI: CHENNAI 600025


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BONAFIDE CERTIFICATE

Certified that this project report DESIGN OF DUAL DIRECTION GEAR

MECHANISM FOR SHAPER MECHANISM is the bonafide work of

D.GOPINATHAN, B.RAGULGANDHI who carried out the project work

under my supervision.

SIGNATURE SIGNATURE

Prof. N.RAMASAMY M.E Mr.T.YOGANANTHAM.

HEAD OF THE DEPARTMENT SUPERVISOR

Head of the Department Head of the Department

Mechanical Engineering Mechanical Engineering

Shri Andal Alagar College of Engg Shri Andal Alagar College of

Engg

Mamandur-603111. Mamandur-603111.

Submitted for the university examination held on ______________________

INTERNAL EXAMINER EXTERNAL EXAMINER

ACKNOWLEDGMENT


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First of we would like to extend our sincere gratitude to our chairPerson

Mrs.PRREMALATHA VIJAYAKANTH and our beloved secretary

Mr.L.K.SUDHISH for having provided the facilities to complete this project

work.

We would like to acknowledge the constant support provided by our

respected principal Dr.P.K.PRATAP CHANDRAN M.Tech, Ph.D., Who

bolstered us in all endeavors and has been responsible for inculcating us all

through ourcareer.

We feel ebullient to thanks our respectable Head of the Department in

charge Prof.Mr.N.RAMASAMY,Who provided laboratory facilities and

guidance to complete this project.

We are most fortunate in having the opportunity to work under our

department supervisor Mr.T.YOGANANTHAM M.Tech, and we express our

sincere thanks to him.

We are having immense pleasure to thank all our department staff

members, beloved parents and our friends for their constant support to do the

project successfully.

ABSTRACT


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Shaper is a reciprocating type machine tool which is primarily intended to

produce flat surfaces. The surfaces may be horizontal, vertical on inclined. This

machine involves the use of a single point cutting tool similar to a tool used in

lathe machine.

The intermediate gear unit may comprise either a spur gear and a

planetary gear assembly, or a pair of planetary gear assemblies. Change of

rotation within the gear unit can be effected easily.

Spur gear drive comprising a driven gear and driving gear wherein the

driving gear has double crowned teeth defined as (i) an envelope to a family of

surfaces generated by a skew or straight rack-cutter having a parabolic tooth

profile in normal section and then (ii) as an envelope to a family of tool

surfaces that are generated while the tool performs a plunging motion with

respect to the driving gear in the direction of the shortest distance between the

axes of rotation of the tool and the driving gear and tool plunging motion is

varied by a parabolic function, whose variable is displacement of the tool in a

direction parallel to the rotational axis of the driving gear.

The dual direction gear mechanism implemented in shaper machine in

this paper. There is used sun gear, ring gear and plant gear. Ring gear and sun

gear is meshed and the plant gear is meshed in sun gear. The plant and sun gear

is connected with electrical motor. The motor is rotating at clock wise direction

the ring and sun gear also rotating clock wise direction. The ring gear is having

50 teeth in 1800

and sun gear is having 14 teeth in 1450

but plant gear is having

28 teeth in 3600.This plant gear is rotated by ring and plant gear at so we get

front and backward direction and also we get dual direction ram of the shaper

machine.

LIST OF CONTENTS


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CHAPTER TITLE PAGE

ABSTRACT

TABLE OF CONTENTS

LIST OF FIGURES

NOMENCLATURE

1 INTORDUCTION

1.1 Shaper Machine

1.2 Function of Shaper Machine

1.3 Types of Shaper Machine

2 HISTORY

2.1 Invention of Shaper Machine

2.2 Machine Tool

2.3 Usage

3 SHAPER MACHINE

3.1 Shaper Machine Components

3.2 Types of Mechanism

3.2.1 With Worth QRM

3.2.2 Slotted QRM

4 REARANGED SHAPER MECHANISM

4.1 Introduction of Gears

4.2 Types of Gears

4.2.1 External vs. Internal Gears

4.2.2 Spur Gear

4.2.3 Helical Gear

4.2.4 Bevel Gear4.2.5 Hypoid Gear


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4.2.6 Crown Gear

4.2.7 Worm Gear

4.2.8 Non-Circular Gear

4.2.9 Rack And Pinion Gear

4.2.10 Epicyclical Gear

4.5 Applications of Gears

5 SPUR GEAR DESIGNE

5.1 Gear Ratio

5.2 Nomenclature of Gear

6 BELT DRIVE

6.1 Introduction of Belts

6.2 Types of Belts

6.2.1 Flat Belt

6.2.2 V Belt

6.2.3 Chain Belt

6.3 History of Belts

6.4 Usage

6.5 Application of Belts

7 BELT DESIGNE

7.1 Chain Drive

7.2 Chains versus Belts

7.3 Uses in Vehicles

7.3.1 Bicycles


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7.3.2 Automobiles

7.3.3 Inside Motors

7.3.4 Motorcycles

8 DESIGN CALCULATIONS

9 PHOTOGRAPHS

10 COST ESTIMATION

11 CONCLUSION

11.1 Conclusion

11.2 Bibliography

CHAPTER 1

INTRODUCTION

.

1.1 SHAPER MACHINE

A shaper is machine used for producing flat surfaces on the given work

piece. It can also be used for doing any type of machining operations but with

little difficulty. The shaper cuts the metal by reciprocating motion of the tool


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carrying ram. The first metal working shaper was developed by James Nasmyth

in the year 1936

A shaper is a type ofmachine tool that uses linearrelative motion

between the work piece and a single-point cutting tool to machine a linear tool

path. Its cut is analogous to that of a lathe, except that it is linear instead

ofhelical. A shaper is analogous to aplaner, but smaller, and with the cutter

riding a ram that moves above a stationary work piece, rather than the entire

work piece moving beneath the cutter. The ram is moved back and forth

typically by a crankinside the column; hydraulically actuated shapers also exist.

1.2 FOUNTION OF SHAPER MACHINE

A shaper operates by moving a hardened cutting tool backwards and

forwards across the work piece. On the return stroke of the ram the tool is lifted

clear of the work piece, reducing the cutting action to one direction only.

The work piece mounts on a rigid, box-shaped table in front of the

machine. The height of the table can be adjusted to suit this work piece, and the

table can traverse sideways underneath the reciprocating tool, which is mounted

on the ram. Table motion may be controlled manually, but is usually advanced

by automatic feed mechanism acting on the feed screw. The ram slides back and

forth above the work. At the front end of the ram is a vertical tool slide that may

be adjusted to either side of the vertical plane along the stroke axis. This tool-

slide holds the clapper box and tool post, from which the tool can be positioned

to cut a straight, flat surface on the top of the work piece.

1.3 TYPES OF SHAPER MACHINE

1)Based on type of mechanism employed for the movement of the cutting

tool i.e. tool carrying ram the shapers are classified in to three types

a. Crank type

b. Gear type
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c. Hydraulic type

2) According to position and movement of ram the shapers are classified in to

three types

a. Horizontal type

b. Vertical type

c. Travelling head type

3) Shapers are classified in to two types based on design of the work table

a. Standard shaper

b. Universal shaper

4) Based on type of cutting stroke employed these are classified in to

a. Push type

b. Draw type

CRANKTYPESHAPER

In these shapers the reciprocating ram is driven by crank mechanism. In

this a single point cutting tool is employed to do the operation. A crank is

connected to the ram and the bull gear to which the power is given through an

individual motor. These are most common type of shapers being used. The

reciprocating length of tool will be always is equal to the length of stroke.

GEAR TYPE SHAPER

These are the rarely used shapers. In these shapers a rack and pinion are

employed the rack is attached to the lower part of the ram and on which the

pinion moves. The power is transmitted from the bull gear. A grain train is

engaged for the transfer of power from the bull gear to pinion.


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HYDRAULIC TYPE SHAPER

These shapers run on hydraulic power. The end of the ram is connected to a

piston fitted in to a cylinder. Oil is fed in to the cylinder initially the oil acts in

one direction and the ram moves in one direction. A varying pressure is applied

on the oil so as to obtain the reciprocating motion of the ram. One of the main

advantage of this shaper is a constant speed can be obtained from the starting of

the machining operation. There will be no fluctuations in the cutting speed and

stroke of the ram. Another important advantage of this shaper is no sound willbe produced hence a noise free environment can be obtained.

HORIZONTAL SHAPER

As the name indicates these shapers have the motion of ram along the

horizontal axis. This type of shapers is generally used for generation of fine a

surface.

VERTICALSHAPER

In these shapers the tool containing ram has its motion in vertical

direction. In some of the shapers a provision of 100 rotation of the ram is also

provided. In vertical shaper the ram may be driven by various types like crank

driven, screw driven, gear driven, or by hydraulic power. Vertical shapingmachines finds many applications in deep hole boring, machining internal

surfaces, keyways, grooves etc. vertical shaper has a very robust table which

can have cross, longitudinal, and rotational movement. The tool used on a

vertical shaper is totally different from that of the normal tool.

TRAVELLING HEAD TYPE SHAPER


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This type of shaper is generally employed for machining very large

objects that cannot be mounted on the table of the machine and cannot be

moved. In this machine the ram having reciprocating movement also provides

crosswise movement simultaneously such that the tool can cut the required

shape on the work piece.

STANDARD SHAPER

In this shaper the table has only two movements i.e. vertical and

horizontal. The table may or may not be supported on the other end. These are

not generally used.

UNIVERSAL SHAPER

In these shapers in addition to the above mentioned two movements of the

standard shaper it provides two more directions.

1) By swelling the table about a axis ram ways.

2) The table can be tilted about an axis perpendicular to the 1st one

so due to these two features any operation at any angle can be performed very

easily. So due to these features the shaper is termed as a universal shaper

PUSH TYPE SHAPER

It is one of the most commonly used shaper. In this the metal is removed

when the ram is moving away from the column. This type of shaper pushes the

work piece while removing the work piece away from it so this shaper is called

as push type shaper.

DRAW TYPE SHAPER

It is just a converse of the push type shaper. In these machines the metalis removed from the work piece when the ram is moving towards the column.


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So due to this the work piece takes a force in the direction towards the column

of the work piece. Due to this action the forces over the column and bearings

are somewhat reduced. The tool is required to be mounted in opposite direction

to the normal conditions. The vibrations on machine components are also

damped to some extent.

CHAPTER 2

HISTORY

1.2 INVENTION OF SHAPER MACHINE

Roe (1916) credits James Nasmyth with the invention of the shaper in

1836. Shapers were very common in industrial production from the mid-19th

century through the mid-20th. In current industrial practice, shapers have been

largely superseded by other machine tools (especially of the CNC type),

including milling machines, grinding machines, andbroaching machines. But

the basic function of a shaper is still sound; tooling for them is minimal and
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very cheap to reproduce; and they are simple and robust in construction, making

their repair and upkeep easily achievable. Thus they are still popular in many

machine shops, fromjobbing shops orrepair shops to tool and die shops, where

only one or a few pieces are required to be produced and the alternative

methods are cost- or tooling-intensive. They also have considerable retro appeal

too many hobbyist machinists, who are happy to obtain a used shaper or, in

some cases, even to build a new one from scratch.

2.2. MACHIN TOOL

Before the Industrial Revolution of the 18th century, hand tools were

used to cut and shape materials for the production of goods such as cooking

utensils, wagons, ships, furniture, and other products. After the advent of

the steam engine, material goods were produced by power-driven machines that

could only be manufactured by machine tools. Machine tools (capable of

producing dimensionally accurate parts in large quantities) and jigs and fixtures

(for holding the work and guiding the tool) were the indispensable innovationsthat made mass production and interchangeable realities in the 19th century

2.3 USAGE

The most common use is to machine straight, flat surfaces but with

ingenuity and some accessories a wide range of work can be done. Other

examples of its use are:

1) Keyways in the boss of apulley orgearcan be machined without

resorting to a dedicatedbroaching setup.

2) Dovetail slides

3) Internal spines
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4) Keyway cutting inblind holes

CHAPTER 3

SHAPER MACHINE

3.1 BASIC SHAPER MACHINE COMPONENTS

It is consist of many components are,

1) Ram

2) Tool post (or) Tool head

3) Tool feed handle

4) Vice5) Adjustable sliding support
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6) Table

7) Clapper Box

8) Graduated collar

9) Ram clamping nut

10)Scale indictor

11)Clutch handle

12) Cross traverse handle

Fig:3.1 Full Shaper machine

Fig:3.2 Shaper machine head

3.2 TYPES OF MECHANISM


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Shaper machine is working at many mechanisms. It is classified 3

types.

1) Quick return mechanism (QRM)

2) Slotted QRM

3) Hydraulic QRM

3.2.1 QUICK RETURN MECHANISM (QRM)

While designing a mechanism either for function generation [1] or

for path generation [2] or for rigid-body guidance applications, it is

necessary to take into account not only the structural error but also the

mechanical error resulting due to tolerances on link-lengths, clearances in

link joints [3], and static and dynamic deflection of links [4]. Various

attempts have been made to analyze and synthesize the mechanical error

of function and path generating linkages. There are two distinct

approaches deterministic and stochastic. The deterministic approaches are

based on worst-case analysis of individual tolerances [1], [2], [3], [5], [6].

On the other hand, Dhande, Mallik and Chakra borty [7], [8] have used a

stochastic model to allocate tolerance and clearance in four-bar function

generators, while Shi [9] allocated them in spatial linkages. In this paper,

the effect of practical manufacturing tolerances is analyzed by using

deterministic approach. It was observed on an example [2] (using a

approach based on the worst case analysis of the individual tolerances)

that the mechanical error resulting due to practical manufacturingtolerances is greater than the mechanical error resulting due to clearances

in link joints.


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Fig:3.3 Quick Return Mechanism

3.2.2 SLOTTED QRM

Slotted link mechanism is very common in mechanical shapers. The

mechanism is simple and compact. It converts the rotary motion of the electric

motor and gearbox into the reciprocating motion of the ram. The slotted link

mechanism gives the rain a higher velocity during the return non cutting stroke

than during its forward cutting stroke thereby reducing the time wasted during

the return stroke. The bull gear is driven by a pinion which is connected to the


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motor shaft through a gearbox with four, eight or more speeds available. The

bull wheel has a slot. The crank pin A is secured into this slot; at the same time

it can slide in the slotted crank B.

When the bull wheel rotates, the crank pin A also rotates and side by side

slides through the slot in the slotted crank B. This makes the slotted crank to

oscillate about its one end C. This oscillating motion of slotted crank (through

the link D) makes the ram to reciprocate. The intermediate link D is necessary

to accommodate the rise and fall of the crank. The position of the crank pin A in

the slot in the bull wheel decides the length of the stroke of the shaper. Thefurther it is away from the centre of bull wheel, the longer is the stroke.

Fig:3.4 Slotted Mechanism

The cutting stroke of the ram is completed while the crank pin moves

from A to A1 and the slotted link goes from left to right. Similarly, during return

stroke crank pin moves from A1 to A and the link changes its position from right

to left. The time taken by cutting and idle strokes of the ram is proportional to

the angles AZA1 and A1ZA respectively.

Cutting time/Idle time = angles of AZA1/angles of A1ZA .

Since the crank pin A rotates with uniform velocity and angles of A1ZA is

smaller, it is obvious that the idle return stroke is quicker than the forward


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cutting stroke and hence the slotted link mechanism is known as quick return

mechanism.

CHAPTER 4

REARANGED SHAPER MECHANISM

4.1 INTRODUCTION OF GEARS

A gear is a rotatingmachine part having cut teeth, or cogs, which mesh

with another toothed part in order to transmit torque. Two or more gears

working in tandem are called a transmission and can produce a mechanical

advantage through a gear ratio and thus may be considered a simple machine.

Geared devices can change the speed, magnitude, and direction of a power
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source. The most common situation is for a gear to mesh with another gear ,

however a gear can also mesh a non-rotating toothed part, called a rack, thereby

producing translation instead of rotation. The gears in a transmission are

analogous to the wheels in apulley. An advantage of gears is that the teeth of a

gear prevent slipping.

When two gears of unequal number of teeth are combined a mechanical

advantage is produced, with both the rotational speeds and the torques of the

two gears differing in a simple relationship. In transmissions which offer

multiple gear ratios, such as bicycles and cars, the term gear, as in first gear,

refers to a gear ratio rather than an actual physical gear. The term is used to

describe similar devices even when gear ratio is continuous rather than discrete,

or when the device does not actually contain any gears, as in a continuously

variable transmission.

The earliest known reference to gears was circa 50 A.D. by Hero of

Alexandria, but they can be traced back to the Greek mechanics of the

Alexandrian school in the 3rd century BC and were greatly developed by the

GreekpolymathArchimedes.

4.2 TYPES OF GEARS

4.2.1 EXTERNAL VS INTERNAL GEARS

An external gear is one with the teeth formed on the outer surface of a

cylinder or cone. Conversely, an internal gear is one with the teeth formed on

the inner surface of a cylinder or cone. For bevel gears, an internal gear is one

with the pitch angle exceeding 90 degrees. Internal gears do not cause direction

reversal.
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Fig:4.1 External Vs Imternal Gear

4.2.2SPUR GEAR

Spur gears or straight-cut gears are the simplest type of gear. They consist

of a cylinder or disk, and with the teeth projecting radically, and although they

are not straight-sided in form, the edge of each tooth thus is straight and aligned

parallel to the axis of rotation. These gears can be meshed together correctly

only if they are fitted to parallel axles.

Fig:4.2 Spur Gear

4.2.3 HELICAL GEAR

Helical gears offer a refinement over spur gears. The leading edges of the

teeth are not parallel to the axis of rotation, but are set at an angle. Since the

gear is curved, this angling causes the tooth shape to be a segment of a helix.

Helical gears can be meshed in a parallel or crossed orientations. The former

refers to when the shafts are parallel to each other; this is the most common

orientation. In the latter, the shafts are non-parallel. The angled teeth engage

more gradually than do spur gear teeth causing them to run more smoothly and

quietly. With parallel helical gears, each pair of teeth first make contact at asingle point at one side of the gear wheel; a moving curve of contact then grows
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gradually across the tooth face to a maximum then recedes until the teeth break

contact at a single point on the opposite side. In spur gears teeth suddenly meet

at a line contact across their entire width causing stress and noise. Spur gears

make a characteristic whine at high speeds and can not take as much torque as

helical gears. Whereas spur gears are used for low speed applications and those

situations where noise control is not a problem, the use of helical gears is

indicated when the application involves high speeds, large power transmission,

or where noise abatement is important. The speed is considered to be high when

the pitch line velocity exceeds 25 m/s

A disadvantage of helical gears is a resultant thrust along the axis of the

gear, which needs to be accommodated by appropriate thrust bearings, and a

greater degree of sliding friction between the meshing teeth, often addressed

with additives in the lubricant. For a crossed configuration the gears must have

the same pressure angle and normal pitch, however the helix angle and

handedness can be different. The relationship between the two shafts is actually

defined by the helix angle(s) of the two shafts and the handedness, as defined:

E = 1 + 2 for gears of the same handedness

E = 1 2 for gears of opposite handedness

Where is the helix angle for the gear. The crossed configuration is less

mechanically sound because there is only a point contact between the gears,

whereas in the parallel configuration there is a line contact.

Fig:4.3 Helical Gear
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4.2.4 BEVEL GEAR

A bevel gear is shaped like a right circular cone with most of its tip cut

off. When two bevel gears mesh their imaginary vertexes must occupy the same

point. Their shaft axes also intersect at this point, forming an arbitrary non-

straight angle between the shafts. The angle between the shafts can be anything

except zero or 180 degrees. Bevel gears with equal numbers of teeth and shaft

axes at 90 degrees are called miter gears.

Fig:4.4 Bevel Gear

4.2.5 HYPOID GEAR

Hypoid gears resemble spiral bevel gears except the shaft axes do not

intersect. The pitch surfaces appear conical but, to compensate for the offset

shaft, are in fact hyperboloids of revolution. Hypoid gears are almost alwaysdesigned to operate with shafts at 90 degrees. Depending on which side the

shaft is offset to, relative to the angling of the teeth, contact between hypoid

gear teeth may be even smoother and more gradual than with spiral bevel gear

teeth. Also, the pinion can be designed with fewer teeth than a spiral bevel

pinion, with the result that gear ratios of 60:1 and higher are feasible using a

single set of hypoid gears. This style of gear is most commonly found in

mechanical differentials.

Fig:4.5 Hypoid Gear
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4.2.6 CROWN GEAR

Crown gears or contrite gears are a particular form of bevel gear whose

teeth project at right angles to the plane of the wheel; in their orientation the

teeth resemble the points on a crown. A crown gear can only mesh accurately

with another bevel gear, although crown gears are sometimes seen meshing with

spur gears. A crown gear is also sometimes meshed with an escapement such as

found in mechanical clocks.

Fig:4.6 Crown Gear

4.2.7 WORM GEAR

Worm gears resemble screws. A worm gear is usually meshed with an

ordinary looking, disk-shaped gear, which is called the gear, wheel, or worm

wheel.

Worm-and-gear sets are a simple and compact way to achieve a high gear

ratio. For example, helical gears are normally limited to gear ratios of less than

10:1 while worm-and-gear sets vary from 10:1 to 500:1. A disadvantage is the

potential for considerable sliding action, leading to low efficiency

Fig:4.7 Worm Gear
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4.2.8 NON-CIRCULAR GEAR

Non-circular gears are designed for special purposes. While a regular

gear is optimized to transmit torque to another engaged member with minimum

noise and wear and maximum efficiency, a non-circular gear's main objective

might be ratio variations, axle displacement oscillations and more. Common

applications include textile machines,potentiometers and continuously variable

transmissions.

Fig:4.8 Non-Circular Gear

4.2.9 RACK AND PINION GEAR

A rack is a toothed bar or rod that can be thought of as a sector gear with

an infinitely large radius of curvature. Torque can be converted to linear force

by meshing a rack with a pinion: the pinion turns; the rack moves in a straight

line. Such a mechanism is used in automobiles to convert the rotation of the

steering wheel into the left-to-right motion of the tie rod(s).

Fig:4.9 Rack and Pinion Gear

Racks also feature in the theory of gear geometry, where, for instance, the tooth

shape of an interchangeable set of gears may be specified for the rack and the
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tooth shapes for gears of particular actual radii then derived from that. The rack

and pinion gear type is employed in a rack railway.

4.2.10 EPICYCLICAL GEAR

In epicyclical gearing one or more of the gearaxes moves. Examples are sun

and planet gearing (see below) and mechanical differentials.

Fig:4.10 Epicyclical Gear

4.5 APPLICATIONS OF GEARS

Gears are mostly used in various machines and industries. With the

moving wheel of science and technology the use of gears has become more

common in all the upcoming industries. They form an essential part in running

of machines and vehicles. There are a number of different types of gears used in

different industries depending upon their properties and usage. They can be

classified under automotive gears, mining gears, wind turbines, bicycle gears,

mill heads, instrumentation gears, conveyor system, marine gears etc.,,

4.6 USAGE

Gears are used for two basic purposes; increase or decrease of rotation

speed and increase or decrease of power or torque. Torque is a measure of a

force to produce torsion and rotation about an axis. To increase speed and

reduce torque a large drive gear is coupled to a smaller driven gear. To reduce

speed and increase torque a small Lego gear turning a larger gear is used. They

are also used for enhancement for positioning systems.
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CHAPTER 5

SPUR GEAR DESIGNE

5.1 GEAR RATIO

The gear ratio is the relationship between the numbers of teeth on two

gears that are meshed or two sprockets connected with a common roller chain,or the circumferences of twopulleys connected with a drivebelt.

In other words, the gear ratio is proportional to ratio of the gear diameters

and inversely proportional to the ratio of gear speeds. Belts can have teeth in

them also and be coupled to gear-like pulleys. Special gears called sprockets

can be coupled together with chains, as on bicycles and some motorcycles.

Again, exact accounting of teeth and revolutions can be applied with thesemachines.

Gear Ratio (GR) = (No of teeth on Gear or driven) / (No of teeth on Pinion or

driver)
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5.2 NAMUNCLATURE OF GEAR Fig:5.1 Gear Namunclature

ROTATIONAL FREQUENCY, N

Measured in rotation over time, such as RPM.

ANGULAR FREQUENCY,

Measured in radians per second. 1RPM = / 30 rad/second

NUMBER OF TEETH, N

How many teeth a gear has, an integer.

GEAR, WHEEL

The larger of two interacting gears.
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PINION

The smaller of two interacting gears.

PATH OF CONTACTPath followed by the point of contact between two meshing gear teeth.

LINE OF ACTION, PRESSURE LINE

Line along which the force between two meshing gear teeth is directed. It

has the same direction as the force vector. In general, the line of action changes

from moment to moment during the period of engagement of a pair of teeth. For

involutes gears, however, the tooth-to-tooth force is always directed along the

same linethat is, the line of action is constant. This implies that for involutes

gears the path of contact is also a straight line, coincident with the line of action

as is indeed the case.

AXIS

Axis of revolution of the gear; center line of the shaft.

PITCH POINT, P

Point where the line of action crosses a line joining the two gear axes.

PITCH CIRCLE, PITCH LINE

Circle centered on and perpendicular to the axis, and passing through the

pitch point.

PITCH DIAMETER, D

Diameter of a pitch circle. Equal to twice the perpendicular distance from

the axis to the pitch point. The nominal gear size is usually the pitch diameter.

MODULE, M

The pitch diameter divided by the number of teeth.

OPERATING PITCH DIAMETERS

Diameters determined from the number of teeth and the center distance at

which gears operate.
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Example for pinion:

PITCH SURFACEIn cylindrical gears, cylinder formed by projecting a pitch circle in the

axial direction. More generally, the surface formed by the sum of all the pitch

circles as one moves along the axis. For bevel gears it is a cone.

ANGLE OF ACTION

Angle with vertex at the gear center, one leg on the point where mating

teeth first make contact, the other leg on the point where they disengage.

ARC OF ACTION

Segment of a pitch circle subtended by the angle of action.

PRESSURE ANGLE,

The complement of the angle between the direction that the teeth exert

force on each other, and the line joining the centers of the two gears. For

involutes gears, the teeth always exert force along the line of action, which, for

involutes gears, is a straight line; and thus, for involutes gears, the pressure

angle is constant.

OUTSIDE DIAMETER,DO

Diameter of the gear, measured from the tops of the teeth.

ROOT DIAMETER

Diameter of the gear, measured at the base of the tooth.

ADDENDUM, A

Radial distance from the pitch surface to the outermost point of the

tooth. a = (Do D) / 2

DEDENDUM, B

Radial distance from the depth of the tooth trough to the pitch

surface. b = (D root diameter) / 2


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WHOLE DEPTH,HT

The distance from the top of the tooth to the root; it is equal to addendum

plus dedendum or to working depth plus clearance.CLEARANCE

Distance between the root circle of a gear and the addendum circle of its

mate.

WORKING DEPTH

Depth of engagement of two gears, that is, the sum of their operating

addendums.

CIRCULAR PITCH, P

Distance from one face of a tooth to the corresponding face of an adjacent

tooth on the same gear, measured along the pitch circle.

DIAMETRAL PITCH,PD

Ratio of the number of teeth to the pitch diameter. Could be measured in

teeth per inch or teeth per centimeter.

BASE CIRCLE

In involutes gears, where the tooth profile is the involutes of the base

circle. The radius of the base circle is somewhat smaller than that of the pitch

circle.

BASE PITCH, NORMAL PITCH,PB

In involutes gears, distance from one face of a tooth to the corresponding

face of an adjacent tooth on the same gear, measured along the base circle.

INTERFERENCE

Contact between teeth other than at the intended parts of their surfaces.

INTERCHANGEABLE SET

A set of gears, any of which will mate properly with any other.


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TOOTH CONTACT NOMENCLATURE

Line of contact

Path of action

Line of actionPlane of action

Lines of contact (helical

gear) Arc of actionLength of action

Limit diameter

Face advanceZone of action

Fig:5.2 Tooth contact nomenclature

POINT OF CONTACT

Any point at which two tooth profiles touch each other.

LINE OF CONTACT

A line or curve along which two tooth surfaces are tangent to each other.

PATH OF ACTION

The locus of successive contact points between a pair of gear teeth,

during the phase of engagement. For conjugate gear teeth, the path of action
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passes through the pitch point. It is the trace of the surface of action in the plane

of rotation.

LINE OF ACTIONThe path of action for involutes gears. It is the straight line passing

through the pitch point and tangent to both base circles.

SURFACE OF ACTION

The imaginary surface in which contact occurs between two engaging

tooth surfaces. It is the summation of the paths of action in all sections of the

engaging teeth.

PLANE OF ACTION

The surface of action for involutes, parallel axis gears with either spur or

helical teeth. It is tangent to the base cylinders.

ZONE OF ACTION (CONTACT ZONE)

For involutes, parallel-axis gears with either spur or helical teeth, is the

rectangular area in the plane of action bounded by the length of action and the

effective face width.

PATH OF CONTACT

The curve on either tooth surface along which theoretical single point

contact occurs during the engagement of gears with crowned tooth surfaces or

gears that normally engage with only single point contact.

LENGTH OF ACTION

The distance on the line of action through which the point of contact

moves during the action of the tooth profile.

ARC OF ACTION, QT

The arc of the pitch circle through which a tooth profile moves from the

beginning to the end of contact with a mating profile.

ARC OF APPROACH, QA
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The arc of the pitch circle through which a tooth profile moves from its

beginning of contact until the point of contact arrives at the pitch point.

ARC OF RECESS, QRThe arc of the pitch circle through which a tooth profile moves from

contact at the pitch point until contact ends.

CONTACT RATIO, MC,

The number of angular pitches through which a tooth surface rotates from

the beginning to the end of contact. In a simple way, it can be defined as a

measure of the average number of teeth in contact during the period in which a

tooth comes and goes out of contact with the mating gear.

TRANSVERSE CONTACT RATIO, MP,

The contact ratio in a transverse plane. It is the ratio of the angle of action

to the angular pitch. For involutes gears it is most directly obtained as the ratio

of the length of action to the base pitch.

FACE CONTACT RATIO, MF,

The contact ratio in an axial plane or the ratio of the face width to the

axial pitch. For bevel and hypoid gears it is the ratio of face advance to circular

pitch.

TOTAL CONTACT RATIO, MT,

The sum of the transverse contact ratio and the face contact ratio.

= +

mt = mp + mF

MODIFIED CONTACT RATIO, MO

For bevel gears, the square root of the sum of the squares of the

transverse and face contact ratios.


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LIMIT DIAMETER

Diameter on a gear at which the line of action intersects the maximum (or

minimum for internal pinion) addendum circle of the mating gear. This is also

referred to as the start of active profile, the start of contact, the end of contact,

or the end of active profile.

START OF ACTIVE PROFILE (SAP)

Intersection of the limit diameter and the involute profile.

FACE ADVANCEDistance on a pitch circle through which a helical or spiral tooth moves

from the position at which contact begins at one end of the tooth trace on the

pitch surface to the position where contact ceases at the other end.

TOOTH THICKNESS NOMECLATURE


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Tooth thickness

Thickness

relationships

Choral thickness

Tooth thickness

measurement over

pins

Span

measurementLong and shortaddendum teeth

Fig:5.3 Tooth Thickness Nomenclature

d

CIRCULAR THICKNESS

Length of arc between the two sides of a gear tooth, on the

specified datum circle.

TRANSVERSE CIRCULAR THICKNESS

Circular thickness in the transverse plane.

NORMAL CIRCULAR THICKNESS

Circular thickness in the normal plane. In a helical gear it may be

considered as the length of arc along a normal helix.

AXIAL THICKNESS
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In helical gears and worms, tooth thickness in an axial cross section at the

standard pitch diameter.

BASE CIRCULAR THICKNESSIn involutes teeth, length of arc on the base circle between the two

involutes curves forming the profile of a tooth.

NORMAL CHORDAL THICKNESS

Length of the chord that subtends a circular thickness arc in the plane

normal to the pitch helix. Any convenient measuring diameter may be selected,

not necessarily the standard pitch diameter.

CHORDAL ADDENDUM (CHORDAL HEIGHT)

Height from the top of the tooth to the chord subtending the circular

thickness arc. Any convenient measuring diameter may be selected, not

necessarily the standard pitch diameter.

PROFILE SHIFT

Displacement of the basic rackdatum line from the reference cylinder,

made non-dimensional by dividing by the normal module. It is used to specify

the tooth thickness, often for zero backlash.

RACK SHIFT

Displacement of the tool datum line from the reference cylinder, made

non-dimensional by dividing by the normal module. It is used to specify the

tooth thickness.

MEASUREMENT OVER PINS

Measurement of the distance taken over a pin positioned in a tooth space

and a reference surface. The reference surface may be the reference axis of the

gear, a datum surface or either one or two pins positioned in the tooth space or

spaces opposite the first. This measurement is used to determine tooth

thickness.

SPAN MEASUREMENT
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Measurement of the distance across several teeth in a normal plane. As

long as the measuring device has parallel measuring surfaces that contact on an

unmodified portion of the involutes, the measurement will be along a line

tangent to the base cylinder. It is used to determine tooth thickness.

MODIFIED ADDENDUM TEETH

Teeth of engaging gears, one or both of which have non-standard

addendum.

FULL-DEPTH TEETH

Teeth in which the working depth equals 2.000 divided by the normal

diametral pitch.

STUB TEETH

Teeth in which the working depth is less than 2.000 divided by the

normal diametral pitch.

EQUAL ADDENDUM TEETH

Teeth in which two engaging gears have equal addendums.

LONG AND SHORT-ADDENDUM TEETH

Teeth in which the addendums of two engaging gears are unequal

PITCH NOMENCLATURE

Pitch is the distance between a point on one tooth and the corresponding

point on an adjacent tooth. It is a dimension measured along a line or curve in

the transverse, normal, or axial directions. The use of the single

word pitch without qualification may be ambiguous, and for this reason it is

preferable to use specific designations such as transverse circular pitch, normal

base pitch, axial pitch.


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Pitch Tooth pitchBase pitch relationships Principal pitches

Fig:5.4 Pitch Nomeclature

CIRCULAR PITCH,P

Arc distance along a specified pitch circle or pitch line between

corresponding profiles of adjacent teeth.

TRANSVERSE CIRCULAR PITCH,PT

Circular pitch in the transverse plane.

NORMAL CIRCULAR PITCH,PN,PE

Circular pitch in the normal plane, and also the length of the arc along the

normal pitch helix between helical teeth or threads.

AXIAL PITCH,PX

Linear pitch in an axial plane and in a pitch surface. In helical gears and

worms, axial pitch has the same value at all diameters. In gearing of other types,

axial pitch may be confined to the pitch surface and may be a circular

measurement. The term axial pitch is preferred to the term linear pitch. The

axial pitch of a helical worm and the circular pitch of its worm gear are the

same.

NORMAL BASE PITCH,PN,PBN

An involutes helical gear is the base pitch in the normal plane. It is the

normal distance between parallel helical involutes surfaces on the plane of

action in the normal plane, or is the length of arc on the normal base helix. It is

a constant distance in any helical involutes gear.
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TRANSVERSE BASE PITCH,PB,PBT

In an involutes gear, the pitch on the base circle or along the line of

action. Corresponding sides of involutes gear teeth are parallel curves, and the base pitch is the constant and fundamental distance between them along a

common normal in a transverse plane.

DIAMETRAL PITCH (TRANSVERSE),PD

Ratio of the number of teeth to the standard pitch diameter in inches.

NORMAL DIAMETRAL PITCH,PND

Value of diametral pitch in a normal plane of a helical gear or worm.

ANGULAR PITCH, N,

Angle subtended by the circular pitch, usually expressed in radians.

degrees or radians

BACKLASH

Backlash is the error in motion that occurs when gears change direction.

It exists because there is always some gap between the trailing face of the

driving tooth and the leading face of the tooth behind it on the driven gear, and

that gap must be closed before force can be transferred in the new direction. The

term "backlash" can also be used to refer to the size of the gap, not just the

phenomenon it causes; thus, one could speak of a pair of gears as having, for

example, "0.1 mm of backlash." A pair of gears could be designed to have zero

backlash, but this would presuppose perfection in manufacturing, uniform

thermal expansion characteristics throughout the system, and no lubricant.

Therefore, gear pairs are designed to have some backlash. It is usually providedby reducing the tooth thickness of each gear by half the desired gap distance. In
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the case of a large gear and a small pinion, however, the backlash is usually

taken entirely off the gear and the pinion is given full sized teeth. Backlash can

also be provided by moving the gears farther apart.

For situations, such as instrumentation and control, where precision is

important, backlash can be minimized through one of several techniques. For

instance, the gear can be split along a plane perpendicular to the axis, one half

fixed to the shaft in the usual manner, the other half placed alongside it, free to

rotate about the shaft, but with springs between the two halves providing

relative torque between them, so that one achieves, in effect, a single gear with

expanding teeth. Another method involves tapering the teeth in the axial

direction and providing for the gear to be slid in the axial direction to take up

slack.

SHIFTING DEARS

In some machines (e.g., automobiles) it is necessary to alter the gear ratio

to suit the task. There are several methods of accomplishing this. For example:

1) Transmission

2) Automatic gearbox

3) Derailleur gears which are actually sprockets in combination

with a roller chain

4) Hub gears (also called epicyclical gearing or sun-and-planet

gears)

There are several outcomes of gear shifting in motor vehicles. In the case ofair

pollution emissions, there are higher pollutant emissions generated in the lower

gears, when the engine is working harder than when higher gears have been

attained. In the case ofvehicle noise emissions, there are highersound

levels emitted when the vehicle is engaged in lower gears. This fact has been

utilized in analyzing vehicle generated sound since the late 1960s, and has been
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incorporated into the simulation of urban roadway noise and corresponding

design of urban noise along roadways.

TOOTH PROFILE

Profile of a spur gearUndercut

Fig:5.5 Tooth Profile

A profile is one side of a tooth in a cross section between the outside

circle and the root circle. Usually a profile is the curve of intersection of a tooth

surface and a plane or surface normal to the pitch surface, such as the

transverse, normal, or axial plane.

The fillet curve (root fillet) is the concave portion of the tooth profile where it

joins the bottom of the tooth space.2

As mentioned near the beginning of the article, the attainment of a non

fluctuating velocity ratio is dependent on the profile of the teeth. Friction and

wear between two gears is also dependent on the tooth profile. There are a greatmany tooth profiles that will give a constant velocity ratio, and in many cases,

given an arbitrary tooth shape, it is possible to develop a tooth profile for the

mating gear that will give a constant velocity ratio. However, two constant

velocity tooth profiles have been by far the most commonly used in modern

times. They are the cycloid and the involutes. The cycloid was more common

until the late 1800s; since then the involutes has largely superseded it,

particularly in drive train applications. The cycloid is in some ways the more
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interesting and flexible shape; however the involutes has two advantages: it is

easier to manufacture, and it permits the center to center spacing of the gears to

vary over some range without ruining the constancy of the velocity ratio.

Cycloid gears only work properly if the center spacing is exactly right. Cycloid

gears are still used in mechanical clocks.

An undercut is a condition in generated gear teeth when any part of the

fillet curve lies inside of a line drawn tangent to the working profile at its point

of juncture with the fillet. Undercut may be deliberately introduced to facilitate

finishing operations. With undercut the fillet curve intersects the working

profile. Without undercut the fillet curve and the working profile have a

common tangent.

CHAPTER 6

BELT DRIVE
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6.1 INTRODUCTION OF BELTS

A belt is a loop of flexible material used to link two or more

rotating shafts mechanically. Belts may be used as a source of motion,to transmit powerefficiently, or to track relative movement. Belts are looped

overpulleys. In a two pulley system, the belt can either drive the pulleys in the

same direction, or the belt may be crossed, so that the direction of the shafts is

opposite. As a source of motion, a conveyor belt is one application where the

belt is adapted to continually carry a load between two points.

6.2 TYPES OF BELTS

6.2.1FLAT BELTS

Flat belts were used early in line shafting to transmit power in factories.[1]

It is a simple system of power transmission that was well suited to its day. It

delivered high power for high speeds (500 hp for 10,000 ft/min), in cases of

wide belts and large pulleys. These drives are bulky, requiring high tension

leading to high loads, so vee belts have mainly replaced the flat-belts except

when high speed is needed over power.

Fig:6.1 Flat Belt

6.2.2ROUND BELTS
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Round belts are a circular cross section belt designed to run in a pulley

with a circular (or near circular) groove. They are for use in low torque

situations and may be purchased in various lengths or cut to length and joined,

either by a staple, gluing or welding (in the case ofpolyurethane). Early sewing

machines utilized a leather belt, joined either by a metal staple or glued, to great

effect.

6.2.3VEE BELTS

V belts (also known as V-belt or wedge rope) solved the slippage and

alignment problem. It is now the basic belt for power transmission. They

provide the best combination of traction, speed of movement, load of the

bearings, and long service life. The V-belt was developed in 1917 by John

Gates of the Gates Rubber Company. They are generally endless, and their

general cross-section shape is trapezoidal. The "V" shape of the belt tracks in a

mating groove in thepulley (or sheave), with the result that the belt cannot slip

off. The belt also tends to wedge into the groove as the load increases thegreater the load, the greater the wedging action improving torque

transmission and making the "V" belt an effective solution, needing less width

and tension than flat belts.

Fig:6.2 V Belt

6.2.4RIBBED BELT
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A ribbed belt is a power transmission belt featuring lengthwise grooves. It

operates from contact between the ribs of the belt and the grooves in the pulley.

Its single-piece structure it reported to offer an even distribution of tension

across the width of the pulley where the belt is in contact, a power range up to

600 kw, a high speed ratio, serpentine drives (possibility to drive off the back of

the belt), long life, stability and homogeneity of the drive tension, and reduced

vibration. The ribbed belt may be fitted on various applications : compressors,

fitness bikes, agricultural machinery, food mixers, washing machines, lawn

mowers, etc..,

6.2.5FILM BELTS

Hough often grouped with flat belts; they are actually a different kind.

They consist of a very thin belt (0.5-15 millimeters or 100-4000 micrometers)

strip of plastic and occasionally rubber. They are generally intended for low-

power (10 hp or 7 kw), high-speed uses, allowing high efficiency (up to 98%)

and long life. These are seen in business machines, printers, tape recorders, andother light-duty operations.

6.2.6TIMING BELTS

Timing belts, (also known as Toothed, Notch, Cog, or Synchronous belts)

are a positive transfer belt and can track relative movement. These belts have

teeth that fit into a matching toothed pulley. When correctly tensioned, they

have no slippage, run at constant speed, and are often used to transfer direct

motion for indexing or timing purposes (hence their name). They are often used

in lieu of chains or gears, so there is less noise and a lubrication bath is not

necessary. Camshafts of automobiles, miniature timing systems, and stepper

motors often utilize these belts. Timing belts need the least tension of all belts,

and are among the most efficient. They can bear up to 200 hp (150 kw) at

speeds of 16,000 ft/min.
http://en.wikipedia.org/wiki/Timing_belthttp://en.wikipedia.org/wiki/Camshafthttp://en.wikipedia.org/wiki/Stepper_motorhttp://en.wikipedia.org/wiki/Stepper_motorhttp://en.wikipedia.org/wiki/Timing_belthttp://en.wikipedia.org/wiki/Camshafthttp://en.wikipedia.org/wiki/Stepper_motorhttp://en.wikipedia.org/wiki/Stepper_motor


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Fig:6.3 Timing Belt

6.2.7SPECIALTY BELTS

Belts normally transmit power on the tension side of the loop. However,

designs for continuously variable transmissions exist that use belts that are a

series of solid metal blocks, linked together as in a chain, transmitting power on

the compression side of the loop.

6.3 HISTORY OF BELTS

Belts used for rolling roads for wind tunnels can be capable of 250 km/h.

6.4 USAGE

The open belt drive has parallel shafts rotating in the same direction,

whereas the cross-belt drive also bears parallel shafts but rotate in opposite

direction. The former is far more common, and the latter not appropriate for

timing and standard V-belts, because the pulleys contact both the both inner and

outer belt surfaces. Nonparallel shafts can be connected if the belt's center line

is aligned with the center plane of the pulley. Industrial belts are usually

reinforced rubber but sometimes leather types, non-leather non-reinforced belts,

can only be used in light applications.
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The pitch line is the neither line between the inner and outer surfaces that is

neither subject to tension (like the outer surface) nor compression (like the

inner). It is midway through the surfaces in film and flat belts and dependent on

cross-sectional shape and size in timing and V-belts. Calculating pitch diameter

is an engineering task and is beyond the scope of this article. The angular speed

is inversely proportional to size, so the larger the one wheel, the less angular

velocity, and vice versa. Actual pulley speeds tend to be 0.51% less than

generally calculated because of belt slip and stretch. In timing belts, the inverse

ratio teeth of the belt contribute to the exact measurement. The speed of the belt

is:

Speed = Circumference based on pitch diameter angular speed in rpm

SELECTION CRITERIA

Belt drives are built under the following required conditions: speeds of

and power transmitted between drive and driven unit; suitable distance between

shafts; and appropriate operating conditions. The equation for power is:

Power (kw) = (torque in Newton-meters) (rpm) (2 radians)/(60 sec

1000 W)

SELECTION CRITERIA

Factors of power adjustment include speed ratio; shaft distance (long or

short); type of drive unit (electric motor, internal combustion engine); service

environment (oily, wet, dusty); driven unit loads (jerky, shock, reversed); and

pulley-belt arrangement (open, crossed, turned). These are found in engineering

handbooks and manufacturer's literature. When corrected, the horsepower is

compared to rated horsepowers of the standard belt cross sections at particular

belt speeds to find a number of arrays that will perform best. Now the pulley

diameters are chosen. It is generally either large diameters or large cross section

that are chosen, since, as stated earlier, larger belts transmit this same power at

low belt speeds as smaller belts do at high speeds. To keep the driving part at its
http://en.wikipedia.org/wiki/Standard_reference_pitch_diameterhttp://en.wikipedia.org/wiki/Torquehttp://en.wikipedia.org/wiki/Standard_reference_pitch_diameterhttp://en.wikipedia.org/wiki/Torque


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smallest, minimum-diameter pulleys are desired. Minimum pulley diameters are

limited by the elongation of the belt's outer fibers as the belt wraps around the

pulleys. Small pulleys increase this elongation, greatly reducing belt life.

Minimum pulley diameters are often listed with each cross section and speed, or

listed separately by belt cross section. After the cheapest diameters and belt

section are chosen, the belt length is computed. If endless belts are used, the

desired shaft spacing may need adjusting to accommodate standard length belts.

It is often more economical to use two or more juxtaposed V-belts, rather than

one larger belt.

In large speed ratios or small central distances, the angle of contact between the

belt and pulley may be less than 180. If this is the case, the drive power must

be further increased, according to manufacturer's tables, and the selection

process repeated. This is because power capacities are based on the standard of

a 180 contact angle. Smaller contact angles mean less area for the belt to obtain

traction, and thus the belt carries less power.

BELT TENSION

Power transmission is a function of belt tension. However, also increasing

with tension is stress (load) on the belt and bearings. The ideal belt is that of the

lowest tension which does not slip in high loads. Belt tensions should also be

adjusted to belt type, size, speed, and pulley diameters. Belt tension is

determined by measuring the force to deflect the belt a given distance per inch

of pulley. Timing belts need only adequate tension to keep the belt in contact

with the pulley.

BELT WEAR

Fatigue, more so than abrasion, is the culprit for most belt problems. This

wear is caused by stress from rolling around the pulleys. High belt tension;

excessive slippage; adverse environmental conditions; and belt overloads

caused by shock, vibration, or belt slapping all contribute to belt fatigue.


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6.5 SPECIFICATIONS

To fully specify a belt, the material, length, and cross-section size and

shape are required. Timing belts, in addition, require that the size of the teeth be

given. The length of the belt is the sum of the central length of the system on

both sides, half the circumference of both pulleys, and the square of the sum (if

crossed) or the difference (if open) of the radii. Thus, when dividing by the

central distance, it can be visualized as the central distance times the height that

gives the same squared value of the radius difference on, of course, both sides.

When adding to the length of either side, the length of the belt increases, in a

similar manner to the Pythagorean theorem. One important concept to

remember is that as D1 gets closer to D2 there is less of a distance (and therefore

less addition of length) until its approaches zero.

On the other hand, in a crossed belt drive the sum rather than the difference of

radii is the basis for computation for length. So the wider the small drive

increases, the belt length is higher.

CHAPTER 7

TIMING BELT DESIGNE

7.1CHAIN DRIVE

Chain drive is a way of transmitting mechanical power from one place to

another. It is often used to convey power to the wheels of a vehicle, particularly

bicycles and motorcycles. It is also used in a wide variety of machines besides

vehicles.
http://en.wikipedia.org/wiki/Bicyclehttp://en.wikipedia.org/wiki/Motorcyclehttp://en.wikipedia.org/wiki/Bicyclehttp://en.wikipedia.org/wiki/Motorcycle


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Most often, the power is conveyed by a roller chain, known as the drive chain or

transmission chain,[1] passing over a sprocket gear, with the teeth of the gear

meshing with the holes in the links of the chain. The gear is turned, and this

pulls the chain putting mechanical force into the system. Another type of drive

chain is the Morse chain, invented by the Morse Chain Company ofIthaca, New

York, USA. This has inverted teeth.

Fig: 7.1 Chain Drive

Sometimes the power is output by simply rotating the chain, which can be used

to lift or drag objects. In other situations, a second gear is placed and the power

is recovered by attaching shafts or hubs to this gear. Though drive chains areoften simple oval loops, they can also go around corners by placing more than

two gears along the chain; gears that do not put power into the system or

transmit it out are generally known as idler-wheels. By varying the diameter of

the input and output gears with respect to each other, the gear ratio can be

altered, so that, for example, the pedals of a bicycle can spin all the way around

more than once for every rotation of the gear that drives the wheels.

7.2 CHAINS VERSUS BELTS

Drive chains are most often made of metal, while belts are often rubber,

plastic, or other substances. Although well-made chains may prove stronger

than belts, their greater mass increases drive train inertia.

Drive belts can often slip (unless they have teeth) which means that the

output side may not rotate at a precise speed, and some work gets lost to the

friction of the belt against its rollers. Teeth on toothed drive belts generally wear
http://en.wikipedia.org/wiki/Roller_chainhttp://en.wikipedia.org/wiki/Chain_drivehttp://en.wikipedia.org/wiki/Sprockethttp://en.wikipedia.org/wiki/Ithaca,_New_Yorkhttp://en.wikipedia.org/wiki/Ithaca,_New_Yorkhttp://en.wikipedia.org/wiki/USAhttp://en.wikipedia.org/wiki/Idler-wheelhttp://en.wikipedia.org/wiki/Gear_ratiohttp://en.wikipedia.org/wiki/Inertiahttp://en.wikipedia.org/wiki/Toothed_belthttp://en.wikipedia.org/wiki/Frictionhttp://en.wikipedia.org/wiki/Roller_chainhttp://en.wikipedia.org/wiki/Chain_drivehttp://en.wikipedia.org/wiki/Sprockethttp://en.wikipedia.org/wiki/Ithaca,_New_Yorkhttp://en.wikipedia.org/wiki/Ithaca,_New_Yorkhttp://en.wikipedia.org/wiki/USAhttp://en.wikipedia.org/wiki/Idler-wheelhttp://en.wikipedia.org/wiki/Gear_ratiohttp://en.wikipedia.org/wiki/Inertiahttp://en.wikipedia.org/wiki/Toothed_belthttp://en.wikipedia.org/wiki/Friction


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faster than links on chains, but wear on rubber or plastic belts and their teeth is

often easier to observe; you can often tell a belt is wearing out and about to

break more easily than a chain.

Chains are often narrower than belts, and this can make it easier to shift

them to larger or smaller gears in order to vary the gear ratio. Multi-speed

bicycles with derailleurs make use of this. Also, the more positive meshing of a

chain can make it easier to build gears that can increase or shrink in diameter,

again altering the gear ratio.

Both can be used to move objects by attaching pockets, buckets, orframes to them; chains are often used to move things vertically by holding them

in frames, as in industrial toasters, while belts are good at moving things

horizontally in the form ofconveyor belts. It is not unusual for the systems to be

used in combination; for example the rollers that drive conveyor belts are

themselves often driven by drive chains.

Drive shafts are another common method used to move mechanical

power around that is sometimes evaluated in comparison to chain drive; in

particular shaft drive versus chain drive is a key design decision for most

motorcycles. Drive shafts tend to be even tougher and more reliable than chain

drive, but weigh even more (robbing more power), and impart rotational torque.

7.3 USES IN VEHICLES

7.3.1 BICYCLES

Chain drive was the main feature which differentiated the safety bicycle

introduced in 1885, with its two equal-sized wheels, from the direct-drive

penny-farthing or "high wheeler" type of bicycle. The popularity of the chain-

driven safety bicycle brought about the demise of the penny-farthing, and is still

a basic feature of bicycle design today.

7.3.2 AUTOMOBILES
http://en.wikipedia.org/wiki/Derailleur_gearshttp://en.wikipedia.org/wiki/Conveyor_belthttp://en.wikipedia.org/wiki/Drive_shafthttp://en.wikipedia.org/wiki/Torquehttp://en.wikipedia.org/wiki/Safety_bicyclehttp://en.wikipedia.org/wiki/Direct_Drive_Mechanismhttp://en.wikipedia.org/wiki/Penny-farthinghttp://en.wikipedia.org/wiki/Derailleur_gearshttp://en.wikipedia.org/wiki/Conveyor_belthttp://en.wikipedia.org/wiki/Drive_shafthttp://en.wikipedia.org/wiki/Torquehttp://en.wikipedia.org/wiki/Safety_bicyclehttp://en.wikipedia.org/wiki/Direct_Drive_Mechanismhttp://en.wikipedia.org/wiki/Penny-farthing


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Chain drive was a popular power transmission system from the earliest

days of the automobile. It gained prominence as an alternative to the System

Panhard with its rigid Hotchkissdriveshaft and universal joints.

A chain drive system uses one or more roller chains to transmit power

from a differential to the rear axle. This system allowed for a great deal of

vertical axle movement (for example, over bumps), and was simpler to design

and build than a rigid driveshaft in a workable suspension. Also, it had less

unsparing weight at the rear wheels than the Hotchkiss drive, which would have

had the weight of the driveshaft to carry as well, which in turn meant that the

tires would last longer.

Frazer Nash was strong proponents of this system using one chain per

gear selected by dog clutches. The Frazer Nash chain drive system, (designed

for the GN Cyclecar Company by Archibald Frazer-Nash and Henry Ronald

Godfrey) was very effective, allowing extremely fast gear selections. The Frazer

Nash (or GN) transmission system provided the basis for many "special" racing

cars of the 1920s and 1930s, the most famous being Basil Davenport's Spider

which held the outright record at the Shelsley Walsh Speed Hill Climb in the

1920s.Parry-Thomas was killed during a land speed record attempt in his car

'Babs' when the chain final-drive broke, decapitating him. The last popular

chain drive automobile was the Honda S600 of the 1960s.

7.3.3 INSIDE MOTORS

Internal combustion engines often use chain drive to power the timing

chain used to drive overhead camshaft valve trains. This is an area in which

chain drives frequently compete directly with belt drive systems, and an

excellent example of some of the differences and similarities between the two

approaches. For this application, chains last longer, but are often harder to

replace. Being heavier, the chain robs more power, but is also less likely to fail.

The camshaft of a four stroke engine must rotate at half crankshaft speed, so
http://en.wikipedia.org/wiki/Automobilehttp://en.wikipedia.org/wiki/Syst%C3%A8me_Panhardhttp://en.wikipedia.org/wiki/Syst%C3%A8me_Panhardhttp://en.wikipedia.org/wiki/Hotchkiss_drivehttp://en.wikipedia.org/wiki/Driveshafthttp://en.wikipedia.org/wiki/Universal_jointhttp://en.wikipedia.org/wiki/Roller_chainhttp://en.wikipedia.org/wiki/Differential_(mechanics)http://en.wikipedia.org/wiki/Axlehttp://en.wikipedia.org/wiki/Frazer_Nashhttp://en.wikipedia.org/wiki/GN_(car)http://en.wikipedia.org/wiki/Archibald_Frazer-Nashhttp://en.wikipedia.org/wiki/Henry_Ronald_Godfreyhttp://en.wikipedia.org/wiki/Henry_Ronald_Godfreyhttp://en.wikipedia.org/wiki/Shelsley_Walsh_Speed_Hill_Climbhttp://en.wikipedia.org/wiki/J._G._Parry-Thomashttp://en.wikipedia.org/wiki/Land_speed_recordhttp://en.wikipedia.org/wiki/Babs_(Land_speed_record_car)http://en.wikipedia.org/wiki/Honda_S600http://en.wikipedia.org/wiki/Internal_combustion_enginehttp://en.wikipedia.org/wiki/Timing_chainhttp://en.wikipedia.org/wiki/Timing_chainhttp://en.wikipedia.org/wiki/Overhead_camshafthttp://en.wikipedia.org/wiki/Valvetrainhttp://en.wikipedia.org/wiki/Automobilehttp://en.wikipedia.org/wiki/Syst%C3%A8me_Panhardhttp://en.wikipedia.org/wiki/Syst%C3%A8me_Panhardhttp://en.wikipedia.org/wiki/Hotchkiss_drivehttp://en.wikipedia.org/wiki/Driveshafthttp://en.wikipedia.org/wiki/Universal_jointhttp://en.wikipedia.org/wiki/Roller_chainhttp://en.wikipedia.org/wiki/Differential_(mechanics)http://en.wikipedia.org/wiki/Axlehttp://en.wikipedia.org/wiki/Frazer_Nashhttp://en.wikipedia.org/wiki/GN_(car)http://en.wikipedia.org/wiki/Archibald_Frazer-Nashhttp://en.wikipedia.org/wiki/Henry_Ronald_Godfreyhttp://en.wikipedia.org/wiki/Henry_Ronald_Godfreyhttp://en.wikipedia.org/wiki/Shelsley_Walsh_Speed_Hill_Climbhttp://en.wikipedia.org/wiki/J._G._Parry-Thomashttp://en.wikipedia.org/wiki/Land_speed_recordhttp://en.wikipedia.org/wiki/Babs_(Land_speed_record_car)http://en.wikipedia.org/wiki/Honda_S600http://en.wikipedia.org/wiki/Internal_combustion_enginehttp://en.wikipedia.org/wiki/Timing_chainhttp://en.wikipedia.org/wiki/Timing_chainhttp://en.wikipedia.org/wiki/Overhead_camshafthttp://en.wikipedia.org/wiki/Valvetrain


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some form of reduction gearing is needed and a direct drive from the crankshaft

isn't possible. Alternatives to chain drives include gear trains, bevel gear and

shaft drives, or toothed flexible belt drives.

7.3.4 MOTORCYCLES

Chain drive versus belt drive or use of a driveshaft is a fundamental

design decision in motorcycle design; nearly all motorcycles use one of these

three designs. See Motorcycle construction for more details.

CHAPTER 8

DESIGN CALCULATIONS

SPECIFICATIONS

Number of Teethes Z1 = 9 teethes

Z2 = 31 teethes

Gear Ratio i = 3.444

PowerP = 3 HP

Speed N = 35 rpm

DESIGN

Selection of Material = Poly Propylene (PP)

Strength of gear tooth (Fs)

Fs=[b] b y Pc=[b] b YPd

[b] = 5400 kgf/cm2 for PP Material

b = 10m from PSG Data book Pg.no:8.14

Y= 20 Involutes for corresponding value forZ1 =0.332
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Pd = 1 m from PSG Data book Pg.no:8.50

Fs = 540010m0.332m

Fs = 17928m2 Kgf

Transmitted Load (Ft)

Ft = HP75 m from PSG Data book Pg.no: 8.50

Power in HP= 3

m = dN6000cmsec from PSG Data book Pg.no:8.15

d1 = mZ1

m = m9356000

m = 0.164933m cmsec

Ft = 3750.164933m

Ft = 1364.18522m

Dynamic Load (Fd)

CHAPTER 9

PHOTOGRAPHS


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Fig:9.1 2D Wire Frame Diagram


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Fig:9.2 3D Diagram


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Fig:9.3 Full Assembly Of Dual Direction Gear Mechanism for Shaper Machine


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CHAPTER 10

COST ESTIMATION

S.NO DISCRIPTION QTY COST

01 Ring Gear Material 01 500

02 Planet Gear Material 01 150

03 Sun Gear Material 01 150

04 Labour -- 2500

TOTAL 3300


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CHAPTER 11

11.1 CONCLUSION

The project performs well under all conditions and enables to improve the

operational efficiency. It also meets all the reqirements specified by the user.

This project has been a great learning process for us to climb the greater

heights of mechanical world. The experience that we have earned from this

project will surely stand in good stead in my future.

Once again we thank whole heartedly all those who helped to complete the

project work.


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11.2 BIBLIOGRAPHY

Websites are used:

http://encyclopedia.org

http://en.wikipedia.org

www.tpup.com

Google search engine

Reference books:

Design data book

Machine design R.S. Khurmi

Automobile engineering vol&2 - Kripal singh

Automobile repair guide 1&2 Lucas peterson.
http://encyclopedia.org/http://en.wikipedia.org/http://www.tpup.com/http://encyclopedia.org/http://en.wikipedia.org/http://www.tpup.com/

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Dual Direction Gera Mechanisum

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