“…In addition, the problem of calculating the optimal gear ratio has been performed for different types of gearboxes such as helical gear boxes [6][7][8], bevel gear boxes [9][10][11], worm gearboxes [12][13][14][15]. Besides, the optimal gear ratios have been determined for two-stage [7,8,14], three-stage [6,10,11], and four-stage gearbo xes [16,17]. Also, different objectives have also been selected when solving this problem such as the minimum mass of gears [16,18], minimum mass of gearbox [19], the minimum gearbox cross-section section [8,10,14], the minimum gearbox length [17,20], or minimum gearbox cost [9,21].…”