Step 3: drawbridge
A little more on how we built the drawbridge, there's a lack of pictures because we were designing, testing, redesigning as we went. The actual "bridge" was made from 6, 2x6"x8' and 2, 2x6"x8.5' and 2 crossbars cut to fit.
The chain is 32' , we didn't cut it because 1. it sounded cool hitting the wood and 2. we ran out of time. Its mounted to the bridge with eyebolts and shackles. The chain passes thru a pipe at the "upper" end where we taped a large carbiner for the winch hook, some bolts,washers and nuts keep the pipe on the chain and keeps the chain spread as its pulled up.
The "hinge" is constructed of eyebolts screwed into the bottom of the door and 2 eyebolts run through the posts, 2 pieces of 1/2' all thread with a connector and some nuts and washers connect it all... We weren't completely happy with this setup because we couldn't get the door to fall from an upright position and so had to leave it open at an angle.
The "bridge" is moved by a small atv type winch mounted up on 2 layers of scaffolding. 2, 4x4's were bolted together with the scaffold bars between them as a platform for the winch and battery. A piece of pvc pipe was added to guide the winch cable