Different Types of Ball Mill Trunnion Bearings

In this article, we discuss different types of ball mill trunnion bearings. These include the swivel type and the floating type. We also discuss how the lubrication system works and how cracks can form. This information will help you choose the right trunnion bearing for your mill.

Floating ball mill trunnion bearing

Before installing the trunnion bearings, make sure to check that the mill has sufficient clearance. This is usually possible through the mill's general assembly drawing. If you don't have a drawing, you can study the parts' weights from the sub-assembly drawings. It is also important to prepare special tools before installing the mill. These tools should include large striker wrenches for the foundation bolts and torque wrenches for bolts.

Before installing the trunnion bearings, the trunnion journals and sole plates must be assembled. They must also be swivelled. Then, oil should be applied to the journals to keep them from rusting.

Swivel type trunnion bearing

In a ball mill, the swivel type trunnion is the key piece of the mill's gearbox. It is located where three lines cross and allows the shafts to swivel freely and are lubricated while running. Because of their design, swivel trunnion bearings are not a single piece but are typically two pieces.

The bearings are lubricated while the mill is in operation with the help of oil rings. It is important to periodically inspect these rings to ensure they are working properly. The rings have small holes that pick up oil from the base of the bearing and transport it to the top. Because the oil rings are not joined with the trunnions, they can be easily damaged.

Oil lubrication system in ball mill trunnion bearings

One of the main causes of bearing failures is insufficient oil lubrication. Various systems have been developed to detect insufficient lubrication. One approach involves using temperature-responsive elements. However, this approach has not been proven to be accurate. Conventional alarm systems are based on fluid pressure in the main lubrication circulating system, which varies with the operation of the ball mill.

An oil lubrication system in ball mills provides both high and low pressure oil for the bearings. It includes temperature sensors, pressure switches, and flow monitors to ensure that there is adequate oil flow in the bearings. This system also has an alarm system that can be triggered by low flow.

Cracks nucleation in ball mill trunnion bearings

The emergence of cracks in the trunnion bearings of ball mills has become an important issue in the cement industry. These cracks usually occur in the R-angle region of the hollow shaft and may extend to the flange. If not treated quickly, these cracks can lead to equipment accidents. Crack prevention methods are essential to ensure the safe operation of ball mills.

Cracks are formed at the contact interface due to oxidation-assisted wear. During the first year of operation, the ball mill trunnion bearings should be subjected to strict quality control. Regular measurements of the ball mill elevation, reducer centerline, and horizontal line should be carried out to ensure that the trunnion is not cracked. It is also important to regularly inspect the hollow shaft for cracks. Regular inspections can extend the life of the hollow shaft and decrease the risk of cracks. Using a slow-turnning device, the trunnion and the flange bolts should be checked for surface cracks and holes.