Gear train with sun, planet, and ring gears matlab. On completion of this short tutorial you should be able to do the following. Design, load analysis and optimization of compound epicyclic gear trains syed ibrahim dilawer1, md. It is the ratio of the reference diameter of the gear divided by the number of teeth.
In the past ive had luck using this site to create an illustrator file that i can extrude in rhino. On the preceding page, i demonstrated a simple, tabular method for calculating speeds in a planetary gearset with one input fixed. The main purpose of this planetary was to see if i could make it with hand cut gears and how smoothly it would operate. Dxf and iges interfaces allow zar5 to be linked to cad and dtp systems. The total sunplanet tooth forces for a threeplanet planetary gear set turn out to be as follows. In a conventional manual transmission gearbox application there are two 2 gears involved driven and drive for any given gear ratio.
Provided that the ring gear has a constant size, different ratios can be realized by varying the number of teeth of the sun gear and the number of teeth of the planetary gears. Choosing which piece plays which role determines the gear ratio for the gearset. Spur gears can be generated as stl files and manufactured by means of a 3d printer. Epicyclic gearing planetary gearboxes neugart gmbh. Calculate the number if teeth required in the ring gear for the ratio 5. Structure and analysis of planetary gear trains prof. Elec tric mo to r gt1 gt2 scre w driv er sh af t sw itc h mo t o r sha f t t. Epicyclic gearing systems also incorporate the use of an outer ring gear or annulus, which meshes. In its manufacturing, because of its shape, the usual hobbing machine used in spur gear production cannot be used. A single tooth, the tooth space, the complete gear, geargenerating tool, planetary gear train and a sectional view of the tooth action can be displayed on the screen or output as a cad drawing. Also the case study to determine the reduction ratio of two stage gear box is discussed. A carrier connected to a drive shaft holds the planet gears.
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. The compound planetary gear block represents a planetary gear train with composite planet gears. Reduction ratios not listed in chart 1 require special design. Zar5 generates drawings of the front and side elevation of the gears calculated, plus tables containing the gear data and dimensions. Planetary gear boxes chapter 10 5 technical information because our supplier is continuously improving its. The tool investigated is from atlas copco st series and consists of three main parts. In this tutorial, we will show you an original and easyto. For simple, epicyclic planetary stages when the ring gear is stationary, the practical gear ratio range varies from 3. Design and optimization of planetary gears considering all. A twostage planetary gear stage is defined using the program. 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. The smallest number of teeth on a spur pinion and gear, onetoone gear ratio, which can exist without interference is np. 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.
When there are three or more planets, as is the usual case, care must be made to make sure the teeth of both planets can engage. This was mainly intended to help build your intuition for these fascinating systems. This block models a gear train with sun, planet, and ring gears. For similar epicyclic planetary stages with compound planet gears, the practical gear ratio range varies from 8. One of the planetary gearsets from our transmission has a ring gear with 72 teeth and a sun gear with 30 teeth. Gears range in size but the important number is how many teeth a gear has.
Design, load analysis and optimization of compound. Compared to conventional simple and compounded planetary gear trains, the mechanical assembly of the gear bearing drive does not require a. In this case, the ratio of the 15tooth driver gear and the 45tooth driven gear is 3. Enter transmission ratio and number of stages for predimensioning of a multi stage planetary gear. In mechanical engineering, a gear ratio is a direct measure of the ratio of the rotational speeds of two or more interlocking gears. 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. The final product of the effort, shown above, was des.
Working out planetary gear turns ratios working out the gear ratio of a planetary gear train can be tricky. A friend and i decided on making a 3d printable planetary gear to test if the idea was fully possible to model into a somewhat modular design that allows for simple assembly and standalone use. How to i design a planetary gear with a gear ratio of 2. The angular speed of the planet carrier can be found since we know the. Gear generator is a tool for creating involute spur gears and download them in svg format. The planet gear in figure 23 rotates about a fixed bevel gear at the center of which is the driven shaft. Technically, a meaningful ratio range for a planetary stage is approx. In this case, the planet gears have 12 teeth, the sun gear has 18 and the ring gear has 42 teeth.
Notice that the first gear ratio listed above is a reduction. Best suited for applications where a great ratio reduction is required between the. Understanding, selecting and applying planetary gearheads. The next steps depend on the state of the planetary gears connected to the carrier, although all use the same formula. The mechanical efficiency of epicyclic gear trains. The gear ratio formula for two meshing gears is simple and intuitive, while the gear ratio formula for the planetary mechanism is not. Another class of gear train has wide application, the epicyclic or planetary train. Planetary gear drive of high reduction ratios, clutches, etc. Each of these three components can be the input, the output or can be held stationary. Ports c, r, and s represent the shafts connected to the planet gear carrier, ring gear, and sun gear. Design of machinery an introduction to the synthesis and.
We can get lots of different gear ratios out of this gearset. These gear arrangements give different speed ratio options. Each composite planet gear is a pair of rigidly connected and longitudinally arranged gears of different radii. The comparison of planetary gear system over helical gears systems is done on the basis of volume, weight and torque density keywords. The number of teeth for spur gears is given by where k 1f fll1 for fulld tht th08f tbt th d ldepth teeth, 0. Solid mechanics tutorial gear systems this work covers elements of the syllabus for the edexcel module 21722p hncd mechanical principles outcome 3.
A gear ratio is the ratio between the driver gear the one being powered and the driven gear the. Two forms of planetary gears of the bevel type are shown in figures 23 and 24. How to derive the formula for the planetary mechanism gear ratio. Reduction ratio i 833 808i 1,500 examplesof selection select the nearest reduction ratio from among the ratios of the standard reduction ratio chart see chart 1. Typically, the planet gears are mounted on a movable arm or carrier, which itself may rotate relative to the sun gear. Let us compare a planetary gear train with a conventional one, with fixed gear axes, designed for the same gear ratio of angular velocities of the input and output mechanism links. Bear in mind the difference between the standard reduction ratio fo framenumbers under 315 and over 355. These gears can only offer two 2 variations between the input shaft and output shaft, forward or reverse but the ratio remains the same. Driver planetary gear character istics this is a c o mp li c a t e d m e c h a n ism to solve. Calculating load on planetary gear from driving torque. Also, locking any two of the three components together will lock up the whole device at a 1. 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. For example, if the sun gear has 20 teeth and the ring gear has 60, the planetary gear has 80 teeth.
Planetary gear train with stepped planet gear set matlab. Internal gear is a gear with its teeth cut in the internal surface of a cylinder and meshes with spur gears. You can click on any of the images for a larger view. Planetary gears, gear train, is 4460, torque density. Calculation of a planetary gear train this tutorial shows the usage of mesys shaft calculation with shaft systems. Pdf the mechanical efficiency of epicyclic gear trains. D rotation of driver per revolution of follower or the driven gear or pulley. Planetary gears are common in transmission systems, where they provide high gear ratios in compact geometries. Design and optimization of planetary gears considering all relevant influences tobias schulze gear design process lightweight construction and consideration of available resources result in gearbox designs with high load capacity and power density.
It is stated that the simple planetary gear train consisting. This factor takes into account the application load conditions. If the carrier is acting as the input in the planetary gear system, rotating the ring gear while the sun gear is still, divide the number of teeth on the ring gear the driven gear by the number of teeth on the planetary gears the driving gears. Ronald walters multilayer planetary drive ronald walters sent me some pictures and a description of a very complicated planetary gear drive that he built. Calculate gear ratio by dividing the number of teeth. Intro planetary gears also refer as epicyclic gearing consisting three elements sun. One more design requirement must be specified to do the remaining calculations. This does not generate planetary gears, and im also unclear as to how design a planetary gear with a 2. The order of the two numbers in a ratio is very important. Planetary gear ratio calculations this article also available in spanish. Please start with the tutorial for shaft calculation to see how to introduce geometry and supports for single shafts.
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