Wheel axle is one of the most classic and reliable simple machines, which achieves torque amplification or speed amplification through the combination of "large wheel+small shaft". It is widely used in teaching demonstrations, scientific research experiments, quality inspection, and industrial transmission scenarios. Laser scale and color division on the wheel surface for easy video recording of motion trajectories. Typical application: Mechanical benefit determination: hanging different weights to verify F ₁ · R=F ₂ · r. Energy conservation demonstration: measuring wheel flange line velocity and shaft falling velocity. Efficiency testing: Input/output power comparison, calculate efficiency η. Industrial scenarios: drum hoist, manual winch, pulley core components.