Is this what you're trying to understand? Even Google translate comes up with something weird, the rest (of the rules) sort of make sense.
中文問題
While I don't really read Chinese (I'm more into Japanese then Chinese), "吃子時沒有階級大小的限制" is the only one of the 6 points that I can't at least vaguely understand even with the help of dictionaries (my favourtie is 6 國王不允許自殺 ). Not sure why it's point 0 either...

Ok, my Chinese isn't that good but the way I read it is that there are no restrictions on capturing pieces depending on their value (in contrast to 斗兽棋 where a lesser piece in general can't capture a greater one).

Well yes, but it also can mean "when". Eg., "When I was little": 我小的时候. Literally "the time when I was little". (Or even more literally, the time of me being little.) Of course, in Chinese it is common to shorten things alot (I suspect it is the same in Japanese?) so in written language you can often remove things as 的 and shorten words (时候 to just 时). Hope this makes sense.

So, the phrase could be translated as: "There are no restrictions on the value/rank of the pieces when capturing."
A more literal translation would be something like: When capturing pieces there are no restrictions &c.
(Of course, my first language is neither Chinese nor English so...)

I'm chinese so I probably have the best chance of understand this out of those already commented:
"I have a question: going through a chess rulebook written in Chinese, I came across this: 'when capturing, there is no restriction on the classes of the pieces [capturing or being captured - this is implied, not written]'. Because my mother tongue is not Chinese, I can't understand this. Can anyone tell me what this means?"
I guess it means that it doesn't matter what pieces captures what piece - pawns can take queens if they want to.

I can confirm what VULPES_VULPES says, as a Chinese speaker myself. "There is no restriction of [size/rank] when capturing pieces." - e.g. pawns can capture queens and vice versa.
Probably was included in the rules because of things like animal chess or stratego restricting what can capture what.

I can confirm what VULPES_VULPES says, as a Chinese speaker myself. "There is no restriction of [size/rank] when capturing pieces." - e.g. pawns can capture queens and vice versa.
Probably was included in the rules because of things like animal chess or stratego restricting what can capture what.
+1
Google translate translates "吃子時沒有階級大小的限制" to "Eat no limit class sizes midnight". I figured that eat probably means take/capture, but couldn't understand what midnight has to do with it. I don't know if it's using unusual or humourous terminology (like 6 國王不允許自殺 - The king is not allowed to commit suicide), but in Japanese 取 (or more precisely 取る) is used to mean take (though, according to my dictionary it can also mean eat ). If in this context, 子 is referring to pieces, then everything makes much more sense:
When taking pieces there is no grade size limit
吃子時 沒有 階級 大小的 限制
I hope I have this right.

Adam, that's pretty much it. 取 does mean "take" in Chinese as well, but I have a feeling it's more like take in the sense of getting something, than capturing/removing something. (An interesting character is 娶, pronounced the same way as 取, which means to take a wife.)
By the way, "midnight" comes from Google translate breaking words incorrectly (whatever that means in Chinese ). 子时 is the time between 11pm to 1am.
If I've messed something up, hopefully a native speaker will correct me.
Edit: Perhaps one should say something about the part “阶级大小的限制“ as well and how to parse it, but that's for another day...
Adam, that's pretty much it. 取 does mean "take" in Chinese as well, but I have a feeling it's more like take in the sense of getting something, than capturing/removing something. (An interesting character is 娶, pronounced the same way as 取, which means to take a wife.)
I think it means the same in Japanese (in that it means to take as in obtaining, collecting, or fetching), but when I read Japanese blogs on here, I often see 取 being used to mean take as in capturing (I suppose, in a sense, that is obtaining, or winning (which it can also mean) a piece?), but of course, it depends on the suffix; there are many forms of the verb that can alter its meaning slightly.

The difference between 吃, 取, and other verbs is the context you usually use it in. 吃 (eat) is used in Chinese, and 取る (to take something) in Japanese simply because it's the norm. After all, in English we also say "capture", or sometimes "take pieces" rather than "eat pieces".
And chrka, you have it right. 取 in Chinese ususally means "acquire/retrieve", but is usually not applied to as many things as it is in Japanese. 子时 is indeed 11pm-1am, although it's not often used where I am.
In xiangqi the term for piece is 子, and some terms are:
吃子: capturing (a piece)
队子: exchanging (pieces)
得子/赚子: win a piece
弃子: sacrifice (a piece)

請問一下,我看中文寫的西洋棋規則表時看到這個: "吃子時沒有階級大小的限制" 因為我母語不是國語所以我看不懂,請問這什麼意思?
I interpret "階級" as "rank." Whoever wrote the sentence was probably trying to say that there are no rules against lower-ranked pieces taking higher-ranked pieces (pawn taking rook, rook taking knight, knight taking bishop, bishop taking queen, etc). My guess it that they thought it was necessary (or at least helpful) to make that clear because some Chinese chess variants have rules relating to the ranks of pieces, where this rank can only capture this rank, or this rank can't capture pieces of a higher rank, etc.

Ok, my Chinese isn't that good but the way I read it is that there are no restrictions on capturing pieces depending on their value (in contrast to 斗兽棋 where a lesser piece in general can't capture a greater one).
Exactly what you said. I didn't see your comment until after I posted mine.
The difference between 吃, 取, and other verbs is the context you usually use it in. 吃 (eat) is used in Chinese, and 取る (to take something) in Japanese simply because it's the norm. After all, in English we also say "capture", or sometimes "take pieces" rather than "eat pieces".
In Japanese, I believe 食べる is usually used to mean "eat". 吃 had me slightly confused because, as far as I can tell, it has no such meaning in Japanese (the dictionary I use says it means "stammer", and I believe it may also have something to do with mahjong), and I believe (correct me if I'm wrong) the vast majority of Japanese Kanji have the same or similar meaning to their Chinese Hanzi counterparts. But I guessed that despite that, there are bound to be some differences, and that "eat" in this context meant take/capture.
Another thing that complicates matters (for me), is that Kanji borrows the traditional form of some Hanzi, the simplified form of others, and in some cases, Kanji has its own simplified form (or at least alters the traditional form slightly), such as the character 脳 (compared with 脑, both simplified from 腦). This can be problematic when trying to read Hanzi based on knowledge of Kanji.
請問一下,我看中文寫的西洋棋規則表時看到這個: "吃子時沒有階級大小的限制" 因為我母語不是國語所以我看不懂,請問這什麼意思?