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submitted 2 weeks ago by xkcdbot@lemmy.world to c/xkcd@lemmy.world

xkcd #3244: Pullback Drive

Title text:

"How does the spring not run out almost immediately?" "We pull it back REALLY far."

Transcript:

Transcript will show once it’s been added to explainxkcd.com

Source: https://xkcd.com/3244/

explainxkcd for #3244

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[-] cybervseas@lemmy.world 15 points 2 weeks ago

I can't remember which car but an early hybrid vehicle did charge up a flywheel instead of an electric battery…

[-] thebestaquaman@lemmy.world 14 points 2 weeks ago

I heard about a version that used springs as well. Basically a pull-back car: When you break, it puts tension on the springs, then it releases that tension when accelerating. Apparently it was very good for city-driving, since you get an absurd number of cycles with very small "charges", which makes it very good when you do a lot of start/stop driving in slow traffic. I'm not sure why I haven't heard any more about it in more recent years.

[-] homesweethomeMrL@lemmy.world 9 points 2 weeks ago
[-] thebestaquaman@lemmy.world 6 points 2 weeks ago

Idk about you, but I usually build tension when I break.

[-] xylol@leminal.space 4 points 2 weeks ago

Maybe its some sort of human degradation fuel system, as you break down it powers the car?

i think it was a bus, and it was used in hills to get extra energy while going down and using ot while going up.

[-] Jakylla@jlai.lu 3 points 2 weeks ago* (last edited 2 weeks ago)

I heard about racing car having spinning wheels too, instead of br~~e~~aking before turns, accumulating energy into them, then after the turn, releasing them for huge acceleration

[-] homesweethomeMrL@lemmy.world 7 points 2 weeks ago
[-] xylol@leminal.space 8 points 2 weeks ago

If its a race car it does both

[-] Jakylla@jlai.lu 2 points 2 weeks ago

Thanks for the fix ;)

this post was submitted on 12 May 2026
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