Does "suck up huge amounts of power" for a seal imply "generate lots of heat"?

If so, is that heat another issue or is it a "don't care" because the heat is over a large enough surface?

It absolutely matters. Every Watt of energy that doesn't become torque at a rotational velocity is just heat.

Contact seals work by contact and friction, friction generates heat proportional to linear velocity and linear velocity goes up proportionally with radius.

The motors I designed were intended for food production washdown areas, and if I were designing large motors for use in road environments, I would use a lot of similar methods, including high quality contact seals.

Teflon seals would probably have the required capabilities, but they will get destroyed by dust and grit. Nitrile seals would do it too with the detraction of a huge power loss at the seal. I wouldn't trust a plain labyrinth seal to do the job.

> Every Watt of energy that doesn't become torque at a rotational velocity is just heat.

Do you have any rough numbers to put on this? If there was 1000w of electrical power going to a wheel like this, what kind of heat loss are we talking? 5%, 10%, 30%?

Depends on the seal manufacturer. Those numbers are usually provided through their engineering data system. Their data will be fit to a particular tolerance for seal race surface finish, which will be influenced by the reality of manufacturing.

Right, but are we talking closer to 5% or 50%?

Allow me to embrace my engineer nature and hedge my bets. A contact seal of that size is usually specced for a power transmitting shaft. An (assumed) 20" shaft is going to transmit a huge amount of power. So much that the seal losses will be negligible. Those same losses would exist on any shaft/seal combo of that size, but would take a greater fraction of total motor power, given the size and power constraints given by an internal motor design.

"People scare better when they're dying." is one of the best movie lines.

> If guns were better regulated

We can't stop drug importation. What makes you think that we can stop guns?

> and we had less of them we would have a safer less violent society.

"less of them"? We can take away all of the deer rifles and not change US violence at all. A collector with 100 guns is not more dangerous than one with 25.

The vast majority of US gun violence is committed by people who are already involved in other illegal activities involving other illegal substances. It is absurd to think that they can be disarmed by legal means.

It takes about 1% of the "by physical volume" drug smuggling to provide them with a new gun per crime.

If anything guns are harder to ban than drugs (because they're easier to make and smuggle), and that was true before 3d printing became a thing.

> We can't stop drug importation. What makes you think that we can stop guns?

Hello, I'm British.

Better solutions don't have to be perfect, as the country of my birth demonstrates: still has drugs smuggled in, sometimes even has firearms, even a few mass shootings.

But firearms are banned so effectively that even the police don't routinely carry them — the handful of officers I've ever seen armed in the UK, in person, were all in airports.

The four nations of the UK combined had around 700 homicides in total in each recent year, which is about the same as Philidelphia plus half of Baltimore. It's not just because the US is more populous, the per-capita homicide rate in the UK is about 80% lower in the UK than in the US.

I know the UK is unusual — I'm in Berlin now, and the cops here have what looks like a pistol, not that I'd be able to distinguish it in the holster from a taser or a pistol shaped pepper spray — but there's a whole world of other ways to do things than what each of us takes for granted, and we can learn from each other if we don't shut out the possibility.

Once I ran the numbers, and the part of the UK that had American Armalite rifles being smuggled in to fuel an armed conflict, Northern Ireland, which also had armed troops on the streets with rules of engagement that allowed them to open fire on civilians, resulting in dead women and children, was still less deadly than Detroit during the 80s.

This looks like something that patricia trees would be good for.

Then again, Eytzinger looks like binary heaps.

One thing that most people get wrong is that Uber doesn't offer taxi services.

In the US at least, there are two classifications for "car for hire."

One is street-hail - you wave down a car or get into one at a stand. That was heavily regulated and taxi companies had the relevant licenses.

The other is "town car". You call for a town-car and it shows up. town-car was very lightly regulated.

Yes, every taxi company offered town-car services, but there were lots of town car companies that didn't do street-hail.

Uber/lyft are town-car companies. Neither one does street-hail.

The UK has a similar distinction. "Hackney carriages" (the classic "black cab") are allowed to pick-up passengers on the street, while private hire vehicles (often called "minicabs") can only be used by pre-booking. The former are more regulated than the latter. Ubers are minicabs.

(Black cabs don't have to be black, but usually are. As to why they're called "Hackney carriages" - the last person to know the reason probably died in 1863.)

It is indeed a hackneyed term.

We don't have to imagine - Flywheel was that company.

It got reasonable funding but couldn't get taxi companies to sign up.

Things got a bit better when it became clear that Uber was going to kill taxi companies but too little, too late.

No, it's not true.

It was used for "graphics" on character-only terminals.

Doug Lenat's AM (https://en.wikipedia.org/wiki/Automated_Mathematician) seems relevant.

That sounds like you're using "type" to mean "representation", albeit with a lot of detail.

I may be odd, but my programming problems are rarely due to the number of bananas or how bananas are represented, but whether I'm working with the correct bananas.