N is the gears teeth number, the sign depends on the type of gear and, in sequence is for external gears. Helical gears can bear more load than spur gears, and work more quietly. Instead of using the theoretical pitch circle as an index of tooth size, the base circle, which is a more fundamental circle, can be used. Lecture 1 introduction motivation and theme of the course lecture 2 laws of gearing, kinematics and geometry part i lecture 3 laws of gearing. Bevel gears are normally mounted on shafts that are at 90 to each other, but bevel gears can be designed for other angles. Spur gear design nptel indian institute of technology madras. Asok kumar mallik department of mechanical engineering iit kanpur. In the middle of the gears appears yellow snap line. Lecture notes elements of mechanical design mechanical. It is not possible to design a gear tooth profile which rolls through the mesh without friction. Worm gear sets consists of a helical gear and a power screw worm, used to transfer motion between non parallel and nonintersecting shafts. Jan 01, 20 types of gears worm gear sets consists of a helical gear and a power screw worm, used to transfer motion between nonparallel and nonintersecting shafts.
Lecture gear unit design failure of gear tooth probable dynamic load and wear load capacity download. The result is called the base pitch p b, and it is related to the circular pitch p by the equation 78 7. Figure 75 shows two meshing gears contacting at point k 1 and k 2. Straight bevel gears can be noisy due to the abrupt line or flank contact. The straight bevel gear is simple to produce and the most widely used type in the bevel gear family. Ancient engineers used the same direct gear design for spur and helical involute gears. Oct 20, 2017 design data book compiled by psg college of technology. Design of machine members 2 pdf notes dmm 2 notes pdf. A disadvantage is the axial thrust force the helix form causes. Module 2 gears nptel pages 1 17 text version fliphtml5.
His teaching and research interests are machine design, gear. Bevel gears are useful when the direction of a shafts rotatidbhdion needs to be changed they are usually mounted on shafts that are 90 degrees apart b t can be designed to ork at otherdegrees apart, but can be designed to work at other angles as well the teeth on bevel gears can bethe teeth on bevel gears can be straight, spiral or. Recognize different gearing systems and relative advantages and disadvantages between them. Spur gear creation american society for engineering. Backlash is a play between tooth surfaces of paired gears in mesh. The simplest arrangement of spur gears is a single pair of gears. Jul 03, 2019 epicyclic gear train nptel pdf to excel pdf files. Design, load analysis and optimization of compound epicyclic gear trains syed ibrahim dilawer1, md. Diametral pitch regulates the proportions or size of the gear teeth.
Apr 08, 2019 epicyclic gear train nptel pdf download. For the love of physics walter lewin may 16, 2011 duration. Determine allowable force on gear teeth, including the factors necessary due to. Design, load analysis and optimization of compound. Gear design in mdesign gearbox march 2012 driveconcepts gmbh, dresden now you have to connect the two gears. One of the important concepts is the velocity ratio, which is the ratio of the rotary velocity of the driver gear to that of the driven gears. 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. Theoretically from the detailed design data it is possible to estimate various parameters shown in the equivalent circuit. Basic gear design pdh continuing education pdh for. Hypoid gear this is a deviation from a bevel gear that originated as a special development for the automobile industry. Bevel gears are most commonly used for power transmission between intersecting shafts. This permitted the drive to the rear axle to be nonintersecting, and thus allowed the auto body to be lowered.
The figure n1 show the involute curve generation with the most important elements. Therefore, foraknownimldto be transmitted, the pitch is chosen which in turn determines the number of teeth to suit the desired ratio and size of gear. This video lecture will teach you how to design spur gears for mechanical strength, dynamic load and surface durability. Rathindranath maiti is at present professor in mechanical engineering department. Gears have many terminologies, parameters and principles. Jul 19, 2011 create a pair of gears using the following data. Tutorial for gear design and calculation with mdesign gearbox. Design of machine members 2 pdf notes dmm 2 notes pdf book starts with the topics covering types of journal bearings, types of rolling contact bearings, thrust in connecting i rod, transmission of power by belt and rope drives, load concentration factor, square acme, helical and bevel gears, worm gears properties of worm gears, etc. Rslqdwk 3uri 0 0 0dxudp,qgldq,qvwlwxwhri7hfkqrorjdgudv module 2 gears. Bevel gears are useful when the direction of a shafts rotatidbhdion needs to be changed they are usually mounted on shafts that are 90 degrees apart b t can be designed to ork at otherdegrees apart, but can be designed to work at other angles as well the teeth on bevel gears can bethe teeth on bevel gears can be straight, spiral or hypoid. Mayuram module 2 gears lhfwxuh bevel gearscrqwhqwv. Calculate centertocenter distances for 2 or more sprockets in a chain drive.
Jan 31, 2016 design and construction of bevel gear 1. Helical gear this is a cylindrical shaped gear with helicoid teeth. Ft transmitted force fn normal force or separating force fr resultant force. The volume of the gear train with spur gears is reduced by 22. Gear design and strength iupital has good strength, durability, wear resistance, and chemical resistance, so can be used to each gear. Note that the involute profile does not prevent the teeth from scraping each other every time they mesh, and this is the dominant source of wear. It starts with an overview of the types of gears, terms used to define gears, materials and manufacture along with illustrative drawings. Pdf procedure for optimum design of a twostage spur.
Nptel provides elearning through online web and video courses various streams. Spur gear design and selection standard proportions forces on. The optimization is based on a multicriterion technique consisting of a minmax method combined with a direct search. It is interesting to note that coefficient of friction is variable and it depends on operating conditions. Design and optimization of planetary gears considering all. Rack and pinion sets a special case of spur gears with the gear having an infinitely large diameter, the teeth are laid flat. It then deals extensively with spur gears, the most common type, including design, mounting, shaft and bearing, and application. Calculate sprocket and sprocket tooth dimensions using pitch and the number of teeth.
Understand geometry of different gears and their dimensional pro perties. Pdf design and contact analysis of plastic spur gears using. Direct gear design for spur and helical involute gears. Kinematic analysis of synchromesh, machine tool gear box, differential gear box self study 3. Pdf procedure for optimum design of a twostage spur gear. Introduction worm gears are gears which are widely used for transmitting power at high velocity ratios between nonintersecting shafts that are generally, but not necessarily, at right angles. In the first three types of gear trains, the axes of the shafts over which the gears are mounted vear fixed relative to each other. History of gears definition of gears types of gears and their applications. It is a mathematical equation that tells how many values can vary and can help in the first three types of gear trains, the axes of the shafts over which the gears are mounted are ger relative to. Spur gear helical gear double helical or herringbone gear internal gear rack and pinion bevel gear a straight b spiral c hypoid 1. The number of teeth in these gears are 15 and 30, respectively. Basic gear design pdh continuing education pdh for engineers.
Parallelshaft gear types cutting tool at an angle to the workpiece and using a di. They are a special case of helical gears, with the pion helix. Bevel gears teeth are formed on a conical surface, used to transfer motion between nonparallel and intersecting shafts. Next, it discusses helical gear design and mounting. Spur gear design and selection objectives apply principles learned in chapter 11 to actual design and selection of spur gear systems. Calculate forces on teeth of spur gears, including impact forces associated with velocity and clearances. The direct design approach that is commonly used for most parts of mechanisms and machines for example, cams, linkages, compressor or turbine blades, etc. The simdesign file for these gears is simdesigngear15. Helical gearing, in which the teeth are cut at an angle with the axis of rotation, was developed after spur gearing and has the advantages that has the smoother action and tends to be trainw fig. Spur gear design nptel indian institute of technology. Mayuram module 2 gears lhfwxuh bevel gears crqwhqwv. Gear design objectives understand basic principles of gearing. Design and construction of bevel gear linkedin slideshare. Do not release the button otherwise you lose the connections between gear and shaft.
Internal gears are often used in planetary gear systems. Bevel gears are gears which have the teeth tapered conical elements that have the same direction as the pitch cone base line generatrix. Gear train it is defined as two or more gears are made to mesh with each epicyclic gear train the axes of the shafts over which the geaar are mounted, may move relative to a fixed axis. Recognize different gearing systems and relative advantages and. Jun 17, 2019 epicyclic gear train nptel pdf merge sijthre to design gear, we need to estimate w n fig.
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