Why are resilient mounts used on a ship?
To reduce the amount of radiated noise transmitted through the ships’ hull
Resilient mounts help in minimizing noise pollution and improving comfort on board.
What safety precautions must be carried out before removing and replacing resilient mounts?
- LOTO procedure
- Sit
LOTO stands for Lockout/Tagout, a safety procedure to ensure that machines are properly shut off and not able to be started up again prior to the completion of maintenance or servicing.
What is the reference for inspecting/replacing resilient mounts?
- Inspecting - UMMS Job Card
- Replacing - MAP 01-473
These references provide guidelines and documentation for maintenance procedures.
What must be carried out when replacing mounts?
- Use jacking bolt closest to the mount
- Prior to jacking up the machine, loosen the mount holding down nuts
- Replace one mount at a time
This ensures safety and proper alignment during the replacement process.
What is the correct method of changing resilient mounts?
- Replaced as a set
- Use correct replacement mounts
- Machine is properly supported using jacking bolts
Following this method ensures that the mounts function effectively and safely.
Name 5 types of mounts.
- J
- M
- L
- PD
- X
These types refer to different specifications or designs of resilient mounts used in various applications.
What measurements must be carried out on a mount after installation and when?
The deflection of the mount. Every 24 hours, for 4 days
Regular measurements help in monitoring the performance and stability of the mounts.
When using X mounts what must not be done?
They must not be used in conjunction with any mother mount. They must not be wrapped, tapped or covered in any other way.
What must mounts not show signs of, when supporting machinery?
Mounts must not show any permanent displacement relative to the ships’ structure. Must allow a degree of dampening to prevent excessive motion. Must not appear spongy or allowed to become impregnated with oil or other contamination.
Once the mounts have been replaced what must you allow the machine to do?
If time allows, especially on M mounts and high loaded X mounts, allow the machine to settle for 24 hours and occasionally rock to allow permanent displacement.
During a build/refit. how are mounts protected?
They should be protected by a waxed wrap followed by water adhesive fabric around them.
What is creep?
The tendency of a solid material to move slowly or deform permanently under the influence of mechanical stresses.
How do you ensure the correct locking of the nuts for the mounts is undertaken?
Nyloc nuts are to be fitted. The holding down bolts are to be sufficient length to fully engage with the nylon element of the locknut, but should not protrude through their nuts by more than one thread.
What are the correct fitting arrangements for an X mount?
The head of the securing bolts should be fitted from the inner of the mount. The treads protruding outwards and nylon brushing provided is to be used.
What should be fitted to the mounts, if they are fitted to a machine in a hostile environment?
Heat and oil shields with a minimum 6mm clearance.
When inspecting mounts what points should be considered?
No Contamination from paint, oil or fuel. Signs of distortion, damage or misshaping. Creep. Over tightening. Incorrect fitting.
What measurements are carried out after installation?
Deflection of the mount or clearance of the base plate from the seating.
When does an X mount need to be replaced?
When greater than 20% of damping compound has seeped.
What allowances should be made when taking measurements after installation?
Temperature changes. X mount 40mm clearances around the machine.
In addition to the mounts what other components are fitted?
Accelerators and decelerator units.
What are the adjustment height for both the L and M type mounts decelerator?
Clearances are set at 3mm (-0mm+1 mm)
What is the outcome if tools or projections are left around or under a machine’s base?
It impairs the efficiency of the mounts and prevents the full movement of the machine during shock /vibration.
What are the correct fitting arrangements for an X mount?
The head of the bolt should fitted from the inner area of the mount. The treads protruding outwards and all nylon brushing provided are used.
