Yanmar KM4A Gear R 1.47 for 4JH5 – KM4ASS-5 is a marine transmission component designed for integration with Yanmar diesel propulsion systems that utilize an inboard gearbox configuration. It functions as the mechanical interface between the engine and the propeller shaft, transferring engine output efficiently in sailboats and auxiliary powerboats operating with inboard diesel installations. This unit forms part of an OEM Yanmar marine propulsion assembly and is intended for standard marine drivetrain layouts where precise alignment is required.
This gearbox is configured with a 1.47 reduction ratio and is specifically compatible with Yanmar 4JH5-series diesel engines specified for KM4A gear applications. The lower reduction ratio supports higher propeller shaft speeds, making it suitable for installations where vessel design and propeller selection require this configuration. When installed according to manufacturer specifications, it integrates with approved engine mounts, controls, and shafting systems without modification as an OEM Yanmar marine gearbox replacement.
This Yanmar marine gearbox is typically used for replacement of existing transmissions, repower projects involving compatible 4JH5 engines, or new marine installations requiring an OEM Yanmar marine propulsion transmission matched to a defined drivetrain configuration.
