Yanmar KM4A Marine Gearbox for 4JH5, 1.47:1 Reduction (KM4ASS-5)

The Yanmar KM4ASS-5 is a KM4A marine gearbox with a 1.47 reduction ratio for Yanmar 4JH5-series diesel engines. It connects the engine to the propeller shaft in inboard diesel installations on sailboats and auxiliary powerboats.

The low 1.47 ratio gives a faster-turning propeller shaft, for boats whose hull design and propeller selection call for it. This OEM Yanmar unit suits 4JH5-series engines specified for KM4A gear applications and, installed to the manufacturer's specifications, fits approved engine mounts, controls and shafting without modification.

It is used for transmission replacement, repowers with a compatible 4JH5 engine and new installations built around a defined drivetrain configuration.

Highlights

• Yanmar KM4A marine gearbox

• 1.47:1 reduction ratio for higher propeller shaft speed

• For Yanmar 4JH5-series diesel engines

• Part number KM4ASS-5

• Fits approved mounts, controls and shafting when installed to spec

Specifications

Good to know

• Installation, rigging and commissioning by a qualified marine technician are recommended; follow the manufacturer's pre-delivery and break-in procedures.