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. So reverted gear train may be called as a compund gear train but all compound gear train can not be a reverted gear train. In epicyclic gear trains there is relative motion between axes which useful to transmit very high velocity ratio with gears of smaller sizes in lesser. Research laboratory new design and improvement of planetary. Pdf the mechanical efficiency of epicyclic gear trains. It require small area during the power transmission and to obtain large speed reduction.
Design, load analysis and optimization of compound epicyclic. The number of teeth on wheels c, d, e and f are 35, 65, 32 and 68 respectively. The mechanical efficiency of epicyclic gear trains. A gear train is a combination of gears used to transmit motion from one shaft to another. Notice how the planet gears roll on and revolve about the sun gear. Epicyclic gear train gear machines free 30day trial. Epicyclic gear trains are powerful when used correctly, but are often misunderstood. The wheels d and e rotate together on a pin fixed to the arm g. In an epicyclic gear train, the axis of at least one of the gears also moves. The book is profusely illustrated and analyzes many applications. The gear train consists of five external gears and 4 internal annulus gears, including sun and planet gears forming an epicyclic gear train. May 02, 2020 working principle of epicyclic gear train. The outermost gear, the ring gear, meshes with each of the planet gears.
A network theory for variable epicyclic gear trains technische. Introduction to gear trainsintroduction to gear trains. Apr 25, 2020 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 gears are mounted, may move relative to a fixed axis. The following two methods may be used for finding out the velocity ratio of. The circulation of the spur gear takes place in analogy to the orbiting of the planets in the solar system. The working principle of the epicyclic gearbox is based on the fact the fixing any of the gears i. The epicyclic gear train family in general has a central sun gear which meshes with and is surrounded by planet gears. In this case, the planet gears have 12 teeth, the sun gear has 18 and the ring gear has 42 teeth.
These are used in various automobiles and by this the effort of the driver will reduce and it increases comfort. An automotive gear differential is a jointfractionated planetary gear train with. Compound train an intermediate shaft carries two wheels connected in series. Gear trains theory of machines engineering reference with. It is interesting to note that coefficient of friction is variable and it depends on operating conditions. The epicyclic gear trains are used in the back gear of lathe, differential gears of the automobiles, hoists, pulley blocks, wrist watches etc. An epicyclic gear, also referred to as a planetary gear, is a gearing system in which gears known as planetary gears revolve around one central gear referred to as the sun gear.
In simple, compound and reverted gear train, gear shaft axis is fixed or not movable but in epicyclic gear trains, the shaft axes are not fixed means the shaft axis is movable. Epicyclic gearing requires a stepbystep process to make it work, and some of the steps are not necessarily intuitive. The advantages of the epicyclic gear train are as follows. The drive train is coupled to a mechanism known as a torque. The input gear has 20 teeth and the output gear has 100 teeth. Notice that the first gear ratio listed above is a reduction the output speed is slower than the input speed. To measure the output torque generated by the epicyclic gear system. Also, locking any two of the three components together will lock up the whole device at a 1. Typically, the planet gears are mounted on a movable arm or carrier, which itself may rotate relative to the sun gear. A planetary gear train is very much like our own solar system, and thats how it gets its name. To create large gear ratio, gears are connected together to form gear trains. A thorough understanding of the sometimes difficult material is facilitated through the use of both schematic and symbolic diagrams. Planetary gear system could be used to secure higher gear ratio in compact space.
Most modern automatic gearboxes have a set of gears called a planetary or epicyclic gear train. Publishers pdf, also known as version of record includes final page, issue and volume numbers. New design and improvement of planetary gear trains. R is the angular speed of the arm, equal to the input angular speed. The analysis is divided into three parts, in which the first. Jan 17, 2018 for the love of physics walter lewin may 16, 2011 duration. Each element consists of the three components illustrated below. By the way it is technically possible to follow the api rules of the special purpose gear units for petroleum, chemical and gas industry services, also for an epicyclic gearbox.
These drives receive an unusually clear treatment because at dr. An epicyclic train is often suitable when a large torquespeed ratio is required in a compact envelope. A planetary gear train is a little more complex than other types of gear trains. The epicyclic gear train is useful for transmitting highvelocity ratio with a gear of moderate size and in less space.
Epicyclic gearing also called as planetary gearing. Planetary gear trains are one of the main subdivisions of the simple epicyclic gear train family. Pdf epicyclic gear train dynamics including mesh efficiency. Following are the different types of gear trains, depending upon the arrangement of wheels. A presentation on epicycle gear train linkedin slideshare. In the running conditions of epicyclic gearbox, it is observed that the speed of the output shaft will be sometimes slow, sometimes fast and sometimes it can even reverse their direction also.
Design, load analysis and optimization of compound. The gear train maybe for spur gear, helical gear and spiral gear. In case there is a third gear there will be 3 trains and then 3 equations. Planetary or epicyclic gear train gear train mechanical. These gear trains are also used in bicycle for controlling power during pedaling. Epicyclic gear trains are known to provide high power density and have become the gear train of choice for the main power flow in virtually all rotorcraft designs. To define a train, consider that it has always the arm r, a gear of the planet and a main gear. Choosing which piece plays which role determines the gear ratio for the gearset. 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.
The following two methods may be used for finding out the velocity ratio of an epicyclic gear train. 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. An elementary gear train is composed of 3 parts or nodes. This is important gear train compared the said above. Centre distance a for the internal gear trains are shorter than the ex ternal gear trains. A pgt has been represented by its functional schematic, structural and kinematic graph. Such a gear configuration has useful applications, but the overall gear ratio. 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. Parts in a epicyclic gearbox sun gear the sun gear is a gear located at the centre of the whole setup and is always meshed with the planetary gears.
Gear trains theory of machines engineering reference. Advantages of planetary gear system planetary gear system has lots of advantage as compared to traditional gearboxes 1. A carrier connects the centers 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. Kinematic and dynamic simulation of epicyclic gear trains. Introduction to epicyclic gear train working and advantages and disadvantages of the epicyclic gear train. Types of gear train and velocity ratio calculation techminy. Epicyclic gearing systems also incorporate the use of an outer ring gear or annulus, which meshes. Each of these three components can be the input, the output or can be held stationary. An epicyclic gear train consists of two gears mounted so that the centre of one gear revolves the fundamental formula of the planetary gear train with a rotating carrier is obtained by recognizing that this formula remains true if the angular. The epicyclic gear train with bevel gears is used in 1.
Although the working principle of planetary gears has been known for many years, there is still a great interest towards this particular device. Table 1 comparison of parallel shaft vs epicyclic gear trains. A gear train is usually made up of two or more gears. An epicyclic gear train also known as planetary gear consists of two gears mounted so that the center of one gear revolves around the center of the other. To measure the different stage epicyclic gear systems speed output. Designing compound epicyclic gear trains for maximum speed at high. 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. Planetary gear is one of the epicyclic gear, which is a gear system consisting of one or more outer gears. Design validation of high speed ratio epicyclic gear. It is made up of a number of elements which are interconnected to form the train. 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. Simple train three or more wheels connected in series. Gear c compound epicyclic gear trainsun and planet gear in an epicyclic gear train, as shown in figure, the wheel c is keyed to the shaft b and wheel f is keyed to shaft a. The admissible contact ratio in a soc transmission after under.
Technique for examing epicyclic gear box krish gupta, ajay sharma amity university, aset, noida, india abstract this paper presents a method for analyzing epicyclic gearboxes by evaluating the speeds, torques and efficiency of the external elements in epicyclic gear mechanisms, as well as the total ratios of. A gear train hav ing a relative motion of axes is called planetary or an epicyclic gear train. This example shows an epicyclic gear drive with overall ratio of 256. In comparison with a differential train formed by spiral bevel gears, the meshing and precision will be substantially improved due to separate meshing of two pairs of gears. A planetary gear set consists of a central gear called the sun gear, an outer ring with internal gear teeth also known as the annulus, or ring gear, and two or three gears known as planet gears that rotate between the sun and ring gears. Jul 11, 2015 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.
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. Types of gear train simple, compound, reverted, epicyclic. 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. Mullers discovery of their perfect analogy to the simple epicyclic drive trains. In this paper, graph theory is used for the study of epicyclic gear trains or planet gear trains e. Interface shear strength in mixed lubrication can be given by. Pdf the paper presents an epicyclic gear train dynamic mathematical. What is epicyclic gearbox main components, working and. 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. 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 on a concentric orbit.
As fixing any of the above causes the variation in gear ratios from high torque to high speed. In a planetary train at least one of the gears must revolve around another gear in the gear train. An epicyclic gear train consists of two gears mounted so that the center of one gear revolves. Technique for examing epicyclic gear box krish gupta, ajay sharma amity university, aset, noida, india abstract this paper presents a method for analyzing epicyclic gearboxes by evaluating the speeds, torques and efficiency of the external elements in epicyclic gear mechanisms, as well as the total ratios of the gear box. The second is an overdrive the output speed is faster than the input speed. The last is a reduction again, but the output direction is reversed. This reverted technology is very much useful when the power is to be transmitted within the less space. Jun 17, 2019 epicyclic gear train nptel pdf merge sijthre. One of the planetary gearsets from our transmission has a ring gear with 72 teeth and a sun gear with 30 teeth.
It acts as a drum or a case for all the others gears. What is the advantage and disadvantage of a epicyclic gear. Internal gear train operates in the same gear direction. A thorough understanding of the sometimes difficult material is. The volume of the gear train with spur gears is reduced by 22. How a planetary gear train functions analogous to solar system.
Introduction to epicyclic gear train working and advantages. 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. It is the case of the gear presented in this paper, which can be considered full api6 compliant. Designing compound epicyclic gear trains for maximum speed at high velocity ratios, machine design, april 4, 1957. Planetary or epicyclic gear train epicyclic gear train.
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