Effect of Lubrication on Gear Efficiency: Experimental Investigation of Power Losses in a Spur Gear Pair

Abstract

The experiment determines the impact of lubrication on the efficiency of a spur gear type of transmission system under controlled operating conditions. Friction between meshing tooth surfaces, formation of lubricant films and heat generation during the transmission of power have a strong effect on gear efficiency. A spur gear pair in this study was subjected to constant speed and load conditions with varying conditions of lubrication which included an unlubricated reference condition, grease lubrication, low-viscosity oil, medium-viscosity oil and high-viscosity oil. The experimental data were processed using a deterministic algorithm of torque/speed calculation. Input power and output power were computed by the algorithm using the relation of power, P=2PIFNT/60, based on measured rotational speed and torque. The ratio of the output power to the input power was then used to calculate gear efficiency and the difference between the input and output power was used to calculate power loss. Comparative ranking algorithm was also used to find the best lubrication condition that has the highest efficiency and minimum power loss. The findings revealed that gear performance had a remarkable improvement due to lubrication. The gear pair with least lubrication gave the lowest efficiency of 87.9% with the greatest power loss of 75.9 W and the highest operating temperature of 58 C. The highest efficiency of 94.2 was the efficiency of the unlubricated gear pair, whereas the least amount of power loss of 75.9 W and the highest operating temperature of 58 C were the maximum power loss and the maximum The medium-viscosity oil produced the greatest performance with the highest efficiency of 97.7, the lowest power loss of 14.7 W and the lowest operating temperature of 27 C. The medium-viscosity oil enhanced the performance of the system by 9.8 percentage points and power loss of about 80.6 W compared with the unlubricated condition. These observations suggest that adequate lubrication minimizes the losses during friction, constrains heat production, and enhances efficiency in power transmission. The research concludes that medium-viscosity oil gives the best lubrication conditions in the spur gear system being tested since it gives an adequate film strength-viscous resistance balance of the lubricant. Keywords: lubricant film formation, spur gear, low-viscosity, heat generation.