Core definition: A coupling is a mechanical component used to connect two shafts (the driving shaft and the driven shaft), enabling them to rotate together to transmit torque and motion.
A simple metaphor: It is like the "joint" in the mechanical world, connecting two parts and allowing power to be smoothly transmitted from one end to the other.
The main function of couplings
Torque and motion transmission: This is the most fundamental function, which is to transfer power from the driving side such as motors and engines to the driven side such as pumps, fans, and gearboxes.
Compensating for deviation: This is the core function of flexible couplings. Due to manufacturing and installation errors or reasons such as thermal expansion during operation and foundation settlement, it is difficult for the two connected shafts to be precisely aligned completely, and there will always be certain deviations. Couplings can compensate for these deviations and protect the equipment.
Radial deviation: Two axes are parallel but their centerlines are not on the same straight line.
Angular deviation: The centerlines of the two axes intersect at a certain Angle.
Axial deviation: There is displacement along the axis direction of the two axes.
Comprehensive deviation: All the above three deviations exist simultaneously.
Buffering and vibration absorption: Some couplings (such as elastic couplings) have elastic elements that can absorb shock, vibration and fluctuating loads during operation, making the transmission smoother.
Safety protection: When overloaded, some couplings (such as safety couplings) will disconnect or slip, thereby protecting the important components of the motor and equipment from damage.
Clutch function: Some special couplings (such as clutches) can achieve the engagement and disengagement of two shafts during the operation of the machine.
Iii. Main Types of Couplings
There are many types of couplings, but they are mainly divided into two categories:
Rigid coupling
Features: No ability to compensate for deviations, and strict alignment of the two axes is required. It has a simple structure, low cost and can transmit a large torque.
Application scenarios: It is used in situations with low rotational speed, no shock, high shaft alignment accuracy and good rigidity.
Common types
Flange coupling: The most commonly used rigid coupling, which connects two half couplings with flanges by bolts.
Sleeve coupling: It has the simplest structure, with a sleeve placed over the two shaft ends, and torque is transmitted by a key or pin.
2. Flexible coupling (flexible coupling)
Feature: It has the ability to compensate for the relative deviation between two axes. This is the most widely used type.
It can be further divided into two categories:
A. Flexible coupling without elastic elements
Features: It compensates for deviations through the relative movement of its own components, but has no buffering and vibration reduction capabilities.
Common types
Gear coupling: It transmits torque through the meshing of internal and external gears, can compensate for comprehensive deviations, has a large torque transmission capacity, and is used in heavy machinery (such as steel rolling mills).
Slider coupling: Simple structure and strong ability to compensate for radial deviation.
Universal couplings: Mainly used in situations with significant angular deviations (such as automotive drive shafts), they are used in pairs.
B. Flexible couplings with elastic elements
Features: It compensates for deviations through the deformation of elastic elements and has excellent buffering and vibration absorption capabilities.
Common types (classified by elastomer materials) :
Metal elasticity: such as diaphragm couplings (compensating for deviations through the deformation of metal diaphragms, no backlash, high temperature resistance, long service life, used in high-precision and high-speed applications, such as pumps, compressors, and aero engines), bellows couplings (high torque rigidity, high precision, often used in servo motors).
Non-metallic elasticity: such as elastic sleeve pin couplings, plum blossom-shaped elastic couplings (relying on the deformation of elastic bodies like polyurethane, with good buffering performance and low cost), tire couplings (with extremely strong deviation compensation capacity and capable of absorbing severe vibration), and star-shaped elastic couplings.
Clutch function: Some special couplings (such as clutches) can achieve the engagement and disengagement of two shafts during the operation of the machine.
