What is a necessary condition for the hub seal?

The necessity of fluid remaining inside the hub seal is crucial for the proper functioning of the vehicle's wheel bearings. The hub seal's primary role is to contain lubricating oil or grease within the hub, which keeps the bearings lubricated and prevents overheating due to friction. If there is no fluid inside, it can lead to increased wear or even failure of the wheel bearings, as they won't have the necessary lubrication. Keeping the proper lubricant level is vital for maintaining the performance and safety of the vehicle, as it influences the hub's ability to operate smoothly and efficiently, ensuring safe operation on the road. This condition also helps prevent damaging issues that could arise from lack of lubrication, such as excessive heat generation and subsequent part failure.