Being the Dope I fully expect the first three responses to be anecdotally proving me wrong but…
It occurred to me recently that it seems that whenever I have a shopping cart that doesn’t work well, it pulls to the left.
I decided to test this. In the past three weeks I’ve been to three different grocery stores, Home Depot 6 times, once to Walmart and once to Target. The Target cart ran pretty true but every other cart I had pulled to the left.
Is there a reason for this or is it just a really big coincidence?
The only thing I can think of (apart from some common manufacturing defect or “feature”) is that the checkout is generally to the left side of the cart so maybe when people are emptying their cart they put some of their weight on the left edge and this has an effect.
But I’ll try to remember to check our local carts to see if they behave similarly.
Hypothesis: Most grocery stores are designed such that you naturally move counterclockwise around the store, so you naturally make many more left turns than right turns. Either the cart wears out because it’s turned left so much more often, or you just notice it “pulling to the left” more often because you’re usually moving in a leftward heading.
I think it may have to do with the way the carts are pushed back into the store by the cart gathering employees. I always see these guys shoving a really long batch of carts into the store. They have to skid the carts sideways to steer them since the rear wheels aren’t casters. This misaligns the rear wheels and causes the left pull.
OK, I pretty much made that up, but I’m pretty sure the sideways skid steering is why every cart at the local Walmarts seems to have flat spots on the rear wheels.
Before we can determine why most carts pull to the left, we need to determine IF they pull to the left.
What was your sample size? How did you select the carts? Was there any bias in your data collection? Have others verified your data? Have others obtained the same kind of data without knowing what your premise is? Have you overlooked any data (forgot to tally a cart or two, discarded it because it didn’t agree with your premise)?
I’m anxiously awaiting your PhD dissertation on this subject.
I would second the theory that grocery stores tend to be left to right biased. The produce and bread on the right side and milk and frozen stuff on the left. A shopper with a degree of organization would get the time-sensitive groceries (stuff you don’t want to thaw out during your shopping trip) last, so the cart would travel from left to right, performing left turns most of the time.
Seriously, I’ve noticed this myself, and I think it’s just because we tend to travel with them with akin to righthand traffic. That is, if we pass others in the isles, we’re more likely to pass on the righthand side and making tighter righthand turns. Thus, the wear patterns ought to be analogous to tire wear patterns. As left-side tires wear faster than right (though less so than than front relative to back front-whell drive which isn’t analogous here), I think it’s reasonable to conclude that typical usage would cause them to pull to the left and then compensating for that would just exacerbate it.
If my theory is correct, then we may find that Brittish shoppers would find their carts tend to pull to the right, unless they shop differently than they drive.
Having been one of the folks pushing a long line of carts back to the store, I’m with California_jobcase. Add to that folks dragging the “push end” to the right to allow someone by in an aisle, you get the back wheels bending to a left bias.
A slight hijack, if I may, because I was just about to post a similar thread.
Why do all the carts at my local Wal-Mart sound like industry?
Seriously. I’ll grab a cart, start pushing it, and BANGBANGBANGBANGBANG, like the sound coming from a Detroit stamping plant. Put that cart away, grab another, and BANGBANGBANGBANGBANG. Every single cart.
Meanwhile, at Wegmans, their carts roll as smoothly as a 1974 Cadillac Fleetwood Sixty Special Brougham on a freshly paved Interstate, even on their ceramic tile floors.
Quick check of local stores:
Safeway #1 - bread on left, milk on right
Safeway #2 - bread on right, milk middle-right
QFC #1 - bread and milk on left
QFC #2 (different city) - bread on right, milk on right
Fred Meyer #1 - bread in center, milk on right
Fred Meyer #2 - bread in center, milk on right
I doubt there is very much consistency in grocery store layout with respect to which side the bread and milk are on.
I worked at Safeway for 12 years, and repaired quite a few carts in my time (“baskarts” in supermarket lingo). In my experience the problem breaks down like this:
Baskarts pull to one side because of a failure in one or more of the moving parts.
The moving parts of a baskart are 2 fixed wheels in the rear, 2 swiveling wheels in front, and each wheel on an axle. That’s 10 total potential points of failure.
The main cause of failure is debris jamming the movement of one of these points.
Typically the items I found jamming up the moving parts of baskarts were pieces or strips of plastic bags, rubber bands, and small pieces of paper (like balled-up receipts or candy wrappers).
Debris at a supermarket is most commonly encountered in the parking lot and in the produce department, but can be anywhere in or around the store.
The produce department, and most all of the aisle shelves, are either recessed at the bottom or raised up off the floor an inch or two.
The produce department is practically impossible to keep clean because customers do things like shuck corn right at the display and throw the debris directly onto the floor. Also, it’s impossible to keep up with the constant dropping of errant onion skins, grapes, and loose greens onto the floor.
Additionally, baskarts are typically composed of wire, welded together or plastic, in either case they are very “open,” and any small items tend to fall out.
Debris tends to collect at the base of displays and shelves, or in the middle of the aisle/floor.
People tend to keep their baskarts to the right, so debris from middle of the aisle/floor tends to get jammed into the left-side wheels, causing them to pull to the left.
Obviously this will not be the case in all instances, but in my experience that is what is happening.
Also, the rough treatment by customers and employees alike as mentioned above will of course be a factor.
Unequal pushing force? The majority are right-handed, which IMO implies that the right arm is stronger, and one might be pushing harder with the right hand without noticing it, thus pushing the cart a little leftward.
I’m not sure how you shop, but I shop by going turning to the right when I enter then going up and down aisles. At the back of the store I make two left turns to get to the next aisle. At the front of the store, I make two right turns to get to the next aisle. That appears to me how most people navigate.