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Types of Gears

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Faculty of Engineering - Shoubra
Benha University
Research Article
in fulfillment of the requirements of
Department Survey...
Benha University
Faculty of Engineering - Shoubra
Academic year 2019-2020
1 | P a g e
TABLE OF CONTENTS
LIST OF FIGURES......
Benha University
Faculty of Engineering - Shoubra
Academic year 2019-2020
2 | P a g e
LIST OF FIGURES
Figure ID Descriptio...
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Types of Gears

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Gearsare a type of mechanical element, the surface with the same space. It is toothed members used for the turning and transmitting of power and/or motion by meshing a pair of elements with no-slip from the driving shaft to the driven shaft. Therefore, gear drives are called positive drives. The smaller one is called pinion in any pair of gears and the larger one is called the immaterial gear that drives the other. The smaller gear is called pinion in any pair of gears and the larger one is called the immaterial gear that drives the other. If the pinion is the driver, the speed is decreased and the torque increases. If the pinion (the smaller one) is the driver, the speed is decreased and the torque increases, vice versa. The gears may be classified according to their shape into spiral, cycloid, and trochoid gears. Depending on the direction of the shaft, it can be categorized as Parallel, non-parallel, transverse, and non-transverse shaft gear.

Gearsare a type of mechanical element, the surface with the same space. It is toothed members used for the turning and transmitting of power and/or motion by meshing a pair of elements with no-slip from the driving shaft to the driven shaft. Therefore, gear drives are called positive drives. The smaller one is called pinion in any pair of gears and the larger one is called the immaterial gear that drives the other. The smaller gear is called pinion in any pair of gears and the larger one is called the immaterial gear that drives the other. If the pinion is the driver, the speed is decreased and the torque increases. If the pinion (the smaller one) is the driver, the speed is decreased and the torque increases, vice versa. The gears may be classified according to their shape into spiral, cycloid, and trochoid gears. Depending on the direction of the shaft, it can be categorized as Parallel, non-parallel, transverse, and non-transverse shaft gear.

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Types of Gears

  1. 1. Faculty of Engineering - Shoubra Benha University Research Article in fulfillment of the requirements of Department Surveying Engineering Department Division Second Year Surveying Academic Year 2019/2020 Course name Electromechanical Engineering Course code EPE/260 Mechanical Part “Topic (5): Types of Gears” By: Name Edu mail B. N Ahmed Yasser Ahmed Mohamed Nassar ahmed170165@feng.bu.edu.eg 210018 Approved by: Examiners committee Signature
  2. 2. Benha University Faculty of Engineering - Shoubra Academic year 2019-2020 1 | P a g e TABLE OF CONTENTS LIST OF FIGURES...........................................................................................................2 1. INTRODUCTION .....................................................................................................3 2. TYPES OF GEARS ....................................................................................................3 (a) SPUR GEAR ......................................................................................................4 (b) SINGLE HELICAL GEAR......................................................................................4 (c) DOUBLE HELICAL GEAR (HERRINGBONE GEAR) ...............................................5 (d) INTERNAL GEAR...............................................................................................5 (e) RACK AND PINION GEAR..................................................................................6 (f) STRAIGHT BEVEL GEAR .......................................................................................6 (g) SPIRAL BEVEL GEARS........................................................................................7 (h) HYPOID BEVEL GEAR........................................................................................7 (i) WORM GEAR ......................................................................................................8 REFRENCES ..................................................................................................................9
  3. 3. Benha University Faculty of Engineering - Shoubra Academic year 2019-2020 2 | P a g e LIST OF FIGURES Figure ID Description Page 1-1 Gears 3 2-1 Types of Gears 3 2-2 Spur Gear 4 2-3 Helical Gear 4 2-4 Hobbing Machine 4 2-5 Herringbone Gear 5 2-6 Double Helical Gear 5 2-7 Internal Gear 5 2-8 Pinion and Annular of Internal Gear 5 2-9 Pinion Cutter 5 2-10 Gear Shaper 5 2-11 Straight-teeth Pinion in Rack and Pinion Gear 6 2-12 Helical-teeth Pinion in Rack and Pinion Gear 6 2-13 Steering Mechanism 6 2-14 Slide Gate 6 2-15 Straight Bevel Gear 6 2-16 Spiral Bevel Gear 7 2-17 Hypoid Bevel Gear 7 2-18 Worm Gear 8 2-19 Various Types of Gears 8
  4. 4. Benha University Faculty of Engineering - Shoubra Academic year 2019-2020 3 | P a g e 1. INTRODUCTION Gears (Figure 1-1) are a type of mechanical element, the surface with the same space. It is toothed members used for the turning and transmitting of power and/or motion by meshing a pair of elements with no-slip from the driving shaft to the driven shaft. Therefore, gear drives are called positive drives. The smaller one is called pinion in any pair of gears and the larger one is called the immaterial gear that drives the other. The smaller gear is called pinion in any pair of gears and the larger one is called the immaterial gear that drives the other. If the pinion is the driver, the speed is decreased and the torque increases. If the pinion (the smaller one) is the driver, the speed is decreased and the torque increases, vice versa. The gears may be classified according to their shape into spiral, cycloid, and trochoid gears. Depending on the direction of the shaft, it can be categorized as Parallel, non-parallel, transverse, and non-transverse shaft gear. 2. TYPES OF GEARS as shown in the (Figure 2-1): (a) Spur gear (b)Helical Gear (c) Double Helical Gear (Herringbone Gear) (d)Internal Gear (e) Rack and Pinion Gear (f) Straight Bevel Gear (g)Spiral Bevel Gear (h)Hypoid Bevel Gear (Figure 2-1) (i) Worm Gear (Figure 1-1)
  5. 5. Benha University Faculty of Engineering - Shoubra Academic year 2019-2020 4 | P a g e (a)SPUR GEAR Spur gears (Figure 2-2) are the simplest gear type. teeth are parallel to the axis of the shaft and are used for power and motion transmission and motion between rotating two parallel shafts. They are simple to construct easy to manufacture, and less expensive. They are extremely efficient and have a high level of precision. They are used in high speed and high load applications in all types of trains with a wide range of speed ratios. Therefore, it is commonly used in clocks, kitchen appliances, bicycles, automobiles and railways for aircraft. (b)SINGLE HELICAL GEAR Helical gears (Figure 2-3) are cylindrical gears that have winding teeth inclined to an axis and are used with parallel shaft drives like spur gears. compared to spur gears They have a better teeth grip, operate smoother and quieter, and have higher load-carrying capacity, and precision rating is good, which makes them suitable for very high-speed and loads applications. thrust bearings must be used when using the helical gears because they generate an axial thrust on the shaft. so, their efficiency is slightly lower than spurs. The Spur Gear hobbing machine (Figure 2-4) and tool can be used to manufacture helical gears. Because of the turn of the teeth, their production has the disadvantages of a very difficult product. (Figure 2-3) (Figure 2-4) (Figure 2-2)
  6. 6. Benha University Faculty of Engineering - Shoubra Academic year 2019-2020 5 | P a g e (c) DOUBLE HELICAL GEAR (HERRINGBONE GEAR) Double helical or Herringbone gears used for transmitting power and motion through 2 parallel shafts. Double helical and herringbone gears are not quite the same. They have opposing helical teeth with a gap (double helical gear) (Figure 2-6) or without a gap (herringbone gear) (Figure 2-5) depending on the manufacturing method used. it overcomes the issue of single helical gears axial thrust by having 2 sets of teeth that are set in a V-shape. The shaft is free from axial force because of Two axial thrusts oppose each other. the need for thrust bearings can be eliminated -thrust load equal zero-. (d)INTERNAL GEAR Internal gears (Figure 2-7) are used for transmission of power between two parallel shafts. it's teeth of an internal spur gear cut inside the surface of a cylinder towards the center and meshed with spur gears. the internal gear (pinion) mesh rotation always goes in the same direction with the external gear(annular) (Figure 2-9). the manufacturing of internal gears cannot be done with the usual hobbing machine (Figure 2-4) used in spur gears. so gear shaper (Figure 2-10) equipped with a pinion cutter (Figure 2-8) is used to manufacture of internal gears. internal gears are useful for applications with high load and high speed with a high reduction rate. (Figure 2-5) (Figure 2-6) (Figure 2-7) (Figure 2-8) (Figure 2-9) (Figure 2-10)
  7. 7. Benha University Faculty of Engineering - Shoubra Academic year 2019-2020 6 | P a g e (e) RACK AND PINION GEAR Rack and pinion gear have a strip of rectangular linear cross-section (the rack), the teeth on one side mesh with the teeth on the smaller gear (pinion). The pinion straight (Figure 2-11) or helical teeth (Figure 2-12) meshed with teeth on the rack which are tilted to the pinion shaft axis. racks are transforming rotating motion into linear motion so that you can control the wheel. Rack and Pinions are used for lifting mechanisms, horizontal movement, positioning mechanisms, stoppers and to allow the rotation of shafts. rack- and-pinion drives used in steering mechanisms (Figure 2-13) to change the direction of cars. Also, it used for several other purposes, such as slide gates (Figure 2-14). The rack and pinion systems on the steering wheel have a simple structure, high stiffness, lightweight, and excellent response. (f) STRAIGHT BEVEL GEAR Straight Bevel Gears (Figure 2-15) have a conical shape and are used to transmit forces between non-parallel and intersecting shafts (intersection axis). They can run under high speeds and loads. Bevel gears teeth are formed on conical surfaces. they offer good service and easy to design and manufacture. But at higher speeds, they are noisy. They are recommended in those cases at speeds up to 1000 ft/min where maximum quietness has no critical importance. (Figure 2-11) (Figure 2-12) (Figure 2-13) (Figure 2-14) 1111 (Figure 2-15)
  8. 8. Benha University Faculty of Engineering - Shoubra Academic year 2019-2020 7 | P a g e (g)SPIRAL BEVEL GEARS Spiral bevel gear (Figure 2-16) is a bevel gear with curved, inclined teeth. It has higher contact rate, strength and durability, better performance of transmitting, and reduced gear noise, because of the higher contact ratio of teeth to provide gradual engagement and larger contact surface at a given time than straight bevel gear. also, they involve some technical problems in manufacturing, so they are too complex to produce. In addition, as the tooth is curved, thrust is formed in the axial direction. Zero cone gears with a turning angle of zero in helical bevel gear are called zero bevel gears. It has many applications such as automobiles, tractors, automobiles, an ultimate cutting tool for ships. Especially suitable for high-speed, high-load drivers. (h)HYPOID BEVEL GEAR Hypoid bevel gears (Figure 2-17) are also used for right angle drive where axes are not intersecting. This allows the pinion axis to be reduced which is an added advantage in automobiles in avoiding the cone within the driveline power transmission. However, non– intersection introduces a considerable amount of flexibility and requires good greasing for the driver to reduce friction and wear. Their performance is lower than the other two types of bevel gears. These gears are widely used in the current automobile driveline power transmission. (Figure 2-16) (Figure 2-17)
  9. 9. Benha University Faculty of Engineering - Shoubra Academic year 2019-2020 8 | P a g e (i) WORM GEAR Worm gears (Figure 2-18) are used to transmit movement between two rods unparalleled and non-intersecting. It has helical gear and power screw (worm). Worm gears can be used to drive spur gears or helical gears. (Figure 2-18) (Figure 2-19)
  10. 10. Benha University Faculty of Engineering - Shoubra Academic year 2019-2020 9 | P a g e REFRENCES Jelaska, D., 2012. Gears and Gear Drives. New York: Wiley. Jones, F. and Ryffel, H., 1984. Gear Design Simplified. New York: Industrial Press. KHK Gears. 2020. Characteristics of Gears. [online] Lynwander, P., 2018. Gear Drive Systems. Boca Raton: Chapman and Hall/CRC. Nptel.ac.in. 2009. NPTEL: Mechanical Engineering - Machine Design II. [online] Oberg.E, Jones.D.J., Holbrook L.H, Ryffel H.H., (2012). Machinery's Handbook. 29th edition. Industrial Press Inc. Bodnar, Nisbett.K. (2008). Shigley's Mechanical Engineering Design. 8th edition. McGraw-Hill Gear Nomenclature, Definitions of Terms with Symbols, American Gear Manufactures Association, Alexandria, Va., 1990. Darle W. Dudley, Handbook of Practical Gear Design, McGraw-Hill Inc., New York, 1984. Robert O. Parmley, Mechanical Components Handbook, McGraw-Hill Inc., New York, 1985. Raymond J. Drago, Fundamentals of Gear Design, Butterworths, Stoneham, Mass., 1988. P. M. Dean, Jr., Gear Manufacturing and Performance, American Society for Metals, Metals Park, Ohio, 1974 Jones, Franklin D, and Henry H Ryffel. Gear Design Simplified. Industrial Press, 1961. Worm Gearing. Industrial Press, 1910.

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