The Probert Encyclopaedia of General Information

CRANK

The crank was a Victorian instrument of punishment introduced in prisons and consisting of a handle attached to a wooden box. The prisoner had to turn the
crank 10,000 revolutions each day, with so many revolutions required before each meal was supplied. Should a prisoner be too quick in completing the required revolutions, the warders could adjust the tension of the crank by means of a screw - from whence the expression 'screws' to describe prison warders - thereby making the labour on the crank more difficult.
Research Crank