Investigating Planetary Gearbox Stage Efficiency in Wind Turbine Applications: A Scaled-Down Prototype Study

Investigating Planetary Gearbox Stage Efficiency in Wind Turbine Applications: A Scaled-Down Prototype Study

Engineering

Tinashe Makuyana

2025

Planetary gearboxes play a critical role in wind turbine drivetrains, enabling the efficient conversion of low-speed, high-torque rotor motion into high-speed rotation for electrical generation. However, frictional and material losses within these gear systems can significantly reduce overall turbine performance, particularly under low-speed operating conditions. This study experimentally investigated the mechanical efficiency of a scaled-down, 3D-printed planetary gearbox designed to replicate typical wind turbine gear ratios. A custom test rig was developed, incorporating a 12 V DC motor driving the input shaft at 5 - 25 rpm, with torque and speed measured using a current sensor, load cell and two infrared proximity sensors. Results validated the theoretical 1:8 step-up gear ratio and showed that efficiency increased from 69% at 5 rpm to a peak of approximately 85% around 15 - 16 rpm before declining at higher speeds. These findings demonstrate that small-scale polymer planetary stages can replicate real gearbox behaviour and offer valuable insight into efficiency optimisation and material selection for larger-scale wind energy applications.

Engineering, planetary gearbox, mechanical efficiency, wind turbine, renewable energy, 3D printing, polymer gear, scaled prototype