In the tractor, the efficiency depends on the transmission system, of all the losses major contribution is given by the transmission elements. To improve the efficiency, it became crucial to monitor the areas of power losses. Power loss in transmission refers the reduction in amount of power which being generated from the engine source to the final drive elements. There are various parameters and factors influence this condition, analyzing those conditions helps in identifying & improving the higher contributing components for driveline power loss. This study presents a comparative analysis of theoretical and experimental data regarding power loss in the gear train of a 70HP 4WD front axle. The investigation incorporates theoretical power loss calculations for individual components, including the bevel gear, bearings, thrust washer and seal arrangements. To evaluate and validate the power losses in the 4WD axle, a Gear Train Endurance test was conducted in a controlled laboratory environment, with the results benchmarked against sub-models developed using KISS-soft software. ISO TR 14179 standard has followed to calculate the power loss in Bevel gear pair due to frictional & churning. "SKF model of frictional moment" has followed to calculate rolling friction, sliding friction, churning & drag of bearing rollers. Torque loss in MFS seal has experimentally taken from 20 no of trial data. Total power loss in axle is the cumulative of individual components losses for different loading conditions. In test bench, input & Output speed, Torque values are measured with maximum attained oil temperature for the respective load. Actual power loss in calculated by taking the difference between input and output power of axle. The findings reveal strong correlation between theoretical and experimental power loss across different load conditions. Additionally, critical parameters contributing to losses in gears and bearings were identified, with theoretical relationships established for further optimization.