The Evolution Marine Shaft System (EMSS) is an oil bath shaft designed for smooth, quiet, low-maintenance propeller shaft installation. EMSS's integrated thrust bearing transfers the propeller thrust directly to the hull, which improves efficiency and allows for a softer mounting for smooth, quiet operation.The EMSS is composed of a typical "22" alloy shaft that runs in an oil-filled shaft tube. At the front of the tube is the thrust bearing, which consists of two conical roller bearings in an oil-filled housing. At the aft end of the shaft a roller bearing and, where needed, intermediate bearing provide additional shaft support.
The shaft tube and thrust bearing housing are sealed with double lip seals at either end, as well as an intermediate seal, which maintains the oil level in the thrust bearing if the aft seal is compromised. All seals run on hardened seal races to provide a long service life.
A monitor tank and pump maintains the oil level in the system and provides circulation to the thrust bearing. For vessels that operate in warm water, an oil cooler can be added to the oil circuit.