The pillow block bearings are a bearing used in rotary positioning applications. The bearings are designed with a central hole to give them high bearing rigidity, which helps maintain accuracy and reduce backlash. The bearings also have very low friction, which makes them ideal for rotating machinery. Some pillow blocks are designed with a pressure seal to fill them with grease, while others are designed to run dry.
Construction
The pillow block bearings use two side plates with a central piece of cast iron called the pillow block. The pillow block ends are split, and each has an inner race forming part of the bearing assembly. The bearing is pre-greased before delivery for easy installation. The inner races have threaded holes in them that allow the races to be screwed together.
Advantages
The pillow blocks appear very simple, but many advantages come from being rigid. This means they are accurate and need only minimal backlash to maintain a circular motion.
Pillow blocks can also resist large loads, which is important because they are used in machinery that moves large amounts of weight.
Disadvantages
The main disadvantage of the pillow blocks is that they are not self-lubricating. This means that the bearings must be oiled between uses, or some parts can be subject to friction.
The lack of lubrication also increases wear, so you may need to replace pillow block bearings much more often than other choices.
Applications
Since pillow blocks are so versatile, their applications are ubiquitous. They can be used in many machines, such as conveyor systems, pumps, lathes, and even lawnmowers. Large machinery that uses pillow blocks often uses them to ensure movement is smooth and without friction.
Pillow blocks may also be found in small items like car parts. The bearings are often used to reduce vibration due to the high rigidity of the bearings.
They are usually found in large industrial machineries, such as conveyors and pumps. The main application for these machines is the smooth motion of the parts.
Types of Pillow Blocks
There are two main types of pillow blocks: dry and greased. Dry pillow blocks allow the parts to rotate with minimal friction, while greased pillow blocks provide more lubrication for longer-lasting parts.
Dry-type pillow blocks work best in machinery with short rotation periods, such as a conveyor system. When used in this application, the dry bearings can provide two benefits: accuracy and minimal wear from friction.
Greased-type pillow blocks work best for longer periods of rotation. They can provide much more lubrication for the rotating part and allow you to use them in more applications without fear of premature wear.
Specifications
When selecting pillow blocks, it is important to consider the bearings’ inner and outer diameters. These are the measurements associated with the bearing. The inner diameter is the measurement of the central hole, while the outer diameter is what you measure outside each plate. The pillow blocks are measured in millimeters, and their specifications may include factors like load ratings and speed. Some bearings are for horizontal use, while others can only be used in a vertical position.
Safety Tips
The pillow blocks are designed with an inner race that can split along its length. This separates the bearings and prevents damage to the shaft and the machinery. The natural tendency is to put pressure on the bearing while attempting to separate them, which can cause injury if the outer race splits. It is important always to use a screwdriver or another tool when prying them apart.
