Definition of Coupling and Its Types: A Concise Guide
4 min
Introduction
Couplings play an extremely important role in mechanical systems. Are you sure you really know them well enough? You who are reading this article may be an experienced engineer or a user with temporary needs. In any case, JLCMC hopes that this article can help you well and deepen your impression of couplings.
1. Coupling definition
What is coupling? A coupling is a device that connects two shafts or a shaft and a rotating part, rotates together during the transmission of motion and power, and keeps the machine from disengaging under normal operation. Of course, there is more than one type. There are also some couplings with other characteristics (such as elastic couplings). They absorb the vibration and impact transmitted from the mechanical parts to a certain extent under the above conditions to buffer the load on the shaft, to improve the stability and life of the entire mechanical system.
Fig. 1 Coupling diagram
2. Coupling types
I. Rigid Coupling
We can even see the basic characteristics of rigid couplings from the name. When precise docking is required in the transmission to firmly connect the two shafts together, we usually choose rigid couplings. Because of its high precision, ultra-low inertia and high sensitivity, it is widely used in machine tool industry and packaging and printing machinery.
Fig. 2 Rigid Coupling
II. Bellows Coupling
Unlike rigid couplings, the working principle of bellows couplings is to use the bending deformation of bellows to transmit torque. Because its elastic element is composed of metal or non-metal bellows, it allows a certain degree of axial, angular and radial misalignment. This design is to compensate for the misalignment of the shaft, thereby reducing the vibration and noise in the transmission system. In harsh environments, the corrosion resistance and sealing of bellows couplings have become the first choice for engineers.
Fig. 3 Bellows Coupling
III. Universal Coupling
Universal couplings come with cross shafts and bearing assemblies. They are very special couplings. Common ones include single universal joints, double universal joints and cross universal couplings. They can transmit multiple angles and even large angle deviations between shafts. They are usually used in transportation vehicles, such as automobile drive systems, ship propulsion devices and heavy machinery, and have very good transmission performance.
Fig. 4 Universal Coupling
IV. Diaphragm Coupling
Diaphragm coupling is widely used in automobile, aviation, shipbuilding, metallurgy, chemical industry and other fields. Because it is a high-performance metal flexible coupling, when the driving shaft rotates, it can use the elastic deformation of the diaphragm to balance the relative displacement (axial, radial and angular) between the main and moving shafts. This can not only play a role in buffering and shock absorption, but also provide protection when the system is overloaded to avoid damage to mechanical equipment.
Fig. 5 Diaphragm Coupling
V. Quincunx Coupling
Quincunx coupling can also be called claw coupling, named because of its design. It mainly consists of two metal claw discs and an elastomer (usually polyurethane plastic or other elastic materials). When the main shaft rotates, the elastomer and metal claw disc of the Quincunx coupling interact with each other, thereby transmitting rotation and torque to the moving shaft. While transmitting, the elastomer continuously absorbs vibration and compensates for radial and angular deviations, thereby ensuring the smoothness and reliability of transmission. It is particularly suitable for working environments with frequent starting, forward and reverse rotation, medium and high speed, medium torque and high-reliability requirements.
Fig. 6 Quincunx Coupling
VI. Elastic Coupling
Speaking of elastic coupling, we will definitely think of rigid coupling, as if they are born to be opposite to it. Elastic coupling is a connection between shafts by springs, rubber and other elastic elements. These materials themselves have good plasticity and vibration and noise reduction characteristics, so their application scenario is almost completely opposite to that of rigid coupling, and it is often used in fan, pump and compressor drive systems.
Fig. 7 Elastic Coupling
VII. Hydraulic Coupling
Hydraulic coupling, a very unique coupling, uses liquid medium (usually oil) to transmit torque through kinetic energy. It must be said that this power transmission processing method is very effective. The hydraulic coupling has outstanding starting ability under soft start, overload protection and no-load conditions.
Fig. 8 Hydraulic Coupling
VIII. Electromagnetic Coupling
Electromagnetic coupling is a non-contact power transmission device based on the principle of electromagnetic induction. The premise of its creation is to eliminate the need for mechanical connection, to perfectly solve the traditional transmission method of complex daily cleaning and device wear in mechanical systems, which is an innovation of traditional transmission methods. Currently, they are commonly used in high-precision and dust-free environments, and can be seen in vacuum systems, semiconductor manufacturing equipment, and other precision industrial fields.
Fig. 9 Electromagnetic Coupling
Keep Learning
Gear Backlash Causes, Effects, and Control in Gear Systems
Introduction In mechanical power transmission, it is standard practice for gears to mesh with a specific amount of clearance. It is this small, intentionally designed gap that allows the gear system to operate smoothly. This movement difference is referred to as backlash in gears. In simple terms, backlash refers to the gap between meshing gear teeth, allowing the gears to rotate without jamming. Although backlash is defined during assembly, its physical basis lies in the thickness of each tooth on a ......
Gear Pitch Explained: How Pitch Diameter Affects Gear Design
Introduction In any gear system, the size, spacing, and meshing of the teeth all impact the efficiency of power transmission. Pitch is one of the key parameters influencing these factors. The spacing between the teeth around the gear is determined by the pitch, which directly affects whether two gears can mesh correctly. The pitch circle diameter is a key dimension in gear definition. It represents a theoretical circle around which all meshing tooth surfaces engage and roll. Pitch not only affects the......
Pressure Angle in Gears: Design, Effects, and Selection Guide
Introduction The pressure angle is a fundamental parameter in involute gear design, dictating the direction of force transmission between mating teeth. While it may seem like a subtle geometric detail, it exerts a decisive influence on tooth strength, bearing loads, noise levels, and overall manufacturability. In essence, the pressure angle determines the efficiency and smoothness of motion. However, in engineering practice, this must be balanced with backlash—the clearance between mating pairs—which,......
Understanding Gear Toothing and Gear Tooth Profile Geometry
Introduction The foundation of gear toothing lies in the tooth profile, defined by a unique and exact geometry for every tooth. The precision of this profile dictates the gear's performance, including noise levels, load capacity, and long-term wear resistance. This article aims to explain the fundamental parameters related to the geometry of the gear tooth profile. By becoming familiar with these parameters, engineers and students (as well as more experienced technical buyers) can gain further insight......
Gear Module: Exploring Its Meaning and Function in Gears
Introduction The gear module is a fundamental metric for determining tooth size and profile geometry. In the world of gear design, while the module is the primary standard for metric systems, it is intrinsically linked to gear pitch—another critical measure of tooth spacing. While many auxiliary parameters can be adjusted independently, the module remains the decisive factor that ensures compatibility between mating gears in any practical application. In engineering practice, the module dictates part ......
Explore Different Types of Gears and Their Applications
Introduction The gear is the basis of mechanical power transmission. Gears are like wheels with teeth, and they have two special features: They form a relationship between the speed of things (typically an engine and wheels). They change the direction of something. Virtually every mechanical device utilizes some type of gear, and gears are modified for a multitude of specialized applications. This guide provides a comprehensive breakdown of common and specialized gear types, exploring their unique fun......