Difference between revisions of "Gears"

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==Types of Gears==
==Types of Gears==

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| [[image:helical gears.png|125px|center]]
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| [[image:worm drive.png|125px|center]]
| [[image:worm drive.png|125px|center]]
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===Specialty Gears===
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{| align="center"
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! Harmonic Drive Gear
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| [[image:harmonic gears.jpg|400px|center]]
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===Spur Gears===
===Spur Gears===


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{| align="left" cellpadding = "25"
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[[image:spur gears.png|125px|center]]
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! [[image:spur gears.png|125px|center]] !! [[image:gear-spurgearhead.jpg|125px|center]]

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{| align="center" cellpadding = "25"
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[[image:spur gears.png|125px|center]] !! [[image:rack and pinion.png|125px|center]]
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[[Image:globe-gearhead.jpg|thumb|300px|Inside the Globe motor gearhead.|left]]

[[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]]


<br clear=all>


===Rack and Pinion===
===Rack and Pinion===

{| align="left" cellpadding = "25"
! [[image:rack and pinion.png|125px|center]]
|}

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===Bevel Gears===
===Bevel Gears===

{| align="left" cellpadding = "25"
! [[image:bevel gears.png|125px|center]]
|}

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===Helical Gears===
===Helical Gears===

{| align="left" cellpadding = "25"
! [[image:helical gears.png|125px|center]] !! [[image:gear-helical2.jpg|125px|center]]
|}

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===Worm Drives===
===Worm Drives===

{| align="left" cellpadding = "25"
! [[image:worm drive.png|125px|center]]
|}

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===Planetary Gears===
===Planetary Gears===


{| align="left" cellpadding = "25"
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===Specialty Gears===
! [[image:gear-planetary-anim.gif|center]] !! [[image:gear-planetarystage.jpg|125px|center]] !! [[image:gear-planetary.jpg|125px|center]]
|}


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{| align="center"

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! Harmonic Drive Gear
===Ball Screw/Lead Screw===

{| align="left" cellpadding = "25"
! [[image:gear-ballscrew-small.gif|125px|center]] !! [[image:gear-ballscrew2-small.jpg|125px|center]]
|}

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===Harmonic Drive Gears===

{| align="left" cellpadding = "25"
! [[image:harmonic gears.jpg|400px|center]]
|-
|-
| [[image:harmonic gears.jpg|400px|center]]
| [[image:gear-harmonicdrive.gif|center]]
|-
| [[image:gear-harmonicdrive2aligned.jpg|400px|center]]
|-
| [[image:gear-harmonic-drive-anim.gif]]
|}
|}


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==Gear Geometry==

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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.
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.


[[image:gear-spurdetails.jpg|center]]
[[image:gear circle geometry.png|center]]
[[image:gear circle geometry.png|center]]


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==Gear Meshing and Forces==

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==Spur Gear Meshing and Forces==


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.


[[image:gear triangles.png|center]]
[[image:gear triangles.png|center]]



==References==
==References==

Latest revision as of 08:34, 2 March 2011

Types of Gears

Spur Gears

Spur gears.png
Gear-spurgearhead.jpg
Inside the Globe motor gearhead.
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.



Rack and Pinion

Rack and pinion.png


Bevel Gears

Bevel gears.png


Helical Gears

Helical gears.png
Gear-helical2.jpg


Worm Drives

Worm drive.png


Planetary Gears

Gear-planetary-anim.gif
Gear-planetarystage.jpg
Gear-planetary.jpg


Ball Screw/Lead Screw

Gear-ballscrew-small.gif
Gear-ballscrew2-small.jpg


Harmonic Drive Gears

Harmonic gears.jpg
Gear-harmonicdrive.gif
Gear-harmonicdrive2aligned.jpg
Gear-harmonic-drive-anim.gif


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.

Gear-spurdetails.jpg
Gear circle geometry.png


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.

Gear triangles.png

References

Retrieved from "https://hades.mech.northwestern.edu//index.php?title=Gears&oldid=20338"