The required rotation speed for your system is 250 rpm, however, the available motor provides a...

  

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The required rotation speed for your system is 250 rpm, however, the available motor provides a much higher speed, 1300 rpm. Therefore, you need to design a speed reducer to fit this motor with your system. You are required to use a double-step reduction, with either Spur or Helical gears. For alignment issues, you must insure that the input and output shafts are aligned as shown in Figure 1. 1. 2. b Figure 1: Sample gear system The power transmitted from the motor to your machine equals to [The last (2 digits)/10 of the SID number in Kilo watts, e.g. if 200475, the power is 75/10 watts, or 7.5 kW]. All shafts are supported by two ball or roller bearings; their selection is part of the design. For your design, it is desired to have an overall reliability of 95%, and a design life of 20.000 h. 3. input output : Determine/Select/Decide on the geometry of the gears: number of teeth, diameters, tooth systems, etc. Also, perform Gear Mechanics: determine the transmitted load W, the axial load Wa, and the radial load Wr, acting Torque, rotation speeds, and transmitted power for each gear. : Based on that information, decide on a number of factors related to gear design, this include gear material, quality level, face width, surface quality. Use that information to determine the applied stresses and strengths for each gear, which in turn would allow you to calculate the factors of safety. : Now that you know the forces acting on each gear, as well as their diameters and locations along each shaft (which you decide as well), you are now able to determine the maximum torque and bending moment acting on each shaft, by developing the shear and bending moment diagrams for each shaft. Also, you can calculate reactions acting on each support (the bearings) of every shaft. Knowing the forces, torques, and bending moments acting on each shaft, you are now ready to design each shaft. You can select material of each shaft, determine its radiuses. The minimum value for the Factor of safety of 2.0, any values lower than that will not be accepted. Remember that for every shaft there are multiple radiuses to be found, as there are keyways, shoulders, and other fittings on each shaft creating stress concentration, which you need to determine and consider it in your design. Also, design of shafts ALSO includes design of its keys & keyways, as well as its holding rings. : Based on the values of the reactions found in step 1, you can select an appropriate bearing for each support of each shaft. In this selection, the design life, the design speed, and reliability requirements should all be considered. Note that the speeds of the shafts are not the same. : Design the casing (box) that would hold the designed speed reducer. (Bearings would be fixed to it). Consider the total weight of all shafts, gears, bearings, and the case itself as a static load acting on the box, and determine its factor of safety (static loading) The required rotation speed for your system is 250 rpm, however, the available motor provides a much higher speed, 1300 rpm. Therefore, you need to design a speed reducer to fit this motor with your system. You are required to use a double-step reduction, with either Spur or Helical gears. For alignment issues, you must insure that the input and output shafts are aligned as shown in Figure 1. 1. 2. b Figure 1: Sample gear system The power transmitted from the motor to your machine equals to [The last (2 digits)/10 of the SID number in Kilo watts, e.g. if 200475, the power is 75/10 watts, or 7.5 kW]. All shafts are supported by two ball or roller bearings; their selection is part of the design. For your design, it is desired to have an overall reliability of 95%, and a design life of 20.000 h. 3. input output : Determine/Select/Decide on the geometry of the gears: number of teeth, diameters, tooth systems, etc. Also, perform Gear Mechanics: determine the transmitted load W, the axial load Wa, and the radial load Wr, acting Torque, rotation speeds, and transmitted power for each gear. : Based on that information, decide on a number of factors related to gear design, this include gear material, quality level, face width, surface quality. Use that information to determine the applied stresses and strengths for each gear, which in turn would allow you to calculate the factors of safety. : Now that you know the forces acting on each gear, as well as their diameters and locations along each shaft (which you decide as well), you are now able to determine the maximum torque and bending moment acting on each shaft, by developing the shear and bending moment diagrams for each shaft. Also, you can calculate reactions acting on each support (the bearings) of every shaft. Knowing the forces, torques, and bending moments acting on each shaft, you are now ready to design each shaft. You can select material of each shaft, determine its radiuses. The minimum value for the Factor of safety of 2.0, any values lower than that will not be accepted. Remember that for every shaft there are multiple radiuses to be found, as there are keyways, shoulders, and other fittings on each shaft creating stress concentration, which you need to determine and consider it in your design. Also, design of shafts ALSO includes design of its keys & keyways, as well as its holding rings. : Based on the values of the reactions found in step 1, you can select an appropriate bearing for each support of each shaft. In this selection, the design life, the design speed, and reliability requirements should all be considered. Note that the speeds of the shafts are not the same. : Design the casing (box) that would hold the designed speed reducer. (Bearings would be fixed to it). Consider the total weight of all shafts, gears, bearings, and the case itself as a static load acting on the box, and determine its factor of safety (static loading)

Answer rating: 100% (QA)

SOLUTION 1 Gear Geometry and Gear Mechanics a Number of Teeth The number of teeth for the gears will be determined based on the required rotation speed and the power transmitted from the motor For a d... View the full answer