ME350 Mechanical Design and Manufacturing ll ME350 Power/Energy Transmission Ill: Gears 1
ME 350 1 ME 350 Mechanical Design and Manufacturing II Power/Energy Transmission III: Gears
Lectures ME350- Power/Energy Conversion (Electrical Motors) Power/Energy Transmission (Gears, Belt Drives, Power Screwsy Joints Transmission (Fasteners, Support Connectors) (Bearings) Structural Support (Frames) Tools Statics,Dynamics, Stress Analysis,etc.. 2
ME 350 2 Lectures Power/Energy Conversion (Electrical Motors) Power/Energy Transmission (Gears, Belt Drives, Power Screws) Power/Energy Transmission (Gears, Belt Drives, Power Screws) Transmission Support (Bearings) Joints (Fasteners, Connectors) Structural Support (Frames) Tools Statics, Dynamics, Stress Analysis, etc
Transmission Elements2 ME350 Gear Drives >Gears change rotational velocity and torque to suit motor and load conditions. >Can be used to simply transport power from one shaft to another. >Highly efficient with output power approximately equal to input power. V-belt drive Chain drive Driven machine (a)Sketch of combination drive th)Photograph of an actual drive installation.Note that from the belt
ME 350 3 Transmission Elements 2 Gear Drives ¾Gears change rotational velocity and torque to suit motor and load conditions. ¾Can be used to simply transport power from one shaft to another. ¾Highly efficient with output power approximately equal to input power
Transmission Elements2 ME350- Belt Drives >Used where rotational speeds are relatively high. >At lower speeds,tension in belt becomes too large for typical belt cross sections >At higher speeds,dynamic effects such as centrifugal forces,belt whip,and vibration reduce effectiveness of drive and its life. Chain Drives >Used at lower speed where high torques are needed. >At higher speeds,noise,impact between chain link and sprocket teeth and lubrication become major problems. 4
ME 350 4 Transmission Elements 2 Belt Drives ¾Used where rotational speeds are relatively high. ¾At lower speeds, tension in belt becomes too large for typical belt cross sections ¾At higher speeds, dynamic effects such as centrifugal forces, belt whip, and vibration reduce effectiveness of drive and its life. Chain Drives ¾Used at lower speed where high torques are needed. ¾At higher speeds, noise, impact between chain link and sprocket teeth and lubrication become major problems
Advantages of Different Transmissions4 ME350 Advantages of Belt Drives >Electrical insulation is provided because there is no metal- to-metal contact between driver and driven units. There is less noise than with a chain drive >Flat belts can be used for extremely long center distances where chain weight would be excessive Flat bets can be used at extremely high-speeds where chain inertia must be considered as influencing chain fit at the sprocket and chain tension. No lubrication is required. >Shaft center distance variation and shaft alignment is much less critical than for gear drives or chain drives. 5
ME 350 5 Advantages of Different Transmissions 4 Advantages of Belt Drives ¾ Electrical insulation is provided because there is no metalto-metal contact between driver and driven units. ¾ There is less noise than with a chain drive ¾ Flat belts can be used for extremely long center distances where chain weight would be excessive ¾ Flat bets can be used at extremely high-speeds where chain inertia must be considered as influencing chain fit at the sprocket and chain tension. ¾ No lubrication is required. ¾ Shaft center distance variation and shaft alignment is much less critical than for gear drives or chain drives