A water jet propulsion unit of the type herein referred to comprises a pump wheel or impeller, mounted on a drive shaft which is inserted through the inlet port. The drive shaft end or the impeller is journalled in the pump housing by means of plain bearings or roller bearings and preferably, as in the disclosed embodiment, by an assembly of roller bearings in cooperation.
The hub assembly of the invention is not limited to the use in water jet propulsion units of a specific kind, but may as well be utilized with units that include a flexible, though torsionally stiff connection between drive shaft and impeller as in units with splined couplings or fixed connections between drive shaft and impeller.
For water jet propulsion units of larger commercial ferries and other vessels, swiftness and simplicity of maintenance is an essential economical factor. Current, known designs do not permit dismounting of bearings or replacement of sealings unless the pump is first dismantled from the transom stern. This procedure is both time consuming and complicated since the weight of the propulsion unit increases substantially with increased size and power.