This is a component that seals the shaft where it exits the pump casing. Here's an overview of its functions and components:

1. Sealing: The primary function of the waterbox or stuffing box is to prevent fluid from leaking along the shaft where it passes through the pump casing. This is essential for maintaining the efficiency of the pump and preventing environmental contamination.

2. Shaft Support: The waterbox also provides support for the shaft, ensuring it remains properly aligned as it rotates. This helps prevent excessive wear on the shaft and bearings, prolonging the life of the pump.

3. Cooling and Lubrication: In some designs, the waterbox may incorporate mechanisms for cooling and lubricating the shaft and sealing components. This can include circulating coolant or lubricant around the shaft to reduce friction and heat buildup which Grease Packing is use together with this part. 

4. Adjustment: The waterbox may be designed to allow for adjustment of the packing or sealing material around the shaft to maintain proper sealing effectiveness over time. This may involve tightening or loosening gland nuts or other fasteners to adjust the compression of the packing material.

5. Access for Maintenance: Depending on the design, the waterbox may provide access to the shaft and sealing components for inspection, maintenance, or replacement. This is important for ensuring the continued reliability and performance of the pump.

Vertical pumps are commonly used in applications such as water and wastewater treatment, chemical processing, power generation, and oil and gas production. The waterbox or stuffing box is a critical component of these pumps, contributing to their overall efficiency, reliability, and longevity. Proper installation, maintenance, and monitoring of the waterbox are essential to ensure optimal pump performance and prevent leaks or other operational issues.