http://www.todsstuff.co.uk/crossbows/crossbows.htm
http://www.todsstuff.co.uk/in-stock/tods-in-stock.htm
Looking at medieval crossbows in general and specifically at a recreation of a German hunting crossbow by Tod, this exampe featuring in the BBC serries Wolf Hall. This example has a draw weight of 380lbs and is loaded using a goat's foot lever.