What is the general rule of thumb for setting friction bearing clearance?

The correct guidance for setting friction bearing clearance is to adhere to a value of 0.0010" of clearance per inch of shaft diameter. This rule of thumb is established based on the need for an optimal balance between minimizing friction and allowing sufficient oil flow for lubrication. The goal is to ensure that the bearing operates smoothly without overheating or causing excessive wear.

Setting the clearance too tight can lead to increased friction, which in turn can generate heat and lead to premature failure of the bearing. Conversely, if the clearance is too wide, it may result in inadequate support for the shaft, potentially leading to vibration and instability in the machinery. Thus, using a measured approach of 0.0010" per inch of shaft diameter provides an ideal compromise for effective operation.

In practical applications, this standard allows for varying conditions based on load, speed, and the lubrication method used, making it suitable for different types of machinery and operational environments. Understanding this standard is essential for millwrights to ensure reliability and longevity in bearing applications.