Talk:3244: Pullback Drive

2026-05-13T19:06:01Z

82.196.111.48:

Is that supposed to be Elon Musk? {{unsigned ip|185.114.120.233|09:24, 12 May 2026 (UTC)}}

There are toy cars that work like this, or that use a flywheel to store energy in a similar way, for example the Fisher-Price Rev 'N Go Stunt Vehicles. The salesman is offering a full sized car on the same principle. The toys don't go very far. Neither will the full sized car, though he implies it will go "far" before stopping. He doesn't offer any practical way to rewind the spring. [[Special:Contributions/2A12:F43:1462:CC00:583C:B3A7:2A0B:2140|2A12:F43:1462:CC00:583C:B3A7:2A0B:2140]] 09:56, 12 May 2026 (UTC) dww
:Pull-back and Rev-up toys work significantly differently (though a pull-back toy ''may'' have a flywheel effect, it doesn't usually rely on this). Both are, of course, ways in which a child puts their effort into a much smaller vehicle that then expends that effort into forward motion (from my childhood, there were 'friction-toys' or even the Evel Knievel Stunt Bike, on one hand, and things like the Penny Racers, on the other).
:The Rev'N'Go type perhaps ''can'' be far more indefnitely charged with energy, upon being released (barring mechanical failures and stripping/melting the plastic cogs), but would not give you the described Clicking that the comic says is happening, which is a sign of a sprung-toy with basic overwind-protection designed in.
:Also, riding a (for example) full-sized Evel Knieval flywheel bike and applying the brakes (assuming they ''could'' stop it in time!) would probably just stop it, and leave no more energy to move off again (unlike the spring-powered car, halted before too unwound). I suppose you ''could'' make the brakes disengage the drive from the still-running flywheel, then 'clutch back on' when you released them again, but still not something that mofe pulling back at the factory is going to help reduce your range-anxiety with. [[Special:Contributions/82.132.221.157|82.132.221.157]] 16:00, 12 May 2026 (UTC)

Energy storage. The devil is in the detail, and the magnitudes. It turns out a rubber spring (aeroplane elastic) stores rather more energy weight for weight than a steel 'clockwork' spring. However batteries, and hydrocarbons, store orders of magnitude more. This subjectwould be good for one of Randall's 2D graphs, plotting use case against energy stored. For instance, a diver's harpoon gun uses a pull-back mechanism quite effectively. {{unsigned ip|82.19.218.32|10:22, 12 May 2026 (UTC)}}

I italicized the "or" in the first section of the transcript [[User:SomebodyElse|SomebodyElse]] ([[User talk:SomebodyElse|talk]]) 11:09, 12 May 2026 (UTC) SomebodyElse 12:08, 12 May 2026 (UTC)
:Isn’t it also bolded?[[User:Commercialegg|Commercialegg]] ([[User talk:Commercialegg|talk]]) 12:51, 12 May 2026 (UTC)
::Looks like it is. :) [[User:SomebodyElse|SomebodyElse]] ([[User talk:SomebodyElse|talk]]) 18:09, 12 May 2026 (UTC)SomebodyElse 17:08, 12 May 2026 (UTC)

Is the mention of worries about gas prices a reference to Trump's war on Iran? [[User:SectorCorruptor|SectorCorruptor]] ([[User talk:SectorCorruptor|talk]]) 14:52, 12 May 2026 (UTC)
:Almost certainly. I've added it in. --'''''[[User:DollarStoreBa'al|DollarStoreBa'al]][[User_talk:DollarStoreBa'al|'''''converse''''']] 14:38, 12 May 2026 (UTC)

Does this count as a [[:Category:Tuesday comics|Tuesday comic]]? Not sure when it went live but it hit explainxkcd at 0900 UTC, which was 2AM Tuesday morning California time. It was still Monday in Hawaii (UTC-1000) though. [[Special:Contributions/64.201.132.210|64.201.132.210]] 15:18, 12 May 2026 (UTC)

May

Probably the real vehicle getting most close to the pullback drive is the Gyrobus: https://en.wikipedia.org/wiki/Gyrobus {{unsigned ip|2a02:3100:8bac:fe00:1e1b:dff:fe9f:401d|20:40, 12 May 2026}}

I'll let another editor handle the writeup and citations, but here are some order-of-magnitude comparisons: The springs actually in your car's engine store a few joules. A garage door spring might store a few kilojoules. An [https://www.shibata-fender.team/files/content/products/SPC-Cone-Fenders/Product_Information_SPC_Fenders.pdf eight-ton chunk of rubber] can absorb 5 megajoules, and a single gallon of gasoline stores >120 megajoules. Even if you have some incredibly machinery to get that energy out, there's several orders of magnitude between (the spring energy you can store inside a car) and (the spring energy needed to make a car go even one mile). {{unsigned ip|206.209.15.112|21:02, 12 May 2026}}
:You can make springs out of petrol? [[Special:Contributions/2001:569:FBCA:1700:986:CE3B:3243:855|2001:569:FBCA:1700:986:CE3B:3243:855]] 00:47, 13 May 2026 (UTC)

Just reading this article and seeing this sentence:

> This is technically true, but cats that run on petroleum or atomicity have the advantage of their energy supply being refillable, while this pullback cat seemingly does not (without another factory-style 'pull back' facility).
[[Special:Contributions/82.196.111.48|82.196.111.48]] 19:06, 13 May 2026 (UTC)

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Talk:3244: Pullback Drive