7.6 Power Transmission - 7.6 Power Transmission

Question 1

Prime Mover(s) Engine(s)

Answer 1

Gas Turbines, Diesel, Steam Turbine

Question 2

Main Reduction Gear (MRG)

Answer 2

Reduces High Speed/Low Torque into Low Speed/High Torque to drive the shaft/propeller

Question 3

Shaft

Answer 3

Transmits power from the MRG to the propeller

Question 4

Propeller

Answer 4

Fixed or Controllable Pitch Propeller (CPP)

Question 5

Characterization of Steam & Gas Turbine MRG

Answer 5

Dual Input
Double reduction
Double helical
Locked train
Articulated

Question 6

Characterization of Diesel (LSD/LPD) MRG

Answer 6

Dual Input
Single reduction
Double helical
Locked train
Articulated

Question 7

Dual Input

Answer 7

Two points of power input from the turbines to the MRG

Question 8

Locked Train

Answer 8

1st reduction pinion placed between a pair of 1st reduction gears
Balances tooth loading
Prevents “gear crawling”
Picture

Question 9

Articulated

Answer 9

“Quill Shaft”
The gears and pinions are mounted on an outer shaft that “floats” and allows limited flexibility
The 1st reduction gear and 2nd reduction pinion outer shaft is mounted to an internal quill shaft
Bearings on each side of each gear vice only on the ends of the shaft

Question 10

Accessory Drives/Connections

Answer 10

Attached Pump
Vent Fog Precipitator
Dehumidifier
Turning Gear
Tachometer
Shaft Brakes Assemblies
Clutches

Question 11

MRG Lube Oil System Composition

Answer 11

1x Attached L/O Pump
2x Electric driven pump
Shell & tube type cooler
Duplex Strainer
L/O sight flow indicators
Oil must be >90o F prior to engaging jacking gear / normal operation
Prior to securing, lower lube oil temp 10-15o F (100o F min)

Question 12

L/O Spray Nozzles

Answer 12

Forms a wide angle spray
Directed to gear mesh area
Provides cooling & lubrication

Question 13

Turning Gear

Answer 13

Provides means to rotate components of the power train
Provides means to lock gears (and main shaft)

Question 14

MRG Physical Security/Access

Answer 14

Placing OOC: CO
Physical Security:
Eng. Officer maintains key custody

If MRG is open, it requires permission and supervision

Question 15

SSS Clutch (GT)

Answer 15

Synchronized Self-Shifting (SSS) clutch
Automatically engages and disengages the engine to the MRG
On the reduction gear input shaft prior to the 1st reduction pinion
Permits independent operation of the GTEs

Question 16

Shafting System

Answer 16

Transfer torque generated by the main reduction gear to the propeller
Transmit the thrust developed by the propeller to the main thrust bearing

Question 17

Main Thrust Bearing

Answer 17

Type:
Absorbs axial thrust transmitted through the shaft from the propeller

Location is specific to class of ship – 1 per shaft

Question 18

Bulkhead Seal

Answer 18

Provides NO radial or axial support to the shaft
Allows for the shaft to traverse through bulkheads
Automatically sets a boundary between spaces due to pressure differentials (air or water)

Question 19

Line Shaft Bearings

Answer 19

Provides radial support to the shaft
-Support the weight of the shaft to prevent it from sagging
Quantity based on length of shaft
Lubricated with 2190
-From its own sump
-Not part of the MRG L/O System
-“Without online purification”
-Remote temperature sensors

Question 20

Stern Tube Seal

Answer 20

Maintain water tight integrity of the shaft traversing the hull
Includes an emergency inflatable seal; the shaft MUST be stopped and locked
Provides NO radial or axial support to the shaft

Question 21

Stern Tube Bearings

Answer 21

Provides radial support to the shaft
Located aft of stern tube seal
Cooled and lubricated by seawater (stern tube seal & bearing)
-Provided by auxiliary seawater
-Flushing water used inport/shallow water
Split upper/lower shell
Made of bronze shell with phenolic strips

Question 22

Strut Bearing

Answer 22

Construction is similar to the stern tube bearing
Supports the end of the shaft radially
Cooled by seawater
No flushing water is provided by the ship
May be more than one strut bearing

Question 23

Types of Propellers

Answer 23

Fixed Pitch Propellers - non-movable blades
CRP/CPP - Propellers with movable blades

Question 24

CRP/CPP - Propellers with movable blades

Answer 24

CRP uses oil to move propeller blades

CRP System Oil:
High pressure oil to hub
Return oil from hub

Prairie air to hub (CG & DDG)
Runs through shaft center
Surrounded by valve control rod
Valve rod supported by spider assemblies

Question 25

Controllable Reversible Pitch (CRP) System

Answer 25

CRP L/O Sump
CRP L/O Pumps
Hydraulic Oil Power Module (HOPM)
Oil Distribution Box (ODBox)
Propellers