Torsional vibration of a shafting system under electrical ...
Shafting process
-
Upload
saiful-habib -
Category
Documents
-
view
63 -
download
0
description
Transcript of Shafting process
-
Engine Room
Shafting and etc.
-
Shafting
-
Shafting The thrust bearing and the thrust shaft (with thrust collar) transmit the
thrust, generated by the propeller, to the hull. The thrust bearing may
be independent of the engine, but mostly is integrated in the engine.
The shaft bearings support the weight of the shafts.
The propeller shaft connects the shafting system inside the ship with the
propeller.
The stern tube guides the propeller shaft through the hull. In the stern The stern tube guides the propeller shaft through the hull. In the stern
tube, the shaft is supported by one or two oil-lubricated bearings: the
aft and forward bearing. These bearings carry the shaft and propeller
weight, and also the transverse hydrodynamic load acting on the
propeller.
The forward stern tube seal assures that the lubrication oil stays within
the stern tube.
The aft stern tube seal has two functions: to keep the lubrication oil in
and to keep sea water out.
-
Shafting
Documents for approval (BKI Rules)
General drawings of the entire shafting, from themain engine coupling flange to the propeller, anddetail drawings of the shafts, couplings andother component parts transmitting theother component parts transmitting thepropelling engine torque, and in addition detaildrawings and the arrangement of the stern tubeseals and the cast resin mount for stern tube andshafts bearings are to be submitted intriplicatefor approval.
-
Propeller shaft
In general shaft are made of forged (mild steel).Sometimes high tensile steel, or alloys such asstainless steel are used and may be of compositematerials. Most often shafts are solid, but theymay also be hollow for example when light shaftsare required in passenger vessels or naval vesselsmay also be hollow for example when light shaftsare required in passenger vessels or naval vesselsor when CPPs are sed.
-
Propeller shaft
Minimum diameter (BKI Rules)
k [-] factor for the type of shaft
- Intermediate
- Thrust
- Propeller
-
Shaft bearings
Shaft bearings support the shafts. In general sleevebearings are used. In sleeve bearings the shaft issupported in a lubricating film in a bearing that isusually lined with white metal. The oil is added tothe bearing through a ring that is mounted on thethe bearing through a ring that is mounted on theshaft, and distributed by the rotation of the shaft.The bearing capacity of these bearings lies in therange of 0.3 to 0.5 N/mm2 on the projectedbearing surface. The length-diameter ratio ofsleeve bearings lies in the range of 0.8 to 1.
-
Shaft bearing
-
Shaft bearing
Maximum distance between bearings (BKI)
-
Thrust bearing
The thrust bearing converts the mechanical
energy in the rotating shaft into translating
mechanical energy to propel the ship. The
thrust bearing has to transfer thrust to thethrust bearing has to transfer thrust to the
hull while sailing both forward and astern.
-
Stern Tube
In general, two types of stern tube can be distinguished:
- Stern tube with oil lubricated bearings
- Stern tube with water lubricated bearings
Water lubricated bearings are rarely applied in Water lubricated bearings are rarely applied inmerchant vessels. In naval vessels the stern tubebearings and the A-bracket bearing are sometimeswater lubricated. In that case, the shaft is fitted with abronze sleeve for protection against corrosion by thesea water. The bearings will consist of a bronzebearing bush on which the bearing material, rubber orsynthetic material, will be mounted.
-
Stern Tube
In case of oil lubricated stern tube bearings, the shaftdoes not need to be protected against corrosionbecause the stern tube is filled with oil from a tank.This tank is located 3 to 5 m above the waterline andensures a slight overpressure relative to the sea waterpressure. The bearing bush is often of cast iron and thepressure. The bearing bush is often of cast iron and theinner surface of the bush is centrifugally cast withwhite metal.
-
Stern Tube
Stern Tube Lenght (BKI Rules)
-
Flexible Coupling
To reduce vibration in a system to an acceptablelevel, flexible couplings need to be fitted.
In a geared drive, these couplings are fittedbetween the engine and gearbox to allow somemisalignment and to control the torquemisalignment and to control the torquevariations within the system.
An elastic coupling introduces a low stiffness, thusreducing the natural frequencies of the system.Also, they may have good damping quality thusreducing the amplitude of the torsionalvibrations.
-
Flexible Coupling
-
Flexible Coupling
Limit shear stress (BKI Rules)
-
Gearbox
Marine gearboxes consist of meshing teeth on
pinions and wheels, which transfer power
from a drive shaft (primary) to a driven shaft
(secondary) andreduce speed: [i = nengine/n(secondary) andreduce speed: [i = nengine/n
propeller]. Three configurations; parallel, locked
train and epicyclic.
-
Gearbox
-
Gearbox
-
Gearbox
Minimum diameter (BKI Rules)
-
Propulsor
-
Propulsor