Spherical roller bearings – a raceway very similar to tapered roller bearings – cup design found in standard tapered roller bearings. The rolling elements are cylindrically shaped and the bearing is equipped with self-aligning properties, which is advantageous in applications where shaft deflection and shock loads may occur.
With tapered roller bearings, the ratio of axial to radial load is determined by the angle between the roller axis and the bearing axis. Heavy axes and thrust forces are supported in one direction, while some variants exist in both directions. Even moderate radial loads can be tolerated, but the radial load is controlled by a pincer bearing (120%), as shown in Fig. 1.
At increasing speed, this type of bearing is not sufficient to control shaft movement and is replaced by floating bearings where there is no inner film to support the shaft and the bearing construction does not rotate in relation to its housing. There are two types of shaft bearings: fixed – sleeve types that twist and support a shaft with an oil film, and bearing designs, such as tapered roller bearings and pliers bearings, that do not.
In dynamic internal shaft bearings, rotating the bearing and subsequent support in its static housing creates a rotation in the outer oil film area into which the oil is pumped. This also leads to the centrifugal movement of the shaft around the inner bearing and has the effect of pumping oil from the inner film into the outer film, as well as a positive effect on the oil pressure on a shaft.
Tipping bearings are designed to transfer high axial loads to the rotating shaft to simplify installation and maintenance. If the shaft is not sufficiently controlled by the bearing system, it can get out of control and allow the oil film to rotate into the outer film, ultimately destroying a turbocharger. In dynamic shaft bearings, the bottom bearing rotates at the same speed as the thrust bearing, regardless of the shaft diameter for which it is designed.
The maximum load for different bearing types ranges from 0.5 to 500 tons, with a maximum load of 1,000 tons for the upper bearing and 1.2 tons for the lower bearing.
The contact angle of the thrust bearing increases to 90 degrees compared to the radial ball bearing, and therefore only axial loads occur. Due to their specific construction, thrust bearings are not considered standard and can be made of any material such as steel, aluminum, glass, or other materials. The thrust bearing is the only type of bearing with a maximum load of 1,000 tons or more.
The function of a bearing of fundamentally different design is to direct the force from the mass center to the outer edge of the ball bearing and back again. The difference to this bearing is that the load is evenly distributed over the rolling element.
Standard radial bearings are designed to absorb radial forces, but can also absorb small to medium axial forces. As with radial or deep groove ball bearings, the load is evenly distributed over the rolling element of the axial bearing. Due to its special design, push-pull bears are particularly useful in cases where the speed is low or medium, and higher rigidity is required.
Just like the hydrodynamic gun bearing, the hydrodynamic thrust bearing uses oil to support the rotor, but in a different way from the radial bearing.
The oil is injected into the thrust disc of the bearing, and an oil wedge is created between the bearing and the rotor. The bearing itself has two different types of oil wedges, one for the radial bearing and the other for a hydrodynamic thrust bearing. This depends on the design and manufacturer of the equipment but is generally the same for both types.
The oil can handle a load of about 500 psi before collapsing, but the equipment the manufacturer has selected to load a maximum pressure of 1,000 psi (1.5 pounds per square inch). In the small ring visible on the surface, there is the oil, which is fed by a hydrostatic lifting system used both at the start and stop to ensure sufficient lubrication of the liquid film even at low speeds.
Taking into account the entire storage is a challenge, and other hydrodynamic bearings are limited to a small fraction of the total oil in the oil film. It is difficult to create a complete picture of all the different hydrostatic forces on a single bearing, so it can be difficult to take everything into account.
In order for the thrust bearing to maintain a continuous load on the ball, the holder must correct for speed fluctuations.
When angular ball bearings cannot provide long service life and high thrust, pendulum ball bearings are used. The spring loading is used to ensure that the bearing is not damaged in a collision with the ball or other object, such as a rock. The bearing accepts a radial load with each push operation, and a spring load can be used at any time during the push cycle.