A1. They don't hold up as well as Kadee's.
A2. You have more placement options with lead or steel weighting. Using axles specifically for weighting is pretty limiting. And seel axles are perfectly acceptable - as long as one side of the axle is insolated. Otherwise, you have a short.
A3. I would guess because most modelers started out with #5 couplers (before semi-scale couplers became available) and converting would not be cost-effective for them. I got into HO in 2004 and quickly adopted & embraced #58/#158 couplers as my standard. They work great for me and they look better, too. And, if somone prefers #5/#148s - that's their prerogative.
I don't base my modeling choices and preferences on "many" or "most modelers". I look at the options and see what works best - for me. A lot of times the tried-and-true is the best choice. However, sometimes...there are different ways to accomplish the same thing. And, sometimes...it turns out a little better.
Tom
https://tstage9.wixsite.com/nyc-modeling
Time...It marches on...without ever turning around to see if anyone is even keeping in step.
3. As others have mentioned, I don't find the scale-head couplers to be quite as reliable as the regular No.5 coupler. I tend to use them only where they'll be seen more than used, like on cabooses or the rear coupler of an observation car, or the front coupler of an engine. So like say an F-unit will have a scale coupler on the pilot but a regular No.5 on the rear to connect to cars or another engine.
F-1. KDs couple and uncouple more reliably than any other knuckle coupler I've tried. It's no more complicated than that.
F-2. I don't avoid steel axles so I have no answer for that. As long as the wheels are insulated on one side, that shouldn't be a problem. On steam locos that have tender pick-up, it can be a problem if one accidently reverses which side the insulated wheels are. I guess the same would be true of lighted passenger cars.
F-3. Two reasons. The smaller couplers are less forgiving and prone to unwanted uncoupling. The other reason is that the smaller couplers look too small to me even though I know they are closer to the correct size. Couplers on real railroad cars are very bulky and the smaller headed couplers just don't convey that look. I prefer the look of the oversized couplers. They look right even though I know they aren't. To my eye, this is a case where perception and reality diverge. When I see a train role by with standard head couplers, I don't think to myself, they look too big.
I'll play.
1. Simply, they don't work as well. They tend to either not couple as well, uncouple as well, the knuckle "spring" wears out over time, or some combination of the above.
2. Steel axles can be pulled by uncoupling magnets, which creates problems. Steel weights inside the car bodies are far enough away to not show the same effect.
3. I started converting to the standard head years ago and most of my fleet has them. I have 6 cars that came with the scale head couplers and I will be changing them to the standard size soon. My experience with the few that I have is that they are more finicky in terms of coupling and uncoupling. That could just be me though.
Mike
"One difference between pessimists and optimists is that while pessimists are more often right, optimists have far more fun."
OK I'll bite.
1 Most non KD are plastic with way too much flex and unreliable.
2 99.99 percent of my cars have metal wheels and steel axles. I prefer lead weight over steel.
3. I would need to replace hundreds of couplers to go with the scale size.
Your English writing is probably better than most American college grads nowadays.
Pete.
It's okay to see other people's answers, but copy-and-paste is not allowed.
F grade test (full score 100 points, pass 90 points or more)
Q. F-1: List the reasons why non-Kadee magnetic knuckle couplers are disliked.
Q. F-2: State why steel weights are accepted while steel axles are discouraged.
Q. F-3: Explain why many modelers prefer the standard head #148 over the scale head #158.
This is also a test of my English writing ability. :-)
E grade (full score 100 points, passing score 80 points or more)677
Q. E-1: Enumerate uncoupling techniques while the rolling stocks remains on the track.
Q. E-2: List reasons why coupler pockets historically changed from metal to plastic.
Q. E-3: Describe why the swinging coupler pockets are adopted for the Walthers long cars.
D grade (full score 100 points, passing score 70 points or more) 1215
Q. D-1: State why truck mount couplers (Talgo trucks) can cause problems are dangerous. (fixed by JaBear's advice)
Q. D-2: Explain why Kadee recommends #231 Greas-em as a coupler lubricant.
Q. D-3: Consider why some modelers install #118 SF shelf couplers on Walthers swinging pockets.
C grade (full score 100 points, passing score 60 points or more) 1585
Q. C-1: Explain the argument that coupling short shank couplers together may cause problems is dangerous. (fixed by JaBear's advice)
Q. C-2: State the points to keep in mind when using non-Kadee knuckle couplers.
Q. C-3: Guess why the narrow pocket #262 was made of polyacetal (POM).
B grade (full score 100 points, passing score 50 points or more) 2233
Q. B-1: Surmise why the Athearn stopped using the swinging coupler pockets on the Genesis long cars.
Q. B-2: Anticipate Kadee's intentions of releasing the #148 (#242) with different mounting dimensions than the #5 (#232).
Q. B-3: Explain why truck-mount couplers (Talgo Talco trucks) are frequently used in N scale.
A grade (full score 100 points, passing score 40 points or more) 3187
Q. A-1: Explain the phenomenon that the coupler head sometimes hangs down even if the mounting height of the pocket is correct.
Q. A-2: Explain the claim that the coupling of underset and overset shank couplers can cause trouble.
Q. A-3: Explain the points to keep in mind when installing Kadee couplers in non-Kadee pockets, with specific examples.
S grade (full score 100 points, passing score 30 points or more) 3472
Q. S-1: Think about the reason why #5 (including #6, 7, 8, 16) made the left and right coupler's reversion forces different.
Q. S-2: Guess why Athearn BB lowered it's center height by 0.040 in. while Horn-hook (developed in 1952-1954) and Kadee both have the height of 25/64 (0.391) in.
Q. S-3: Anticipate the phenomenon of concern for #804 for O scale, which has a structure in which the centering spring contracts when a pulling force is applied. (including #K4, #K15 in HO, also MTL #1025)