Compound gear train in a compound gear train at least one of the shafts in the train. In a gear train when the axis of the first and the last gear coincide or coaxial is. The number of teeth on gears b, c and d are 75, 30 and 90respectively. Types of gear train and velocity ratio calculation techminy.
The velocity ratio of an epicyclic gear train is determined by the following methods. The speed and direction of gear c when gear b is fixed and the arm amakes 100 rpm. In this example, gear 1 and gear 3 are on the same axis. Gear train, modification, gear ratio, direction, spur gear. Introduction to gear trainsintroduction to gear trains. This type of arrangement is used in clocks and in simple lathe where back gears are used to give a slow speed to the chuck. R5 model the forces and torques in a gear train as a system of linear.
The image to the left shows a schematic of a reverted geartrain. Epicyclic gear trains are known to provide high power density and have. Design a compound, reverted gear train with spur gears that has a ratio of 25. The pinion has 21 teeth and the gear has 126 teeth with a diametral. The gear b meshes with gear a and has its axis on the arm o 2, about which the gear b can. The sun gear has 80 teeth, and the follower gear has 20 teeth. They are used to achieve high gear ratio within limited space. L where a gear a and the arm c have a common axis at o 1 about which they can rotate. Gear trains theory of machines engineering reference. Govindaraju,ssec 25 reverted gear train the driver and driven axes lies on the same line. Determine the length of the contact line and the contact ratio. Ppt gear trains powerpoint presentation free to view.
Jul 03, 2019 epicyclic gear train nptel pdf to excel pdf files kinematic analysis of synchromesh, machine tool gear box, differential gear box self study 3. The teeth of this type can be spur, helical or herringbone. Types of gear trains asimple gear train bcompound gear. Works on home computers pc or mac as well as smartphones and tablets. The reciprocal of the speed ratio or velocity is known as train value. A gearbox is to be designed with a compound reverted gear tr. Reverted gear is use in compound gear train which is a difference between simple gear train and reverted gear train. In a gear train when the axis of the first and the last gear coincide or coaxial is known as reverted gear train. 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. I am a mechanical engineer, with great thirst to learn more, apply more, and work hard more.
A gearbox is to be designed with a compound reverted gear. Gears 4 and 1 are in line, and gears 2 and 3 are on the same shaft. In a reverted gear train, the motion of the first gear and the last gear is same. A calculator for designing a multistage compound gear train. Jan 17, 2018 for the love of physics walter lewin may 16, 2011 duration. When a series of gears are connected in such a way that two or more gears rotate about an axis with the same angular velocity. Riveted gear train gear ratio is calculated similar to compound gear train. The epicyclic gear train is useful for transmitting highvelocity ratio with a gear of moderate size and in less space. The gear b meshes with gear a and has its axis on the arm o 2, about which the gear b can rotate. It should be pointed out that six planets do not necessarily give a gearing twice the capacity of a similar. Reverted gear trains are a type of compound gear trains in which input and output shafts are on the same axis. So reverted gear train may be called as a compund gear train but all compound gear train can not be a reverted gear train. The train will end up being reverted gear 1 and 3 will be in line and gear 2.
Reverted gear has two or more rigidly fixed gears of different size and has different number of teeth on the same shaft with same axis of rotation and same angular velocity. Gear 2 and 3 are mounted in same shaft the gear 3 rotate in same direction as that of gear 2. If two gears in mesh eg, a drive gear and a driven gear also constitute a gear train which are called simple gear train and in. For various reasons you dont want gears smaller than 10. In a reverted gear train, the motion of the first gear and the last gear is like. If the axes of driver shaft and driven shaft is coaxial, then the gear train is termed as reverted gear train. Sep 25, 2017 in this lecture i have discussed about the numerical problem on reverted gear train from theory of machines in hindi. The input gear has 20 teeth and the output gear has 100 teeth. Compound reverted gear design project by obadah yaghi on prezi. Methods of lubrication gear transmission mechanics.
Govindaraju,ssec 4 gear trains any combination of gear wheels employed to transmit motion from one shaft to the other is called a gear train. Determine the numbers of teeth and pitch diameters for each gear. We use a train of gears because it is more compact than doing it with a single pair of gears. The gear 3 which is now the second driver drives the gear 4 i. Consequently, the dimensions of the sun gear would be onethird of the pinion of a parallel shaft geartrain designed to transmit an equivalent torque. For the gear train shown below, determine the train value, output speed, output direction, output torque, and output power. The conventional gear trains described in the previous sections are all onedegreeof free dom dof devices. Spur gears with 20 pressure angle are used, with 16 teeth on each of the small gears and 48 teeth on each of the larger gears. Compound gear trains allows to achieve higher gear ratios without having the need for more number of shafts. Compound gear trains are those which have more than one gear on the same shaft. For the love of physics walter lewin may 16, 2011 duration. A reverted gear train is very similar to a compound gear train.
Ppt gear trains powerpoint presentation free to view id. In this example, gear1 and gear3 are on the same axis. Pdf minimisation of the overall weight of the reverted and the nonreverted compound gear trains of arbitrary number of stages are formulated as. These are used in speed reducers, clocks and machine tools. Gears are compact, positiveengagement, power transmission elements. The diametral pitch to be used for the gears is 9 teethinch. Epicyclic gear train application the reverted gear trains are used in automotive transmissions, lathe back gears, industrial speed reducers, and in clocks where the minute and.
Join 5,540,000 engineers with over 3,340,000 free cad files join the community. Two inputs are needed to obtain a predictable output. In the first three types of gear trains, the axes of the shafts over. However, feel free to share your opinions on the comment section, i would. Govindaraju,ssec 24 reverted gear train concentric input output shafts dr. In this lecture i have discussed about the numerical problem on reverted gear train from theory of machines in hindi. 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. 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. Apr 04, 20 reverted gear train when the axes of the first gear i. Types of gear train simple, compound, reverted, epicyclic. An example is a gear box that modifies the torque speed characteristic of a prime mover to match that of the load, and comprises gears, shafts, bearings, and seals. In the case of the reverted gear train, the driver and the last gear are coaxial. What are application of reverted gear train answers. In an epicyclic gear train, the axes of the shafts, over which the gears are mounted, move relative to a fixed axis.
Let t1 number of teeth on gear 1, r1 pitch circle radius of gear 1, and n1 speed of gear 1 in r. R5 work out an analogous matrix for another gear body whose free body. An automotive gear differential is a jointfractionated planetary gear train with two degreesoffreedom. A gearbox is to be designed with a compound reverted gear train that transmits 25 horsepower with an input speed of 2500 revmin. The angular velocity is simply the reverse of the tooth ratio. Consequently, the dimensions of the sun gear would be onethird of the pinion of a parallel shaft gear train designed to transmit an equivalent torque. One is that the bushing needs to be wider to t over the cap on the pinion. 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. Another class of gear train has wide application, the epicyclic or planetary train.
Provides teeth counts from any given overall ratio. A reverted gear train has the first and last gears as. A number of gears grouped into a single unit is called gear train. What is the difference between compound gear train and. If two gear s in mesh eg, a drive gear and a driven gear also constitute a gear train which are called simple gear train and in. It is a compound gear with, two gearspairs, and a special condition that makes the total number of teeth of the first gearpair equals the number of teeth of the secondgearpair, when the module is the same. Reverted gear train pdf following are the different types of gear trains, depending upon the arrangement of wheels. This chapter will explore the theory of gear tooth action and. The concept of a gear train is a rather simple one. Thus we see that in a reverted gear train, the motion of the first gear and the last gear is like. Gear trains are widely used in all kinds of mechanisms and machines, from can openers to aircraft carriers. Suppose an epicyclic gear train has 2 gears gear a and gear b and an arm arm c. This type of gear train is used in applications like clock where we need two coaxial or colinear shafts to rotate in same direction but at different speeds like hands of a clock.
The image to the left shows a schematic of a reverted 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. The output should deliver the power at a rotational speed in the range of 280 to 300 revmin. Although my true skills shine in the mechanical design and heat transfer fields, i have a strong interest towards integrating mechanical devices with electronics.
Gears get used to change speed of rotation and at times direction. Design of machinery an introduction to the synthesis and. A compound reverted gear train is to be designed as. Following are the different types of gear trains, depending upon the arrangement of wheels. Additionally, for the reverted compound gear train, applicability of the solution. If the axis of the first and last wheel of a compound gear coincide it is called reverted gear train.
Pdf on aug 18, 2014, amar kumar and others published epicyclic gear train. Reverted gear train when the axes of the first gear i. Kinematics of gear trains conventional gear trains. They could also be used to change the axis of input and ou. It is a compound gear with, two gearspairs, and a special condition that makes the total number of teeth of the first gear pair equals the number of teeth of the second gear pair, when the module is the same. Reverted gear train as shown in figure, when gear 1 and 2 are rotate in opposite direction. Solutions to chapter 10 exercise problems problem 10. Jan 01, 20 kinematics of gear trains conventional gear trains. Pdf gear ratios for compound gear trains of minimum weight.
Gear train conguration appendix a8 another interesting design aspect is that the gear train reverts back to the axle about which the pinion turns. The most common of the gear train is the gear pair connecting parallel shafts. But in simple reverted gear train the direction of rotation of input and output shaft is same. Mechanical analysis gear trains city, university of london. The first and last gear are mounted on same axis of rotation in shaft is known as reverted gear trains.
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