Shaft Line

Question 1

Describe Main & intermediate A-Brackets

Answer 1

• Suppport weight of shaft outside the hull
• Take no thrust
• Bearings are lubricated by sea water (hydrodynamic lubrication)
• a minimum of 50rpm must be adhered to for this lubrication to happen

Question 2

Describe Plummer blocks

Answer 2

• Supports the weight of the shaft inside the ship,without absorbing thrust

Question 3

Describe Plummer block lubrication

Answer 3

• Dynamic lubrication “Michell principle”
• As the shaft is rotated it picks up oil from the bearings,as it continues to rotate it collects more oil that creates a wedge that lifts the shaft into a central position.
• 50rpm must be kept to allow the wedge to form

Question 4

Describe Bulkhead glands

Answer 4

• Maintain watertight integrity as the shaft passes through compartments
• Absorbs no thrust
• Are flexible to allow movement in case of damage to shaft

Question 5

Describe Stern seal

Answer 5

• A mechanical seal
• Maintains watertightness as shaft passes through the hull
• A rotating face & a stationary face held together by a spring
• Also a inflatable seal made from neoprene in case of emergency

Question 6

What is a flange?

Answer 6

A flange is a protruded rim, that increases strength; for easy attachment with another object; or for stabilizing and guiding the movements of a machine or its parts

Question 7

Describe SKF Coupling

Answer 7

• A hydraulic coupling that allows the tail shaft to seperate from the intermediate shaft
• It consists of an inner and outer sleeve that slide over each other
• High pressure hydraulic oil is forced between the 2 sleeves then released to allow them to clamp together

Question 8

Propellers

Answer 8

• Creates the force that moves the ship
• Rotary motion from the shaft is converted into axial thrust
• Fixed blade, maximum efficiencey at maximum power, less efficient at low power or when going astern
• CPP controllable pitch propeller-pitch of blades is changed to provide ahead or astern,a hydraulic system is used to change blade angle

Question 9

Brake application checks

Answer 9

1. No fire risk
2. All brake pads are applied
3. Shaft is stationary

Question 10

Brake release checks

Answer 10

1. All pads clear
2. No fire risk
3. Shaft is running