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Space Gopher
Jul 31, 2006
BLITHERING IDIOT

Rorac posted:

Why the gently caress.



Seriously, that's all I can think about that.

It's the early 1900s, and you've got a problem: you need a lightweight, small, high-power engine for one of those newfangled "aeroplanes." Unfortunately, gas engines in those days tended to run pretty rough, and needed a big heavy flywheel - not what you'd want to cart around when power-to-weight was critical. Solution: make the engine block the flywheel. As a bonus, they could get to pretty impressive power levels for the day without worrying about cooling problems; spinning the block gets you very good air cooling.

Rotaries had an interesting effect on early fighter tactics, too: that huge gyroscope of a spinning engine block up front made turns... interesting. The Sopwith Camel is one of the most famous examples: the gyroscopic effects were so strong that turns in either direction required left rudder, and while it could make a right turn nearly instantly, left turns were so slow that some pilots just preferred to whip it around 270 degrees to the right if they had to turn in a hurry.

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Space Gopher
Jul 31, 2006
BLITHERING IDIOT

CaptBubba posted:

Anything with two engines was a bomber.

I have read about some pilots who would swap the propeller with a pusher propeller, easily available because many early aircraft used rear facing engines until they figured out how to shoot through a propeller. They would then have their mechanic start the engine in reverse (these were all simple two strokes). This would let them surprise the enemy with an extremely fast turn in exactly the opposite direction than they normally would expect.

I don't know the truth to those stories or how widespread it would have been.

Most of them weren't two-strokes. Everything about rotaries was wacky, including the valvetrains. One fairly popular design had a conventional exhaust valve on top driven by a pushrod, and an intake valve in the piston held shut by a spring and counterweight. On the exhaust and compression strokes, the counterweight assembly held the valve shut, and on the power stroke the pressure of the burning fuel mixture held it shut, but on the intake stroke the vacuum in the cylinder combined with the counterweight assembly to open the valve and let the air/fuel/oil mixture in from the crankcase.

Here's how the whole thing looked:


And, to get things back on track for this thread - it wasn't terribly uncommon for that valve to stick open. I don't believe that there are any pictures out there, but that's the sort of scenario that makes "rod just hangin' out the side of the block" look positively sedate in comparison.

Space Gopher fucked around with this message at 07:56 on Nov 22, 2011

Space Gopher
Jul 31, 2006
BLITHERING IDIOT

EightBit posted:

But he had to remove the belt to do the alternator

But you don't need to take all the other belts off and take it completely off. If the belt doesn't need to be replaced (or you're lazy), you can just leave the alternator belt flopping around on the pulley, then pull it back on when you're done.

Space Gopher
Jul 31, 2006
BLITHERING IDIOT

InitialDave posted:

If I buy a TVR and stick it into a hedge, it's not the fault of the car or the manufacturer if I decided to get cocky with 400bhp per ton. It's my fault for going outside the envelope of my abilities, and that is something which should have consequences.

And if you're carrying a passenger, or there's a minivan in the oncoming lane that you drift into, or there's a pedestrian on the sidewalk between you and the hedge - well, they deserve to take part in the consequences of your bad driving too.

Space Gopher
Jul 31, 2006
BLITHERING IDIOT

EightBit posted:

Having a chain on both sides of the cam actually does a lot to help keep the cam in-sync with the crankshaft at higher rpm's or high valve spring pressures.

Performance at high RPMs or with tough valve springs was never a priority for that engine, and it doesn't have a chain on both ends of each camshaft. The design was based on an OHV engine, so there's a short timing chain that runs from the crank to where an OHV camshaft would be in the middle of the V. Then, on each end of the shaft-with-no-cams, there's a gear and a separate timing chain that runs up to the heads. One bank's chain is at the front of the engine, and the other bank's chain is at the back.

Oh, and all the tensioners and chain guides are made of crappy plastic, too.

e: have a picture!

Space Gopher fucked around with this message at 18:22 on Aug 2, 2012

Space Gopher
Jul 31, 2006
BLITHERING IDIOT

Throatwarbler posted:

What is the balance shaft for and why is it only on the 4x4 version?

Balance shafts are eccentric weights that cancel out some of the vibration in an engine; they're fairly common on 4 and 6-cylinder motors. I don't know why it's only on the 4x4 version, though; maybe that drivetrain is more sensitive to vibrations?

As far as unconventional valvetrain setups go, I'm a big fan of the Toyota slave cam system. It was more a legendary mechanical success than anything, given that it was part of the ubiquitous and nigh-unkillable 4A-FE, but you can't deny that cams spinning in opposite directions is pleasantly funky:



(also for the love of god don't ever search for anything that includes "slave cam" without safesearch)

Space Gopher
Jul 31, 2006
BLITHERING IDIOT

some texas redneck posted:

Supposedly it was a RWD car towed with the rear wheels on the ground with the car in park.

Somebody give that park pawl a loving medal, goddamn.

Space Gopher
Jul 31, 2006
BLITHERING IDIOT

Melting Eggs posted:

What were they thinking?



"If most of them make it through the warranty period, we'll come out ahead!"

Space Gopher
Jul 31, 2006
BLITHERING IDIOT

thelightguy posted:

To be fair, I live with a clean vehicle policy lobbyist, and cats do nothing significant for emissions either, especially when compared with the emission reductions from enforcing higher efficiency standards

That depends a lot on what emissions you're concerned about. Cats do nothing for CO2 emissions, which are the focus of a lot of regulatory concern these days - the only way to put out less carbon dioxide is to burn less gas. But, cats are still significant for pollutants like unburned or partially burned hydrocarbons and oxides of nitrogen (which are especially important if you're talking about CO2 reductions, because lean-burn engines are efficient but tend to put out a lot of NOx). Clean-vehicle advocates don't tend to pay a lot of attention to those emissions, because they've effectively won the battle. The latest EPA Tier III standards have the maximum for a lot of the traditional acid rain and smog-causing villains at zero, or very close to it.

If manufacturers can meet those emissions standards without a catalytic converter, they're free to do it. The EPA just cares about tailpipe emissions when they're certifying an engine; you just can't take it off because it'd be modifying an engine's emission controls so it's no longer certified. But, despite the fact that cats aren't required, every manufacturer includes a cat full of incredibly expensive precious metals.

Space Gopher
Jul 31, 2006
BLITHERING IDIOT

A student posted:

What exactly is broken with the tractor part?

Those splines are supposed to be straight.

Space Gopher
Jul 31, 2006
BLITHERING IDIOT

kastein posted:

Sir, we're going to need you to return your ez-snaps to the nearest retailer for warranty service, they are clearly not functioning as designed.

It's like the 100 mpg carb legend, but with photographic evidence.

Space Gopher
Jul 31, 2006
BLITHERING IDIOT

kastein posted:

Jesus

I'm not usually one for a seizure/impoundment solution to a problem, but is there any sort of a law in your state where you can declare a vehicle unfit for the road and only allow it to leave on a tow truck or after repairs?

This might sound like a good idea at first, but just imagine how places like Midas would use it.

"I'm sorry, with only six millimeters of material left, your brake pads are clearly unsafe to drive on according to our corporate safety standards for non-warranty work. I'm sorry, but you can't leave the shop until the work is done. We take cash, check, debit, Visa, and Mastercard. I'malsolegallyrequiredtotellyouthatyoucangetatow."

Space Gopher
Jul 31, 2006
BLITHERING IDIOT

Slavvy posted:

IV8 can you please explain to me exactly what truck ramps are meant to do? How does crashing the truck into a big mound of whatever help anything?

We don't have them here (or really, really big trucks for that matter) so I don't really get the circumstances that they're supposed to be useful in. Are they just dotted around everywhere because brake failures on trucks are really common? Or are they put in certain places because brakes fail more often there? Or something...?

American roads are weird.

They're put on the downgrade side of long, steep hills, because brakes are more likely to fail when they're overworked, and because that's obviously one of the most dangerous places for a brake failure (on a long straight road, you can just coast to a stop). The idea isn't that they're there "a big mound of whatever" to crash the truck into, either. It's more like a giant gravel pit built on a level or slightly uphill slope, that the truck can get bogged down in gradually. Just crashing a heavily loaded truck likely moving at 60-90 mph into something would not be a good result for the driver.

Also, they're not just an American thing. Physics means that anybody in a place with steep downgrades and heavy vehicles is going to come up with pretty much the same design.

Space Gopher
Jul 31, 2006
BLITHERING IDIOT

Mooseykins posted:

I think Naptha is the main ingredient in brake cleaner. I think..

Tetrachloroethylene (also used as a dry-cleaning solvent) is the main ingredient in most chlorinated brake cleaner. Don't get it hot, because it'll decompose into WWI-era chemical warfare agents. The non-chlorinated stuff is usually a mix of fun and only mildly neurotoxic solvents like acetone and toluene. Any can of brake cleaner you grab off the shelf is likely to be quite a bit more aggressive than naptha.

Space Gopher
Jul 31, 2006
BLITHERING IDIOT

spog posted:

At what point is it cheaper for the manufacturer to simply scrap the car, rather than pay for it to be stripped down and rebuilt?

Pretty much never. The heater core is a cheap part, and it'll take an awful lot of labor to add up to even a cheap car's total value.

Plus, even if you ran into some edge case where it cost more to repair the car than to replace it, the manufacturer would still probably opt for the repair. It's better than the bad PR of "a problem so bad they scrapped the car." If you're familiar with the aviation industry, Qantas has done similar wacky things (~$100M worth of repairs on an aircraft worth much less) to keep their "never lost a jet" record intact.

Space Gopher
Jul 31, 2006
BLITHERING IDIOT

thylacine posted:

Well, it has some safety features, unlike the first one posted. Looks like it makes a big mess though.

What is wrong with hydraulics? Couldn't you use a little engine like that to pump some hydraulic fluid through broken down excavator parts bought at the junk yard? Too complicated than welding an axe head to a big wheel?

Hydraulics need to be designed with at least a basic understanding of the principles at work - otherwise you'll end up with either a uselessly weak tool, or one that blows itself the gently caress up from overpressure. With purely mechanical stuff, it's a lot easier to build on the "just weld poo poo to it until it kinda does what I want" principle.

Space Gopher
Jul 31, 2006
BLITHERING IDIOT

Splizwarf posted:

Wait wait wait. What about the fuel?

I was curious about this too. Apparently it used cylinder pressure to drive a piston, so it drew air from inside the engine compartment rather than making a tire-bomb. Without the spark plug, of course, you'd still be shooting unburned gas out the exhaust, but in the days before cats that wasn't such a big deal unless you'd gotten the exhaust manifold really hot.

Space Gopher
Jul 31, 2006
BLITHERING IDIOT

Shifty Pony posted:

All so they could use the same head castings on both cylinder banks.

That's not quite fair. They also wanted to parts bin their OHC engine's block design from a cam-in-block engine. That's why it has the third, short timing chain that runs up to the "jackshaft" in the valley, right where you'd expect to see a camshaft if it was OHV.

Space Gopher
Jul 31, 2006
BLITHERING IDIOT

Raluek posted:

If you want more power at less RPM, you'll want to use a VFD.

Screw that. And what's with this fancy variac nonsense, anyway? Those things cost money!

A lamp dimmer is practically free at goodwill, and there's a pretty good chance it won't catch fire or rattle the chain into high-velocity pieces with crazy harmonics.

Space Gopher
Jul 31, 2006
BLITHERING IDIOT

IOwnCalculus posted:

Unless I'm way off here, that shouldn't change the fact that no matter how hard you try, you can't generate more than 1 atmosphere of pressure difference by just pulling a vacuum.

14.7 psi across that size filter is a lot of force, though. It's about 6"x10". 6 in. * 10 in. * 14.7 pounds/in.^2 = roughly 882 pounds of force on a flimsy little paper and rubber filter. Pneumatics can be a hell of a thing.

Of course, a straight atmospheric-to-vacuum pressure drop isn't likely to happen - but even 1 measly psi of difference is still 60 pounds. It's evenly distributed across the face of the filter, but it's still enough that if there's some tiny weak point where an assembler didn't put on just the right amount of glue, it'll find it and eventually do unpleasant things.

Space Gopher
Jul 31, 2006
BLITHERING IDIOT

InitialDave posted:

Ugh, one of the problems with filling out quality reports and the like with my job is that "human error" is not an acceptable reason for anything. Has to be a failure in a system or procedure etc.

System failure: Instructions and warning notices were not easily noticeable by operator, resulting in a presumably accidental deviation from specified procedure

Suggested remediation: Redesign manuals with bright, colorful pictures, and ensure that all text is printed in minimum 36-point bold font and readable at a first-grade level. Leverage technology used in electronic greeting cards to ensure that operators are aware of relevant warnings at all times

Space Gopher
Jul 31, 2006
BLITHERING IDIOT

um excuse me posted:

Most cars don't need hubcentric rings because of the conical lugs most cars have nowadays. Are there any production cars that still have flat seat lugs?

Uh, no.

With hub centric wheels and hubs, the hub itself is designed to support the road forces coming from the wheel; the lugs and lug nuts are just fasteners to keep the wheel from falling off the hub.

With lug centric wheels and hubs, the lug nuts are part of a bolted joint. As long as there's enough preload, you're fine - the lugs stay in tension and transmit shear forces to the hub. But, if a lug nut backs off or a lug stretches enough to lose correct preload, all of a sudden you're depending on a lug in shear to hold up your car and transmit road forces to your suspension - a job it was never designed or specced to do. And, there's the question of whether the whole system is set up to handle the necessary preload at all. Conical lug nuts don't do anything for you.

Using lug centric wheels on a hub centric hub without an adapter ring is a bit like using mild steel hardware in your suspension. Sure, it's cheaper than doing things right, and it'll probably work as long as nothing goes wrong - but the actual savings are tiny, and the risk is huge.

Space Gopher
Jul 31, 2006
BLITHERING IDIOT

IPCRESS posted:

How does that happen? It's a rotating magnet setting up an eddy current against a spring - unless we've discovered a new fundamental property of Chinesium?

Crappy tolerances causing intermittent physical contact between the magnet and drag cup would probably do it.

Space Gopher
Jul 31, 2006
BLITHERING IDIOT

Metal Geir Skogul posted:

According to Fuelio, my fuel cost for the crown vic over the past 10 months has been $0.117/mile in gas. I've driven just about exactly 10k miles, which is two oil changes at an additional cost of $40/5,000 miles, or .008/mile. Adding in ICE-specific replacement parts at .02/mile, that's $.145/mile total ICE-specific running costs (excluding tires/suspension/glass).

Electric, for me at between .09-.24c/kWh electric cost depending on time of day, would be 100% for convenience. Being able to avoid filling up by charging at home would be baller, because gently caress gas stations, but that's about it.

An electric car that's not some ancient lead-acid-powered milk-hauling monstrosity should be able to do a lot better than 1 mile per kWh. For instance, the Nissan Leaf does about 80 miles on 24 kWh; that puts it at 3.5 mi/kWh. A Tesla with a 90 kWh battery goes for roughly 300 miles; that's 3.3 miles per kWh. Even if you say that only 75% of the energy you pull from the grid makes it into usable battery charge, and you only charge at peak $0.24/kWh times, you'd still come out way ahead with electric.

Of course, that's just the per-mile running costs; it doesn't count buying the car, installing the charger, or any number of other things. But electric cars are really, really good at turning energy put into the car into energy at the wheels.

Space Gopher
Jul 31, 2006
BLITHERING IDIOT

iForge posted:

A previous job had the chuck key glued to the key for a mechanical interlock switch, so you had to put the chuck key back on its "holder" before the drill press would start.

How long did it take for somebody to get another chuck key and put it in the interlock so they didn't have to bother?

Space Gopher
Jul 31, 2006
BLITHERING IDIOT

MrOnBicycle posted:

Pretty lucky that it didn't get stuck in moving parts there, wasn't he? Do mechanics do tool counts like surgeons/surgical nurses do (and obsess about)?

You can accidentally stash a bunch of stuff in an engine bay. Most of the moving parts are fairly well shielded, and things tend to fall into little crevices in non-moving parts or splash shields or whatever. I've definitely found sockets an oil change or two after I've done some work, and once a used car came with a bonus Snap-On mini breaker bar.

Aerospace mechanics are obsessive about tool control. Outside of that, though - there's a reason this multipack of 10mm sockets exists.

Space Gopher
Jul 31, 2006
BLITHERING IDIOT

As Nero Danced posted:

He's also the one that sends Torx bit screws to punish us for our hubris.

The gods' true punishment for the careless and unwary is the unholy trinity of Philips, JIS, and Pozidriv.

Mistake not one for the other, lest your heads be stripped and you rend your garments in agony.

Space Gopher
Jul 31, 2006
BLITHERING IDIOT


Safety aside, an actual flat-top jackstand is worth every penny for unibody cars.

The real mechanical failure is holding up your car on a pinch weld with a design that exists to hold frame rails and solid axles.

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Space Gopher
Jul 31, 2006
BLITHERING IDIOT


A hockey puck has a flat base. That works great with a jack pad or a flat-topped jack stand. It's not a good idea with the standard cheap jack stand that has a U or V shaped top.

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