What is the theoretical limit for the number of consecutive checks? The known record for the longest sequence of consecutive checks (i.e. white checks, then black checks on the next move, white checks next, and so on) in a legal position without promoted pieces, is 37. See this article on Tim Krabbe's site entitled &quot;Check!&quot;
Is there a theoretical limit for the length of such a sequence, or is a repetition possible, allowing checks forever?
Another way to get an infinite series of checks is by using a fairy piece. Consider this position, except that the black piece on e5 is not a knight but a camel (a (3,1)-leaper). Then the given sequence of four crosschecks restores the diagram position with White to move. (Unfortunately the PGN-viewer can't display it because of the fairy piece.)

[Title "Infinite series of checks"]
[fen "1k1b4/8/8/KN2n1r1/8/6B1/8/1R6 w - - 0 1"]
[StartFlipped "0"]

1. Nc7+ Cb6+ 2. Nb5+ Ce5+