This is just a design study, my first subassembly castle in 40+ years.  It is not intended as a finished work of “art”, it is more of a “proof of concept” exercise.

Gate entrance opening is 8 pin wide and 10 brick high.  The drawbridge is 8x32 pin and sea-saws with a moat on one side and a pit on the inside as per Caernarvon Castle.  Interior of the pit has steep sided slopes and intended to operate with water in the hope that invaders wearing armor may not be expert swimmers.

For a portcullis I used 8 bars PN 42445, hung together with one 10x2 plate and one 10x1 plate. It moves in a 1 pin slot but not very well, it is too light and it sticks, but I like how it looks.

Two Technic beams lift the drawbridge with chains; those beams are in turn lifted with dental floss by a roof mounted windlass.  Beams retreat into two vertical slots above the drawbridge.  In photos the center section between the slots is removed to display the inner workings.

It is more difficult than one may think to properly locate the axis location of the lift arms for proper operation.  In my case the arms are withdrawn entirely within the wall when lifted. 

I like the etching of the knight on the drawbridge and tried to recreate the same exterior aesthetic with the same two side slopes protecting the flanks of the drawbridge. 

The windlass that operates the drawbridge is slaved to the windlass that operates the portcullis by an axel with idle gears.  As the drawbridge is drawn up the portcullis drops and each reach the proper amount of travel at the proper time.

I didn’t give much thought to crenellations, machicolations or arrow loops at this stage.  The gatehouse towers on each side are missing. 

The grey bricks don’t match, and I don’t even know how to use my new camera but I hope you enjoy lookin’.