When power turns one gear, its teeth in turn force the next gear to move, and so forth. Following are the different types of gear trains, depending upon the arrangement of wheels. A gear train is a mechanical system formed by mounting gears on a frame so the teeth of the gears engage gear teeth are designed to ensure the pitch circles of engaging gears roll on each other without slipping, providing a smooth transmission of rotation from one gear to the next. Ok i have 4 spur gears inline, gear a 100 rpm 80 teeth input motor. Torque measurement in epicyclic gear train international journal. The new gear set is a fine mesh type which give more gear teeth contact area between the two gears.
That means that if you connect the purple gear to a motor spinning at 100 revolutions per minute rpm, the green gear will turn at a rate of 500 rpm and the red gear will turn at a rate of 2,500 rpm. One simple way is to do the gearing in a number of stages in a gear train. The gear ratio is calculated simply by dividing the number of teeth on one gear into the number of teeth on the other. The current equivalent emd ratio for new locomotives began with gp50 is 70.
Simple explanation of gears, gear trains, and gear ratio calculations. That gear train mainly used for multiple speed reduction in between long distance. 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. Please start with the tutorial for shaft calculation to see how to introduce geometry and supports for single shafts. The basics gear ratio velocity ratio technology student. Pdf gear ratios for compound gear trains of minimum weight. You can calculate the gear ratio by using the number of teeth of the driving gear a. Gear a revolves at 60 revsmin in a clockwise direction. A gear train is a set or system of gears arranged to transfer rotational torque from one part of a mechanical system to another, with some gear ratio performing a mechanical advantage. Introduction to gear trainsintroduction to gear trains. Numerically, on a racing bike the front crank pedal wheel has 52 teeth and the back wheel gear has teeth for the fastest, flat sections, ratio is 4.
The first employs the speed and torque equations and the concept of virtual gear teeth ratios. Based on the motors output and some measurement and calculation, we would expect an output torque of 6. The gear train allows the watch to run for many hours by multiplying the output rotation. Gear ratios or velocity ratios, vr are calculated using the same principle as for simple gear trains, i. Orbiting gear centres planetary geartrains a planetary gear train.
They find the gear ratio for trains of simple gears. Consequently, the dimensions of the sun gear would be onethird of the pinion of a parallel shaft gear train designed to transmit an equivalent torque. Learn vocabulary, terms, and more with flashcards, games, and other study tools. Simple gear train with two gears torque ratio calculator.
Determining compound gear ratios multiple stages when a gear train has multiple stages, the gear ratio for the overall gearing system is the product of the individual stages. Zoltan levai received 9 february 1968 abstract both compound and internal or external planet gears are considered as well as the paired planet gears. In epicyclic gear train, different types of gear are used like spur gear, helical gear, bevel gear and many more. A worm gear is a gear in which a wheel resembles a screw, with parallel helical teeth, while the other is like a normal spur wheel.
Prudens, i dont mean to brush you off, but have you looked at. The simplest example of a gear train has two gears. Since the gear ratio of a train is not a function of the modules of the component gears, in an attempt. Simple gear trains, compound gear trains for large speed reduction, epicyclic gear trains algebraic and tabular methods of finding velocity ratio of epicyclic gear trains. Simple, compound and epicyclic are types of gear train used in modern industry. The overall gear ratio is found by multiplying all the individual gear ratios. The driver gear or pulley is the one connected to the power e. Vr driverdriven to calculate the speed of the driven gear multiply the speed of the driver gear by the velocity ratio. Design, load analysis and optimization of compound. This is the same convention as used in automotive transmissions. Jul 24, 2017 i took a class at purdue from a professor henry zhang, who used to design automatic transmissions for vehicles, alongside studying multidisciplinary correspondent. Simple gear train a simple gear train uses two gears.
In this train, the smaller gears are onefifth the size of the larger gears. Beyond its usefulness, a gear train is visually compelling because of its constant movement. Gear ratio you can think of gear ratio as a multiplier on speedand a divider on torque. Such a system uses gears which have two different gear sizes on the same wheel. The worm gear can achieve a higher gear ratio than spur gears of a comparable size. During the second stage, introducing a greater number of criteria, which represent the essential gear train performances, solves the multicriteria optimization problem. Gear ratio is ratio of the rotational speeds of two or more mating gears. In the example shown in the image below from the how stuff works article on gear trains each gear has a ratio of 2.
You can place a big gear between them if you want them to have the same direction of rotation. When faced with three gears the question can be broken down into two parts. The gear ratio can be calculated directly from the numbers of teeth on the gears in the gear train. In the reduction gear train, operating conditions consists in high nominal rotation speed up to 45 000 rpm on the drive pinion with potentially an inflight authorized rotation speed range from 90 to 110 %. Structure and analysis of planetary gear trains prof. The target function for multistage gear train representing the volume of the. This arrangement is known as a gear train and is a good way of gearing down a rapidly revolving electric drive motor for example. Jan 24, 20 simple explanation of gears, gear trains, and gear ratio calculations. Consequently, it is possible to create very large gear ratios and hence generate very large torque and low speeds from highspeed, lowtorque motors, for example. Simple gear train basic concept about gear train, speed ratio and train value duration. Tooth load and torque calculations in epicyclic gear trains.
In the first three types of gear trains, axes of shafts over which the gears are mounted are fixed relative to each other 112320. The gear train shown below has a higher gear ratio. You have two red gears that you want to keep synchronized, but they are some distance apart. That means that if you connect the purple gear to a motor spinning at 100 revolutions per minute rpm, the green gear will turn at a rate of 500 rpm and. For example, for the gear at left the blue gears are 7 and 21 teeth, while the green gears are 9 and 30 teeth. The speed ratio of the gear train is defined as the ratio between speed of the driver to speed of the driven. The more velocity gained, the more torque sacrifice. The gear ratio of a gear train, also known as its speed ratio, is the ratio of the angular velocity of the input gear to the angular velocity of the output gear. The procedure is to start with the input, and to calculate how the angular velocity propagates through each successive intermeshing pair of gears based upon the number of teeth. It may be noted that ratio of the speed of the driven or follower to the speed of the. The gear ratio can be calculated directly from the numbers of teeth on the gears in t. Analysis of a gear train using finite element modelling. Consider a motor driving a rotary load through a gear train, as shown in figure 1. The determination of optimal design of the planetary gear train with a.
Transmission or movement ratio can be expressed as. On the preceding page, i demonstrated a simple, tabular method for calculating speeds in a planetary gearset with one input fixed. Genetic approach for multiobjective optimization of epicyclical gear. It should be pointed out that six planets do not necessarily give a gearing twice the capacity of a similar. To obtain the gear ratio, tv output rateinput rate, of a compound gear train, an illustrated example is presented in this section. The gear ratio of an epicyclic gearing system is somewhat nonintuitive, particularly because there are several ways in. Types of gear train and velocity ratio calculation techminy. The gear connected to the power source is called the drive gear. However, the velocity ratio for each pair of gears must then be multiplied together to calculate the total velocity ratio of the gear train. Design, load analysis and optimization of compound epicyclic. That is done but now am not sure of my calculations for power in out and torque in and out, so hopefully someone can help.
Jul, 2017 the gear ratio of a gear train, also known as its speed ratio, is the ratio of the angular velocity of the input gear to the angular velocity of the output gear. Vr number of teeth on the driver gear divided by the number of teeth on the driven gear. What is velocity ratio in simple gear train theory of. The gear train consists of five external gears and 4 internal annulus gears, including sun and planet gears forming an epicyclic gear train. Gear trains theory of machines engineering reference with.
Homework statement this is a final hurdle of a long question designing a simple gear train. The general objective of optimal gear transmission design is not. A gear train is a mechanical system formed by mounting gears on a frame so the teeth of the. The most important component inside a single planetary gear transmission single pgt is a mechanism providing a transmission ratio between two rotating. This is basically made up of wheels that have teeth cut around their circumference. For a simple gear train, velocity ratio is the ratio of published on 06 aug 15. Thus, they differ from an ordinary train by having a.
It is stated that the simple planetary gear train consisting. Let t1 number of teeth on gear 1, r1 pitch circle radius of gear 1, and n1 speed of gear 1 in r. The mechanical advantage of the gear train is the ratio of the output torque tb to the input. A read is counted each time someone views a publication summary such as the title, abstract, and list of authors, clicks on a figure, or views or downloads the fulltext. Or you can use two equalsized gears if you want them to have opposite directions of rotation.
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. Types of gear train simple, compound, reverted, epicyclic. The gear train is also responsible for dividing time into useful segments hours, minutes, and seconds. For climbs the back gear might be changed to 26, a ratio of 2. Gear train definition and meaning collins english dictionary.
The gear 3 which is now the second driver drives the gear 4 i. The compound gear train allows you to multiply gear ratios together. I took a class at purdue from a professor henry zhang, who used to design automatic transmissions for vehicles, alongside studying multidisciplinary correspondent. 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. Calculation of a planetary gear train this tutorial shows the usage of mesys shaft calculation with shaft systems. Sharing is caring 1 1sharegear ratio is the ratio of output and input number of teeth on a shaft. If the ring gear is held stationary and the sun gear is used as the input, the planet carrier will be the output.
Gear ratios for compound gear trains of minimum weight. In this article we will discuss gear ratio calculations for various gear train. To create large gear ratio, gears are connected together to form gear trains. A twostage planetary gear stage is defined using the program. The advantage of epicyclic gear train is that, it can get very high or very low velocity ratio compared to simple gear trains and compound gear trains. This was mainly intended to help build your intuition for these fascinating systems. A simple gear can change magnitude and line of action of an effort force. The pitch point has moved, but in proportion to the move of the center distance and the gear radii. The velocity ratio is unchanged despite the shift in center distance. You can continue this process along a train of many gears to find a ratio for the whole train. The smaller gear can then be used to drive a large gear on a second shaft to cause a second gear reduction. Design of machinery an introduction to the synthesis and. Thus, they differ from an ordinary train by having a moving axis or axes. The angular position of the motor is given by m, while the angular position of the load is given by l.
The planocentric gearbox has coaxial input and output shafts, and large transmission ratios can be achieved based on a gear ring with internal gearing in. In epicyclic gear trains there is relative motion between axes which useful to transmit very high velocity ratio with gears of smaller sizes in lesser. The diagram above shows a gear train composed of three gears. Reverted gear train when the axes of the first gear i. Velocity ratios are calculated by dividing the driver gear by the driven gear. Gear trains linearity videos stem concept videos mit. The analytical expression of the efficiency of planetary gear. This is the lowest gear ratio attainable with an epicyclic gear train. An epicyclic gear train consists of two gears mounted so that the center of one gear revolves. Two procedures are presented for obtaining the analytical expression for the efficiency of any planetary gear train.
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