A torque is produced on the two-meter scale by hanging a weight on the right side of the fulcrum. This torque can be balanced by pulling downward with the dynamometer with different forces at various angles on either side of the plumb line.
The photographs above shows the torque lever with the protractor in place with its plumb bob and the counterweight on the right, and then show the system balancing the torque created by a weight at the right end of the lever by pulling downward on a spring scale at two angles measured by the protractor.
Note that this demonstration and demonstrations B2-21 and B2-32 use many of the same components.