Learn Farsi: این مکانیزم ظریف با چرخدنده‌های کوچک کار می‌کند. - This delicate mechanism works with small gears.

Exactly. Because mechanisms are inanimate (non-living) objects, Farsi grammar dictates that the verb takes the 3rd-person singular form, even when the subject is plural. The sentence would still end with کار می‌کند just like it does here.

What is the literal breakdown of the word چرخدنده‌های?

It is a compound of چرخ (wheel) and دنده (tooth). A "toothed wheel" is a gear! To make it plural, we add ـ‌ها (hā), and finally, the ezāfe ی (ye) connects it to the adjective کوچک (small).

Why do we write ی at the end of چرخدنده‌های instead of just using the standard invisible ezāfe vowel?

Because the plural suffix ـ‌ها ends in a long vowel sound (a). When adding an ezāfe to a word ending in a vowel, we must add the consonant ی (ye) to bridge the gap, making it pronounced "-hā-ye".

Does the verb کار می‌کند literally mean "working" as in having a job?

Yes, the compound verb کار کردن means "to work." While some languages use a different verb for a machine "functioning," Farsi operates just like English. You can use it for people working a job or for systems and machines operating successfully.