This is a video from Gettyimages of the mechanism of big ben. I did not make this video, I just wanted to share it on youtube because it's really cool.
Interesting fact: On August 5, 1976 at 3:45 AM. The hollow tube that connected the fly fan mediating the speed of the chime train fractured. Because of this, When the chime was triggered, it had spooled up so fast that the quarter chime side blew itself apart, and the frame was broken in five places. Thankfully nobody was in the movement room when this happened. A clockmaker and his team of workmen assessed the damage, and had got it back up in running within a year in time for Her majesty, Queen Elizabeth II's visit to the Westminster hall in 1977.
It is basically the same mechanism as in any striking clock of the period (and up to today, if mechanical rather than electronic) - just bigger; the only part upi wouldn't find in any normal clock is the nest of grears (above the main mechanism, driven by the shaft the comes out at an odd angle) that splits the drive four ways as the clock has four faces.
Try this. It was uploaded a week or two ago and its the mechanism chiming again after the mechanism was restored. I have to say the difference will amaze you. The bells sound better after cleaning and the mechanism runs like silk. ru-vid.com/video/%D0%B2%D0%B8%D0%B4%D0%B5%D0%BE-CGSzApbCp4w.html
I agree, finding clear videos of the mechanism is difficult. The best _explanation_ IMO is in the Time Out one, ru-vid.com/video/%D0%B2%D0%B8%D0%B4%D0%B5%D0%BE-dMT-OOrLBik.html
I'm not sure why it's hitting it. I can tell you however that it rotates 4 times per hour bell strike and a peg on one end of that arm has its path blocked by a peg on a horizontal arm to eventually stop the striking This happens when the blocking arm's left section falls into a notch in a disc called the count wheel which turns very slowly. This is the brass coloured disc towards the left hand side. The camera unfortunately pans away just as this happens.
