Transmissions Flashcards
What are the functions of the gearbox
To transmit power from prime mover to shaft
Allow variations in speed and power
Allow changes between ahead and astern
What are the uses are gears
Change of SPEED
Change of DIRECTION
What are the main components of a gearbox
Plummer block
Bulkhead gland
Stern seal
Name the 4 different types of gears
Straight spur
Helical
Double helical
Worm wheel
What is a quill shaft
A thin solid shaft that can manage torque between the two joining gears
What are the advantages of a worm wheel gear
Large gear reductions are possible
Slow but high torque output
How can gear wheels change speed and direction
Change of direction- BY ADDING ANOTHER GEARWHEEL
Change of speed- BY ADDING DIFFERENT SIZED GEARWHEELS
What is a thrust block
A large bearing designed to absorb the force of the propeller so the ship moves ahead
What does the serkstat do
Controls oil temperature
What pressure should the oil not drop below
18.5PSI
What is a Plummer block used for
To support the weight of the shaft
What are bulkhead glands
They allow the shaft to pass through different compartments
What does the stern seal do
Keeps the shaft watertight as it passes through the ships hull
Advantages and disadvantages of fixed propellers
ADVANTAGES
Highly efficient at full power
DISADVANTAGES
The gearbox must have a reverse gear
Loss of efficiency and power when moving backwards
Advantages and disadvantages with Controllable Pitch Propellers (CPP)
ADVANTAGES
Can change the propeller to move in any direction
