Unusual Engineering Gadgets: Test Your Intuition and Share Your Pics!

I saw this on Facebook today, and thought it might be a fun general thread for Engineering to post pics of things that made you stop and think about what they were designed for. I had to click into the FB post to see if my intuition was right on this one. Thoughts on this one?

Do you have other interesting pics that can challenge our Engineering intuition and knowledge? Post answers in spoiler tags please.

I don't know anything about boats.

berkeman said:

I had to click into the FB post to see if my intuition was right on this one. Thoughts on this one?

It looks like the ROI for this energy-saving gadget is about 1 year, with a 5% energy savings in propulsion. Pretty cool -- I'd never seen this before.

Looks like a rope cutter in case of getting a rope wrapped around the prop.

berkeman said:

I saw this on Facebook today, and thought it might be a fun general thread for Engineering to post pics of things that made you stop and think about what they were designed for. I had to click into the FB post to see if my intuition was right on this one. Thoughts on this one?

Maybe trying to get a little more thrust from the water along the axis of the propeller.

IIRC, yachties etc have a superficially similar whatsit, but mounted in front of prop as weed / line / net cutter. Pictured is a hub vortex recovery device, akin to aircraft winglets that reclaim some of their tip-swirl. Valuable fuel economy accrues and, IIRC, significantly reduces the gap before another aircraft may safely fly through that disturbed air. I don't know if translates to reduced airport fees, but certainly reduces the 'flip' risk should a 'light' follows a 'heavy' towards same runway...

Vortex diffuser boss. I'm most familiar with them from fast attack subs, where's it's less about efficiency and more about reducing the noise from the vortex.

Makes sense for commercial shipping, though. Every little savings adds up.

Well I guessed incorrectly --- thought it was a cavitation suppressor to improve efficiency. Got it half right.

This isn't exactly from FB but I think it goes with the overall intention of the thread. Engineering curiosity.

While my time in the NC USA I didn't see any escalators for shopping carts so this might be somewhat new for some people from there. I guess it's because there is enough horizontal free space that building malls with multiple floors is not economically ideal. However, here in Spain, these escalators are everywhere.


Carts have a built in system in the wheels so that they don't roll downhill. I never really understood how these things worked because I always took it for granted until I checked it a couple of days ago. It's surprisingly simple and effecticve.

The wheels have some grooves that match grooves in the escalator so the wheel is flying while the cart is in the ramp. Only the fixed rubber bumper will contact the floor acting as a break.


I think it's a simple and clever solution. The best kind of solution in my opinion!

Juanda said:

While my time in the NC USA I didn't see any escalators for shopping carts so this might be somewhat new for some people from there.

The only one I remember seeing is in a Target store in Metairie, Louisiana. It was different than the one you show, the carts remained horizontal, and were in a separate track, next to the normal "human" escalator.

Here, I found a photo:

gmax137 said:

The only one I remember seeing is in a Target store in Metairie, Louisiana. It was different than the one you show, the carts remained horizontal, and were in a separate track, next to the normal "human" escalator.

Here, I found a photo:

View attachment 337827

Hey, I remember one of those in Sacramento, CA. No clue if it's still there or not, but it was certainly interesting.

Those escalators where the cart remains horizontal are new to me. I guess it can be convenient if you want to overcome a greater slope.
I'd say that must be the last step before giving up completely and installing an elevator.
In each case there's a tradeoff between available space and carrying capacity.

gmax137 said:

The only one I remember seeing is in a Target store in Metairie, Louisiana. It was different than the one you show, the carts remained horizontal, and were in a separate track, next to the normal "human" escalator.

Here, I found a photo:

View attachment 337827

There is a large Target store around here that has that cart escalator; and also an elevator. It's further than the local stores, but is occassionally worth the trip for their huge selection.

Juanda said:

In each case there's a tradeoff between available space and carrying capacity.

As for that trade-off, I expect that an elevator would cost much more than a cart escalator ... and have a lower capacity for both people and carts due to floor space.

Cheers,
Tom

I know this one isn't really a mystery, but it's the most ingenious name for a gadget (even if it is slang).

Jesus Nut.

The reason for the name is rather obvious.

sbrothy said:

Jesus Nut.

The reason for the name is rather obvious.

That's too funny. I grew up with another definition of "Jesus nut". When you are working on your car engine and drop a bolt or nut down into the bowels of the engine, and have no hope of finding or retrieving it, that's a "Jesus" nut because of what you say at that moment. Your only choice is to drive to the auto parts store to buy another one like it, but oh wait...

Incidentally I think most aircraft have 2 sparkplugs per cylinder. I think helicopters have at least 4. You don't want your sparkplug to fail in midair, or the next person you're gonna meet is Our Lord Saviour himself (well, if've you've behaved that is. Otherwise it's a whole other story). Going down anyone?

sbrothy said:

Incidentally I think most aircraft have 2 sparkplugs per cylinder. I think helicopters have at least 4. You don't want your sparkplug to fail in midair, or the next person you're gonna meet is Our Lord Saviour himself (well, if've you've behaved that is. Otherwise it's a whole other story). Going down anyone?

How many helicopters nowadays have piston type engines? Not disputing the need for redundancy concerning ignition systems on any engine.

If when you get there, you cannot find Jesus, just ask for an explanation from the red-faced man with the pitchfork.

Averagesupernova said:

How many helicopters nowadays have piston type engines? Not disputing the need for redundancy concerning ignition systems on any engine.

Apparent mostly smalller and training helicopters. Larger and more more modern helicopters use turboshaft engines.

sbrothy said:

Incidentally I think most aircraft have 2 sparkplugs per cylinder. I think helicopters have at least 4. You don't want your sparkplug to fail in midair, or the next person you're gonna meet is Our Lord Saviour himself (well, if've you've behaved that is. Otherwise it's a whole other story). Going down anyone?

True on the first point, false on the second. Dual plugs only, quad plugs just adds complexity.

Fun addendum: Each spark plug on a cylinder is fed by an independent source, usually a magneto. They're weird little units, and definitely a bit of an anachronism, but they're (usually) reliable as hell.

Averagesupernova said:

How many helicopters nowadays have piston type engines? Not disputing the need for redundancy concerning ignition systems on any engine.

The biggest name I can think of would be Robinson and the R22/R44. Not sure how many other major certificated models are still in production with pistons. Lots of homebuilt/kit helos with pistons, though.