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Automatic Transmission Model

by emmett

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Have you ever wondered how an automatic transmission works? I did, so I looked it up and then designed this desktop model. It has six forward speeds and one reverse. Real automatic transmissions have a hydraulic or electrical system that engages different clutches and brakes to shift gears depending on the driving situation. With this model you control those simplified brakes and clutches yourself.

The clutch is actuated by sliding the drive shaft through to different positions (which each have two gear markings), while three separate brakes each also have two gear markings. You select a gear by engaging the brake and clutch position associated with your desired gear. See demonstration video: http://www.youtube.com/watch?v=-FyC3dn3HJY

I tried to design the gear ratios to be fairly close to what some real cars use, and this is the result, where the input is the crank and the output is the annulus:
1st gear: 1 : 4.29
2nd gear: 1 : 2.5, 71% increase
3rd gear: 1 : 1.67, 50% incre

Gear LulzBot model openscad parametric planetary snapfit transmission Gear LulzBot model openscad parametric planetary snapfit transmission Gear LulzBot model openscad parametric planetary snapfit transmission

Source

Thingiverse

What you need to print this: Beginner Low confidence

Single piece

Supports 1/3

Assembly 0/3

Settings 1/3

Bed size 0/3

Post-process 0/3

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FDM / FFF

File format