Transmissions

Question 1

4 advantages of involuted gear teeth form

Answer 1

Universally adopted by gear manufacturers
Mostly a rolling contact during meshing
Relatively straight forward to manufacture
Variation in centre to centre distances making installation easier

Question 2

What are five checks to be done before closing a gearbox after installation

Answer 2

Ensure all work is complete, check UMMS for any additional near future work

Ensure no loose traps, fittings or fastenings

Forced lub pumps checked for oil form and flow correct

Jointing surfaces and connections are to be checked

On completion of previous checks the MEO is to double check the gearbox and watch the replacement of covers

Question 3

How are defects to gear teeth reported

Answer 3

All new cases of damage to teeth are reported on s2022 form

Serious defects should be reported on OPDEF signal

Question 4

What activity should be undertaken after extensive work to the main gearing and briefly explain the method used, how it is used, how it is achieved and why it is done? No requirement to give full itemised procedure.

Answer 4

significant work to the oil system and or main gearbox will require cleaning once all the work is complete.

The cleaning process is called flushing whereby all pipes, sumps, oil coolers and drain tanks, oil is sprayed around gearing internals and covers by an appropriate repair authority to clean out any debris and particles

100 gauze meshes are added to the system, the system is flushed for a period then the meshes are checked to determine the level of debris inside

Done to determine the level to get a known standard of cleanliness inside the system before being run

Question 5

Very little significant ship staff work is required for the main shaft brakes. Explain routine checks and maintenance practices should however be undertaken by ship staff?

Answer 5

It is recommended that the brake paths on the disc should be cleaned at regular intervals to prevent/remove contamination with oil or grease,

all hydraulic connections should be checked for leakage and tightened.

At the same time, all bolted connections should be checked for tightness, painted alignment marks on the holding down bolts and tie rod nuts will enable a quick visual check to be made.

As brake pads become worn, the clearance between the pads and the disc will increase and operation will become slower. Re-adjustment will be necessary.

Initial thickness of each pad is 25mm. Pads should be replaced when thickness is reduced to 12mm or notably uneven wear. Should also be replaced if they become badly contaminated with oil or grease and replaced in pairs.