This results in different ratios being generated by the. When the two gear are mating together, they rotating in opposite direction to each other. Lightweight design for planetary gear transmissions. The epicyclic or planetary train is a two dof device. Experimental analyses of vibration and noise of faulted. In mech designer, it is easier to add compound geartrains than simple gear trains the image to the left shows a compound gear train. The mechanical efficiency of epicyclic gear trains. Please start with the tutorial for shaft calculation to see how to introduce geometry and supports for single shafts. Files are available under licenses specified on their description page. Understanding, selecting and applying planetary gearheads.
An epicyclic train with a sun gear and planet gear orbiting around the sun, held in orbit by the arm. Planetary gear trains are one of the main subdivisions of the simple epicyclic gear train family. Two forms of planetary gears of the bevel type are shown in figures 23 and 24. In this project, a three stage epicyclic planetary reduction gear unit is designed to meet the output specifications. Generally, single stage epicyclic gear trains are more efficient than equivalent parallel shaft gear trains because. A study on optimization of planetary gear trains i. When driver gear is rotated in a clockwise direction, driven gear will rotate in anticlockwise direction. 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. An epicyclic gear train consists of two gears mounted so that the center of one gear revolves. Equation and calculators to determine ratios of planetary or epicyclic gear assemblies. Analysis of dynamic behavior of multiplestage planetary. The gear train may be either of simple single stage or compound double stage design and the. They are more difficult to analyze because they are a two. Having more teeth in mesh, not shifting the load so abruptly, also reduces the noise level.
Research article analysis of dynamic behavior of multiple. A multiple stage gear train composed of a two stage planetary gear train and a one stage parallel axis gear is shown in figure 3. So this one set of gears can produce all of these different gear ratios without having to engage or disengage any other gears. Suppose an epicyclic gear train has 2 gears gear a and gear b and an arm arm c. A second solution takes the original gear set and splits the two stage reduction into two branches, and the third calls for using a two stage planetary or star epicyclic. Foot operated 2 speed and reverse epicyclic transmission footbrake, 1908 for 19 yrs 9 million were made. It consists of twostage planetary gear trains in parallel with floating sun gears. So the absolute speed of a gear is the relative speed with respect to the shaft plus the shafts speed with respect to ground. Research article analysis of dynamic behavior of multiple stage planetary gear train used in wind driven generator jungangwang, 1, 2 yongwang, 1, 2 andzhipuhuo 1, 2 school of mechanical engineering, shandong university, jingshi road, jinan, shandong, china.
There is more than one gear pair and two shafts have two gears. This tutorial shows the usage of mesys shaft calculation with shaft systems. 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. Planetary gears, gear train, is 4460, torque density. Free body diagrams of gear trains american society for. Some epicyclic gear trains employ two planetary gears which mesh with each other. Each gear train consists of a sun gear in the centre, three planet gears, a planet linkage and an internal or ring gear. Based on the number of degrees of freed om, the epicyclic gear trains can be further categorized as differential and planetary gear trains.
One of these planets meshes with the sun gear, the other planet meshes with the ring gear. Following are the different types of gear trains, depending upon the arrangement of wheels. Theory of machines is an applied science of the relationships between geometry and relative motion of the parts of the machine, and concerns to the forces which. Introduction planetary gear trains, also referred to as epicyclic gear trains, are those in which there is one or more gears orbit about the central axis of the train. The tool investigated is from atlas copco st series and consists of three main parts. This paper presents the advantages of planetary gear systems over other, consideration to be given while determining the reduction ratios of gear box, minimum and maximum reductions per stage of planetary gear pairs. Epicyclic or planetary gear trains 45 the conventional gear trains are all one degree of freedom dof devices. New design and improvement of planetary gear trains. Calculation of a planetary gear train this tutorial shows the usage of mesys shaft calculation with shaft systems. The outermost gear, the ring gear, meshes with each of the planet gears. Other uses for gears how gear ratios work howstuffworks. Minimization of surface fatigue life factor and minimization of volume of gear box are two con. Motion from 2 to 3 and 2 to 4 are simple gear trains axes fixed.
Also the case study to determine the reduction ratio of two stage gear box is discussed. The circulation of the spur gear takes place in analogy to the orbiting of the planets in the solar system. For a planetary gear stage we need at least two shaft groups. 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 are mounted on shafts that turn in planet carrier and meshes with both. The comparison of planetary gear system over helical gears systems is. Planetary gear trains are extensively used for the power transmission and are the most critical component. You can see a picture of a two stage planetary gear system on the electric screwdriver page, and a three stage planetary gear system of the sprinkler page.
The comparison of planetary gear system over helical gears systems is done on the basis of volume, weight and torque density keywords. Types of gear train simple, compound, reverted, epicyclic. Types of gear trains the meshing of two gears may be idealised as two. L where a gear a and the arm c have a common axis at o 1 about which they can rotate. Show students how the gear ratio can be expressed as a fraction. Definition and types with pdf saswata baksi refrigeration and airconditioning leave a comment. 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. Therefore, it agrees the definition of the compound gear train. A pgt has been represented by its functional schematic, structural and kinematic graph. In this paper, graph theory is used for the study of epicyclic gear trains or planet gear trains e. All structured data from the file and property namespaces is available under the creative commons cc0 license. Planetary epicyclic gear ratios equations and calculators.
For the love of physics walter lewin may 16, 2011 duration. Design of machinery an introduction to the synthesis and. In the first three types of gear trains, the axes of the shafts over which the gears are. In an epicyclic gear train, the axes of the shafts, over which the gears are mounted, move relative to a fixed axis. Pdf design and analysis of an epicyclic gearbox for an electric. To draw a fbd of gear train, the first step is to isolate the system a shaft with gears mounted from its surroundings meshing gears and bearings, as shown in fig. Special issue of the 3rd international conference on. Types of gear train and velocity ratio calculation techminy. Experimental characterization of the coupling stage of a twostage. This page was last edited on 19 october 2019, at 01. Fbd of a gear train in a double reduction gear train shown in fig.
Another class of gear train has wide application, the epicyclic or planetary train. Gears with reduction ratios not incluted in the above table may be manufactured at request. The gear trains is having only one gear on each shaft is known as simple gear train. Epicyclic trains epicyclic trains give the engineer an opportunity to produce huge speed reductions or increases in a relatively small space. The conventional arrangement of single or double stage reduction. Planetary gearboxes are used frequently to match the inertias, lower the motor speed, boost the torque, and at the same time provide a sturdy. Describe three types of epicyclic gear boxes solve gear box ratios.
Pdf the mechanical efficiency of epicyclic gear trains. A two stage planetary gear stage is defined using the program. The output shaft is attached to the blue ring gear, and the planet carrier is held stationary this gives the same 6. One example of two gear train is shown in the image below. With two of these gearsets in a row, we can get the four forward gears and one reverse gear our transmission needs. 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. All the components are modelled in catia to check the assembly and the.
With these requirements in mind, lets look at three possible solutions, one involving a single branch, two stage helical gear set. The planet gear in figure 23 rotates about a fixed bevel gear. This apparatus consists of two standard epicyclic gear trains. The epicyclic gear train family in general has a central sun gear which meshes with and is surrounded by planet gears. We can find the ratio of any two gears if we know the number of teeth on each of the gears. Developing the gear ratio formula sae international. 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. Introduction to gear trainsintroduction to gear trains. The basic idea consists of the fact that a traditional multi stage gear transmission unit with stationary shaft axes and. The sun gear, ring gear and planet carrier all rotate about the same axis. This accounts for epicyclic gear trains being more quiet than parallel shaft gear trains. Epicyclic gear train is a special type of gear train which is used to transmit motion and power from one shaft to another shaft.28 855 30 1316 1131 466 1615 1562 1088 798 355 1176 394 1402 1354 742 1327 242 1433 1186 877 1331 547 1524 292 1210 663 1227 511 599 235 903 1137 1492 1236 975 701 1345 50 254 527 754 360 1442 1309 902 647 2 1296