In some epicyclic gear trains, we may find two or more planetary gears. This lesson tells about basics of planetary gear train. Problem no 1 on epicyclic gear trains gear trains kinematics of machinery theory of machines duration. The stationary gear sun gear or ring gear can be referred to as the central gear. Gear surfaces coated with boundary additive or antifriction. 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. Apr 04, 20 epicyclic gear train in an epicyclic gear train, the axes of the shafts, over which the gears are mounted, may move relative to a fixed axis.
This is sometimes referred to as conepulley backgearing because of its use within the cone pulleys of certain types of machine tools. What is the advantage and disadvantage of a epicyclic gear. Mar 30, 2016 epicyclic gear train with bevel gear the bevel gears are used to make a more compact epicyclic system and they permit a very high speed reduction with few gears. Pdf the mechanical efficiency of epicyclic gear trains. 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. Gear train conguration appendix a8 another interesting design aspect is that the gear train reverts back to the axle about which the pinion turns. We use the method introduced in epicyclic ratio calculation for determining the final gear ratio of an epicyclic gear train. Epicyclic gearing requires a stepbystep process to make it work, and some of the steps are not necessarily intuitive. 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. When two or more gears are made to mesh with each other to transmit power from one shaft to another, such a combination is called gear train or train of toothed wheels. Please start with the tutorial for shaft calculation to see how to introduce geometry and supports for single shafts.
If a simple gear train or compound gear train is attached to the epicyclic gear train, do not include it in the analysis and treat it as part of a separate simple gear train. This method is extremely methodical, which is appropriate since use of intuition is quite futile with an epicyclic gear train such as the following example. In an epicyclic train, the axis of at least one of the gears also moves relative to the frame. Two inputs are needed to obtain a predictable output. These drives receive an unusually clear treatment because at dr. The epicyclic gear train with bevel gears is used in 1. The elementary planetary, or epicyclic, gear train is shown in figure 2, along with the simplified representation to be used for the remainder of this thesis. Mathematics a circle whose circumference rolls along the circumference of a fixed. Epicyclic gear train free download as powerpoint presentation.
The derivation for gearing ratios between sun gear, planet carrier and ring gear motions are given in the attached excel file. Enable power transmission at varied angles and varied lengths. Advantages and velocity ratio of epicyclic gear train. Often gears are treated as pitch cylinder, which roll together without slip as shown in fig. Gate problems on planetary or epicyclic gear train duration. Planetary gear trains are one of the main subdivisions of the simple epicyclic gear train family. Planetary or epicyclic gear train epicyclic gear train. Right an example of an epicyclic gear sketch lecture. Apr 08, 2019 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. Mechanical analysis gear trains city, university of london. Find the fixed gear if any and substitute a value of zero for its angular velocity 5. Enable speed reduction between engine and the drive wheels in. Calculation of a planetary gear train this tutorial shows the usage of mesys shaft calculation with shaft systems. Users may download and print one copy of any publication from the public portal for the.
Design of machinery an introduction to the synthesis and. Provide means of connection and disconnection of engine with rest of power train without shock and smoothly. Advantages of planetary gear system planetary gear system has lots of advantage as compared to traditional gearboxes 1. Introduction to gear trainsintroduction to gear trains. Hi, this is a simple, configurable, epicyclic planetary gear train created in creo parametric 3. A network theory for variable epicyclic gear trains citation for published version apa. For a more involved epicyclic gear train example, please refer to the epicyclic gear train example section. The computeraided design cad files and all associated content posted to this website are created, uploaded, managed and owned by third party users. It is made up of a number of elements which are interconnected to form the train.
A network theory for variable epicyclic gear trains. Planetary gear ratio calculations this article also available in spanish. The present work on epicyclic gear trains carries out the design of all the gears, shafts, keys and the loads are calculated for individual gears in the epicyclic gear train system. Design, load analysis and optimization of compound epicyclic. Epicyclic gear train with bevel gear the bevel gears are used to make a more compact epicyclic system and they permit a very high speed reduction with few gears. Planetary gear trains are one of the main subdivisions of the simple epicyclic. Generic power split modelling for compound epicyclic four. Usually, following two types of lubrication mechanisms are commonly used for gear lubrication. Pdf design, load analysis and optimization of compound. For more videos click on playlist link shown below v kinematics of machinery komtom degree. If the arm is the input and the planet is the output, the overall gear ratio is 31 3. Theory of machines 1 for gate aspirants 17 lessons 2 h 31 m. But in case of epicyclic gear trains, the axes of the shafts. The mechanical efficiency of epicyclic gear trains.
Following are the different types of gear trains, depending upon the arrangement of wheels. Most gears are in the hardness range of approximately rc 30 to rc 38 or rc 55 to rc it is interesting to note that oil sample collected after 3 hours of operating gear at rpm no load conition show wear fig. Nov 12, 2017 problem no 1 on epicyclic gear trains gear trains kinematics of machinery theory of machines duration. However if the wheel s is fixed so that arm a can rotate about the axis of s. A thorough understanding of the sometimes difficult material is. The epicyclic gear first analysed here have the following components. Planetary gear system could be used to secure higher gear ratio in compact space.
In case there is a third gear there will be 3 trains and then 3 equations. In order to achieve the above objective, methodology of design used is explained in next point. Higher value of t f cause scuffing failure of gears. Epicyclic gear train solution techniques with application. 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. Iif the calculated result is negative, the driver and follower will rotate in opposite directions. A twostage planetary gear stage is defined using the program. In ptolemaic cosmology, a small circle, the center of which moves on the circumference of a larger circle at whose center is the earth and the circumference of which describes the orbit of one of the planets around the earth.
Planetary epicyclic gear ratios equations and calculators. In ptolemaic cosmology, a small circle, the center of which moves on the circumference of a larger circle at whose center is the earth and the. Circumferential velocities in a complex gear train have 3. Textile engineering mechanics of textile machinery nptel. An elementary gear train is composed of 3 parts or nodes. Two or four parameters model gear construction or scalar and vectorial power split. Due to the high speed and torque ratios and compact and effective structure planetary gear train systems are widely. Another class of gear train has wide application, the epicyclic or planetary train. R is the angular speed of the arm, equal to the input angular speed.
The following two methods may be used for finding out the velocity ratio of. The gear have more than one gear on the shaft in any epicyclic gear trains, there is called compound epicyclic gear train. Publishers pdf, also known as version of record includes final page, issue and. In all cases, if d is known, f 1 d, or, if f is known, d 1 f. 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.
To define a train, consider that it has always the arm r, a gear of the planet and a main gear. In this case, the planet gears have 12 teeth, the sun gear has 18 and the ring gear has 42 teeth. In an epicyclic gear train, the axis of at least one of the gears also moves. One is that the bushing needs to be wider to t over the cap on the pinion.
Asok kumar mallik department of mechanical engineering iit kanpur. A generic power flow model for compound epicyclic fourspeed gears is presented. A thorough understanding of the sometimes difficult material is facilitated through the use of both schematic and symbolic diagrams. The epicyclic gear trains are used in the back gear of lathe, differential gears of the automobiles, hoists, pulley blocks, wrist watches etc. A planetary gear train is defined as any gear train containing at least one gear that orbits by rotating about its own axis and also about the axis of an arm, or carrier. All the components are modelled in catia to check the assembly and the.
Write down the relative velocity equations on the lhs 4. A gear train having a relative motion of axes is called a planetary or an epicyclic gear train. The planet gear in figure 23 rotates about a fixed bevel gear at the center of which is the driven shaft. A gear train is a combination of gears used to transmit motion from one shaft to another.
It will be extremely useful to american engineers since it stresses the efficiencies of new and existing transmission designs and provides concise guide rules as well as worksheets. Epicyclic gear train in an epicyclic gear train, the axes of the shafts, over which the gears are mounted, may move relative to a fixed axis. Mullers discovery of their perfect analogy to the simple epicyclic drive trains. Kinematic and dynamic simulation of epicyclic gear trains. Epicyclic gear train nptel pdf merge friction losses can be divided into two major categories. Gear trains train of gears widely used on machines to transfer motion from one element to many elements. Jul 18, 2017 a gear train is a combination of gears used to transmit motion from one shaft to another. The book is profusely illustrated and analyzes many applications. With the rotation of each element of the gear train in hand, the overall gear ratio becomes easy. Example for, sun and planet gear is a compound epicyclic gear train. If the arm a is fixed the wheels s and p constitute a simple train.
N is the gears teeth number, the sign depends on the type of gear and, in sequence is for external gears. An epicyclic train is often suitable when a large torquespeed ratio is required in a compact envelope. By using epicyclic gear, different torque speed ratio can be obtained. Epicyclic gear train solution techniques with application to. Epicyclic definition of epicyclic by the free dictionary. As such, this article aims to provide assistance and guidelines for people designing epicyclic gear trains for the first timeand perhaps, if you will, ease their degree of suffering. A question that i often get is how to work out planetary gears using the gear template generator working out the tooth counts for planetary gears is actually not that complicated, so i initially neglected to mention how to do it.
Also different methods like tabulation and formula methods are discussed which are used to solve the questions based on planetary gear train. Provide a varied leverage between the engine and the drive wheels provide means to transfer power in opposite direction. Planetary gear trains pdf planetary gear is one of the epicyclic gear, which is a gear system consisting of. Design, load analysis and optimization of compound. In this lesson, we will study about epicyclic gear trains, planetary gear trains, easy method to solve numerals on epicyclic gear train and holding torque of gears. A gear whose axis itself is revolving is called a planetary gear.
If a number of bodies are assembled in such a way that the motion of one. Since the speed ratio or velocity ratio of gear train is the ratio of the speed of the driver to the. The following two methods may be used for finding out the velocity ratio of an epicyclic gear train. Types of gear train and velocity ratio calculation techminy. A network theory for variable epicyclic gear trains technische. Working out planetary gear turns ratios working out the gear ratio of a planetary gear train can be. Modelling ensures free choice of state variables, potential pregears and folding. The elementary planetary, or epicyclic, gear train is shown in figure 2, along with the simplified representation to. The gear train consists of five external gears and 4 internal annulus gears, including sun and planet gears forming an epicyclic gear train. Each element consists of the three components illustrated below. A gear train hav ing a relative motion of axes is called planetary or an epicyclic gear train.
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