The gear train may be either of simple single stage or compound double stage design and the derived formula for each arrangement is as follows. Power analysis and efficiency calculation of the complex and closed planetary gears transmission. Having more teeth in mesh, not shifting the load so abruptly, also reduces the noise level. 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. It is a gear system that consists of one or more outer gear planet gear rotating about a central sun gear. Input torque, output torque and holding or braking torque are. 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. 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. Example 6 figure shows a compound epicyclic gear train.
Gear ratio is also equal to the ratio of output torque to input torque. The planet gear are mounted on a moveable arm carrier. Following are the different types of gear trains, depending upon the arrangement of wheels. 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. The gear train maybe for spur gear, helical gear and spiral gear. Simple train three or more wheels connected in series. Introduction to epicyclic gear train working and advantages. Best epicyclic gear train in mechanical engineering. Some epicyclic gear trains employ two planetary gears which mesh with each other. The gear train may be either of simple single stage or compound double stage design and the. Calculation of a planetary gear train this tutorial shows the usage of mesys shaft calculation with shaft systems. A gear train consists of a series of series of gears to transfer power from one shaft to another.
The kinematic design of gear trains is principally involved with the selection of appropriate ratios and gear diameters. A twostage planetary gear stage is defined using the program. Planetary gear ratio calculations this article also available in spanish. In this paper, graph theory is used for the study of epicyclic gear trains or planet gear trains e. It is stated that the simple planetary gear train consisting. 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. It is the case of the gear presented in this paper, which can be considered full api6 compliant. Types of gear train and velocity ratio calculation techminy. Choosing which piece plays which role determines the gear ratio for the gearset. A gear train is a combination of gears used to transmit motion from one shaft to another. For example, if the sun gear has 20 teeth and the ring gear has 60, the planetary gear has 80 teeth.
Most of the pictures and animations are from norton, design of machinery mcgrawhill, 2004. Plane t a r y gear tra i n s consis t o f the follo w i n g. Therefore output torque is calculated by multiplying input torque with gear ratio. Epicyclic gear train is a special type of gear train which is used to transmit motion and power from one shaft to another shaft. This method is extremely procedural, which is appropriate since use of intuition is often quite futile when applied to complex gear trains.
Zoltan levai received 9 february 1968 abstract both compound and internal or external planet gears are considered as well as the paired planet gears. Pdf epicyclic gear train dynamics including mesh efficiency. The epicyclic gear train family in general has a central sun gear which meshes with and is surrounded by planet gears. Planetary kinematics note that point 1 on the planet gear is stationary zero velocity due to noslip assumption note that point 2 on the planet gear has the same velocity as point 2 on the sun gear also due to noslip assumption, which is given by. Planetary epicyclic gear ratios equations and calculators. Planetary gear trains are one of the main subdivisions of the simple epicyclic gear train family. Please start with the tutorial for shaft calculation to see how to introduce geometry and supports for. 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. Generally, singlestage epicyclic gear trains are more efficient than equivalent parallel shaft gear trains because.
How to derive and calculate epicyclic gear ratio equations. Planetary or epicyclic gear gear ratios are the rates at which the selected gears rotate relative the mechanical advantage. Calculate the suitable numbers of teeth for the gears. One of these planets meshes with the sun gear, the other planet meshes with the ring gear. The fundamental formula of the planetary gear train with a rotating carrier is obtained by. The outermost gear, the ring gear, meshes with each of the planet gears. Each of these three components can be the input, the output or can be held stationary. Power analysis and efficiency calculation of the complex. Planetary or epicyclic gear train epicyclic gear train. Pdf the mechanical efficiency of epicyclic gear trains. 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. 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. The next steps depend on the state of the planetary gears connected to the carrier, although all use the same formula. In this video, we have discussed how to tackle questions related to gear train, how to make the necessary table and reach the desired conclusion.
In addition it let you compose full gear layouts with connetcted gears to design multiple gears system with control of the inputoutput ratio and rotation speed. Intro planetary gears also refer as epicyclic gearing consisting three elements sun gear, planet gear and ring gear. It require small area during the power transmission and to obtain large speed reduction. Gears can be animated with various speed to demonstrate working mechanism. Gear trains theory of machines engineering reference. The angular speed of the planet carrier can be found since we know the. R is the angular speed of the arm, equal to the input angular speed. Internal gear train operates in the same gear direction. 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. In this research paper torque calculations are done for epicyclic gear train. Epicyclic gear train nptel pdf automatic transmission has. Solid mechanics tutorial gear systems this work covers elements of the syllabus for the edexcel module 21722p hncd mechanical principles outcome 3.
The mechanical efficiency of epicyclic gear trains. The tool investigated is from atlas copco st series and consists of three main parts. An epicyclic gear train consists of two gears mounted so that the center of one gear revolves. Gears in the epicyclic gear trains are one of the most critical components in the mechanical power transmission system in which failure of one gear will affect the whole transmission system, thus it is very necessary to determine the causes of. We present here a simple, methodical procedure for determining the final gear ratio of an epicyclic gear train. Structure and analysis of planetary gear trains prof. When pinion is the driver, it results in step down drive in which nptl output speed. Epicyclic gearing requires a stepbystep process to make it work, and some of the steps are not necessarily intuitive.
Introduction to epicyclic gear train working and advantages and disadvantages of the epicyclic gear train. Another class of gear train has wide application, the epicyclic or planetary train. One of the planetary gearsets from our transmission has a ring gear with 72 teeth and a sun gear with 30 teeth. But in case of epicyclic gear trains, the axes of the shafts on which the gears are mounted may move relative to a. On completion of this short tutorial you should be able to do the following. Centre distance a for the internal gear trains are shorter than the ex ternal gear trains. Tabular method for epicyclic gear trains watch more videos at. A formula for selecting the correct efficiency value, to be used in the model, depending on the direction of power flows along the epicyclic 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. The design of planetary gear trains consists of following steps. A pgt has been represented by its functional schematic, structural and kinematic graph.
Design, load analysis and optimization of compound. This results in different ratios being generated by the. A complete gear train design will necessarily involve considerations of strength of. Lightweight design for planetary gear transmissions. Epicyclic gear trains are useful for transmitting high velocity ratios with gears of moderate size in a comparatively lesser space. Compound train an intermediate shaft carries two wheels connected in. Driver and driven instrumentality should be in line to avoid further gearing. Epicyclic gearing also called as planetary gearing. Equation and calculators to determine ratios of planetary or epicyclic gear assemblies.
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. Calculation of number teeth of sun, planets and ring gear. 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. Types of gear train simple, compound, reverted, epicyclic. This accounts for epicyclic gear trains being more quiet than parallel shaft gear trains. Pdf design, load analysis and optimization of compound. Table 1 comparison of parallel shaft vs epicyclic gear trains. The advantage of this gear train is the possibility to obtain a low gear ratio, that is not permissible by a conventional face gear train. Sun gear is located at the center that transmits torque to planet gears orbiting around the sun gear. Gear generator is a tool for creating involute spur gears and download them in svg format. We use the method introduced in epicyclic ratio calculation for determining the final gear ratio of an epicyclic gear train. Epicyclic gear train overdrives are so arranged that the input shaft drives the pinion carrier while the output shaft is driven by the annular gear ring figs 3.
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