None of the others in town have these, thought it was unusual enough to share
My local store uses these but they lock up if you bring them out to the 2nd row of parking spaces out front. It’s enough to get the cart to your car, then you go to return it and it’s totally locked, so everyone just shoves them into the planters in a big pile of tipped over carts instead of physically lifting the whole thing and hefting it to the cart returns to return it. The store has signs everywhere now telling people not to throw carts into the planters, and the employees know the problem, and the city has evidently complained multiple times, but district management evidently refuses to believe it’s got anything to do with the cart locks and I was told by an exasperated checker that they’re apparently considering getting security guards to confront people and make them return carts?? lmaooo
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Locking wheels would really mess with the shopping cart theory.
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Yup. Never not returned a cart. The day it becomes actively frustrating to do so is the day I place it somewhere really inconvenient out of spite. Maybe figure out the managers car and corral it in.
They’d be better off getting security guards to help people carry shit to their cars.
apparently considering getting security guards to confront people and make them return carts?
Oh that’s going to go down just great. How long until some rent-a-cop ends up under a car?
3 minutes. I give it 3 minutes.
Oh no, not security guards! What are they gonna do, lecture me?
Some Walmart GM must have a brother or something with an anti-theft wheel business because wtf?
some models use a wire in the ground that emits a low frequency radio signal… which can be also be transmitted by the speaker in a phone by simply playing these mp3 files: https://www.tmplab.org/2008/06/18/consumer-b-gone/ (!)
Of course, it’s not the sound that blocks the wheel but the electromagnetic parasites that are produced by the coil in any speaker
What the fuck am I reading?
I’m not an expert in electricity and magnetism by any stretch of the imagination, but the way that I understand it is with any electrical current, there is an induced magnetic field, and vice versa. So the little parasites the article is referring to are the magnetic fields induced by the current to play the audio in the speaker. That magnetic field is the signal that triggers the antitheft device.
I think they mean that the electromagnetic field generated by sending an alternating current through a coil (or just a wire) induces a current and electrical field on the conductor. I’ve heard the term “parasitic losses” caused by reactance but I’ve never heard parasite or parasitic related to generation of EM radiation.
Given the current behavior of autocorrect, I’m assuming that’s not the author’s fault. My brain has reached the point that it skips over that and just reads “currents.” I don’t know how you get from a typo for currents to become parasites, but I’ve seen even worse corrections in my writing.
My guess would be “interference” that got autocorrected.
It’s absolutely insane that a speaker coil works as an antenna in this case, but perhaps even more insane that the signal survives mp3 compression.
It has to cover a parking lot full of radio signals from cars. They’re probably just listening for “close enough”.
It’s more likely a buried loop antenna, like an invisible fence.
Why is that insane? The entire point of an mp3 file is to be able to reproduce signals with reasonable accuracy. Seems like the signal has a frequency of around 8khz, which is very much in the range of human hearing and should be preserved by an mp3.
No, the point of MP3 is to compress audio in a lossy manner while minimizing the introduction of artifacts detectable by human hearing using psychoacoustic analysis. The coincidence that the necessary parasitic EM signal induced by speaker drivers happens to be created by a signal that doesn’t suffer degradation by a relatively specific lossy compression method is remarkable.
Right, but artifacts in the ~8khz range will be detectable by human hearing. mp3s are going to be perfectly acceptable for many sounds in that frequency range… The fact that this works is evidence of that.
Plus, you know what else is lossy? Radio. If the signal is that fragile there’s a good chance the locking mechanism wouldn’t work in the first place.
Go actually read about MP3 compression before you continue misusing the term “lossy.”
It’s just going to be pulses of an 8khz signal. Why would an MP3 not encode this just fine?
Like I said before, the coincidence is what’s remarkable.
Can you imagine what would happen if someone went into a crowded store with a device playing this. A short loop through the isles and til queues would wreak havoc.
Sounds like a basis for a fantastic prank.
Many grocery stores in my area have these wheel locks. If I recall from college, if you took the cart out of the parking lot by carrying it over the plant beds, the lock would not engage.
These most likely lock from a small electric loop around the lot triggering an internal magnet, so y’all found a gap in the loop.
Nice hacking.
You can just lift the wheel about a foot off of the ground when passing the loop that engages the lock. Much easier.
The safeway near my apartment is so ghetto the wheels lock as soon as you leave the store exit. You have to take everything in one trip or wait for your car to pull around to load.
I’m pretty stubborn. I’d probably just drag it across the parking lot like a neanderthal and let the asphalt grind flat spots onto the wheels.
The ones I’ve seen usually only lock one wheel, maybe two on a side. So you can wheelie the carts just fine.
Half the carts I’ve ever used have a busted wheel anyway lol.
Even better of you can figure out how to grind the asphalt away with the wheels. Make it reeeeeeally annoying for them.
I’d go one step further and take the cart, for spite
Seems inconsistent! The one by my house had the wheel lock but it worked fine.
Must be working. I haven’t seen a cart on cinder blocks in a while.
Bubbles would be really disappointed
The cart boy would easily find a solution to that weak level of protection. Couple of furniture dollies under a cart instantly restores the rollability and then he could disassemble the wheels back at the shed
for the small price of a hex head wrench, you too can be the owner of a proud new Walmart shopping cart…. I wonder if walmart sells replacement wheels.
Steal another for spare parts
If places where I am in the UK don’t have this, they have a coin return on them.
(at least in poland) people usually just leave their coins in the carts, I’ve never had to put my own coin in there
Just more proof of how stingy we are here in England. But if I worked at a supermarket and people did this, I’d just put away the carts and pocket the cash everyday.
25¢ for a shopping cart is a pretty good deal if you think about it
And if they are like the US Aldi locations, the coin is in the cart. So you even get to take the money with you.
they can’t even charge you with theft because you still technically paid for it
If they don’t, they’ll be fishing them out of the canal.
Still see them in back streets all the time
It depends on the exact location of the store… pretty common in urban areas. Makes sense as carts cost hundreds of dollars and people will just walk off with them and ditch them once they get home, or of course homeless people often take them and use them for a while. First time I saw this was in Uptown Minneapolis about 20 years ago. Seen them all over since then. I found a brand new Safeway cart in the alley behind my house and was ‘great!’. I wheeled it into my yard and then wondered wtf I was planning to do with it exactly. Apparently, if you call them they have someone who goes around picking up carts, so I let them know and someone from the store came and got it.
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these are pretty common at supercenters in Chicagoland
I’ve only ever seen these in malls so you don’t take the carts to other places in the mall. Do they really use these for carts going out to the parking lot too? How’re you supposed to get your groceries out of the store?
My local Kroger has these, the perimeter extends all around the parking lot.
That makes more sense. Prevents them from (easily) leaving the property
I’ve only seen these in action by accident. Happened to me when I tried to go around a planter to reach the eating area at a Whole Foods. Apparently that was beyond the perimeter and I got stuck.
I saw one just last week lock up right at the door of Safeway when a lady was trying to go out to her car (it’s not supposed to block you from exiting the store). She was stuck in the door, cart half outside.
But people who actually do want to take the carts away know exactly how to avoid the mechanism.
We’ve had these in the UK for a long time, mainly to stop people carting shopping home using the trolley and then abandoning it.
There is a walmart locally that has these or used to have them. Theirs were easy enough to disable.
Do you know how it works? Doesn’t seem to be electronic or so… Perhaps mechanical magnet based or so
There’s a talk at DEFCON on YouTube about hacking them. Great way to see how it works.
https://www.youtube.com/watch?v=-QKcprQD0zc
It’s a fancier version of the electric dog collars. If you go over a perimeter line it’ll turn on a parking brake for that one wheel.
Probably an electrical fence type deal. When the signal gets too weak the pins pop out to prevent the wheel from rotating. Didn’t park near the edge of the property to test it lol
But what powers the wheels? Charged by spinning? What happens if they don’t get used long and the wheel dies.
By spinning yes, they operate mostly passively and therefore last a long time, including by having terrible security to save battery life.
If you live in a dystopian place where this exists, fuck is wrong with you?! RUN, and don’t look back.
