A 4-bar linkage (pink rockers, violet cranks and yellow conrods) is used for converting oscillation into continuous rotation.
Washing tub is fixed to the base. Washing cage is fixed to the violet cranks.
For easy start do not stop the machine at dead positions of the 4-bar linkage (where the violet cranks and the yellow conrods are in line).
This mechanism may be used for the machine in video:
/watch?v=SUgF24GcDi0