Gearbox Flashcards
What checks should be carried out on a reduction gearbox and what kind of bearings are in use?
Visual inspection around the gearbox, look for any leaks. On the gear teeth we are looking for any missing teeth or damaged teeth. Even signs of cracks and fractures.
We are taking an oil sample and sending off to be tested.
Listening for any noises and vibrations when running.
Any signs of overheating.
The bearings in used could either be roller bearings to cope with the high loads or thrust bearings to deal with axial forces acting upon the shaft.
How would you check the thrust bearing? What material are they?
Inspect the thrust bearing housing and surrounding components for any signs of oil leaks, corrosion, or damage.
Check for excessive wear or scoring on the thrust bearing surfaces, which may indicate improper alignment or lack of lubrication.
Look for any signs of overheating, discolouration, or metal transfer, which could indicate excessive friction or insufficient lubrication.
Use a feeler gauge to measure the axial play (end play) of the shaft supported by the thrust bearing.
Apply a slight axial force to the shaft in both directions and measure the amount of axial movement then compare the measured axial play to the manufacturer’s specifications. Excessive axial play may indicate wear or damage to the thrust bearing or other components.
Explain the procedure for opening up a gearbox?
- Get a permit and risk assessment completed.
- Inform the bridge
- Isolate and tag out the engine and gearbox and cooling
- Toolbox talk with all involved
- Refer to maintenance manual
- Lock the shaft
- Draw an oil sample
- Drain the oil and remove filters
- Remove the heat exchanger
- Remove any pipework/ cabling that may get in the way
- Open the top of the gearbox
- Carryout inspection and repairs
- Rebuild in reverse order
- Follow recommend torque settings
- Add new oil
- Remove tag outs
- Close permit
- Run and test
You find a missing tooth on your gearbox, what would you do?
- Take an oil sample
- Drain oil
- Inspect gearbox and find the tooth
- Inspect all other tooth for cracks
- Do not use until tooth has been found
- Once shore side look into welding a tooth or new gear
How would you fix a damaged tooth while at sea?
- Use dye penetrant
- Non Destructive Testing with testing hammer,
- Find if there is any further cracking, - File the damage area so it was smooth as to not cause any further damage and have good meshing of the gears.
- Run at low RPM,
- increased checks during watchkeeping
- Arrange repair at soonest opportunity
When sending off gearbox oil analysis, what are you looking for?
Trend analysis, water, wear metals,
particularly zinc, tin and lead from the bearings.
Draw and label a gearbox reversing diagram?
See onenote
Explain the reversing of a gearbox?
Reversing a gearbox involves changing the direction of rotation of the output shaft relative to the input shaft.
This often includes a shift mechanism or selector mechanism that controls the engagement of gears.
The shift mechanism may consist of levers, linkages, solenoids, or hydraulic actuators that move gears or gear clusters into different positions to change the direction of rotation.
What type of gears are found in a gearbox?
Depending on the manufacture it is most common to see either Herringbone gears or Spur gears
The thrust block ahead pads are worn, what can we do to get to port?
Switch out with the reversing thrust pads and have a procedure in place to stop the captain from using reverse.
The clutch on the gearbox is slipping, you don’t have a functioning gearbox, how can you overcome this?
I would lock the clutch to the shaft making it a direct drive. We would operate at a low rpm which will allow us to get to port.
