Gearbox having internal cooling pins

A drivetrain system includes a housing configured to at least partially contain a liquid lubricant such as oil that flows through a gearset. Within the housing is arranged a plurality of bearings configured to constrain respective trajectories of respective shafts. An inner surface of the housing includes a first region surrounding a motor gear bearing that is actively cooled by a coolant. The inner surface also includes a second region that is distal to the motor gear bearing and that is not actively cooled by the coolant. Cooling pins are arranged in the first region and are configured to provide heat transfer from the liquid lubricant to the coolant. The gear set can include more than one shaft, with at least one gear configured to splash oil onto the cooling pins to transfer heat from the liquid lubricant to a coolant flowing in a motor housing adjacent the first region.