This thesis examines the multiplicator assembly, one of the core parts inside the transmission of the M-84 main battle tank of the Armed Forces of the Republic of Croatia. The primary aspect of this thesis encompasses the creation of an accurate multiplicator 3D model using the Solidworks modeling software, the 3D model in the context of this thesis provides a more accessible view of parts encompassed by the multiplicator assembly compared to the one available while the assembly is mounted inside the tank. After a general analysis of the assembly as a whole and the parts it powers, the paper comprehensively analyzes the functions the multiplicator and its parts serve in conjunction with the work they perform within the transmission. The transmission hydraulic control and lubrication system is showcased along with the parts of the system the multiplicator assembly is tasked with. Finally the key elements of the rapair process and workshop lubrication are outlined.