(To the younger crowd: Kadee used to make couplers that were mechanically actuated--trip pins, and all that. The #4 was one of those. Then they introduced magnetic actuation--MK-4, etc.)
Either because "everyone" abandoned using them. Or Kadee wanted "everyone" to go over to the magnetics.
It does seem odd that they did that, though. Sales is sales, it seems to me.
As far as the #1, etc.: A good question. Perhaps 1 through 3 were never released to the public. Or perhaps 4 superseded them.
Old magazines would probably answer some of the last question. To sell couplers, you had to advertise. In Model Railroader, in particular. And you had to "display your wares". So a tip-toe through old mags will reveal if #1-3 was ever released.
Ed
why did kadee stop making the earlier couplers?
i have a set of #4 couplers from when I was in high school. why did kadee stop making them?
and what were the first three Kadee couplers like?
greg - Philadelphia & Reading / Reading