Thank you very much. I searched on the phrase "bridge pull" and didn't find any reference other than the local one, ever. The method of installing the bridge you found is identical to the one I watched this morning. Your bridge's write-up has the mechanical advantage that I didn't have here: that "two oxen can do the work of 180 oxen."
The blocks and tackle they used were the same as I remember from the US Frigate Constellation.
John / Billybob