Abstract: A modular PTO assembly and an engine system comprising a modular PTO assembly are disclosed. The modular PTO assembly is configured to be mounted and secured to a crankcase of an engine, and includes a front cover positioned on a base plate so as to define a housing. The modular PTO assembly also comprises a power input sprocket mechanically coupled to a power output sprocket via a chain. The power input sprocket is coupled to a nose of a crankshaft and is configured to rotate at an approximately same speed as the crankshaft. The power output sprocket is configured to be coupled to a shaft of an auxiliary component and to rotate at an approximately same speed as the shaft, thereby transferring power from the engine to the auxiliary component.