How to lubricate a sealed bearing

A bearing is a unit that allows you to fix a rotating part in a mechanism. Structurally, the bearing consists of two rings, an inner and an outer ring, between which balls or rollers are installed. Closed bearings are considered the most popular. They are designed to work in conditions where dust and abrasive particles are possible. To keep the grease inside for a long time, seals are installed in the bearing between two rings. They come on one or both sides.

A self-lubrication system in the bearings is necessary to ensure an uninterrupted supply of lubricant. If there is not enough lubrication, the part will overheat and break. But to extend the service life of the bearing by 2-3 times, you need to open it and change the oil. But we will look at how to do this in this article.

Required materials and tools

To carry out such an operation, you will need some materials and tools:

Wallpaper or shoe knife;
A sharp awl or a special grip;
White spirit or acetone, or gasoline or kerosene;
Rags or ordinary rags;
Lithium or other thick grease such as “Ciatim” or “Litol”.

Disassembly and lubrication process

The O-ring can be plastic, metal-rubber or metal. To disassemble, the protective seal must be carefully pryed with some sharp object over the edge of the ring and slightly lifted. This must be done with an awl, a gripper or a knife; you can use a small screwdriver used for repairing watches. You need to pick it up carefully without damaging the protective boot. If the ring is deformed, it will be impossible to put it back in place.

We carry out the same procedure on the other side of the bearing. Then you need to remove the old grease using some solvent. Thoroughly wash the bearings and seals in gasoline or kerosene. If possible, blow with compressed air to remove any remaining old grease and wipe thoroughly with a rag. After this, the bearing must be dried.

Before filling the container with new lubricant, it is necessary to diagnose the bearing in the following sequence:

Conduct a visual inspection for wear of the separator and the presence of chips, cracks, shells and corrosion;
No noticeable play of the clips relative to each other;
Holding the inner ring with your fingers, turn the outer race with your other hand. The movement should be smooth without grinding or metallic rustling.

If your bearing passes the diagnostic test with a score of five, then we proceed to the next operation. Carefully install one protective ring into place. Turning the bearing over, fill it with grease to 80% of the total volume. Scroll several times so that the lubricant is distributed evenly. Excess grease must be removed with a clean cloth.

And finally we install the second cover in place.

Bearings with metal housings are difficult to remove. They can be filled with lubricant using a grease gun with a sharp tip. You can use an ordinary 5 mg medical syringe. Lubricant is applied to the seal lip where it contacts the bearing race. For better penetration inside, the lubricant must be heated. The heated lubricant penetrates into the cracks more easily.

Additional recommendations

By performing this type of maintenance, you will significantly extend the life of the bearing and save money at the same time. After removing the boots, you must carefully remove the old grease. Not all types of lubricants can be mixed with each other. It is difficult to guess whether lithium, silicone or polyurea grease was installed. Mixing different types of lubricant will change the original consistency and technical characteristics.

When removing o-rings with a sharp cutting tool, you must be very careful. If the knife slips, you may cut yourself. I would recommend wearing the glove on your left hand. When working with solvents or acetone, care must be taken. These liquids are highly flammable.

Main types of lubricants for sealed bearings: