Planetary gear is a widely used industrial product in midlevel precision industry, such as printing lathe, automation assembly, semiconductor equipment and automation system. Generally, a second central gear is driven by the planet gear fig. Planetary designs also cannot have ratios less than 3. Design of machinery an introduction to the synthesis and. Gear train with sun, planet, and ring gears matlab. This paper presents planetary gear transmissions, designed according to iso 6336 ref. They explore these relationships as constant values that depend on the number of teeth on the two gears. Planetary gear systems have very smalllarge train ratios and are very compact. 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. 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 planet gear in figure 23 rotates about a fixed bevel gear at the center of which is the driven shaft. Epicyclic gearing systems also incorporate the use of an outer ring gear or annulus, which meshes. So ive found the following formula for calculating the gear ratio of a planetary gear. Calculate gear ratio by dividing the number of teeth on the driven gear by the number of teeth on the driving gear.
Planetary gear train with stepped planet gear set matlab. Gear box ratio the ratio of the gear box is defined as 2 1 n n output speed input speed g. N is usually in revmin but the ratio is the same whatever units of speed are used. The central gear around which the planet gears revolve.
A practical method to analyze planetary gear train for speed ratio determination is. One of the planetary gearsets from our transmission has a ring. This paper presents analysis and design of planetary gear arrangements that provide extremely high gear ratios. To compare with traditional gearbox, planetary gear has several advantages. In manual transmission, the discontinuity of power during gear shifting. Each of these three components can be the input, the output or can be held stationary. Article information, pdf download for a heuristic synthesis of multistage planetary gearbox. Finally, we include a general kinematic analysis of wheeled mobile robots wmrs. Relations between size and gear ratio in spur and planetary gear trains. Abstract it has been said that deriving the formulas for the ratios between the various gears of an epicyclic planetary gear system is nonintuitive and taxes the human intellect to say the least. Download mitcalc planetary gearing a smallsized and reliable piece of software specifically built to provide you with various solutions for designing spur. Understanding, selecting and applying planetary gearheads.
This block models a gear train with sun, planet, and ring gears. Which ratio is best for a planetary reduction can be resolved by studying a series of optimal. Computational methodology the compound planetary gear train taken from the elecon engineering shown in figure 2. Gear stages gear ratios gear types bearings materials lubrication interfaces etc. Question about calculation of planetary gear ratios. Each composite planet gear is a pair of rigidly connected and longitudinally arranged gears of different radii. Choosing which piece plays which role determines the gear ratio for the gearset. Planetary gearing could increase torque and reduce load inertia while slowdown the speed. A heuristic synthesis of multistage planetary gearbox layout for. 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. Another class of gear train has wide application, the epicyclic or planetary train. This is a fully functional handcranked model of a multistage planetary reducer. Typically, the planet gears are mounted on a movable arm or carrier, which itself may rotate relative to the sun gear. 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.
Gearing ratio definition, formula how to calculate. Developing the gear ratio formula sae international. 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. The general formula for calculating the gear ratio in a gear. 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. Planetary gears are common in transmission systems, where they provide high gear ratios in compact geometries.
Please start with the tutorial for shaft calculation to see how to introduce geometry and supports for single shafts. Pdf dynamics equations of planetary gear sets for shift. Calculat ion of a plane tary gear train this tutorial shows the usage of mesys shaft calculation with shaft systems. For a singleplane transmission, the planet gear has no size of the sun and ring.
Selecting gears in metric unit the gear tooth profile of the spur gear will be in module. 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. The exponent to use in the calculation of equivalent load depends on material type, heat treatments. Planetary gear trains are one of the main subdivisions of the simple epicyclic gear train family. Gearing ratio is commonly used by financial analyst to understand the overall capital structure of the company by dividing total debt to total equity.
The planet gears are also meshed and rotate within an internal ring gear a. Planetary gear boxes chapter 10 5 technical information because our supplier is continuously improving its. The larger gear engages a centrally located sun gear, while the smaller gear engages the ring gear. To determine the gear condition in a simple planetary gear set always look at what the carrier is doing. A twostage planetary gear stage is defined using the program. 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. Ports c, r, and s represent the shafts connected to the planet gear carrier, ring gear, and sun gear. In this tutorial, we will show you an original and easyto. A carrier connected to a drive shaft holds the planet gears. Pdf relations between size and gear ratio in spur and planetary. If ever the carrier is an output in a simple planetary gear set, the condition will be forward reduction. In this case, the planet gears have 12 teeth, the sun gear has 18 and the ring gear has 42 teeth.
Effects of planetary gear ratio on mean service life. Dynamics equations of planetary gear sets for shift quality by lagrange method. The planetary gear system is named after its likeness to an orbital planetary system. However, the rotation of the planet gear is seldom used directly. Two forms of planetary gears of the bevel type are shown in figures 23 and 24. A planetary gear set can give a higher powertoweight ratio than a parallel shaft gear set while keeping the input and output shaft coaxial.
This factor takes into account the application load conditions. The main advantages of this transmission are its high efficiency, its compactness, its large transmission ratio and its large powertoweight ratio, etc. Intro planetary gears also refer as epicyclic gearing consisting three elements sun. One of the two gears engages the centrally located sun gear while the other engages the outer ring gear. Working out planetary gear turns ratios working out the gear ratio of a planetary gear train can be. The higher the ratio, the higher the chances of default and hence more hindrance in the growth of the company. The epicyclic gear train family in general has a central sun gear which meshes with and is surrounded by planet gears. The outermost gear, the ring gear, meshes with each of the planet gears. I have also checked the ratios against machinerys handbook 27th edition page 2115.
Planetary epicyclic gear ratios equations and calculators. Pdf in this report equations for the minimum gear sizes necessary to drive a given load are derived. In the past ive had luck using this site to create an illustrator file that i can extrude in rhino. Lightweight design for planetary gear transmissions. How to derive the formula for the planetary mechanism gear ratio duration. The contact ratio is an index of the quantity of overlap occurring between two conjugate cams. Outer gears meshes with an outer internal geared wheel willis formula allow to calculate reduction ratio for an epicyclic. The compound planetary gear block represents a planetary gear train with composite planet gears.
This does not generate planetary gears, and im also unclear as to how design a planetary gear with a 2. The dualwheel transmission dwt, proposed elsewhere using epicyclic gear. How to i design a planetary gear with a gear ratio of 2. Atlas copcos previous knowledge about power losses in planetary gears. Calculate the number if teeth required in the ring gear for the ratio 5. A gear in the centre is called the sun gear, the gears rotating around the sun are called planet gears, and the gear. Calculating gear ratios within a planetary gear set duration. Since, i am working in the metric unit every dimension will be in mm. Relations between operating pressure angles in the gear. The gear ratio formula for two meshing gears is simple and intuitive, while the gear ratio formula for the planetary mechanism is not. The real scope of this paper is on design parameter, gear ratio, gear tooth combination, stress, and factor of safety. 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.