Output torques have the reverse sign of input . Traditional gears rely small number of contact points between two to transfer the driving force. If the sun gear has Ns teeth and each planet Np then ratio is equal to . The gear ratio in this case will be Nr Ns which can also written

Read More →Paul Kinematics and Dynamics of Planar Machinery Prentice Hall. Reduction gears Pratt Whitney Canada PT gas turbine engine. In this case the curve traced by point on pitch circle of planet hypocycloid. The gear ratio in this case will be Nr Ns which can also written . History edit In the ndcentury AD treatise Almagest Ptolemy used rotating deferent and epicycles that form epicyclic gear trains predict motions of planets

Read More →In Italian military engineer Agostino Ramelli invented the bookwheel bookstand containing epicyclic gearing with two levels of planetary gears to maintain proper orientation . The fundamental formula of planetary gear train with rotating carrier is obtained by recognizing that this remains true if angular velocities sun and ring gears are computed relative to velocity. The axes of planetary gears join at pencil sharpening angle. Torque applied radially onto the gears of planetary train is transferred by without lateral pressure teeth. Shigley Theory of Machines and Mechanisms Oxford University Press New York

Read More →With this theory Claudius Ptolemy in Almagest AD was able predict planetary orbital paths. For instance if the sun gear has teeth and each planet then ratio is this means that one clockwise turn of produces. Compared to simple planetary gears compound have the advantages of larger reduction ratio higher torqueto weight and more flexible configurations. Epicyclic gearing was used the Antikythera Mechanism circa BCE to adjust displayed position of moon for ellipticity its orbit and even apsidal precession

Read More →Citation needed This type of efficiency ensures that high proportion about the energy being input transmitted through gearbox rather than wasted mechanical losses inside . Extending this case from the one above turn of sun gear results p displaystyleN text turns planets ring So with planetary carrier locked . This has ratio from input sun gear to output black ring of . The whole set of planetary gear system revolves on its own axis and along external ring where output shaft connected to carrier achieves goal speed reduction. Gears and Their Vibration Basic Approach to Understanding Noise. This had two outer ring gears each half the thickness of other

Read More →In discussing the spur gear differential use of term ring convenient way to distinguish sun gears two epicyclic trains. Compound planets of SturmeyArcher AM bicycle hub gear ring removed Torque ratios standard epicyclic gearing edit gears two speeds must be known order determine the third . At around BC the Greeks invented idea of epicycles circles traveling on circular orbits

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Epicyclic gearing From Wikipedia the free encyclopedia Jump to navigation search For used starter motors see . Thus the angular velocity of carrier spur gear differential is average velocities sun and ring gears. The planetary gear train also provides stability due to even distribution of mass and increased rotational stiffness. The efficiency loss in a planetary gear train is typically about per stage