Around the other machine elements, retaining rings are very important ones. In different kinds of applications, we use various shapes of them. Furthermore, you can find detailed information about these machine elements. Here, you can find;
- What is a retaining ring?
- What are the types of these rings?
- Assembly of retaining rings.
- Applications of them.
- Advantages and disadvantages of them.
What is Retaining Ring?
We use the retaining rings in the applications where we attach other machine elements on shafts. They are working like set screws. But there is no extra torque or power on these elements. They are holding these parts in place by their physical existence.
In general, these rings are in different kinds of shapes. But the most important ones are in circular shapes. And we attach them into the grooves of shafts. For example, we want to attach a pulley to a shaft. Also, we do not want to move the pulley axially. So, two retaining rings will be enough to hold this pulley.
For different kinds of applications, they developed different rings.
Types of Retaining Rings
According to their assembly methods and shapes, there are different types.
Constant Section Retaining Rings
As you understand from the name, the cross-section of this class is constant. The application of these rings both into the external and internal grooves.
Tapered Section Types
Also, this class of retaining rings has a cross-section that decreases starting from the lug holes. The assembly of these elements is generally on external or internal grooves of shafts. The types of tapered sections;
- Axial assembled,
- Beveled types,
- Bowed types,
- Inverted types,
- Radially assembled,
These types of retaining rings are the most common ones. By using pliers, we assemble them both into the external and internal grooves of the shafts. Also, they are circular shapes.
In these types of rings, there is a bevel angle which is around 15°. This angle provides extra wedging between the part and the groove of the shaft. So, the assemblies are much more rigid with these types.
These are the curved versions of the retaining rings. In their applications of them, there is a pre-load application. So, after the assembly, they have a pre-load and rigid structure.
In these types, the lug holes are inverted. So, a bigger diameter of parts can be assembled on shafts.
Radially Assembled Retaining Rings
These retaining rings are assembled on the internal grooves. And also these types do not have lug holes.
They are the self-locking types that do not have lug holes again. There is no need for grooves. Also, they are non-detachable. So, we need to destroy it to disassemble it.
Spiral Retaining Rings
Spiral retaining rings are the easiest to install and disassembled ones. They produce these types of rings from flat wire coilings. Also, there are notches for assembly and disassembly.
Assembly of Retaining Rings
In the assembly of these mechanical elements, we need to use special tools. Because, during the placing the rings inside the grooves, we need an extra strain on the ring to place them. We are doing this by using different tools.
One of the most common tools is pliers. We attach the tips of pliers to the holes of rings, and we squeeze or extract to place in the external or internal grooves on shafts.
Applications of Them
There are different kinds of applications of retaining rings. You can find their common applications of them here.
There are different kinds of accessories that we are attaching to shafts. Because shafts are generally load-carrying units. So, to hold these accessories in alignment, we use retaining rings. For example, we are placing pulleys between two retaining rings.
These machine elements are generally not carrying loads. They are only physical obstacles to the other elements. So, we are not expecting any mechanical strength from the just like other elements.
Rings of Pistons
This is the most important application of these elements. There are rings at the head of engine pistons. But the general purpose of the placement of these rings is not usual. We place these elements on pistons to provide ideal lubrication for the piston heads. So, they act as sealing equipment to prevent the oil that filtrates inside the cylinders.
Advantages and Disadvantages of Retaining Rings
Like the other mechanical elements, we need to consider the advantages and disadvantages of retaining rings.
- The most important advantage of them is, that they are not requiring any mechanical strength like other machine elements. So, we are producing them from low-strength and economical materials.
- Also, they are acting as sealing equipment if there is a lubrication application on the system.
- They are generally cost-effective parts. So we can replace these elements with the new ones easily.
- The most important disadvantage of them is, that their attachment and detachment of them are not easy. We need a special tool for the assembly.
- Groove structures on shafts will result in the decrement of mechanical strength. So, we need to consider it thoroughly.
- In the assembly operations, they create extra costs on the labor.
Total Holding Force Calculations for Retaining Rings
The holding force of the retaining rings is a very important factor. Designers need to consider the holding force of these machine elements. So, we need to be sure about which forces these rings can withstand. We use the equation below to calculate the total shear force that rings provide as holding force;
In this equation;
- C is the ring correction factor that comes with the catalogs of these elements.
- d is the diameter of the shaft in meters or feet.
- t is the depth of groove that we attach rings on the shaft. The unit is meters or feet in English units.
- S is the tensile strength of the shaft material. The unit of this value is N/m or lbf/ft.
- n is the safety factor. We define safety factors according to the design considerations.
There are different factors affecting the holding force. The most important one is the chamfer and corner radii on the grooves. They provide additional support for the retaining rings to stay in the groove. So, we generally use the chamfers and fillets on the shaft grooves.
The other important factor that affects the strength of the ring system, is the vibrational characteristics. Also, if there are vibrations in systems, the holding force will be significantly reduced.
Also, another important factor is the rotations of the parts. If the parts that are held by these elements are rotating, the effect of the ring will reduce.
Above all, as you can see, retaining rings may seem very basic mechanical parts. But their job is not basic. There are different kinds of applications that we use them.
We use these machine elements in the placement of other elements on shafts. Also, the assembly of them is made with special tools.
There are different types of these elements. So, we can choose a proper one to use in our applications. But also, the holding force calculations are very important for these machine elements.
Finally, do not forget to leave your comments and questions below about the retaining rings.
So, your precious feedbacks are very important to us.
FAQs About Retaining Rings
Their working principle of them is very simple. After the assembly, they prevent the sliding of elements that are attached to the shafts. They provide a physical obstacle for them.
The installation of these elements is simple. But you need to have a special tool which we call pliers. You can hold the holes of the rings, and attach them to the grooves of shafts or other structures.
The removal of these elements is very simple again. You need to use pliers to remove them. So, you need to attach the pliers to the holes of the retaining rings. And you can open them.
We are using them in the shafts to hold the other elements on the shaft in alignment. So, they prevent the sliding of other elements on shafts.
We use pliers to detach and attach the retaining rings on the shafts. We just need to attach the pins of pliers to the holes of the rings. So, we can easily detach and attach them by using pliers.
There are commonly two classes of them. The first class is the tapered forms. And the second class is the spiral forms. Also, in the first class of rings, these are the general types; axial assembled, beveled types, bowed types, inverted types, radially assembled, and self-locking retaining rings.
There are different kinds of them. You can use the detailed catalogs of retaining ring manufacturers to select the proper one for your mechanical applications. So, they are very good guides.