Leonardo draws dozens of crossbows, but it is on folios 143, 153 and 155 of the Codex Atlanticus that we find the most interesting and innovative one.
This is a crossbow in which the loading system is speeded up compared to the traditional one. The crossbowman, by opening and closing the tiller could load the crossbow without ever touching the bowstring and without using external tools, thus speeding up the charging process considerably.