The tool investigated is from atlas copco st series and consists of three main parts. Often the term transmission refers simply to the gearbox that uses gears and gear trains to provide speed and torque conversions from a rotating power source to another device in british english, the term transmission refers to the whole drivetrain, including clutch, gearbox, prop. The gear b meshes with gear a and has its axis on the arm o 2, about which the gear b can. The planet gears red are being driven by the sun gear green and the ring gear light blue. Epicyclic definition of epicyclic by the free dictionary. It is a gear system that consists of one or more outer gear planet gear rotating about a central sun gear. An epicyclic gear train also known as planetary gear consists of two gears mounted so that the centre of one gear revolves around the centre of the other. Typically, the planet gears are mounted on a movable arm or carrier, which itself may rotate relative to the sun gear. The following two methods may be used for finding out the velocity ratio of an epicyclic gear train. Litvin, alfonso fuentes, daniele vecchiato, and ignacio gonzalezperez university of illinois at chicago chicago, illinois 606077022 summary the development of new types of planetary and planetary face gear drives is proposed. The advantage of epicyclic gear train is that, it can get very high or very low velocity ratio compared to simple gear trains and compound gear trains.
Equation and calculators to determine ratios of planetary or epicyclic gear assemblies. A preselector gearbox is a type of manual transmission mostly used on passenger cars and racing cars in the 1930s, in buses from 19401960 and in armoured vehicles from the 1930s to the 1970s. This is particularly true for planetary gearboxes in industrial gear. Epicyclic gear train, output torque, holding torque. Informative paper epi cyclic gear calculator this is the way some automatic transmissions work. Solid mechanics tutorial gear systems this work covers elements of the syllabus for the edexcel module 21722p hncd mechanical principles outcome 3. The epicyclic gear trains are used in the back gear of lathe, differential gears of the automobiles, hoists, pulley blocks, wrist watches etc. In epicyclic gear train, different types of gear are used like spur gear, helical gear, bevel gear and many more.
Design and fabrication of epicyclic gear box ijarcce. Small gear driving large gear under drive under drive happens when carrier is the output under drive increases torque decreases speed large gear driving smaller gear overdrive overdrive happens when the carrier is the input if the carrier is held, the gear set goes to reverse. D rotation of driver per revolution of follower or the driven gear or pulley. Epicyclic gearing also called as planetary gearing. However, the application of api6 design requirements, on top to those provided by the agma, which shall be considered the mandatory baseline, determines a general increase of the gear rating and therefore of the gear. Introduction to epicyclic gear train working and advantages. November 17, 2017 by danielle collins leave a comment a planetary gearbox offers high torque transmission with good stiffness and low noise, in a more compact footprint than other gearbox types. We present here a simple, methodical procedure for determining the final gear ratio of an epicyclic gear train. The epicyclic gear train is useful for transmitting highvelocity ratio with a gear of moderate size and in less space. Epicyclic gearing planetary gearboxes in an epicyclic or planetary gear train, several spur gears distributed evenly around the circumference run between a gear with internal teeth and a gear with external teeth. The bevel gear shown in blue, which revolves around the shafts of the wheels, is also referred to as the spider gear. In an epicyclic gear train, the axes of the shafts, over which the gears are mounted, move relative to a fixed axis.
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. The heart of the planetary gearbox is the reduction group composed by the sun pinion. The planetary gear set, also known as the epicyclic gear train, is one of the most important and interesting inventions in engineering. Epicyclic gearing requires a stepbystep process to make it work, and some of the steps are not necessarily intuitive. The basic of epicyclic gear is that it has an sun gear, planetary gears and ring gears this type of gear mechanism is used in the pto shaft of the tractors a. In 1588, italian military engineer agostino ramelli invented the book wheel, a. Design, modelling and analysis of a 3 stage epicyclic planetary reduction gear unit of a flight vehicle k akhila1 and m amarnath reddy2 corresponding author. L where a gear a and the arm c have a common axis at o 1 about which they can rotate. Most modern automatic gearboxes have a set of gears called a planetary or epicyclic gear train. It features a sun gear, planetary gears, carrier and a ring gear. The gear ratio in an epicyclic gearing system is somewhat nonintuitive, particularly because there are several ways in which an. The planet gear are mounted on a moveable arm carrier. Planetary gear is one of the epicyclic gear, which is a gear system consisting of one or more outer gears, or planet gears, revolving about a central, or sun gear. In this simple example of an epicyclic train, the only gear left to take an output from.
Epicyclic gear calculations pdf with four core components, calculating the gear ratio of planetary gear systems, also known as epicyclic gear systems, may seem daunting. Design, load analysis and optimization of compound. Table 1 comparison of parallel shaft vs epicyclic gear trains. Introduction to gear trainsintroduction to gear trains. On completion of this short tutorial you should be able to do the following. These gears are different in size and have different number of teeth, which is. Epicyclic gearing or planetary gearing is a gear system consisting of one or more outer, or planet, gears or pinions, revolving about a central sun gear or sun wheel. Introduction to epicyclic gear train working and advantages and disadvantages of the epicyclic gear train. R is the angular speed of the arm, equal to the input angular speed. The gears were modeled procedurally with a python script i wrote, and the rotation values for the. Industrial gearboxes are being designed as increasingly compact with smaller design envelope while their power levels are continually increasing. An epicyclic gear train consists of two gears mounted so that the center of one gear revolves.
But they differ in construction in some important details. The working principle of the epicyclic gearbox is based on the fact the fixing any of the gears i. Design of two stage planetary gear trains for reduction ratio 78. Choosing which piece plays which role determines the gear ratio for the gearset. Pdf design and analysis of an epicyclic gearbox for an electric. Epicyclic gearing planetary gearboxes neugart gmbh. As the input power flow and ouput one are on the same axes, the efficiency of the gearbox is directly obtained from the efficency of the basic epicyclic gear, which depends on speed, torques and. One of the planetary gearsets from our transmission has a ring gear with 72 teeth and a sun gear with 30 teeth. 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.
A carrier connects the centres of the two gears and rotates to carry one gear, called the planet gear or planet pinion, around the other, called the sun gear or sun wheel. New design and improvement of planetary gear trains faydor l. Epicyclic gear train an epicyclic gear train,the axes of the shafts, over which the gears are mounted, may move relative to a fixed axis. And indeed, the differential gear can be seen as a special form of a planetary gearbox more on this later. Automatic transmission basics linnbenton community.
The gearboxes from these manufacturers work on the same principle, i. Types of gear train simple, compound, reverted, epicyclic. What is epicyclic gearbox main components, working and. Design of machinery an introduction to the synthesis and. Reverted gear train, planetary or epicyclic gear train. Planetary gear bearing arrangements in industrial gearboxes. In principle, this spider gear is nothing else than a planet gear as it is known from planetary gears.
The working of epicyclic gear box can not be explained briefly as it requires more study. This method is extremely procedural, which is appropriate since use of intuition is often quite futile when applied to complex gear trains. Design validation of high speed ratio epicyclic gear. Consequently, this work extends the scope of engineering analysis of epicyclic gearing. Epicyclic gearing arrangements are comprised of four different. Pdf the mechanical efficiency of epicyclic gear trains. And it can be wildly used in industry, such as printing lathe, automation assembly, semiconductor equipment and automation system. As fixing any of the above causes the variation in gear ratios from high torque to high speed.
Each of these three components can be the input, the output or can be held stationary. Here is a single stage epicyclic gearbox where we can obtain only 2 speed ratios i. What are the drawbacks to using a planetary gearbox. Planetary gear ratio calculations this article also available in spanish. 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.
An epicyclic gear train includes planetary gears rotatably mounted on spindles supported by an annular carrier and including axially spaced apart forward and aft sets of output teeth extending radially outwardly from a planetary gear hub and axially spaced apart forward and aft roller bearings disposed between planetary gears and spindles. A planetary gear set consists of a central gear called the sun gear, an outer ring with internal gear teeth. It is the case of the gear presented in this paper, which can be considered full api6 compliant. This increase in power density within a very small space places increasingly high demands on the rolling bearings used. Planetary epicyclic gear ratios equations and calculators. Epicyclic gearing systems also incorporate the use of an outer ring gear or annulus, which meshes. Epicyclic gear train problems and solutions pdf best of all, they are entirely free to find, use and download, so there is no cost or stress at all.
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