Lubrication of bearings - Machine parts. Course design

Lubrication of bearings

Typically, the bearings are lubricated with the same oil that the transmission parts are lubricated.

With crankcase lubrication, the rolling bearings are lubricated by oil mist formed when the oil is sprayed with the rotating parts of the gearbox. At the circumferential speed of the wheels V more than 1 m/s, oil spray covers all the gear parts and the inner surfaces of the shell walls. Oil, draining on the walls of the body, falls into the bearings.

To prevent unnecessary oiling, the bearings are protected with oil-resistant washers (rings), which are installed so that the ring protrudes into the body by 1.0-1.5 mm (Figure 6.9). This design is used in cases where a high-speed shaft is mounted helical or worm. Inclined wheel tines or turns of the worm pump oil onto the bearing, which leads to excessive heating of the bearing.

These rings also have another function - they protect the bearings from washing out of them a grease that is used at low rotational speeds of the rotating bearing ring and in those cases where the shaft bearing is located at a considerable distance from the oil bath level (for example, the upper bearing vertical shaft). In this case, the bearings are greased with grease, which fill the free space inside the bearing between the bearing cover and the ring (Figures 5.10, 5.11, 5.13, 5.14, 6.11).

Bearing grease is also used when the shafts are horizontal, when the shaft rotation frequency is relatively small, so that the formation of oil mist is difficult.

The criterion for applying the last lubrication method is the condition:

where c! - diameter of the inner ring of the bearing, mm; п - frequency of rotation of the inner ring of the bearing, rpm.

To apply lubricating grease to the bearings, press nipples are used (Figure 6.10). The oil is supplied under pressure with a special syringe. An example of installing a grease fitting is shown in Fig. 6.11.

Fig. 6.10

Fig. 6.11

If oil access to the bearings is difficult (for example, in the upper support with a vertical shaft arrangement), then the circulating method can be used instead of the greasing method of bearings.

With circulation lubrication, the oil from the pump through the cleaning filter and the nipple is fed into the switchgear, which is fed to the bearings by separate pipes.

The circulating method of lubricating bearings is used for high-speed shafts (in this case, crankcase lubrication is not recommended due to large energy loss for oil mixing) and at low shaft speeds (in this case, oil mist formation is difficult).

To the rolling bearings, the oil is fed from the outside of the bearing so that it flows into the crankcase through the bearing (Figure 6.12). The constructions of the nipples are shown in Fig. 6.6 and 6.8.

The lower supports of the vertical shafts in order to prevent the abrasive particles formed in the wear of the gear from getting into the bearing are usually isolated from the oil bath and lubricated with liquid oil from the pump or a grease plastic. In this case, to prevent the liquid lubricant from getting into the bearing from the crankcase, an insulating glass with vertical walls is installed (Figure 6.13).

Fig. 6.12

Fig. 6.13

thematic pictures