The top gear case contains the input shaft, 1st stage bevel gear unit and vertical shaft which are supported by roller bearings. The bottom gear case contains the2nd stage bevel gear unit and propeller shaft. The main thrust roller bearing is mounted on the front end of the propeller shaft to withstand the propeller thrust. The propeller is usually shrouded in a kort nozzle to raise the propeller thrust at bollard pull condition and low cruising speed during pushing or towing operation. 3or 4 pcs. of the oil seal are provided on the propeller shaft, and they are protected by the special seal guard to avoid any damage from foreign materials in sea
i.e. wire and rope -- . Vertical shafts on the top and pinion gear shaft in bottom
gear case are connected by gear tooth couplings.
These power transmission shafting lines seem like as a letter "Z", so we named this unit "Niigata Z- peller".
2-3. Steering System (Fig.-3 & 4)
The steering system is consists of the swivelling mechanism and hydraulic unit.The swivelling cylinder is mounted on the installation bed with large size swivelling bearing with a internal spur ring gear, and connected to the bottom gear case respectively as the swivelling mechanism. The oil seals are provided on the lower position of the swivelling cylinder to prevent water ingress and oil leakage.
The hydraulic oil motor is mounted on the installation bed and connected to the pinion gear shaft for swivelling at the full 360 degrees of propeller thrust. This steering system has a performance to quickly change the direction of propeller thrust. The hydraulic pump is usually driven by the main engine or electric motor. In case of the electric motor driven pump, whole hydraulic system is completly mounted on the installation bed, not any piping work is required by shipyard except from the cooling sea water piping to the lub. oil cooler of Z-peller.
