Automatic transmission basics linnbenton community. May 02, 2020 posted in automobile engineering by mohammed shafi may 2, 2020 may 1, 2020 epicyclic gearbox is also known as planetary gearbox or planetary gear train or epicyclic gear train. 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. Also, locking any two of the three components together will lock up the whole device at a 1. How to derive the formula for the planetary mechanism gear ratio duration. A epicyclic gear train consists of one or more planet gears revolving around a sun gear. Planetary epicyclic gear ratios equations and calculators. What is epicyclic gearbox main components, working and. An automatic transmission will select an appropriate gear ratio without any operator intervention. The planet gear in figure 23 rotates about a fixed bevel gear at the center of which is the driven shaft. I which have a fixed annulus with the planet carrier rotating in the same direction as the sun gear. The planetary gearbox design is fairly simple, consisting of a central sun gear, an outer ring also referred to as an internal gear, because its tooth face inward, planetary gears, and a carrier.
This system is reminiscent of the planets orbits around the sun, thus giving the gear. Pdf design and analysis of an epicyclic gearbox for an. Calculation of a planetary gear train this tutorial shows the usage of mesys shaft calculation with shaft systems. The planet gear are mounted on a moveable arm carrier. Epicyclic gearbox diagram, working, advantages of epicyclic gearbox epicyclic gearbox. This gear set is used in most threespeed automobile automatic transmissions. The reliance catalogue gearbox range includes planetary, bevel and hypoid gearboxes, which provide housed, modular solutions, as well as an epicyclic gear module, which can be used in single or multiple stacks to build a customised gearbox. This method is extremely procedural, which is appropriate since use of intuition is often quite futile when applied to complex gear trains. At the same time, expectations for gear reliability are high. The circulation of the spur gear takes place in analogy to the orbiting of the planets in the solar system. Most modern automatic gearboxes have a set of gears called a planetary or epicyclic gear train. High efficiency bicycle propulsion system using two motors. Some of the simplest gearboxes merely change the physical rotational direction of power transmission. Introduction to epicyclic gear train working and advantages and disadvantages of the epicyclic gear train.
The epicyclic gear train with bevel gears is used in 1. Sun gear i t is the gear with angular cut teethes and is placed in the middle of the. Gear selection for gear train is depend upon various different aspect like position of shaft axes, velocity of gear, increasing or reducing speed, etc. Please start with the tutorial for shaft calculation to see how to introduce geometry and supports for single shafts. Low efficiency due to the high gearing power occurring in an epicyclic train is an important problem. The epicyclic ring gear is directly attached to the rotor of the main motor, while the sun gear is driven by the coreless gearing motor. This type of transmission are used by skoda,toyota, lexus, etc epicyclic gearing planetry gearing. Chapter 11 drive lines, differentials, drive axles, and. In this video simple explanation of epicyclic gear box is explained. Most if not all ivts result from the combination of a cvt with an epicyclic gear system with a fixed ratio. Automobile transmission and planetary gear sets youtube.
The second is an overdrive the output speed is faster than the input speed. In the case of epicyclic gearing, at least one of the gears not only rotates about its own axis but also rotates about some other axes. Selecting the proper atf is critical mixing fluids can ruin a transmission always look up and use specified fluid. It require small area during the power transmission and to obtain large speed reduction. The procedure for the design was an iterative process to determine the optimum dimensions and materials for the gearbox. Solid mechanics tutorial gear systems this work covers elements of the syllabus for the edexcel module 21722p hncd mechanical principles outcome 3. In this study, an epicyclic gearbox has been designed, analysed and manufactured for its use in an. The selector rods lie parallel with shafts carrying the gears.
Automatic transmission system is the most advanced system in which drives mechanical efforts are reduced very much and different speeds are obtained automatically. The gear wheel transmitted motion between one shaft to another shaft, so the multiple set of gear transmit motion from single main gear to various revolving parts is known as gear train. For instance, consider a transmission with an epicyclic gear set to 11 gear ratio. Gearbox precision gearboxes reliance precision limited. The working of epicyclic gear box can not be explained briefly as it requires more study. An automotive gear differential is a jointfractionated planetary gear. Suppose an epicyclic gear train has 2 gears gear a and gear b and an arm arm c. Another class of gear train has wide application, the epicyclic or planetary train. A planetary gear set consists of a central gear called the sun gear, an outer ring with internal gear teeth. Pdf design and analysis of an epicyclic gearbox for an electric.
The most popular design is the constantmesh gearbox. Transmission is the mechanism which is used to transfer the power developed by engine to the wheels of an automobile. In an epicyclic gear train, the axes of the shafts, over which the gears are mounted, move relative to a fixed axis. Epicyclic gearing also called as planetary gearing. A gearbox can be set up to do the opposite and provide an increase in shaft speed with a reduction of torque. R is the angular speed of the arm, equal to the input angular speed. Weight and size became important considerations since thepower source and transmission were no longer stationary objects, but an integral part of the moving machine. Design and analysis of an epicyclic gearbox for an electric drivetrain.
A planetary gear set consists of a central gear called the sun gear, an outer ring with internal gear teeth also known as the annulus, or ring gear, and two or three gears known as planet gears that rotate between the sun and ring gears. The exploded view shows the components of the gearbox that will be explained in this chapter. The housing with integrated internal teeth is known as a ring gear. In some cases, such as the automotive differential, one input is. In this type of transmission different speed ratio or gear ratio is selected by the driver manually. Epicyclic gearbox epicyclic gear trains are used to get the various gear ratios. Design and optimization of planetary gears considering all. The conventional gear trains described in the previous sections are all onedegreeoffreedom dof devices. The drive train is coupled to a mechanism known as a. The combination of the fixed ratio of the epicyclic gear with a specific matching ratio in the cvt side results in zero output. Epicyclic gear trains for automotive automatic transmissions. Nov 23, 2017 a gearbox is a transmission device which is used between engines output shaft and the final drive in order to transfer required torque and power to the wheels of the vehicle, a gearbox consists of the set of gears i.
Besides, this finds applications in case of scooters and motorcycles, where space available is limited. We have listed 38 trends in mechanical engineering. The gear b meshes with gear a and has its axis on the arm o 2, about which the gear b can rotate. Allterrain vehicles atvs are used to handle a wider variety of terrains and are specifically used in border patrol, oil exploration and surveying. The electrical equipment is from the proven astat range and is highly resistant to vibration, dust, heat and electric supply disturbances. Description of various types of clutches and gear boxes has been given in the following sections of this unit. The gear train maybe for spur gear, helical gear and spiral gear. This system is reminiscent of the planets orbits around the sun, thus giving the gear system its name. Automatic transmission basics linnbenton community college. A basic example is a singlestage gear unit withthree fixedplanets and a rotating carrier know as a star epicyclic gear. The epicyclic gear train is useful for transmitting highvelocity ratio with a gear of moderate size and in less space.
Epicyclic definition of epicyclic by the free dictionary. Comparative tests of cars fitted with selfchanging and ordinary gears. An epicyclic differential is at the heart of the toyota prius automotive drive train, where it interconnects the engine, motorgenerators, and the drive wheels which have a second differential for splitting torque as usual. On completion of this short tutorial you should be able to do the following.
Jun 23, 2019 recent trends in mechanical engineering 38 recent trends in mechanical engineering. Astat advanced options for epicyclic gearbox control eb eb. The drive train is coupled to a mechanism known as a torque. It contain epicyclic gear arrangement, fluid coupling and torque converter. As the figure shows the front view and side view of the gearbox. The driving sun pinion is in the center of the ring gear, and is coaxially arranged in relation to the output. 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. Design and analysis of an epicyclic gearbox for an electric. Typically, the planet gears are mounted on a movable arm or carrier, which itself may rotate relative to the sun gear. O e of the prime and biggest use of a planetary gearbox is for running the armature of a wind turbine. What are the drawbacks to using a planetary gearbox. A planetary gearbox gives a balance between weight and power transmitted. One of the most important considerations for an epicyclic gear is to assure uniform load distribution among the planets. In a simple situation, a set of gears or a chain could perform this task, but automotive vehicles usually are not designed for such simple operating conditions.
Pdf the term automobile or automotive stands for a vehicle which can be moved by itself. Notice that the first gear ratio listed above is a reduction the output speed is slower than the input speed. Technique for examing epicyclic gear box krish gupta, ajay sharma amity university, aset, noida, india abstract this paper presents a method for analyzing epicyclic gearboxes by evaluating the speeds, torques and efficiency of the external elements in epicyclic gear mechanisms, as well as the total ratios of the gear box. The drive is built of two ringplanet elements as shown in the gearbox schematic. Therefore, an automobile is a selfpropelled vehicle.
Pdf on aug 18, 2014, amar kumar and others published epicyclic gear. Department of mechanical engineering, national sun yatsen university. Design of machinery an introduction to the synthesis and. Two inputs are needed to obtain a predictable output. Planetary epicyclic gearing is a gear system consisting of one or more outer gears. Types of gear train and velocity ratio calculation techminy.
The planetary gears and holding devices 4 the hydraulic controls. Types of gearbox complete explanation mechanical booster. Epicyclic gearing systems also incorporate the use of an outer ring gear or annulus, which. Our high quality standards apply to all our planetary gearbox series. Epicyclic gear train with bevel gear the bevel gears are used to make a more compact epicyclic system and they permit a very high speed reduction with few gears. Epicyclic mechanisms have found wide applications in industry, especially in auto mobiles and robotics. Cutaway view of a torque converter showing the impeller, turbine and reactor. An epicyclic gear, also referred to as a planetary gear, is a gearing system in which gears known as planetary gears revolve around one central gear referred to as the sun gear. Epicyclic train overall ratio calculation we present here a simple, methodical procedure for determining the final gear ratio of an epicyclic gear train.
Epicyclic gearing planetary gearboxes 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. The torque converter clutch is applied by hydraulic pressure the pcm will control a torque converter clutch tcc solenoid to send atf under pressure to the lock. Lanchester is generally credited with being the first to use epicyclic gears in automotive applications with the annulus of the. Epicyclic gearing requires a stepbystep process to make it work, and some of the steps are not necessarily intuitive.
As fixing any of the above causes the variation in gear ratios from high torque to high speed. A planetary gearbox offers high torque transmission with good stiffness and low noise, in a more compact footprint than other gearbox types. Recent articles in gear solutions have discussed epicyclic gearing, but often in the context of experienced engineers. About the size of a cantaloupe, this one part creates all of the different gear ratios that the transmission can produce. In this chapter you will learn the fundamentals of operation and upkeep of the drive lines, differentials, drive axles, and power takeoffs. Generally, these are called planetary, star, and solar arrangements. Many typical automobile transmissions include the ability to select one of several gear ratios. This thesis develops a novel family of epicyclic transmissions, based on cams and rollers. A differential is a gear train with three shafts that has the property that the rotational speed of one shaft is the average of the speeds of the others, or a fixed multiple of that average. Pdf this paper focusses on the designing and optimizing of a planetary gearbox for an fsae formula electric car. Mar 30, 2016 epicyclic gear train with bevel gear the bevel gears are used to make a more compact epicyclic system and they permit a very high speed reduction with few gears.
The epicyclic gearbox control system can operate with new or existing slipring motors and is compatible with most overall crane control systems. There would be numerous applications of planetary gearbox, but i will anser with the one which im sure about. At2301 automotive transmission unit i clutch and gear box transmission system chief function of the device is to receive power at one torque and angular velocity and to deliver it at another torque and the corresponding angular velocity. Types of gear train simple, compound, reverted, epicyclic. The last is a reduction again, but the output direction is reversed. An incredibly odd hydraulic system that controls the clutches and bands. The basic of epicyclic gear is that it has an sun gear, planetary gears and ring gears this type of gear mechanism is used in the pto shaft of the tractors a. At least one wheel not only rotates about its own axis but also rotates about some other axis automatic gearboxes typically use one or more compound planetary gear sets having two sun gears and two sets of intermeshing planet gears. This investigationisprimarily concerned with planetary gear drives fig. The gearbox focused on, and used for model validation in this report is a 2 stage planetary gearbox made by atlas copco. Gearbox in mainly divided into two types based on the type of transmission 1. The gear lever, operated by the driver, is connected to a series of selector rods in the top or side of the gearbox.
Epicyclic gear systems in the range 746 to 10 445 kw fixed point is called the pitch point. The word transmission means the mechanism that transmits the power from the engine crank shaft to the rear wheels function of gearbox provide a means to vary torque ration between the engine and the road wheels as required. The stationary gear sun gear or ring gear can be referred to as the central gear. Automated guided vehicles agv distribute picked goods in roomy warehouse and. These relationships can be used to analyze any epicyclic system, including those, such as hybrid vehicle transmissions. A twostage planetary gear stage is defined using the program. The sun pinion is usually attached to a clamping system in order to provide the mechanical connection to the motor shaft. Gear trains are used in various machines and there is large number of examples like in automobile, gearbox, lathe machine, milling machine, clock, toys, etc. As such, this article aims to provide assistance and guidelines for people designing epicyclic gear trains for the first timeand perhaps, if you will, ease their degree of suffering. Subscribe to our youtube channel to see models built by londons meccano enthusiasts, plus occasional coverage of meccano events elsewhere in the uk. An automotive gear differential is a jointfractionated planetary gear train with two degreesoffreedom. This system is generally also called hydramatic transmission. 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.
The angular speed of the planet carrier can be found since we know. Students can take individual topics and can make the ppts for their technical seminars so that they can know about the latest technologies in the field of mechanical engineering. The ring of the original prototype design has 78 teeth and the sun 30 teeth while the planet gears have 23 teeth each. An epicyclic differential can use epicyclic gearing to split and apportion torque asymmetrically between the front and rear axles. It is a gear system that consists of one or more outer gear planet gear rotating about a central sun gear. They primarily use hydraulics to select gears, depending on pressure exerted by fluid within the transmission assembly. The working principle of the epicyclic gearbox is based on the fact the fixing any of the gears i.
This is made possible in a 3 or more planet arrangement. The transmission system of an automobile includes clutch, gear box, propeller shaft axle and wheels, etc. In ordinary gearing, the axes of various gears are fixed. An epicyclic gear train consists of two gears mounted so that the center of one gear revolves. The video course teaches you everything about modern cars. Epicyclic gear trains are known to provide high power density and have.
Introduction to epicyclic gear train working and advantages. Ring gear i t is a type of gear which looks like a ring and have angular cut teethes at its inner surface,and is placed in outermost position in en epicyclic gearbox, the inner teethes of ring gear is in constant mesh at outer point with the set of planetary gears,it is also known as annular ring. All the components are modelled in catia to check the assembly and the. In this planetary gears sets are placed in series to provide transmission. Designing compound epicyclic gear trains for maximum speed at high velocity ratios, machine design, april 4, 1957. In this gearbox, it has three gears sun gear, planet gear and ring gear. L where a gear a and the arm c have a common axis at o 1 about which they can rotate. Gearbox, fsae formula electric car, gear design, shaft design. An epicyclic gear train is usually employed to achieve high reduction ratio in small and power dense packages to use in various applications such as automatic automobile transmissions and hybrid transmission systems. As more and more of these engineers reach retirement age younger engineers must pick up where they left off, and for many epicyclic gearing is an area where they lack experience.
The planet gear is mounted on the planet carrier and the ring gear is mounted on planet carrier shaft. Automatic transmission epicyclic gearing or planetary gearing are as used in an automatic transmission. A large gear pump to move transmission fluid around. Advantages of an epicyclic gear artec machine systems.
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