Gears: Difference between revisions
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==Types of Gears== |
==Types of Gears== |
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===Specialty Gears=== |
===Specialty Gears=== |
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! Harmonic Drive Gear |
! Harmonic Drive Gear |
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| [[image:harmonic gears.jpg|400px|center]] |
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===Spur Gears=== |
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! [[image:spur gears.png|125px|center]] !! [[image:gear-spurgearhead.jpg|125px|center]] |
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[[Image:globe-gearhead.jpg|thumb|300px|Inside the Globe motor gearhead.|left]] |
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[[Image:globe-gearhead-closeup.jpg|thumb|300px|A closeup of the gearhead, clearly showing 5 stages of spur gear reduction (the gearhead output shaft is disconnected) resulting in a 187.68:1 gear ratio.|right]] |
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===Rack and Pinion=== |
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! [[image:rack and pinion.png|125px|center]] |
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===Bevel Gears=== |
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! [[image:bevel gears.png|125px|center]] |
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===Helical Gears=== |
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! [[image:helical gears.png|125px|center]] !! [[image:gear-helical2.jpg|125px|center]] |
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===Worm Drives=== |
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! [[image:worm drive.png|125px|center]] |
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===Planetary Gears=== |
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! [[image:gear-planetary-anim.gif|center]] !! [[image:gear-planetarystage.jpg|125px|center]] !! [[image:gear-planetary.jpg|125px|center]] |
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===Ball Screw/Lead Screw=== |
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! [[image:gear-ballscrew-small.gif|125px|center]] !! [[image:gear-ballscrew2-small.jpg|125px|center]] |
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===Harmonic Drive Gears=== |
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! [[image:harmonic gears.jpg|400px|center]] |
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| [[image:gear-harmonicdrive.gif|center]] |
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| [[image:gear-harmonicdrive2aligned.jpg|400px|center]] |
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| [[image:gear-harmonic-drive-anim.gif]] |
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==Gear Geometry== |
==Spur Gear Geometry== |
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For external spur gears (most common), the gear geometry is as shown in the figure below. The '''''line of action''''' is the line that passes through the intersection of the pitch circles and also tangent to the base circles. |
For external spur gears (most common), the gear geometry is as shown in the figure below. The '''''line of action''''' is the line that passes through the intersection of the pitch circles and also tangent to the base circles. |
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[[image:gear-spurdetails.jpg|center]] |
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[[image:gear circle geometry.png|center]] |
[[image:gear circle geometry.png|center]] |
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Gear meshing results in contacts with normals along the line of action, so the resultant force, <math>W</math> is along this line. This results in both tangential and radial forces, <math>W_t</math> and <math>W_r</math>, on the gear pair. When these gears are mounted on a shaft, the radial force causes a bending moment while the tangent force causes both a bending moment and a torque. |
Gear meshing results in contacts with normals along the line of action, so the resultant force, <math>W</math> is along this line. This results in both tangential and radial forces, <math>W_t</math> and <math>W_r</math>, on the gear pair. When these gears are mounted on a shaft, the radial force causes a bending moment while the tangent force causes both a bending moment and a torque. |
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[[image:gear triangles.png|center]] |
[[image:gear triangles.png|center]] |
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==References== |
==References== |
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Latest revision as of 08:34, 2 March 2011
Types of Gears
Spur Gears
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Rack and Pinion
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Bevel Gears
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Helical Gears
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Worm Drives
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Planetary Gears
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Ball Screw/Lead Screw
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Harmonic Drive Gears
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Spur Gear Geometry
For external spur gears (most common), the gear geometry is as shown in the figure below. The line of action is the line that passes through the intersection of the pitch circles and also tangent to the base circles.
Spur Gear Meshing and Forces
Gear meshing results in contacts with normals along the line of action, so the resultant force, is along this line. This results in both tangential and radial forces, and , on the gear pair. When these gears are mounted on a shaft, the radial force causes a bending moment while the tangent force causes both a bending moment and a torque.
References
- Stock Drive Products/Sterling Instrument, http://www.sdp-si.com
- McMaster-Carr, http://www.mcmaster.com
- Harmonic Drive, LLC, http://www.harmonic-drive.com
