The use of a wobbly, spring support to destabilise the apparatus is highly original. I can remember an innocent playground ride from childhood constructed in similar fashion but the object then was to stay on despite the wobbling (a mild version of modern 'bucking bull' machines).
The sadistic operatives on hand to shake things up will also stir playground memories for some. They seem to be trying to foil an attempt by the prisoner to lift himself clear of the apex by bracing his heels on the slope.
The detail is rather too explicit and gruesome for my taste, I'm glad it's not in colour.
Don't try this at home!
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