The 'willing to be a screw' line comes from Lei Feng's (雷锋) diary and became a famous PRC slogan in the 1960s: small, interchangeable, but essential to the machine. Still used (often ironically now) to describe a humble cog in a big system.
Selfless service exemplified by soldier Lei Feng (1940-1962), whose diary popularized the 'I want to be a screw' metaphor for devoted labor under socialism.
