Solution: Coupling solves the center / vibration / shock / string that you cannot solve!

For the choice of motor and pump equipment, we certainly attach great importance, but for the coupling connecting the two devices, the importance of their choice may be greatly underestimated by us, and the installation and correct steps of the selected couplings are often ignored. Wrong installation and uncontrolled misalignment can cause premature wear and potential failure of the coupling, as well as possible damage to the pump and motor. The basic function of the coupling is to transfer power, adapt to alignment and compensate for axial motion. Sometimes, the coupling can also absorb the shock or vibration. The choice of a suitable coupling depends on the four basic conditions of shaft misalignment or movement:

In the parallel mismatch, the end surface of the axis is parallel, and the axis center lines move laterally relative to each other.

In the misaligned angles, the unaligned angles may be symmetric or asymmetric.

The end of the axis floats. For example, temperature changes can also cause the thermal expansion and position changes of the axis.

Impact or vibration usually results in a torsional motion.

Elastic coupling can adapt to most equipment system inherent defects and state, even if the equipment shaft perfectly, once the equipment began to run, temperature will change, operating conditions will change, the foundation will change, such as these changes, must be a coupling, and not only the coupling, must be the right size, appropriate application of coupling.

1: the elastic coupling and the mismatch through the elastic coupling, to allow the pump and the drive equipment to be connected in a slight mismatch. Elastic couplings generally contain one or two elastic components to allow for slight misalignment. There are many kinds of elastic coupling, such as: diaphragm coupling. However, there are always some limitations to the allowable deviation of the elastic coupling. When the centrifugal pump and the motor are installed through the elastic coupling, the additional load and vibration are caused. As the coupling manufacturing become higher, they can withstand higher misalignment than before. However, even in the tolerance range of the coupling, each rotation will cause the bending deformation of the elastic element. In the long run, it will cause the coupling fatigue. Even with high-quality couplings, reducing misalignment is still beneficial.

Here is an overview of the various couplings, and the advantages and disadvantages of each one.

Metal flexible couplings: High speed, high torque applications Although elastic couplings are commonly used in many general industrial pump applications running up to 115 HP / 100 RPM, the limits of elastomer materials have been exceeded in applications that require higher torque and speed transmission. Gear couplings, grille couplings, and diaphragm couplings are metal couplings with greater torsionical rigidity and advantages in these applications.2.1: The tooth coupling is composed of a sleeve with the teeth on the outside of the hub. They are popular in high speed, high horsepower and high torque, low speed applications, and work well in applications requiring torsional stiffness. The coordination of the teeth in the coupling allows for misalignment, but the degree of compensation in the angle misalignment depends on the profile of the gear teeth and the gap between them. Due to their design, these torsional elastic couplings can withstand some impact loads, but they cannot absorb large amounts of impact loads.

Figure 1: Tooth couplings ideal for high torque applications

2.2: The snake spring coupling consists of two trench flanged hubs connected by springs in a grid. As with tooth-type couplings, they require lubrication. At high torque, both high speed and low speed have considerable flexibility and efficiency. Snake spring coupling operating speed up to 400 HP / 100 RPM. Because of the stronger rigidity, their misalignment capacity is not as good as the elastomer coupling, so the alignment of the motor and the pump shaft is still critical.

Figure 2: Snake-shaped spring coupling

2.3: Membrane diaphragm coupling

The diaphragm coupling is designed evenly and can rotate at very high speeds, making it ideal for high-speed pumps. And the diaphragm coupling, like the elastic coupling, does not require lubrication. However, the diaphragm couplings are more sensitive to not neutralizing the axial motion. A disk or a metal component bending beyond its yield point can cause fatigue, and extensive axial motion can also lead to failure (Figure

Figure 3: Membrane coupling Using flexible metal diaphragm, which is preferred for high-speed applications. Three: elastomer coupling: floating, vibration isolation, impact load application

There are three basic types of elastic couplings: tire type coupling, sleeve type coupling and claw type coupling. The tire and sleeve coupling operate under shear (rather than compression) to absorb impact and protect the equipment.

1, the elastic element in the coupling can deform in the displacement and shear under the influence of the load. Torsional displacement or elastomer deformation can absorb the shock energy.2, The elastic element is also easy to compress and can accommodate end floating.3, suppress the vibration amplitude and isolate the axis from the axis.

3.1: Tire-type coupling

The energy generated during the impact load is essentially absorbed by the elastomer in twisting. One of the biggest advantages of tire type and sleeve type elastic coupling: failure under excessive impact load and disconnecting the pump from the motor under any excessive impact to protect the pump.

Tyre-type couplings are often used for continuously working ANSI pumps to obtain minimum vibration requirements. For example: applications that require variable flow rates. As the flow rate changes, the vibration of the entire pump increases. Tire type coupling plays the role of damper and can absorb vibration.

Figure 4: Tire Coupling

3.2: Slesleeve coupling is ideal for many common pumps. These torsional elastic couplings are ideal for applications in a moderate mismatch. Typical sleeve coupling applications include deep well pump, vertical end suction pump, vertical turbine pump, etc. (Figure 5).

Figure 5: sleeve couplings are chosen for many universal pump applications.

3.3: Claw-type coupling deviceThe claw couplings are squeezed to deliver torque, and therefore do not have the same alignment capacity as the two elastic couplings, as well as axial and torsional damping capabilities. Caw couplings are usually used for low power applications where cost is the primary selection criterion. Caw couplings can be used in a variety of pumping applications including gear pumps, screw pumps, Roots and cam pumps (Figure 6).

One major advantage of the claw coupling is its fault safety design. If the elastomer fails, the device will continue to be driven.

Figure 6: Coupling

4: Coupling selection trap is selected through the coupling, and the pump user needs to pay attention to the "the more, the better" trap.

1. The large size of the coupling leads to reduced flexibility or compensation misalignment, while the large coupling causes additional stress to the coupled pump and motor.

2, couplings with too much mistolerance may be too soft or "submissive", which may cause vibration or rotation imbalance.

3, it is important to check the surrounding environment of the pump / motor operation when selecting the suitable elastic coupling. Is there exposure to extreme temperature changes.