Understanding Temperature Rise in Bearings

Bearings are essential components in machinery that allow for relative motion between parts while reducing friction. The temperature rise in a bearing is primarily due to the friction generated during operation. This friction converts mechanical energy into heat, causing the bearing temperature to increase.

The amount of friction generated depends on several factors, including the type of bearing, the load applied, the speed of rotation, the viscosity of the lubricant, and the contact area between the moving surfaces.

Comparing Partial and Full Bearings

Let's compare the characteristics of partial and full bearings relevant to temperature rise:

• Full Bearing: A full journal bearing encloses the journal (shaft) over its entire circumference (360 degrees). The lubricant is sheared throughout this full circle.
• Partial Bearing: A partial journal bearing supports the journal over only a part of its circumference, typically less than 180 degrees (often around 120 degrees or less) at the loaded region. The load is applied directly onto the bearing surface over this partial arc.

Friction and Heat Generation

For a given load and speed, the friction in a bearing is related to the area over which the lubricant is sheared and the pressure distribution.

• In a full bearing, the lubricant is sheared over the entire 360-degree circumference. While the load is supported on the loaded side, lubricant also flows and is sheared on the unloaded side. This larger shearing area generally leads to higher total friction.
• In a partial bearing, the lubricant is primarily sheared over the limited arc of contact where the load is supported. There is less lubricant shearing over the remaining circumference where there is no contact or minimal film pressure. This smaller effective shearing area under load results in less friction compared to a full bearing under the same load and speed conditions.

Since temperature rise is directly related to the heat generated by friction, a bearing with less friction will experience a smaller temperature rise.

Conclusion on Temperature Rise

Based on the comparison of friction generation:

A partial bearing, supporting the load over a limited arc, generates less friction than a full bearing supporting the same load because the effective lubricant shearing area related to load support is smaller. Therefore, the heat generated in a partial bearing is less, leading to a lower temperature rise compared to a full bearing.

Thus, the temperature rise in the partial bearing is less than the temperature rise in the full bearing.