MDE Unit 4 Q11

A resilient or flexible mounting system for a marine diesel engine is designed to isolate the engine from the ship’s hull, reducing vibration and noise transmission. This is crucial for ensuring passenger comfort, equipment protection, and overall vessel integrity.  

1. Marine Engine Mounts – AV Industrial

Key components of a resilient mounting system:

• Engine bed: The base that supports the engine.
• Resilient elements: These are the components that provide isolation from vibration. They can be made of rubber, elastomers, or other materials with vibration-damping properties.
• Mounting brackets: These connect the engine bed to the ship’s hull.

Types of resilient mountings:

• Rubber mountings: These are commonly used due to their good vibration isolation properties and cost-effectiveness.   1. 5 Benefits of Rubber Engine Mounts www.rpmrubberparts.com
• Hydroelastic mountings: These use a combination of rubber and hydraulic fluid to provide superior vibration isolation.   1. Hydro Mounts – Buy Online Now | AV Industrial www.avindustrialproducts.co.uk
• Spring mountings: While less common in marine applications, spring mountings can be used for specific vibration frequencies.

Design considerations:

• Vibration isolation: The mountings should effectively isolate the engine from hull vibrations in all six degrees of freedom (three translational and three rotational).
• Load capacity: The mountings must be able to support the engine’s weight and dynamic loads.
• Durability: The mountings must be resistant to environmental factors such as seawater, temperature extremes, and fatigue.
• Stability: The mountings should prevent excessive engine movement, which could affect alignment and performance.

By carefully selecting and designing the resilient mounting system, it is possible to significantly reduce vibration and noise levels in a marine vessel, improving overall comfort and operational efficiency.

Understanding the Cross-Section

A cross-section of a resilient engine mounting would typically reveal the following components:

• Metal Base Plate: This is the rigid part that connects to the engine or the ship’s structure.
• Rubber or Elastomeric Layer: This is the core of the mounting, providing the vibration isolation properties. It might be solid rubber, or it could have internal voids for better damping.
• Metal Top Plate: This part connects to the engine or the engine bed.

Visual Representation:

crosssection of a resilient engine mounting

Additional Features:

• Reinforcing Elements: Some mountings may have internal reinforcing elements, such as metal inserts, to improve load-bearing capacity and durability.
• Damping Material: In some cases, a damping material might be incorporated to reduce vibration transmission further.

By understanding the components and their arrangement, you can better appreciate how these mountings work to isolate vibrations and protect the engine and the vessel.

When installing an engine with resilient mountings, several factors need to be considered to ensure optimal performance and longevity:

Alignment and Leveling

• Precise alignment: The engine must be accurately aligned with the propeller shaft to prevent vibration and excessive load on the mountings.
• Level installation: The engine should be level to distribute weight evenly across the mountings and prevent uneven loading.

Mounting Orientation

• Load distribution: The mountings should be oriented to effectively distribute the engine’s weight and dynamic loads.
• Vibration isolation: The mountings should be positioned to isolate the engine from the hull’s primary vibration frequencies.

Mounting Stiffness

• Engine weight: The stiffness of the mountings should be matched to the engine’s weight to achieve the desired level of vibration isolation.
• Operating conditions: The mountings should be able to withstand the engine’s operating loads and environmental conditions.

Installation Torque

• Tightening procedures: The mounting bolts should be tightened according to the manufacturer’s specifications to ensure proper load distribution and prevent premature failure.

Regular Inspection

• Mounting condition: The condition of the mountings should be inspected regularly for signs of wear, cracking, or deformation.
• Alignment check: Periodically check engine alignment to ensure the mountings are performing as intended.

By following these guidelines, you can maximize the benefits of resilient mountings and ensure the long-term performance and reliability of the engine and vessel.