Each composite planet gear is a pair of rigidly connected and longitudinally arranged gears of different radii. Torque and efficiency the power transmitted by a torque t nm applied to a shaft rotating. Planetary gear train pgt has been widely used in the transmissions of helicopters, automobiles, wind turbine, aircraft engines, etc. The planet gear in figure 23 rotates about a fixed bevel gear at the center of which is the driven shaft. Effects of planetary gear ratio on mean service life. In case the motion of the planet gear is required directly, the shaft of the planet gear can, for example, be coupled to another shaft output shaft by universal joints fig. Two forms of planetary gears of the bevel type are shown in figures 23 and 24. The epicyclic gear train family in general has a central sun gear which meshes with and is surrounded by planet gears. Planetary gear train with stepped planet gear set matlab. A practical method to analyze planetary gear train for speed ratio determination is. Pdf relations between size and gear ratio in spur and planetary.
However, the rotation of the planet gear is seldom used directly. Planetary designs also cannot have ratios less than 3. The main advantages of this transmission are its high efficiency, its compactness, its large transmission ratio and its large powertoweight ratio, etc. An example of the differentialplanetary gear actuator with common planet gears is shown in figure 3. In this case, the planet gears have 12 teeth, the sun gear has 18 and the ring gear has 42 teeth. This is a fully functional handcranked model of a multistage planetary reducer. Planetary gear boxes chapter 10 5 technical information because our supplier is continuously improving its. Each of these three components can be the input, the output or can be held stationary. Finally, we include a general kinematic analysis of wheeled mobile robots wmrs.
Planetary gear trains are one of the main subdivisions of the simple epicyclic gear train family. This paper presents analysis and design of planetary gear arrangements that provide extremely high gear ratios. The higher the ratio, the higher the chances of default and hence more hindrance in the growth of the company. Lightweight design for planetary gear transmissions. Epicyclic gearing systems also incorporate the use of an outer ring gear or annulus, which meshes. Since, i am working in the metric unit every dimension will be in mm. A planetary gear set can give a higher powertoweight ratio than a parallel shaft gear set while keeping the input and output shaft coaxial. Gear box ratio the ratio of the gear box is defined as 2 1 n n output speed input speed g. 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. A gear in the centre is called the sun gear, the gears rotating around the sun are called planet gears, and the gear.
The central gear around which the planet gears revolve. N is usually in revmin but the ratio is the same whatever units of speed are used. Pdf in this report equations for the minimum gear sizes necessary to drive a given load are derived. Gear stages gear ratios gear types bearings materials lubrication interfaces etc. Understanding, selecting and applying planetary gearheads. The compound planetary gear block represents a planetary gear train with composite planet gears. Internet searches for how to proved fruitless and dare i say information is being withheld, so this programmer set out to demystify the methods for calculating the widely used equations of. One of the planetary gearsets from our transmission has a ring. Planetary gear systems have very smalllarge train ratios and are very compact.
The general formula for calculating the gear ratio in a gear. Computational methodology the compound planetary gear train taken from the elecon engineering shown in figure 2. The dualwheel transmission dwt, proposed elsewhere using epicyclic gear. Design of machinery an introduction to the synthesis and. The range of possible reduction ratios is bounded from below and above by limits on the relative size of the planet gears. The outermost gear, the ring gear, meshes with each of the planet gears. Pdf dynamics equations of planetary gear sets for shift. This paper presents planetary gear transmissions, designed according to iso 6336 ref. Calculate gear ratio by dividing the number of teeth on the driven gear by the number of teeth on the driving gear. So ive found the following formula for calculating the gear ratio of a planetary gear. Calculate the number if teeth required in the ring gear for the ratio 5. How to i design a planetary gear with a gear ratio of 2. Please start with the tutorial for shaft calculation to see how to introduce geometry and supports for single shafts. This does not generate planetary gears, and im also unclear as to how design a planetary gear with a 2.
Relations between operating pressure angles in the gear. The larger gear engages a centrally located sun gear, while the smaller gear engages the ring gear. Typically, the planet gears are mounted on a movable arm or carrier, which itself may rotate relative to the sun gear. To determine the gear condition in a simple planetary gear set always look at what the carrier is doing. Developing the gear ratio formula build knowledge introduction what students do in this activity in this activity students make observations about the rotation relationships in the tables they made during the recording gear rotations activity.
The real scope of this paper is on design parameter, gear ratio, gear tooth combination, stress, and factor of safety. This essay is dedicated to the planetary gear sets, with a focus on the ravigneaux planetary gear set which represents, in fact, improved version of simpsons planetary gear set. Gear ratio 7 half shaft helical gear 5 horsepower 3 hypoid gear 6 manual transmission 8 overdrive 7 pinion gear 8 pitch diameter 4 planet carrier 11 planetary gear set 11 power transfer unit 16 rearwheel drive rwd ring gear 11 spiral bevel gear 6 spur gear 5 sun gear 11 torque 2. For a singleplane transmission, the planet gear has no size of the sun and ring. How to derive the formula for the planetary mechanism gear ratio duration. Working out planetary gear turns ratios working out the gear ratio of a planetary gear train can be. Developing the gear ratio formula sae international. Generally, a second central gear is driven by the planet gear fig. Epicyclic gearing or planetary gearing is a gear system that consists of one or more outer gears, or planet gears, rotating about a central, or sun gear. A compound configuration for planetary gear train is selected and an optimization. In this tutorial, we will show you an original and easyto.
Relations between size and gear ratio in spur and planetary gear trains. The exponent to use in the calculation of equivalent load depends on material type, heat treatments. For example, if the sun gear has 20 teeth and the ring gear has 60, the planetary gear has 80 teeth. A heuristic synthesis of multistage planetary gearbox layout for. Planetary gear transmissions are compact, highpower speed reducers that use parallel load paths. Planetary epicyclic gear ratios equations and calculators. Dynamics equations of planetary gear sets for shift quality by lagrange method. The contact ratio is an index of the quantity of overlap occurring between two conjugate cams. In manual transmission, the discontinuity of power during gear shifting.
I have also checked the ratios against machinerys handbook 27th edition page 2115. Ports c, r, and s represent the shafts connected to the planet gear carrier, ring gear, and sun gear. One of the two gears engages the centrally located sun gear while the other engages the outer ring gear. Planetary gear ratios from a loadcapacity point of view, the most suitable gearhead ratio has the highest torque density for the most compact and costeffective package. A twostage planetary gear stage is defined using the program. Planetary gearing could increase torque and reduce load inertia while slowdown the speed. Planetary gears are common in transmission systems, where they provide high gear ratios in compact geometries. Introduction an epicylic gear is a planetary gear arrangement consisting of one or more planet epicyclic gears p meshed and rotating round a central sun gear s. Gear train with sun, planet, and ring gears matlab.
Another class of gear train has wide application, the epicyclic or planetary train. Intro planetary gears also refer as epicyclic gearing consisting three elements sun. Atlas copcos previous knowledge about power losses in planetary gears. Download mitcalc planetary gearing a smallsized and reliable piece of software specifically built to provide you with various solutions for designing spur. Gearing ratio is commonly used by financial analyst to understand the overall capital structure of the company by dividing total debt to total equity.
They explore these relationships as constant values that depend on the number of teeth on the two gears. In the past ive had luck using this site to create an illustrator file that i can extrude in rhino. Which ratio is best for a planetary reduction can be resolved by studying a series of optimal. If ever the carrier is an output in a simple planetary gear set, the condition will be forward reduction. This factor takes into account the application load conditions. Question about calculation of planetary gear ratios. To compare with traditional gearbox, planetary gear has several advantages. 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 a widely used industrial product in midlevel precision industry, such as printing lathe, automation assembly, semiconductor equipment and automation system. Article information, pdf download for a heuristic synthesis of multistage planetary gearbox. Selecting gears in metric unit the gear tooth profile of the spur gear will be in module. Outer gears meshes with an outer internal geared wheel willis formula allow to calculate reduction ratio for an epicyclic.
1337 1120 688 877 706 933 1566 1515 851 1332 823 991 1246 906 838 1081 1216 385 396 971 269 1554 1169 393 663 476 415 760 1420 144 1270 1012 1165 450 129 557 590 215 161 838 867 1460 1079 372 450 13 342