Oscillating cycle $φ$
<img src="https://eng-calculations.com/SVG/Mechanical_engineering/Sliding_PTFE-based_bearings/Oscillating cycle (and36)φ(and36).svg" alt="Oscillating_cycle_(and36)φ(and36)" title="Oscillating_cycle_(and36)φ(and36)">
https://eng-calculations.com/SVG/Mechanical_engineering/Sliding_PTFE-based_bearings/Oscillating cycle (and36)φ(and36).svg