Specifications
163
and can be hazardous to the operator. Using heating
equipment facilitates easy and quick removal while reducing
the risk of damage to the ring and shaft.
Removing bearings using hydraulic techniques.
Hydraulic pressure is another available method to
remove bearings. Pullers or wedges may be used to remove
the bearing after the hydraulic pressure has expanded the
race. Hot oil or heat may be used along with the pullers or
wedges. When the puller has been placed on the bearing
and pressure is applied, the bearing race should expand
and be easily removed. For own safety, do not strike the
bearing directly with any hard object such as a hammer or
chisel. Apply force to the part of bearing that has highest fit.
15.5 Fitting Bearings
Ball and roller bearings are manufactured to very close tolerances and are therefore easily
damaged by careless handing and fitting. Hence, utmost care is required in fitting up and
maintaining them. The bearing housing and the shaft end over which the bearing fits, should be
thoroughly cleaned so that the bearing fits neatly and just push tight. Bearings should never be
driven tight, because it will distort the race and damage the bearing. Grease, of the best quality,
should be, lightly packed into the bearing itself and the bearing then fitted into position in its
housing. The inner race may be pressed on to the shaft but if this is not practicable; it can be
fitted into position by lightly tapping with a wooden mallet over a tube passing over the shaft end.
Care must be taken to ensure that the bearing is square on the shaft.
15.6 Maintenance of Bearings
Keep the bearings dirt-free, moisture free, and lubricated. Water will rust the bearings and
dirt will destroy the smoothness of the super finish on the bearing races, increasing friction.
Clean the bearings when they become dirty or noisy with the most environmentally friendly
cleaner that is suitable for dissolving oil, grease, and removing dirt from the steel, plastic and
rubber surfaces. To obtain a long service life of bearings, they must be relubricated periodically.
Used grease together with wear debris and any contamination should be removed from the
contact zone and be replaced by fresh grease. The frequency of relubrication is of decisive
importance for long service life and depends on many factors including
the magnitude of the load, the type of load, the angle of oscillation,
the frequency of oscillation, the operating temperature
the sealing arrangement and other environmental conditions.
Long service lives are possible when the following relubrication conditions are observed:
the same grease is used as originally applied;
the relubrication should be carried out at the operating temperature;
the bearing should be relubricated before a long interruption in operation occurs.
Fig.15.1 - Bearing removal using puller