Pillow block bearings are bearings with anti-friction properties. They are accommodated by a metal casing made from cast iron, cast steel, and ductile iron housing units. The whole structure is also known as a unit of the housed bearing. This means they are made as self-contained and set for installation and application.

For application, they are typically secured on a flat surface. This means the shaft and the surface will be parallel to each other. To offer a range of choices, the bearings can be distinguished by housing. Therefore, they can either be split housing or solid housing types of bearing. Other forms of distinction include the shape of the bearing structure. And under this category, they can be- roller, ball or tapered bearing.

For attachment, the shaft can either be an eccentric lock, set screw, concentric lock, single set collar, tapered adapter or double set collar. Each of them has its own pros and cons. Other parts which differ include their seal. There are auxiliary seals, heavy contact seals, light contact seals, and clearance seals.

With the availability of various variations of these devices, one is given a wide range of selection. Most of them are designed for durability, and this can only be achieved by making the right choice of the device. Apart from that, the installation also forms part of the vital factors that determines how long the device is going to last.

Installation is quite simple and easy when you follow the right guideline. To look out for you, we have provided you with the various categories of these devices, their use, capabilities and even a simple stepwise guideline of installation.


The types of the bearings according to Model, Material, and Housing

  1. Model

Needle roller bearing

This type uses rollers which are cylindrical in shape to minimize friction between the components which are moving. They have a structural resemblance to cylindrical roller bearing. The only difference between the two is the diameter compared to length ratio.

The needle roller bearings are smaller. The rolling needles are contained parallel to each other by circumferential clearance that is between the needles. At the same instance, they are also in a parallel configuration to the shaft. The design of Needle roller bearing applies where there is a desire for a low profile. For example: – application in the radial load.


Unlike the needle roller bearing which utilizes cylindrical shaped rollers, ball bearing uses ball-shaped rollers to minimize friction between the components which are moving. Due to the shape of the rollers, the bearing has a higher performance output and also longer life.

The rollers spin smoothly and maximally due to the least contact with the space they are contained. The model comprises of balls, inner ring, outer ring and also a sort of cage which separates the spheres.

Despite their efficiency, the balls bearing have a major limitation, that is, the balls can be flattened during operation. This is caused mainly by exertion of excess weight on them due to leading to its failure. Therefore during its installation or application, monitor the rating of the load on a regular basis. Also, ensure the load limit is not exceeded.

Plain bearing

There use is to limit glide and at the same time minimize friction in linear or rotary applications. Rather than rolling which is prevalent in the needle, ball, and roller bearings, they use sliding mechanism for motions. The structural materials are mostly plastic, graphite or bronze even though other variety of metals being applicable.

 For maintenance, they are regularly lubricated and at times given a lubricant impregnation or self-lubricating mechanism. This is to minimize friction and prevent wear and tear, through this, their serving life lengthens. The plain bearings are usually economical. This is since they are inexpensive, very compact and lightweight, as well as having a great carrying capacity of the load.

Cylindrical roller bearing

They are characterized by a moderate thrust capacity of the load but a high capacity in radial load. They have a resemblance to the needle roller bearing, but they are a bit bigger. To reduce the stress on the bearing, they can either be end relieved or crowned. Through that, they receive low friction which results in a higher speed during application; oil is utilized as a lubricant and coolant in the cylindrical roller bearing.

Their structures are made of either low carbon steel or alloy steel. Their applications include- power generation, cement processing, metal recycling, and briquetting machines among other machines. Others are also applicable in construction equipment such as electric motors, crushers, gears and so much more.

Tapered roller bearing

This type uses conical races which utilize conical rollers to minimize friction during movement. The tapered roller bearing structure comprises an inner ring and outer ring with a couple of tapered rollers. Also, both the rings are also tapered into a conical shape.

This bearing provides an area contact of large surface area; through this, they have the capacity to withstand loads both radial and axial. The structures of this bearing are made from polymers or non-ferrous metals. The lubrication of the moving parts is done to reduce noise, friction as well as act as a coolant.

Spherical roller bearing

Rollers which are barrel-shaped are used in this case to minimize friction. The spherical roller bearing comprises two rows of the barrel-shaped rollers. They are based between the inner and outer ring raceways. The rollers are sometimes crowned or barrel-shaped.

They are best in instances where you are operating with high loads which also have a sensitivity to shock. Thus they are applicable in most of the industries which require a heavy-duty application.

It has holes which are found on the outer ring that allows for lubrication when necessary. The same hole serves in the flushing out of unwanted elements from the raceway. And for uniform lubrication of the moving parts, there is an annular groove.

Hydrodynamic bearings

They rely on fluids or air which serves as the rollers between the stationary and moving elements. Despite the similarity in appearance, the hydrostatic and hydrodynamics uses a totally different mechanism in functioning. They are very costly, and also intricate in design, unlike the ordinary bearing which is inexpensive, and they use lubricants for friction reduction and the direct contact between the shaft and the bearing.

The applications of Hydrodynamics are mostly in operations that require precision in high stiffness and motion. The lubrication must be available constantly for the efficient and safe operation of this bearing. It must be cooled to eliminate the heat generated due to the oil shear and must also be maintained warm to ensure swift flow.   

  1. Material

The bearing material has a significant influence on the impact of its performance. Below are some of the common materials which most of the bearings are made from:

Graphite metal

It is an alloy which is formed from molten metal and graphite. It forms the bearing surface and has a trait of self-lubrication.

Stainless steel

Stainless steel is featured with high-quality resistance to corrosion and can withstand ratings of high pressure.

Sintered metals

Like graphite metal, they also have self-lubrication features. They are characterized by bearings that are powdery, very simple and inexpensive. They are limited to lighter loads but come in handy where lubrication is unnecessary.


Due to their smooth surfaces, lubrication is unnecessary. They are also characterized by intense strength that enables it to support a variety of functions. The common types include Teflon, PTFE, Polyamide, Nylon, and Acetal.


It has lower levels of carbon content which is about 1.7%. Under suitable conditions it’s malleable. Through low carbon content and malleability, it distinguishable from cast iron.


  1. Housing

Pressed steel

Its steel with low carbon content, the manufacture is through a pressing process rather than through machines. They are also inexpensive compared to the machined blocks and they support lower loads


This refers to materials that are thermoplastic/thermosetting polymers with molecular weights that are high and can be transformed into objects, filament or films. The common types which are applicable for housing structure are- Teflon, PTFE, Nylon and Acetal polymer.

Acetal polymers

They have the following traits which make them best for housing:

  • They are semi-crystalline
  • Self-lubrication
  • Resistant to fatigue
  • Resistant to chemicals

Limitations of these materials include:

  • At low temperatures they become brittle
  • Elevation of temperature causes the material to outgas
  • Lacks the flame repellant grades



  • It’s made of polyamide several grades
  • Have multipurpose applications
  • The material is very tough and also resistant
  • The pressure rating of the material is good

PTFE (polytetrafluoroethylene)

  • It’s a compound which is highly insoluble
  • Have extreme resistance to chemical corrosion
  • Have a lower friction coefficient


  • Has a high carrying capacity of the load
  • Resistant to fatigue
  • And a good thermal conductivity

Cast iron

The bigger portion of this material is iron, but also has trace levels of silicon and carbon which play an important role in its properties. The properties of cast iron are dictated by its microstructure constituents.


How to install pillow blocks

  • Start by cleaning the shaft and bores ensuring its smooth with no rough edges. It should be cylindrical with an equivalent diameter to that of the pillow block. You can clean the surface by use of scotch bright or use sandpaper with very fine grits. Then apply oil on the surface and use a soft piece of clothes to wipe clean the debris that might be on the surface. Before installing, do a second examination to ensure the shaft and bores are dry and clean.
  • When installing, insert the shaft through the side with the clump nut. Through this, you will have convenient access and tightening of the shaft. This will also enable efficiency during an inspection in the future. Also, loosen the clamp nut by unscrewing it up to 5 times. Just to be sure the adapter sleeves have enlarged enough, tap the nut face.
  • On the shaft, locate the bearing on a convenient position, this will allow the shaft to slide freely into the bore. If that’s not the case, examine carefully the bore of the sleeves and shaft for burs or defects. Once you have addressed the issue, the shaft should be able to slide in freely.
  • To initiate the clamping effect on the sleeve of the adapter, use a plank of wood and hammer to tap the end of the large sleeve which is just opposite the clamp nut. The use of wood will also prevent damages on the bearing.
  • When you are through with setting the shaft perfectly, tighten the clamp nut using a spanner wrench by your hands. Also, check for proper alignment of the bushings and the grease fittings. This can be done through the cover of the grease fitting. In this case, they have to be aligned with the opening. This will be beneficial later as it allows for shaft contraction or expansion during its rotation.
  • To clamp tightly the adapter sleeve on the shaft, place the spanner wrench on the clamp nut accurately, then hit the wrench with a hammer a few times in order to tighten the nut.
  • Once you are through with tightening the clamping nut and the adapter sleeve, you can secure the clamp nut from loosening. This is made possible by bending the lock washer prong into the clamp nut slot of your choice. This will prevent the nut from becoming loose.
  • Now the bearing can be secured on the mounting support by bolts. Meanwhile, you can counter check the alignment of the bushings and grease fitting through the cover of the grease fitting. It is imperative as it will ensure the continuous shaft rotation without interference. As mentioned earlier, the perfect alignment of the two components ensure any alterations of the shaft as a result of contraction or expansion during functioning is taken care of.
  • After engaging the installed bearing for a while, it’s imperative to do a close examination of specific parts. This will ensure the safety of the machine. These parts include the clamp nut and the adapter sleeve. Confirm if they are still tight enough. Any slight movement should be addressed immediately.