How do shopping carts’ wheels lock when they’re taken outside of the vicinity they’re in?


I always walk by this one grocery store and always see shopping carts lined up just before the end of the parking lot as it seems people really think the signs stating the wheels will lock is just to deter you from trying, but how does it work? My only guess would be magnetics but even then I still have no idea how that all works but I find it oddly interesting.


EDIT: Just to add on, I live in Ontario Canada. Not all businesses have this sort of thing but a lot of the bigger companies do. And yes, they are in fact real, I’ve tried to push one before, those things don’t move AT ALL once they’re across the line! Quite interesting.

In: Technology

Buried around the perimeter of the parking lot is a wire coil that puts out a magnetic field. When the wheels of a cart pass over the field, locks engage in one of the wheels. The ones at my local grocery store work very well. I know this from experience.

There’s a wire buried at the edge of the parking lot. There are locking mechanisms connected to the wheel that are released (by an electromagnetic system) when the cart passes the wire.

That’s the basic principle of [this Rocateq system]( and others.

There are other systems that have a cleat that presses down on one wheel, making the cart unable to push in a straight line. Same deal, though, there’s a wire loop that defines the area of the parking lot, and the system to stop the wheel(s) is activated after it passes outside that loop.

There’s a mechanism inside one of the wheels that stops it from turning, usually by sticking a pawl into teeth on the inside of the wheel.

It’s controlled by a very short-range radio. There’s an antenna loop around the parking lot that continuously transmits the lock command. Try to cross it and the wheel locks.

Then you can unlock it with a special key fob.

Same basic idea as in wireless dog collars.

In which country are you? In germany I would be pretty proud if the anti theft system were this advanced for shopping carts.

Next question;
Can you reverse this process by bringing the carts back? If not, how do they make them work again?

I’ve always just assumed that they don’t, given how many carts I see in random places from grocery stores who claim this to be the case, and also from using shopping carts for years and never seeing anything on them remotely capable of stopping a wheel on a caster.

I worked at a business with a lot of outdoor property when I was a kid, and we had a sign that said something like “smile you’re on camera” so people would know there were security cameras. There weren’t. It was just cheaper to make a sign than invest in cameras that people would probably ignore anyway. Customers (mostly kids) would ask me where the cameras were, and we would say they were hidden, and if you couldn’t see them, then they were doing their job. I don’t even think that made sense, 18 years later. Why would you hide a thing that is partly a visual deterrent to crime?

What magic land do you live in? I have never seen this. LOL. 👀

Sometimes you have a moving walkway in your trolley store. We have them in IKEA and our local big supermarket. Wheel the trolley onto the ramp, brakes engage. Reach end of ramp, brake is released. They seem to do it hundreds of times a day without complaint.

They have a wire embedded in the parking lot. It’s actually an mp3 sound on the wire. You can download it and play it back while in the store. Watch the store manager get frustrated trying to figure out how the carts are all randomly locking up.