Abstract This article examines the gear transmission of a two-stage gearbox as a tribological system whose performance is determined by friction conditions and the contact fatigue endurance of the tooth surfaces. The geometric parameters of the transmission were calculated and contact and bending stresses were analyzed using the APM WinMachine software package. It was shown that when using steel 45 with heat treatment—hardening with high tempering, the acting contact stresses reach the maximum permissible values, which leads to intensive wear and a short transmission life. To improve durability, it is proposed to replace the gear pinion and wheel material with 20CrNi structural alloy steel with a chemical-thermal carburization treatment, which reduces the relative level of contact stresses and increases contact endurance. An analysis of the influence of loading cycle parameters on the contact and bending stresses determining the nature of tooth wear is conducted. It is shown that for cemented gears, the calculated fatigue stresses do not depend on the cycle parameters, which indicates increased stability of the tribological characteristics of the transmission.