Gearbox and Shaftline Flashcards
State the 4 purposes of the gearbox.
- The Gearbox Transmits the rotation from the Main Engine (M/E) to the shaft
- Reduces the RPM from the M/E
- Increases the Torque of the propeller which improves Maneuverability of ship
- The shaft further transmits the rotation to the propeller
State the 2 purposes and the 2 cooling mediums of the plummer box bearings.
Purposes:
1. To provide support for the rotating shaft
2. Reduce friction and power loss from the rotating shaft
Cooling Mediums:
Seawater & L/O
State the qty of plummer box bearings and shaft segments in the PORT and STBD shaftlines.
Plummer Box Bearings: 3x PORT, 6x STBD
Shaft Segments: 4x PORT, 5x STBD
State the 7 gearbox components and their functions.
- Oil Sump: Contains the L/O required for clutch-in
- Gearbox-driven p/p: Main p/p used to pressurize the L/O for clutching in. Since it is gearbox-driven, it cannot work if the M/E is not running
- Standby P/P: In case the main p/p fails to provide enough pressure for clutching in, It will cut in and help to increase the pressure. It is an Electric P/P
- Trailing P/P: Able to pump L/O to lubricate the Gearbox Even without the M/E running. It is an electric P/P
- Duplex Filter: Removes impurities from L/O
- Cooler: Cools Down L/O
- Solenoid v/v: Controls the flow of L/O to the clutch, controls the clutch-in and clutch-out
State the purpose of splitting the shaft into segments.
To make maintenance of the shaft easier
State the process to activate the inflatable shaft seal.
- Connect the rubber hose from the shaft seal to the 2.5 bar service air manifold
- Turn it on
State the 6 conditions before the M/E can undergo clutching-in.
- L/O Level Higher than dipstick max
- M/E Speed 330-345rpm (Check SCMMS pg 10)
- CPP Pitch 0 degrees (Check SCMMS Pg 10)
- Gearbox L/O Pressure 16-20 bar (Check Pressure Gauge on Gearbox)
- Shaft Lock Disengaged (SCMMS pg 10)
- Turning Gear Disengaged (Check Turning Gear)
State Tier 1, 2 & 3 Control Points for controlling the gearbox & their locations. State how to switch to auto and semi-auto mode for Tier 3 control point, and the buttons to clutch-in and clutch-out.
Tier 1: Gearbox Control Valve @ Gearbox
Tier 2: Main Engine Local Operating Panel @ E/R (Switch to LOCAL)
Tier 3: PCMS (Propulsion Control Monitoring System) @ MCR
Auto: Switch M/E LOP to “AUTO”
- Press Driven → Clutch-in
- Press Disengage → Clutch-out
Semi-Auto: Switch M/E LOP to “REMOTE”
- Clutch-in button → Clutch-in
- Clutch-out button → Clutch-out
State the following gearbox parameters:
Gearbox Reduction Ratio
L/O Pressure
L/O Temp
L/O Duplex Filter Differential Pressure
Standby p/p cut-in Pressure
Direction of Port M/E Propeller Input & Output
Direction of Stbd M/E Propeller Input & Output
Gearbox Reduction Ratio: 4318:1
L/O Pressure: 16-20 bar, Min. 12 Bar to clutch in
L/O Temp: 60 - 70 degree Celsius, High Alarm 80 Degree celsius
L/O Duplex Filter Differential Pressure: 0.5 - 1 bar
Standby p/p cut-in Pressure: 13 Bar
Port M/E Propeller: CW Input → ACW Output
Stbd M/E Propeller: ACW Input→ CW Input
State the 2 purposes of the shaft lock.
- Physically blocks the shaft from rotating unexpectedly
- Send a signal to prevent the M/E from starting
State the purpose of the turning gear.
Used to make micro-adjustments to the shaft, especially when locking the shaft.
State the process to lock and unlock the shaft using the LOP.
- Switch turning gear LOP to “LOCAL”
- Align turning gear by pressing “Clockwise” and “Anticlockwise” as needed
- Engage turning gear by pushing it into the shaft gear
- Have one operator at the LOP and the other in the shaft alley. Shaft alley operator comms LOP operator to turn CW/ACW until shaft notches align.
- Insert key to lock shaft
- Remove key to unlock shaft
State the process to lock and unlock the shaft using the Remote Controller.
- Switch turning gear LOP to “LOCAL”
- Align turning gear by pressing “Clockwise” and “Anticlockwise” as needed
- Engage turning gear by pushing it into the shaft gear
- Switch Turning Gear LOP to “REMOTE”
- Operator to go into the shaft alley and connect the Turning Gear Remote Controller to the port in the ceiling
- Turn CW/ACW until Shaft Notches Align
- Insert Key to Lock Shaft
- Remove Key to Unlock Shaft
State what causes trailing mode to occur and what occurs during trailing mode.
Trailing mode occurs when only one of the propellers are rotating during sailing, commonly due to one of the M/Es unexpectedly stopping.
During trailing mode, trailing p/p is activated which will pump L/O to lubricate the non-rotating shaft to ensure that the non-active propeller can rotate freely through the water and minimize drag.
What is the purpose of the reduced reduction inverse marine gearbox?
Provides transfer of ‘Thrust Force’ from the propeller to the ship’s hull which directly causes the ship to move forward astern
