In a previous Tip of the Week, we discussed considerations for operators when selecting the appropriate grease for use in an electric motor bearing, but not every bearing operating within a motor requires grease. For example, double-sealed- or “sealed for life”- bearings are manufactured to be largely maintenance free, keeping grease inside the bearing and keeping contaminants out of the lubricant.
So, how can operators determine what type of bearings are in operations within the electric motor?
Take a look at the Equipment Builder (EB) Plate, or more specifically the two serial numbers at the top of the plate:
These numbers, labeled “SHAFT END BRG” and “OPP END BRG,” describe the bearings within the motor.
By using the chart below, operators can look to the suffix of these serial numbers to determine what type of bearing is in operation.
In this example, the shaft end bearing number is 6208-2ZJ/C3, but we are only going to focus on the number’s suffix: 2ZJ/C3.
Now, take a look at this chart:
The suffix of the serial number begins “2Z” and, by using the above chart, we can determine that the bearings in this electric motor are shielded on both sides. As they are not sealed-for-life bearings, they will occasionally require maintenance to replace any grease that has deteriorated or leaked away.