Why Total Reliance Is Placed On Frictional Grip In Conventional Built Up Crankshaft On Main Engine

In conventional built-up crankshafts used in main engines, total reliance is placed on frictional grip primarily due to the following reasons:

1. Assembly Convenience: Built-up crankshafts are typically composed of multiple components, including crankpins, crank webs, and main journals. These components are assembled together and secured using interference fits and bolts. Frictional grip provides a convenient means of assembling these components without the need for complex or specialized joining techniques such as welding or brazing.

2. Adjustability: Frictional grip allows for some degree of adjustability during assembly, which is advantageous for achieving proper alignment and balancing of the crankshaft components. By adjusting the interference fits or tightening the bolts, engineers can fine-tune the assembly to ensure optimal performance and minimize vibrations.

3. Maintenance and Repair: Frictional grip facilitates disassembly and reassembly of the crankshaft components for maintenance and repair purposes. Bolts can be easily removed, allowing access to individual components for inspection, replacement, or repair without requiring extensive dismantling of the entire crankshaft assembly.

4. Flexibility in Design: Built-up crankshafts offer flexibility in design, allowing engineers to tailor the crankshaft configuration to specific engine requirements, such as varying stroke lengths, journal diameters, or crankpin arrangements. Frictional grip enables the integration of different components with varying sizes and shapes, providing versatility in crankshaft design.

5. Cost Considerations: Frictional grip assembly methods are generally more cost-effective compared to alternative joining techniques such as welding or forging. They require fewer specialized tools and equipment, making them suitable for mass production and economical for engine manufacturers.

While frictional grip offers several advantages in conventional built-up crankshafts, it's essential to ensure proper design, material selection, and assembly techniques to maintain reliability and performance. Factors such as surface finish, lubrication, bolt torque, and preload must be carefully controlled to optimize the frictional grip and prevent issues such as loosening, fretting, or premature failure of the crankshaft assembly.