"Jedoch kam keine dieser Maschinen in die Produktion."

[elae]

Your "correct" English solution is incorrect-- it should be "none were", not "none was".

[Soglio]

"None was" is also correct. Indeed, some people feel "none," i.e. "no one"--can only be singular.

[elae]

http://data.grammarbook.com/blog/singular-vs-plural/none-were-vs-none-was/ According to this and other resources, "none" can be followed by both was and were, yes-- but it depends on what is being quantified. With your example, turning none into no(t) one: "Not one of these machines were produced" would still use were. "None of this ore was mined" would take was, because you can't count it.

[Soglio]

Yes, there are plenty of arguments about whether the plural is appropriate. Some of us were taught in school that it is never appropriate with "no one" or "everyone" or similar word; but many take a more liberal view. Ultimately, common usage decides what is acceptable, and I'm inclined to agree with you that the plural sometimes sounds more natural. I can think of no case, however, when a singular verb is actually wrong with such a word. In this case, the subject is "not one," so the singular verb is correct. (The positive statement would be "One of these machines was produced.)

[Denis44]

Should it not be keine diese, as Maschinen is plural?