Design and Analysis of the Transmission System for a Semi-Automatic NPK Fertilizer Spreader Machine for Oil Palm Plantations

Abstract

The distribution of NPK (Nitrogen, Phosphorus, Potassium) fertilizer in oil palm plantations is still largely carried out manually, which often leads to dosage inaccuracy, fertilizer waste, and higher labor requirements. One effort to overcome this problem is to develop a semi-automatic fertilizer spreader machine equipped with a reliable power transmission system. This study aims to design and analyze the transmission system of a semi-automatic NPK fertilizer spreader machine so that it can operate efficiently, stably, and safely. The research method included a literature review, theoretical transmission design, and component analysis using mechanical calculation and static simulation. The transmission system is driven by a 3 HP single-phase AC electric motor rotating at 1,000 rpm, combined with a pulley and V-belt mechanism. The driver pulley has a diameter of 150 mm and the driven pulley has a diameter of 100 mm, producing a transmission ratio of 0.67. Static simulation was carried out to evaluate the von Mises stress, displacement, and factor of safety (FOS) of the pulley components made of AISI 1020 low carbon steel to ensure structural reliability under actual operating conditions. The design results show that the driver pulley rotating at 1,000 rpm drives the driven pulley at 1,500 rpm, with a V-belt linear speed of 7.85 m/s, a belt length of 1,234 mm, and a shaft center distance of 655.77 mm. The simulation results show maximum von Mises stresses of 6.329 MPa on the driver pulley and 5.814 MPa on the driven pulley, with minimum FOS values of 48 and 60, respectively, both of which are far above the minimum safety limit. This study confirms that proper selection of pulley diameter and V-belt dimensions significantly affects transmission efficiency, which is estimated to be in the range of 90%-95%. Therefore, the results can serve as a useful reference for the development of an efficient and easy-to-maintain semi-automatic fertilizer spreader machine for small- to medium-scale oil palm plantations.