a) Resilient/Flexible Mounting for a Diesel Engine: Main Components
A cross-section through a resilient/flexible mounting for a diesel engine typically consists of several key components that work together to isolate vibrations:
- Engine Mounting Base: This is a rigid metal plate that securely attaches to the engine block at designated mounting points.
- Elastomeric Isolator: This is the core vibration-isolating component. It’s typically made from a high-performance rubber or elastomer compound formulated to absorb and dampen engine vibrations. The elastomeric isolator can take various shapes depending on the design:
- Cylindrical Isolators: These are common and consist of rubber cylinders bonded to metal plates on each end.
- Cone-Shaped Isolators: These offer a progressive stiffness characteristic, providing better isolation at lower frequencies.
- Sandwich Isolators: These multi-layer mounts use rubber sandwiched between metal plates for increased isolation and load capacity.
- Metal Support Plate: This rigid plate connects the elastomeric isolator to the foundation (e.g., engine bed frame or ship hull) where the engine is mounted.
- Hardware: Bolts, nuts, and washers are used to securely fasten the mounting base to the engine block and the support plate to the foundation.
(b) Special Considerations for Engine Installation with Resilient Mountings:
While offering vibration isolation benefits, resilient mountings require some special considerations during engine installation:
- Alignment: Precise engine alignment with the driven equipment (e.g., gearbox, propeller shaft) is even more critical when using flexible mounts. Misalignment can introduce additional loads and potentially damage the mounts or other components.
- Engine Movement: Resilient mounts allow some degree of engine movement due to vibration isolation. This needs to be factored in during installation to ensure adequate clearance between the engine and surrounding components.
- Load Capacity: Each mounting has a specific load capacity. The total weight and dynamic forces of the engine must be within the combined capacity of all the mounts used.
- Natural Frequency: The design of the mounting system should consider the engine’s natural vibration frequencies. The mounts should be chosen to have natural frequencies that are significantly lower than the engine’s operating frequencies to achieve optimal vibration isolation.
- Maintenance: Over time, the elastomeric isolators in resilient mounts can degrade due to aging and environmental factors. Periodic inspection and replacement of the mounts might be necessary to maintain optimal vibration isolation performance.
By carefully considering these factors during engine installation with resilient mountings, you can ensure proper engine operation, minimize vibration transfer to the surroundings, and extend the lifespan of both the engine and the mounts.