How many bolts per rail are required to secure fish plates?

The requirement of four bolts per rail to secure fish plates is based on standard practices that ensure stability and safety in elevator rail installations. Fish plates, which are used to connect rail sections, must be securely fastened to handle the lateral and vertical loads they may encounter during operation. Using four bolts per rail creates a robust connection, distributing forces evenly and reducing the risk of rail misalignment or failure due to movement or vibration.

Having only two bolts per rail would not provide sufficient support, leading to potential instability. Similarly, increasing the number to six or eight bolts could introduce unnecessary complexity and material costs without significantly enhancing the integrity of the connection. Therefore, four bolts strike an optimal balance, ensuring that the fish plates are adequately secured while maintaining efficiency in installation and maintenance.