A. B.
C. 
 A. Preparing to loose Vlachernai's Traction Trebuchet (Version 1.)
B. The pivot bar and sling in action.
C. The resultant spilt in the pivot support beam caused by inferior materials being used and the stress placed on the whole pivot support section by the sling beam coming into contact with main structural beam.

 A.B.
A. Sven standing in front of Vlachernai's Traction Trebuchet (Version 2.).
B. Sorting out the rope before loosing of the trebuchet.
Notice the addition height and strength of the pivot support section. The only material failure this time was in the support struts of the sling beam. Thanks to Russel Miners (Grey Co.) for the use of his sling (mine were too bulky) and to Kate Bugden for the photographs.
A fuller report of Vlachernai's Traction Trebuchet is available.