The thrust bearing between the nut and the swivel box is provided by which component?

• A. Phosphorous Bronze Washer
• B. Steel Washer
• C. Copper Washer
• D. Aluminum Washer

Answer: (A)

The thrust bearing between the nut and the swivel box is provided by a phosphor bronze washer. This material is ideal for sliding interfaces in marine hardware because it combines good wear resistance with relatively low friction, so it can handle the axial load of the nut while allowing smooth rotation. The phosphorus content helps harden the surface and improve wear resistance, and bronze alloys resist galling when sliding against steel parts, which is important in a naval setting.

Steel washers, while strong, can seize or wear unevenly under sliding motion and are more prone to galling with steel parts. Copper washers are softer and deform more easily, increasing friction and wear. Aluminum washers are lightweight but too soft for a durable thrust surface in this application.