The last time I played a strike machine it was a standard 25 cent slot machine that had (among the other symbols) a single bar that said "coin", double, and triple bar (all said coin).

In this machine's case, if three triple bars came up you would win the $40 strike, double bars were the $20 strike and single bars where the $10 strike. The strikes were dispensed immediately. In the case of mixed bars it was additional credits that could be cashed out like other slots. There were other winning combinations as well that also added credits.

I have seen other machines that just have the $10 strikes. Someone else will have to answer that one. I try to go by the "more lights and colors = worse EV" rule.