this post was submitted on 12 Jun 2024
842 points (98.2% liked)
Technology
59598 readers
3457 users here now
This is a most excellent place for technology news and articles.
Our Rules
- Follow the lemmy.world rules.
- Only tech related content.
- Be excellent to each another!
- Mod approved content bots can post up to 10 articles per day.
- Threads asking for personal tech support may be deleted.
- Politics threads may be removed.
- No memes allowed as posts, OK to post as comments.
- Only approved bots from the list below, to ask if your bot can be added please contact us.
- Check for duplicates before posting, duplicates may be removed
Approved Bots
founded 1 year ago
MODERATORS
you are viewing a single comment's thread
view the rest of the comments
view the rest of the comments
?
Every automatic transmission car sold since the 1970's and probably earlier has had a transmission cooler, right there alongside or in front of the radiator.
Also all of them have locking torque converters so there is no energy loss at constant speed. Also also, unless going upward at an incline. Most of the power requirements come from aerodynamic drag, not rolling friction of the trailer.
You can't lock the converter when accelerating because ~~that's not a constant speed~~ you'll stall the motor under the torque load, and to accelerate you need to overcome momentum. Neither drag nor rolling friction are anywhere close to high torque.
And I have no idea what the previous poster meant with a transmission cooler, I guess it's a different thing because a torque converter very much is not a transmission, if you want to compare it to anything then to a clutch. In any case I've got that explanation from an actual American actual car mechanic and random lemmings aren't going to change my mind especially while making no mechanical sense.
Wow. The remaining 7,950,999,999 people on this planet now have something to be thankful for, because none of them are as wrong as you.
You clearly did not actually understand what your mechanic told you.
A transmission cooler is exactly what it sounds like. It is built exactly like a radiator and works the same way. It is mounted in front of or next to the radiator for the engine. On a lot of newer cars it is actually part of the main radiator. Transmission fluid flows through it and excess heat is dumped into the air. On many vehicles it's also served by the radiator fan, i.e. for situations where the vehicle is not getting airflow because it's not moving.
The torque converter is part of your automatic transmission literally operates by moving the transmission fluid. There is no separation between the transmission fluid used in the torque converter and the rest of the transmission where the hydraulic valves use it to actuate the clutch bands, etc. to shift gears. The same bath of transmission fluid is circulated through the torque converter, the rest of the transmission, and the transmission cooler.
This is not a truck thing. Even my dinkum Saturn SL I had when I was a teenager that was so pathetic it was literally made of plastic and did not crack 100 horsepower had a transmission cooler -- as designed from the factory. The vast majority of passenger vehicles made in the last half century or more with automatic transmissions have transmission coolers built in. It has nothing to do with towing, either.
Your torque converter absolutely can be locked under acceleration and in fact, nearly all vehicles equipped with a locking torque converter do so as part of their normal shifting pattern when moving up through their gears. This is observable from the driver's seat if you know what's happening. The locking and unlocking of the torque converter feels like an "extra gear" in between the gears. Some Japanese cars from the 80's have a "TC Locked" light on a dash that illuminates when the converter is locked and you can watch this happen in real time. The usual pattern is 1st gear, shift to 2nd gear, lock converter, unlock converter and shift to 3rd, lock converter, unlock converter and shift to 4th, etc. A traditional automatic transmission only has 4 gear ratios, but it will feel like it has seven. Guess why.
Think about it real hard for a minute. A locked torque converter is the same, mechanically, as a fully engaged clutch. If you could not lock the torque converter during acceleration, by the same logic you would not be able to fully release the clutch pedal during acceleration on a manual transmission car, either. It is glaringly obvious that this is not the case.
I am not a "random lemming." I have four decades of actual real world mechanical experience and have disassembled and rebuilt more transmissions, engines, and vehicles in general than you have probably sat in throughout your entire life.
Drop the mic, bro. You earned it.
Which stalls the motor under high torque load.
Tell us you didn't read what I just wrote without telling us you didn't read it.
The engine will only stall under load if it is at so low of an RPM that it is generating insufficient torque to overcome the inertia. Which if you are moving and in the correct gear for your speed is never.
Which is why your transmission has more than one gear.
Remember back 30 seconds ago when I told you to think? Actually try it this time. Or maybe plug some of your bullshit into Google first before continuing to make a fool of yourself in front of everybody.
In stop and go traffic it's practically always. The car needs to be able to handle that, it can't be rated higher than that situation.
Which is why automatics have torque converters and manuals have clutches. It's almost like we've come full circle or something!
Millions and millions of vehicles are driving on the world's roads right now, happily tooling along under the sound mechanical and physical principles known as "reality," completely heedless of your apparent inability to understand it.
Yes and a manual can slip the clutch, it's built for that. A torque converter can't slip the lock, it's not build for that, it has to stay open. And that generates a fuckton of heat.
And? Come on, you're almost there. Just two more neurons to put together:
That's why the transmission cooler is there.
Wrap up: Your original claim that Americans "can't" tow due to predominantly driving automatic transmission cars, in addition to being an uncreative and tired thinly veiled attempt at insulting Americans, is not only wrong but also prima facie absurd.
And is the cooler in cars big enough to have noticeable towing capacity, or do you need a bigger one that only really fits a truck? How much additional radiator area do you need per additional ton of towing capacity (overcoming momentum, not tongue weight that can easily be zero just get a four-wheeled trailer)? For manuals, that's zero additional radiator area. For automatics, I'll leave the maths to you.
Yes, it is. Do you realize that manufacturers publish a maximum towing capacity as part of their specifications for every vehicle? This is publicly available information, right there on the internet. It's not a secret. The required surface area for the cooler is designed right in by the manufacturer for the transmission to work for the vehicle's application. This not a case of something "extra" being added. It's just how cars with automatic transmissions are built to begin with.
The published towing capacity for most vehicles that are available in both automatic and stick are exactly the same. Would you care to guess why that is? You could have figured it out for yourself if you would bother to actually do some extremely minimal internet research instead of continuing to shoot your mouth off on whatever this ill-informed little crusade of yours is.
Your initial claim is false. End of discussion. Just stop. You're making a fool of yourself.
And have you compared EU spec manuals vs. American model versions? When it comes to specs there's another big difference which I didn't mention: Tongue weight. Which isn't towing capacity and EU spec trailers have drastically lower tongue weight for their rated carrying capacity: Because we actually pull loads with light vehicles. As already said, put four wheels on a trailer and the tongue weight is practically zero. Our trailers also come with brakes.
What, so now you're trying to split hairs over the regulatory differences between the US and Europe to attempt to distract from the fact that you still haven't addressed making the following demonstrably false statements?
For the benefit of anyone else reading this, the difference in rated tow capacities between US spec and Euro spec vehicles is, as you have almost correctly observed, down to regulations and the trailer designs and not the tow vehicles themselves. There is no difference between the cars or their transmissions mechanically (nor the laws of physics -- anywhere on the planet, I guarantee it). European regulations have two critical differences between the US, to wit:
This is because it is dangerous to tow a low tongue weight trailer at high speed. America has no such speed or tongue weight restriction, and we also have interstates with 85 MPH speed limits. Thus our target tongue weight is roughly 15% of the total load, largely in order to keep the trailer under control at speed and prevent it from snaking all over the place and rolling itself and the vehicle. All other things being equal this ultimately winds up in the tongue weight being the limiting factor for most unibody vehicles. If your tongue weight is limited at e.g. 200 pounds, which it is for my bog standard Subaru Crosstrek, solving for the estimated tow capacity assuming 15% of it is 200 lbs would be roughly 1333 lbs. What's the US spec rated tow capacity of a Crosstrek? Oh wow, it's 1500 pounds. Imagine that. (For both the manual and automatic/CVT versions, by the way.)
FYI, we also have trailer brakes over here, and many states require them to be used on loads exceeding 3000 pounds. Below that, the trucks most people use have adequate mass and braking capacity to handle towing trailer loads in and of themselves. It turns out, the actual reason Americans tow with trucks is because Americans tow with trucks, and our towing regulations and trailers are designed around the expectation of towing with trucks. It's a just a cultural thing. No need to try to make it complicated nor make up fictitious bullshit about automatic transmissions.
But none of this has anything to do with your original assertions re: automatic vs. manual transmissions. I'm not arguing any other points with you.
As a matter of fact, I'm not arguing any more points with you at all. You have no idea how cars work. Go away.
I'm saying that to pull heavy loads they need active cooling. And they do. They also have cooling when not designed for heavy pulling, but they don't need as much cooling because all the mechanics you literally agree with me over: More cooling is needed under heavier loads. This isn't some far-out concept it's physics, it's what happens when you put oil in essentially a blender, it gets hot.
Then, and this seems to get ignored by you: Americans aren't pulling heavy loads with cars. Why? Do you have an alternative explanation?
1270 kg over here (with trailer brakes, 12% incline). That's nearly twice. Tongue weight: 80kg. That's less.
And that's a Japanese SUV. You can get VW Golfs with 1.8t towing capacity, that's a compact car. Also pure combustion ones, the Crosstrek is a hybrid it's easy to get low-end torque with one of those and transmission is a whole another topic.
That's why trailer brakes exist and don't pretend 140km/h are fast... though with a trailer you're generally limited to 80 or 100 here, depending on make and whatnot. Maybe you should introduce speed limits, regulations for brakes on trailers, etc. Maybe you would if your small cars could even tow that much, physically. You should also start to use the left lane for overtaking only and get rid of those ludicrous amounts of stop signs and build your cities so that people can move in them, not just cars, but I'm digressing.
1200 kg isn't a heavy load.
For a lorry, no. For a private vehicle, yes. Standard driving licenses only allow for up to 3.5t combined permissible weight (that is, vehicle and trailer plus maximum load), 750kg of those for trailer and load. If you want to drive a combination of vehicle and trailer individually up to 3.5t (so total 7t) you need a trailer license, anything above that you need a lorry license with all bells and whistles such as regular medical checkups.
Or, differently put: A standard VW Golf can pull almost thrice as much as most drivers are allowed to pull.
A small load for a private vehicle would be a small empty caravan, or a light trailer with some bikes. A Smart Fourtwo can pull 550kg which will definitely look silly but is otherwise perfectly reasonable, that's enough for both applications.
What a sad country.
Also, towing heavy, actually heavy, not 1200 kg, went away in cars about 1990. Emissions regulations, really. 1985 olds, Chrysler, could safely yank around a 4500 kilogram horse trailer. That all went away, now it's cars that could maybe 1000 lbs amd trucks that can pull 5 to 15000 kg loads. Btw, the old auto tow transmissions like the hydromatic 400, didn't have a lock up at all. Jaguar used to buy them.from Chevy for use in the old XJS v12s .
A torque converter is part of the whole transmission system even if it's a separate housing. When you buy a new transmission, it comes with a torque converter.
Torque converters also create the majority of heat in automatic transmissions and are why automatic transmissions get coolers in the first place. How many manuals have you seen with transmission coolers?
You're right, granted, it's probably just a bad name.
Then, though, are those cooling systems systems you find in small cars sufficient to cool the thing under sustained high torque loads? Like stop and go city traffic on flat terrain with 2.5t of fully-packed caravan behind it? How much space and weight does it take to beef them up to be able to deliver the same performance of a manual? Is it still sufficient to hook the thing up to the engine cooler, how much more radiator area do you need? Does that even fit a car? Is that why SUVs are designed to hide small kids in front of them? (ok I'll stop now).
Stop and go city traffic isn't all that sustained, because of the stop part.
None of my cars so far have had any issues towing ~2 tons, I'm not sure why 2.5 would be that much worse.
Of course, they've each had 400 newton-meters of torque out of their dinky little diesel engines.
Torque converters use transmission fluid to operate, that tranny fluid goes through a cooler.
No, you can accelerate and deccelerate. Only needs to unlock for gear changes.
Only in city would the torque converter spend an appreciable amount of time unlocked but then again, in the city you won't be moving fast either
Neutral to one is a gear change and connecting gear one firmly to the motor is going to stall it when you're accelerating from standstill. With a petrol engine just the torque needed to get going is going to stall it that's why you slip the clutch with a manual, a trailer will also stall diesels.
With a torque converter in between you'll also have to let it slip as it's serving the function of a clutch. Trying to slip the lock of the converter will kill it pretty much instantly, it's not build for that so you have to have it unlocked.
I was interpreting "constant speed" as "zero speed difference between motor and drive train" which was probably a bit of a brain fart. You need that slippage to not stall the motor.