Gear trains pdf nptel

Pressure line is the common normal at the point of contact of mating gears along which the driving tooth exerts force on the driven tooth. Epicyclic gear train nptel pdf merge the total mechanical loss is then given as the sum of losses from all gear meshes and bearings. A knowledge of the e ects of a gear train is important to the control systems designer. Many worm gears have an interesting property that no other gear set has. Types of gear train and velocity ratio calculation. Simple gear train compound gear train reverted gear train epicyclic gear train in the first three types of gear trains, the axes of the shafts over which the gears are mounted are fixed relative to each other. Following are the different types of gear trains, depending upon the arrangement of wheels. Epicyclic gear train nptel pdf download n is the gears teeth number, the sign depends on the type of gear and, in sequence is for external gears.

Thus we see that in a reverted gear train, the motion of the first gear and the last gear is like. Small electric motors are usually lowtorque and highspeed and a speedreducing gear train is necessary. Introduction rolling cylinders the fundamental law of gearing gear tooth nomenclature gear types simple gear trains compound gear trains reverted gear trains epicyclic or planetary gear trains examples 2. Another class of gear train has wide application, the epicyclic or planetary train. Introduction to machine design, methodology, strength, rigidity, fracture, wear, and material considerations in design, use of standards, selection of materials and processes. Epicyclic gear train nptel pdf merge helical gearing, in which the teeth are cut at an angle with the axis of rotation, was developed after spur gearing and has the advantages that has the smoother action and tends to be trainw fig. This gradual engagement makes helical gears operate much more smoothly and quietly than spur gears. Basic gear terminology and calculation lets learn the basics of basic gear technology. One of the most common uses of gear trains is in the gear boxes of cars. Introduction to mechanisms carnegie mellon school of. Gear trains theory of machines engineering reference.

The gear wheel transmitted motion between one shaft to another shaft, so the multiple set of gear transmit motion from single main gear to various revolving parts is known as gear train. Jul 03, 2019 the gear train in an automobile differential is a common application of gears, but nptell misunderstood by the lay public. Gear train is nothing but a combination of gears which are used to connect the input shaft to the output shaft. Pdf me6401 kinematics of machinery kom books, lecture. This type of transmission are used by skoda,toyota, lexus, etc epicyclic gearing planetry gearing. In the first three types of gear trains, the axes of the shafts over which the gears are mounted are fixed relative to each other. The same gear train may consist of a few spur gears.

At least one wheel not only rotates about its own axis but also rotates about some other axis automatic gearboxes typically use one or more compound planetary gear sets having two sun gears and two sets of intermeshing planet gears. Whenever a change in the speed or torque of a rotating device is needed, a gear train or one of its cousins, the belt or chain drive mechanism, will usually be used. It is having the radial teeth parallel to the axis so we have the axis gear axis and the teeth are parallel to the gear axis and the teeth are straight and are mounted on the parallel shafts. Provide a varied leverage between the engine and the drive wheels provide means to transfer power in opposite direction. This is because the angle on the worm is so shallow. Epicyclic gear train nptel pdf another class of gear train has wide application, the epicyclic or planetary train. Unit 3 power transmission devices power transmission devices. A gear can be defined as a toothed wheel which, when meshed with another toothed wheel with similar configuration, will transmit rotation from one shaft to another.

The pitch circle is an imaginary circle that contacts the pitch circle of any other gear with which it is in mesh. Simple gear trains, compound gear trains for large speed reduction, epicyclic gear trains algebraic and tabular methods of finding velocity ratio of epicyclic gear trains. Yi zhang with susan finger stephannie behrens table of contents. Compound planetary gear train planetary gear train with more than one arm r14 t1t3. Gears and gear trains study notes for mechanical engineering. Gears is a positive drive which transmits exact velocity ratio from one shaft to another shaft, gear drive is used when the distance between driver and follower is very less, when two or more gears are made to mesh with each other to transmit power from one shaft to another, the combination is called gear trains gears. Straight bevel gearing is similar to spur gearing with perpendicular shaft arrangement. Oct 23, 2012 spur gearing is a parallel shaft arrangement, and these gears can achieve much higher efficiencies compared to other gear types. The first gear known as the driver has 12 teeth, the second gear called the idler has 16 teeth, and the third gear. This text will not deal with the stress analysis aspects of gear design. Gears is a positive drive which transmits exact velocity ratio from one shaft to another shaft, gear drive is used when the distance between driver and follower is very less, when two or more gears are made to mesh with each other to transmit power from one shaft to another, the combination is called gear trains. Tooth load and torque calculations in epicyclic gear trains. The epicyclic gear first analysed here have the following components.

It is a mathematical equation that tells how many values can vary and can help in the first three types of gear trains, the axes of the shafts over which the gears are mounted are ger relative to each other. Module 14 3 hr interference and undercutting, minimum number of teeth, contact ratio, bevel helical, spiral and worm gears module 15 3 hr gear trains simple, kunematics and epicyclic gear trains. This chapter will explore the theory of gear tooth action and the design. All books are in clear copy here, and all files are secure so dont worry about it. Its efficiency varies from 94% to 98% with lower gear ratios. Nptel nptel online certification course course on spur. Planetary gear trains pdf planetary gear is one of the epicyclic gear, which is a gear system consisting of. They are used to increase or decrease the speed or torque of the output shaft. Depending upon the type and accuracy of motion desired. In the simplest form, the crash gear box, a collection of spur gears were arranged to give different ratios of input to output speed and in the case of the reverse gear, change the direction of the output rotation. A gear train is a combination of gears which are used for transmitting motion from.

Nptel syllabus kinematics of machines video course s note on the model curriculum prepared by aicte five of the seven topics listed under the heading kinematics of machine belongs to dynamics. Unit 3 power transmission devices devices structure 3. Section 1 gear types, characteristics and applications section 2 gears fundamentals section 3 power transmission fundamentals section 4 gear trains. Worm gears are used when large gear reductions are needed.

When two teeth on a helical gear system engage, the contact starts at one end of the tooth and gradually spreads as the gears rotate, until the two teeth are in full engagement. It is a basic dimension from which many other features of. Epicyclic gear trains in roving machine bobbin diameter and speeds of bobbin, roving stretch, relation between bobbin speed and bottom cone pulley speed, epicyclic gear train in combing machine. In a simple and compound gear train all the centre of rotation of the gears are fixed, we are going to look at examples and understand this. Let t1 number of teeth on gear 1, r1 pitch circle radius of gear 1, and n1 speed of gear 1 in r. Gear trains image from simon fraser university image from jtekt torsen na, inc. Gear ratio is the ratio of output and input number of teeth on a shaft. Types of gear train and velocity ratio calculation techminy. Calculation of a planetary gear train this tutorial shows the usage of mesys shaft calculation with shaft systems. Oct 11, 2018 kinematics kinematics of machines nptel gears and gear trains kinematics of machines nptel is decided that the topics on dynamics listed above i to v will be covered in the course on dynamics of machines whereas the topic a above will be covered in kinematics of machines course. It is common for worm gears to have reductions of 20. The gear train is idealized as a weakest link kinematic chain. The geometry of gears theory of machines engineering.

Procedure for optimum design of a twostage spur gear system. Asok kumar mallik department of mechanical engineering iit kanpur. The number of teeth for spur gears is given by where k 1f fll1 for fulld tht th08f tbt th d ldepth teeth, 0. The tooth numbers are n 2 24, n 3 18, n 5 22, and n 6 64.

Epicyclic gearbox epicyclic gear trains are used to get the various gear ratios. One is that the bushing needs to be wider to t over the cap on the pinion. Now let us move to the various types of gear different gears are available so first one is the spur gear very commonly used type of gear is the spur gear. Introduction to gear trainsintroduction to gear trains. Gear train it is defined as two or more gears are made to mesh with each epicyclic gear train the axes of the shafts over which the geaar are mounted, may move relative to a fixed axis. A complete gear train design will necessarily involve considerations of strength of materials and the complicated stress states to which gear teeth are subjected. In the examination of the failures, the varying reasons or causes of failure, along with suggested remedies, are listed. This course provides an outline of gear fundamentals and is beneficial to readers who want to acquire knowledge about mechanics of gears. Provide means of connection and disconnection of engine with rest of power train without shock and smoothly. Electrical, electronics and communications engineering.

If the mating gear has more teeth than the pinion, that is. The tip of one wheel will undercut the root of a tooth on its mating gear if contact continues outside the common tangent to the base circles. A gear train is a set or system of gears arranged to transfer rotational torque from one part of a mechanical system to another, with some gear ratio performing a mechanical advantage epicyclic gearing or planetary gearing is a gear system consisting of one or more outer gears, or planet gears, revolving about a central, or sun gear key facts. Two inputs are needed to obtain a predictable output. In some epicyclic gear trains, we may find two or more planetary gears. Helical gearing, in which the teeth are cut at an angle with the axis of rotation, was developed after spur gearing and has the advantages that has the smoother action and tends to be trainw fig. Mar 29, 2020 epicyclic gear train nptel pdf merge sijthre. In this planetary gears sets are placed in series to provide transmission. Find the ratio of the output speed to the input speed.

Detailed course content with modules for video lectures module 1 3 hr. Epicyclic gear train nptel pdf in the first three types of gear trains, the axes of the shafts over which the gears are mounted are. The gear b meshes with gear a and has its axis on the arm o 2, about which the gear b can. Gear design objectives understand basic principles of gearing.

Planetary gear trains are one of the main subdivisions of the simple epicyclic. For example, commonly used epicyclic gear train, for the same purpose that it can create two output speeds from one input speed is in automobile differential. It require small area during the power transmission and to obtain large speed reduction. The pitch circle is a circle on the face of a gear that passes through points that are radially half way up the working depth of the teeth.

Jan 01, 20 planetary gear trains example for the speed reducer shown, the input shaft a is in line with output shaft b. A twostage planetary gear stage is defined using the program. Gears are machine elements that transmit motion by means of successively engaging teeth. Enable speed reduction between engine and the drive wheels in. Epicyclic gear train nptel pdf automatic transmission has not better fuel economy. Gear ratio is numbers of teeth of larger gear to smaller gear. Read online nptel course material digital communication book pdf free download link book now. Ordinary gear trains have axes, relative to the frame, for all gears comprising the train. The smallest number of teeth on a spur pinion and gear, onetoone gear ratio, which can exist without interference is np. In a set of gears, this is most likely to occur between teeth of the largest gear wheel, acting against those of the smallest pinion. L where a gear a and the arm c have a common axis at o 1 about which they can rotate.

Understand geometry of different gears and their dimensional pro perties. Theory of machines is an applied science of the relationships between geometry and relative motion of the parts of the machine, and concerns to the forces which. Gear train conguration appendix a8 another interesting design aspect is that the gear train reverts back to the axle about which the pinion turns. When more than one gear is arranged together for transmitting torque or power from one system to another system then the arrangement is called a gear train. Nptel course material digital communication pdf book. The gear train maybe for spur gear, helical gear and spiral gear. A gear whose axis itself is revolving is called a planetary gear. A gear a mounted on shaft x having 50 teeth drives the gear b having 75 teeth mounted. Epicyclic gear train nptel pdf an intermittent rotation i is superimposed on to a constant rotation c generated from the cylinder comb shaft in the epicyclic gear train. Gear trains simple, compound and epicyclic gear trains. Design of machinery an introduction to the synthesis and.

Download me6401 kinematics of machinery kom books lecture notes syllabus part a 2 marks with answers me6401 kinematics of machinery kom important part b 16 marks questions, pdf books, question bank with answers key, me6401. Recognize different gearing systems and relative advantages and. Planetary gear trains example for the speed reducer shown, the input shaft a is in line with output shaft b. Kinematics of gears and gear trains it is decided that the topics on dynamics listed above i to v will be covered in the course on dynamics of machines whereas the topic a above will be covered in kinematics of machines course. Please start with the tutorial for shaft calculation to see how to introduce geometry and supports for single shafts. A gear train is a mechanical system formed by mounting gears on a frame so the teeth of the gears engage gear teeth are designed to ensure the pitch circles of engaging gears roll on each other without slipping, providing a smooth transmission of rotation from one gear to the next. Gear trains are widely used in all kinds of mechanisms and machines, from can openers to aircraft carriers. What are the sources of errors in gears and measurement of spur gear. Recognize different gearing systems and relative advantages and disadvantages between them. Mechanical vibrations nptel online videos, courses iit. In an epicyclic gear train, the axes of the shafts, over which the gears are mounted, move relative to a fixed axis. Software gto provides the required results in a very short time. The gear tooth is a component of a mechanical power transmission system that does not lack for descriptive terminology. Gear train analysis it is very common to use a gear train following a fractionalhorsepower motor in servo positioning applications.

Nptel video lectures, iit video lectures online, nptel youtube lectures, free video lectures, nptel online courses, youtube iit videos nptel courses. Gear trains theory of machines engineering reference with. Image from blog of haja sherief image from hpi racing image from proquest image from sandia national labs image from piaget image from fortune, apr. Figure 76a shows a simple ordinary train in which there is only one gear for each axis. The disc with teeth on their periphery is known as gear. The volume of the gear train with spur gears is reduced by 22. Pressure angle is the angle between the pressure line and common tangent to pitch circles.

The total mechanical loss is then given as the sum of losses from all gear meshes and bearings. But in case of epicyclic gear trains, the axes of the shafts on which the gears are mounted may move relative to a. In this lecture, i shall give a brief history of toothed gear invention and development and next something about the gear train, then special sophisticated gearing. Five of the seven topics listed under the heading kinematics of machine belongs to dynamics. Enable power transmission at varied angles and varied lengths.

Download nptel course material digital communication book pdf free download link or read online here in pdf. Epicyclic gear trains are generally used for automatic transmission, overdrives, and final drives. Gear size, pressure angle, number of teethwe introduce the basic terminology, measurement, and relational expressions necessary to understand basic gear technology. Comparison of gear efficiencies spur, helical, bevel, worm.

When pinion is the driver, it results in step down drive in which nptl output speed. The teeth on helical gears are cut at an angle to the face of the gear. The epicyclic gear train is useful for transmitting highvelocity ratio with a gear of moderate size and in less space. Epicyclic planetaryspeeds of element of gear train, tabulation and formula methods. Gear design national broach and machine division,of lear siegler, inc. Usually, following two types of lubrication mechanisms are commonly used for gear lubrication. Gear trains, speed ratio, train value, idler gears, compound gear.