What are bearings?

The bearings in your pump electric motor seem like small, hidden, unassuming components. They are anything but as they play a crucial role in the efficient and reliable operation of electric motors. Bearings are a component in an electric motor that both reduce friction between the motor shaft and the housing and keep it aligned properly. They also handle the weight and thrust on a drive shaft that is rapidly spinning while connected to a load, in our case, the impellors and housing of a water pump. These functions ensure that the motor and its pump runs smoothly and efficiently.

When we talk about bearings, we generally mean a roller bearing. A roller bearing is a 3 part round device that fits over a shaft. It allows it to have really low rolling resistance, need less maintenance and lubrication and hold the shaft in place properly. The 3 parts of the bearing are:

• The inner race, that part that joins onto the shaft.
• The outer race, this part is pressed or held by the outside part of the machine.
• The rollers, there are usually 10-15 of these and they are either balls or cylinders made from hardened metal. These are pressed into a groove between the inner and outer race and allow both parts to spin without much friction.

Why do we need bearings in an electric motor?

An electric motor as a complex machine of different parts working together to convert electrical energy into mechanical rotating motion. The rotor, which is the spinning part of the motor, needs to rotate freely without physically touching the outer stator part of the motor. Touching can cause unnecessary wear and tear and electrical short circuits. This is where bearings come into play by supporting the rotor and allow it to spin with minimal resistance, reducing friction and heat buildup.

Without bearings, the rotor would grind against other parts of the motor, leading to increased friction, excessive heat, and ultimately, mechanical failure. Bearings take on the load, literally and figuratively, by ensuring that the rotor moves smoothly and consistently. This not only prolongs the life of the motor but also helps in maintaining its efficiency. In addition to supporting the rotor, bearings help manage the forces generated by the motor's operation. They keep everything aligned and stable, preventing unwanted vibrations and noise. This is particularly important in high-speed motors, where even the slightest imbalance can cause significant problems.

So, while bearings might not be the largest  part of an electric motor, they're absolutely essential. They keep everything running smoothly, reduce wear and tear, and ensure that the motor can do its job efficiently. In short, bearings are the unsung heroes of electric motors, quietly ensuring that everything spins along as it should. At Rural Pumps we stock exclusively SKF brand bearings as they are top quality and reliable.  We have a wide range IN STOCK and with our pump selector, we can guide you to get the right type for your pump. 

How to measure and select a replacement bearing

At Rural Pumps there are 2 ways to select replacement bearings, you can select your pump brand and model in our pump selector tool or search by bearing type. Bearings have distinct markings on them that specify what they are. They are assigned a classification or model number that laid out in the ISO 15:2017 standard. This classification number is 3 to 5 digits long and gives a description of the bearing. The parts are:

1. Digit 1 can be a number from 0 to 8 or a letter (C, N, NN or QJ). 
2. Digit 2 is the ISO code for the width or height. This isn't specified in deep groove single row roller bearings. 
3. Digit 3 is the ISO diameter code for the outside diameter. 
4. Digit 4 and 5 is the code for the inner or shaft diameter. 

So for example, a 6304 bearing is a 6 (single row deep groove ball bearing type) 304 (width 15mm, outer diameter 52mm and shaft diameter of 20mm). 

To then measure the dimensions of a bearing accurately, you should always use a set of vernier calipers. Using a ruler or measuring tape means you can easily be out by 1mm which is the difference between being the correct or incorrect replacement type. 

The dimensions to measure then are:

1. The width.
2. The outer diameter of the outer race.
3. The inside diameter of the inner race (or the shaft diameter you are pressing the bearing onto). 

The other part of the code on a bearing can also be important. In our example the bearing is a 6203-2RSH. The designation of 2 RSH means that it has rubber sealing caps on 2 sides of the bearing race. This stops dust and debris from contaminating the bearings and keeps the lubricant oil inside. This allows the bearing to not need further lubrication and will give it a long service life in environments like a pump where moisture and contaminants are common. 

We hope this has given you a brief overview of how bearings work in a pump electric motor to help make your pump more reliable and efficient. Please contact us if you need help getting the right bearings for your pump or for any other parts you require.