Plain shafts are mechanical components that are tasked with the duties of propelling movements, (either sliding movement or rotational) between two parts of a machine. Its main purpose is to avoid wear and tear in the point of support in the machine, which could occur when the two points were to roll directly on themselves or the structure.
If you are into any project but do not know which shaft to use or making a choice is giving you a headache? Do not worry, in this article we will talk about why a plain shaft is needed, uses and even types.
The plain bearings consist of two parts. On the one side, there is a fixed part, which supports the loads, this is called the support, and then, on the other hand, there is the surface that gets worn. This is the part that gets in contact with the moving elements.
In order to minimize the losses caused by the friction of the shaft, pairs of low friction materials are generally used or a lubricant is added between the parts: the solid is graphite or Teflon, while the liquid is oil and then the gaseous is compressed air.
Types of bearings
The shaft to use depends on the Kind of contact between the two parts and the bearings to be used and vice versa. Find below some bearings to be used:
This is used if the moving surfaces are a fixed surface, which has sliding friction and also has an oil firm to separate it.
They are also known as solid bearing, bushes, and friction shafts, and they generally have a cylindrical shape. In addition, they have no moving parts.
In these, there is a shaft journal and a rolling surface for the support, which are both separated by rolling elements. This is because so that when the bearing or the journal rotates, there is a rotational movement generated instead of the sliding movement.
They consist of two rotating rings and are separated from each other by other elements that are also rolling, and whose shape varies depending on the use.
– Depending on the lubrication system used, there are three basic types of plain shaft:
- The Self-lubricating bearings: you do not need external lubrication for this. They consist of porous materials which are saturated with oil, absorb and distribute it slowly through the moving parts of the machine.
- Regularly lubricated bearings: limited periodic lubrication is required for this bearing.
- Continuous lubrication bearings:
The lubricant is fed by an external pump. The main disadvantages are that a failure of the lubricant supply compromises the installation and their high costs.
The hydrodynamic shafts do not require external injection of lubricants, however, it’s the moving parts that produce a hydrodynamic effect that allows the oil to lubricate the parts in contact. These bearings do their work on their own and they don’t require an external supply of pressurized oil. Its use is essential for machines with high starting torque.
– There are three types depending on the position of the shaft with respect to the load:
• Axial: these can handle loads in the same direction of their shaft.
• Radial: they collect charges perpendicular to their shaft and not longitudinally.
• Thrust: these can both absorb axial and radial loads.
Why you would need a plain shaft.
There are reasons why you would need the plain shaft or prefer it over the other, and some of them are listed below.
Plain shafts are lighter.
Plain shafts allow for a longer fatigue-free service and life of their elements.
The shafts have Lighter weight.
The noise is less because it is Quieter in operation
It needs small or less radial space because they are built using thin walls.
They require simple installation.
Using self-lubricating shafts, the lubrication procedures are not required.
They allow higher rotational speed.
Greater and better shock resistance.