Orlando is prone to long trips down Memory Lane, or, more specifically, the biographer really likes to get into Orlando’s head. When the clock strikes, however, Orlando is reminded of his (or her) present moment and situation. The striking of the clock is described in rather brutal and violent terms. Orlando is "violently assaulted" and "struck" by the ringing of the clock, which is actually quite similar to being yanked out a great daydream. The chiming of the clock, moreover, also serves as a mechanism for Virginia Woolf to pull Orlando out of past memories and move the story forward.
Shmoop sobre a simbologia dos relógios em Orlando, de Virginia Wolf