# Screw backdriving and self-locking
# Scope: Square-thread geometric backdrive screen; no collar friction.
# Status: illustrative worked example; engineering review pending.
# Inputs are example values. Checks are editable example requirements, not standards.

lead = 4 mm
meanDiameter = 20 mm
friction = 0.15

leadAngle := atan(lead/(pi*meanDiameter)) [deg]
frictionAngle := atan(friction) [deg]

check self locking screen: leadAngle < frictionAngle

scenario alternative: lead = 3.2 mm