Flexible couplings are one of the major types of couplings. They find use to connect two shafts, end-to-end in the same line to transmit power that is torque from one shaft to another, thereby causing both to rotate in unison, at the same rpm. The other purpose is to compensate for small amounts of misalignment and random movement between the two shafts. Several factors should always be taken into consideration when looking to specify flexible couplings.
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These are torsional stiffness, backlash, torque, life, and attachment system. All of these have bearing on coupling selection. Specific details vary depending on the different types and their functions. In this article, we review the different types of flexible coupling in all aspects. Follow this new blog in Linquip to find out more about these types of couplings.
Most Flexible couplings are characterized as belonging to one of four main categories:
Mechanical Flexible Couplings
Elastomeric Couplings
Metallic Membrane Couplings
Miscellaneous Couplings
The mechanical flexible coupling generally obtains its flexibility from loose-fitting parts by rolling, sliding, or from both with some flexure of material. Flexible mechanical couplings provide a flexible or movable connection that accommodates misalignment between the shafts. This flexible feature reduces the forces or loads caused by the reaction to the misalignment. The mechanical nature of these types of flexible coupling allows for nearly unlimited horsepower and torque capabilities.
They maintain high torsional rigidity and allow a considerable degree of angular misalignment; however, they are not maintenance-free and require occasional lubrication unless one moving part is made of a material that supplies its own lubrication needs. Several different types of mechanical flexible couplings are as follow:
Gear Couplings
A common type of mechanical flexible coupling is gear coupling. Each coupling consists of two hubs with crowned external gear teeth. The hubs mesh with two internally splined flanged sleeves that are bolted together. They are called gears as a result of the generally huge size of the teeth. These couplings are commonly constrained to precise misalignments of 4° to 5°.
The gear coupling provides good torque characteristics. Gear couplings transmit the highest amount of torque and the highest amount of torque in the smallest diameter of any flexible coupling. Gear couplings require periodic lubrication depending on the application. These couplings have a service life of 3 to 5 years and in some cases, they can last for decades.
High torque density
All types of misalignment (angular, parallel, axial)
High torque at high speeds
Sensitive to lubrication failures
Application: Metal industry such as steel or wire mills, large industrial machines such as pumps, blowers, compressors, mixers, etc.
Grid Couplings
Grid couplings are multi-piece mechanical couplings used to transmit torque and rotation between shafts in mechanical power transmission assemblies. Grid couplings are comprised of two radially slotted hubs, a grid spring element, and a split cover kit. These types of flexible coupling are a popular option where both high torque levels and dampening requirements exist.
Grid couplings have a unique ability to reduces vibration by as much as 30%, and cushions shock loads to safeguard driving and driven power transmission equipment. They are available with either a horizontal or vertical split cover design. Grid couplings transmit torque and accommodate angular, parallel, and axial misalignment from one hub to the other through the rocking and sliding of a tapered grid in the mating hub slots.
Interchangeable components
High power density
Relatively straightforward
Simple installing
Good resistance to environmental conditions
Available for both inch and metric bores
Not maintenance-free
Require periodic lubrication
Application: Motors, pumps, reducers, conveyors, etc
Roller Chain Couplings
Roller Chain type couplings consist of two radially sprocketed hubs that engage a strand of double pitch roller chain. These couplings find a use for low to moderate torque and speed applications. The meshing of the sprocket teeth and chain transmits torque and the associated clearances accommodate angular parallel, and axial misalignment. These couplings are also able to accommodate up to 2 degrees of misalignment. They have flanges that are linked with duplex roller chains, giving them a high level of strength. Roller chain couplings are considered an economical way to transmit power between shafts.
High levels of torque
Requires frequent lubrication
Not suitable where slip and precise motion is required
Not affected by temperature and environmental conditions
Easy to install
Application: Transportation industry, woodworking machinery, agricultural machinery, oil well drilling rigs, building construction, material handling equipment, lifting load
Slider Block Couplings (Oldham’s)
Oldham’s couplings consist of three discs, one coupled to the input, one coupled to the output, and a middle disc that is trapped by 90° displaced grooves between the tongue and groove. These couplings can accommodate lateral shaft misalignments up to 10% of nominal shaft diameters and up to 3 angular misalignments. Some manufacturers claim an ability to tolerate up to 5-degree angular misalignment through the use of cylindrical, rather than rectangular, sliders. Lubrication is a problem but can be overcome by choosing a wear-resistant plastic or an elastomer in place of steel or bronze floating members.
No velocity variation as with universal joints
High lateral misalignments possible
High torque capacity
Oil resistance and electrical insulation
Suitable for small transmission torque occasions and connecting two coaxial transmission shafts
Sliders Can be chosen with different materials
Requires periodic lubrication due to relative sliding motion unless nylon or rubber construction is employed.
Possible loss of loose members during disassembly
Application: Robotics, printers, copy machines
Metallic Beam Couplings
Beam couplings are one-piece metal beam cylinders with spiral slots that are cut to form a spring-like flexing portion. Beams are shaped to allow torque transmission in either direction. They are considered miniature and used in small-sized equipment applications where and easy installation is important. The beam couplings are classified into two series: helical beam coupling and parallel slit coupling.
These couplings can accommodate parallel misalignments up to 0.025 inches and angular misalignments up to 7 degrees. They are used primarily for motion control applications where torques are typically below 100 inch-lbs. Zero backlash designs available ensure positioning accuracy between driving and driven shafts. These types of flexible coupling generally feature excellent flexibility and a lower price, as well as zero need for maintenance.
Good misalignment capabilities
No need for lubrication
Torsional stiffness for accuracy
Strong for carrying torque loads
Not suited for extreme operating environments with extreme temperatures and harsh chemicals
Identical clockwise and counterclockwise rotation characteristic
Application: CT scan, laser marking device, confectionery equipment, automatic rotation stage, matching box for RF power, 3D printer, food processing equipment, index table, encoders, tachometers, and other instrumentations
Bellows Couplings
Bellows couplings are single-piece flexible shaft connectors that are used to couple driving and driven shafts in mechanical power transmission assemblies. They consist of two hubs connected by a flexible bellows section. Typical bellows couplings tolerate angular misalignment of 1° to 2° and parallel misalignment from 0.01 to 0.02 in. Bellows couplings are known for their exceptional torsional rigidity to accurately transmit velocity, angular position, and torque.
They are used where precise rotation, high speeds, and dynamic motion must be transmitted. They exhibit zero-backlash and a high level of torsional stiffness, offering distinct performance advantages. Unlike other mechanical flexible shaft couplings, these generally need no lubrication.
Bellows couplings are often selected in place of low-cost jaw couplings and disc couplings by engineers looking to benefit from their well-documented performance advantages. It is also used in some heavy industry applications, where its ability to accommodate axial thermal growth makes it useful for installations with large temperature swings.
Able to run at speeds up to 12,000 to 32,000 rpm
Offers high rigidity
Suitable for sensitive motion-control applications
Capable of handling high accelerations and dynamic motions
Withstands high speed and thermal growth
Low tolerance for misalignment
Application: Bar feeder encoder, laser engraving machine, grinding machine, linear and ball screw actuators, robots, step motors, light-duty pumps, tube production machine, motor test bench, laser cutting machines, radars, etc.
Universal Coupling
The universal couplings are mechanical joints used for connecting two rotating shafts or rods whose axes are inclined at an angle to each other. They consist of a pair of hinges or fork shapes yokes oriented at 90° to one another and connected by a cross shaft. The universal coupling is also known as a Universal joint, U-joint, Cardon Joint, and Hooke’s joint.
They compensate for the angular misalignment and allows the shafts freedom of movement in any direction while transmitting rotary motion. These couplings operate at 250 rpm with an operating angle of 10°. The universal joint is mainly used for the lengthy shaft linings supported by bearings. They are used to transmit motion, power, or both. Universal joints can also be used in series to eliminate velocity fluctuations, to connect offset (non-intersecting) shafts, or both.
Large angular displacements are possible
High torsional stiffness
High torque capacity
Negligible backlash
Corrosion resistance
Capability for high-speed operation
Velocity and acceleration fluctuation increases with the operating angle.
Shafts must lie in precisely the same plane
Application: Automobiles, aircraft applications, driveshafts, stone crushers, control mechanisms, belt conveyors, metal forming machinery, control mechanisms, electronics, instrumentation, medical and optical devices, ordnance, radio, sewing machines, textile machinery, and tool drives.
These types of flexible coupling use a resilient material to transmit torque between two metallic hubs. Elastomeric couplings obtain their flexibility from stretching or compressing a resilient material such as rubber, and plastic. Some sliding or rolling may take place, but it is usually minimal.
The design of elastomeric couplings means that the elastic material is meant to wear out before any metal components. This not only saves time and money on maintenance but also means that the couplings do not require lubrication. A few advantages of this coupling are the high vibration dampening, shock absorption abilities, and toleration of a high degree of misalignment. They are also inexpensive and of lighter weight than mechanical couplings. The elastomeric element is sufficiently resistant to fatigue failure to provide an acceptable life compared to the cost of the coupling.
Exposing elastomeric couplings to high temperatures and UV light will reduce the coupling’s lifecycle. Due to the limitations of the flexible element, this type of coupling is used up to 37 kW and rpm.
Popular elastomeric couplings are as follows:
Tire Coupling
Jaw Coupling
Pin and bushing Coupling
Torsional Coupling
Tire Couplings
Tire-type couplings resemble the tires on a car. These couplings consist of two flanged hubs equipped with clamping plates, which grip the coupling’s hollow, ring-shaped element, by its inner rims. Tire coupling elements are rubber or polyurethane derivative elastomers with layers of cord, such as nylon, vulcanized into the tire shape. The coupling transmits torque through the friction of the clamp applied to the inner rims of the tire and the shearing of the element.
When the coupling fails, usually only the elastomeric part is replaced. Axial forces on the shaft caused by centrifugal forces working on the elastomer, restrict the speed of these couplings. Additionally, their bulky size limits what applications they could be applied to, although there is a variant with the tire inverted to reduce the coupling’s size.
High misalignment capacity
Easy assembly w/o moving hubs or connected equipment
Wide range of torque capacity
Easy installation
Virtually maintenance-free
Can accommodate angular, parallel, and axial misalignment
Application: Centrifugal compressors and pumps, machine tools, metal presses, mills, winches, and fans
Jaw Couplings
The jaw coupling or Spider coupling is a general, all-purpose industrial power transmission device. Jaw coupling is a material flexing coupling that transmits torque through the compression of an elastomeric spider insert placed between two intermeshing jaws. These couplings have two hubs with projecting jaws that mate with a one-piece elastomeric spider insert. For higher power applications, individual load cushions can be substituted for the spider. Torsional stiffness and torque capacity vary with the number, width, and shape of the jaws.
They operate in a range of temperatures, handle angular misalignment and the accompanying reactionary loads, resist chemicals, and have good speed and dampening capabilities. They are not extremely tolerant of misalignment as compared with other types of flexible coupling. The design of the jaw coupling is considered to be fail-safe, which could be a positive or a negative factor, depending on the application.
Useful in high acceleration/deceleration motion control applications
Electrically isolates the motor from the driven equipment
Continues driving upon loss of the flexible element
Application: Conveyors, blowers, mixers, winders, compression pumps, propeller pumps, printing presses, shredders, excavators, stone crushers, hammer mills, welding machines, etc
Pin And Bushing Couplings
They are simple types of flexible coupling with two flanges bolted with the help bolt and nuts covered by a bush made up of rubber. Pin and bushing couplings consist of two hubs that can be made of different materials and are fitted with pins where rubber bushes are attached. Relative movement is accommodated by the compression of steel-bonded bushings. This type of coupling can handle misalignment of 0.5 mm laterally and 1.5° angular misalignment.
These couplings are mainly used as flexible links in applications where reliable link transfer is required under severe operating conditions. Because of their simple design, these are less expensive. They are widely applied to hoisting applications.
More radial space is required compared to other couplings
Easy to assemble & disassemble
Application: Fans, line shafting, alternators, pulp grinders, shakers, rotary dryers, wire mills, cement mills, pulverizes, cranes, mechanical shovels and dredges, winding gears and drums, prolonged and reversing drives
Torsional couplings
Torsional couplings are mostly to accommodate the torsional vibration. Most of these are rubber coupling which can dampen the vibrations moving from one shaft to the other and also accommodate the misalignments. Spring torsional couplings are available as torsional couplings.
The goal of torsional coupling is to tune the system above or below its natural frequencies. Both torsionally soft (incorporating soft rubber) and torsionally hard (often incorporating hard plastics) are available to tune the system. These are very stiff couplings designed to shift critical speeds well above the operating range.
Torsional couplings are made to adapt to shafts, flywheels, or universal joints.
Low weight, low moment of inertia
Short profile for tight engine housing, or shaft-to-shaft requirements
Easily assembled, no special bands, tools, or time-consuming assembly procedures
Oil, heat, and corrosion-resistant elements
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Fail-safe operation
Applications: Diesel engine generators, marine applications, crawler tractors, manlifts, compactors, skid steer loaders, excavators, and lift trucks
Metallic membrane couplings rely on the flexure of metallic elements to accommodate misalignment and axial movement in shafts. These flexible couplings obtain flexibility through the bending of a membrane within the coupling. They have been around longer than the other three major types of couplings. These couplings require low maintenance and no lubrication, however, they may be more expensive than mechanical flexible couplings.
Metallic membrane couplings are somewhat expensive flexible couplings that, do not usually permit offset misalignment. These types of flexible coupling obtain their flexibility from the flexing of thin metallic, disc, or diaphragms. Classified as metallic membrane couplings, disc, and diaphragm couplings transmit torque and accommodate the slight misalignment anticipated between most equipment shafts.
Disc Couplings
The disc couplings have a thin sheet of discs laminated as the main part of the coupling for the flexibility to accommodate the misalignments. They consist of two hubs on each side and a spacer as a center member joined by the discs on both sides. The disc coupling’s principle of operation has the torque transmitted through flexing disc elements. It operates through tension and compression of chorded segments on a common bolt circle bolted alternately between the drive and driven side. A single-disc pack can accommodate angular and axial misalignment. Two-disc packs are needed to accommodate parallel misalignment.
A true limited end float design
A zero-backlash design
High-speed rating and balance
Finds use on fractional to 100,000 hp drives
Application: Hydrostatic application (Gearbox to hydraulic pump), turbomachinery, blower, compressor, mixer, servo motor applications, stepper motors, high-speed machine tools, semiconductor manufacturing equipment, actuator, surface chip mounting, and packaging machine
Diaphragm Couplings
Diaphragm couplings also use thin sheets as a flexible element like disc coupling. These couplings handle misalignment through the use of a single or a series of flexing metal plates or diaphragms in parallel for the flexible members. It transmits torque from the outside diameter of a flexible plate to the inside diameter, across the spool, and then from inside to outside diameter.
The outer diameter side of the diaphragm will be bolted with the hub and the inner side diameter portion of the diaphragm disc will be fitted into the slots of the spool portion also known as a spacer. On the other end of the spool will be again joined by a diaphragm disc with a hub. Diaphragm couplings can accommodate all three misalignments. It can accommodate more range of misalignment axially.
Diaphragm couplings were originally introduced to service very high speed, high horsepower applications in the petrochemical industry and have since progressed to other extreme applications such as helicopter drives. Diaphragm couplings are known for their large outside diameters, and, generally, very high cost. Diaphragm couplings are generally sold as custom solutions, and there are a wide variety of options to consider.
Used in high torque, high-speed applications
Finds use been used from fractional to 100,000 hp drives
Application: Turbomachinery, high power water pump, chemical pump, fan, compressor, hydraulic machinery, petroleum machinery, printing machinery, textile machinery, chemical machinery, mining machinery, metallurgical machinery, aviation, and high-speed power transmission system of ships
These types of flexible coupling obtain their flexibility from a combination of the mechanisms described above or through a unique mechanism like Spring and Schmidt couplings. Many of these designs require lubrication.
Spring Couplings
Consist of one or more square-wire springs that are concentrically wound and connected to hubs at each end of the spring. They are available in standard and miniature sizes and different lengths. The spring coupling can have many different hubs or flanges fitted to the ends and are available in. Spring couplings have been a part of powertrains for more than 80 years.
Multistage stiffness for optimized system tuning
Lubricated and non-lubricated environments
Drop-in replacement for original drive plates, no spacers required
Minimal impact from the temperature on performance or durability
Performance can be optimized for a given application
Space-efficient design
Application: Agriculture vehicles, construction equipment, industrial equipment, marine, mining equipment, gearbox, pump drive, hydrostatic drive, hybrid transmission,
Schmidt Couplings
Schmidt couplings are designed specifically to operate on shafts that are offset and to adapt to various drive conditions. They consist of an arrangement of links and discs. Three discs rotate in unison and are interconnected in series by three or more links between each pair of disks. These couplings offer great flexibility in shaft displacement while maintaining undisturbed power transmission at a constant angular velocity and torque in a wide range of parallel shaft misalignment. They use precision sintered parts for the hubs which are connected to the shafts.
Can adapt to very wide variations in radial displacement while running under load
Allows radial displacement greater than twice the radius of the disks
zero-backlash
Application: Papermaking machine, packaging machine, printing machine, wood processing machines, roll forming machines and, food industry
For the applications being compared, mechanically flexible gear coupling is most often considered because of torque, misalignment, speed, and environmental requirements.
Taking time to determine the right type of flexible coupling is worthwhile. Selecting a flexible shaft is fairly easy once you understand its basic operation and performance limitations. It might lead you to something different that will work better and last longer. The right flexible coupling design may also prevent shafts fretting, minimizing noise and vibration, and cutting long-term maintenance costs.
So, there you have every single fact about different types of flexible coupling. If you enjoyed this article in Linquip, let us know by leaving a reply in the comment section. Is there any question we can help you through? Our experts will be happy to assist you in finding the best flexible coupling needed for your technical challenge. Feel free to contact us on our website to get the most professional advice and answer your questions.
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After spending money on a powerful new pump and the motor to run it,the next big decision is how to connect the two in a way that maximizes their efficiencies and protects them from normal wear and tear.
Coupling the driving and driven shafts would be simple if they were perfectly aligned, machines did not vibrate and the shafts never actually moved. In the real world of power transmission, however, a flexible coupling can accommodate for the flaws and dynamics inherent in most systems.
“Even if you can get the shafts aligned perfectly, you are doing it when the equipment is not actually running,” said Paul Konkol, Marketing and Business Development Manager, Industrial Couplings, for Altra Industrial Motion.
“Once things start moving, temperatures change, operating conditions change, foundations settle. So you need a coupling, but not just any coupling. You need the right coupling, in the right size, for the right pump application.”
The basic function of all couplings is to transmit power, accommodate misalignment and compensate for axial movement (end movement of shafts). Sometimes, a coupling is asked to absorb shock or vibration. Selecting the right coupling depends on four basic conditions of shaft misalignment or movement.
Parallel misalignment occurs when the two shafts do not share the same rotation axis. Their end faces may be parallel, but their center axes are laterally displaced with respect to each other.
Angular misalignment applies when shafts are neither coaxial nor parallel. The angle at which the shafts are misaligned may be symmetrical or asymmetrical.
End float occurs when either or both shafts display axial movement, moving in and out. A sleeve-bearing motor, for example, “floats” as the rotor hunts for the magnetic center of the winding. Temperature variation can also cause thermal expansion and variation in position of the shafts.
Torsional flexibility is the torsional movement in planes perpendicular to the shaft axis. Shock or vibration typically causes this. A torsionally flexible coupling absorbs and dampens these movements.
Four basic conditions of shaft misalignment or movement that determine selection of the correct coupling.
The basic construction of the most flexible couplings consists of two flanges or hubs, which attach to the shafts being coupled, and a connecting element that may be metallic (such as in disc couplings), or a sleeve made from elastomeric material such as EPDM rubber, neoprene, Hytrel or urethane, or a mechanical connection (as in a
u-joint or gear coupling).
To be considered flexible, a coupling must handle parallel and angular misalignment. Couplings with four-way flexibility accommodate both end float and torsional movement.
One example of a four-way flexible coupling with good torsional flexibility is an elastomeric coupling that operates in shear (as opposed to compression). The elastomeric flexible member can deform or stretch in shear, displacing under a load. The amount of torsional displacement or elastomer “wind-up” is a measure of the shock that can be absorbed. It also compresses easily and stretches to handle end float.
The torsional flexibility allows the elastomeric shear coupling to dampen the amplitude of vibrations, isolating one shaft from the effects of the other. The energy absorbed during shock loads is essentially used to wind the elastomer in a twisting action. Since the force of the shock from the motor is reduced by the amount of energy expended in winding the flexible member, the pump shaft is cushioned from the shock. This energy is then released back into the drive system as the coupling unwinds.
Elastomeric shear couplings will also fail under excessive shock loads and disconnect the pump from the motor to protect the pump in the event of a lock-up or any other condition creating excessive shock.
“Couplings that use the elastomeric material in compression do not have the same amount of misalignment capacity or axial or torsional dampening capabilities as when you are running them in shear,” said Konkol. “In compression, you are squeezing the rubber to transmit torque, rather than twisting it.
“The molecular structure of the elastomer material in shear couplings is highly engineered because the material has to be much stronger to withstand shear forces. I liken it to the difference between cast metal and forged steel where, in forging, you basically align the molecular structure to make the material stronger.”
While elastomeric couplings are popular for many general industrial pump applications running up to 115 hp/100 rpm, the limits of elastomeric materials are exceeded in applications that require transmission of higher torques and speeds. Gear, grid and disc couplings are metallic couplings that are more torsionally rigid and offer advantages in these applications.
“Gear and grid couplings are excellent with higher torques, but as with anything, when you make gains in one area of design, there are things you have to give up in other areas,” Konkol said. “In this case, it is torsional dampening. These are stiffer couplings so more vibration is going to be transmitted through to the pump.”
Gear couplings are constructed with a sleeve containing internal teeth that mesh with teeth on the outside of the hubs. Popular for both high-speed, high-horsepower and high-torque, low-speed applications, they work well in applications that require torsional rigidity.
The fit of the teeth in a gear coupling allows for misalignment, but the degree of angular misalignment compensation depends on the contour of the gear teeth and the clearance between them. Because of their design, these torsionally stiff couplings can withstand some shock loading, but they cannot absorb significant amounts of it.
Grid couplings consist of two grooved flanged hubs connected by a tapered steel spring in the form of a grid. Like gear couplings, they require lubrication, but allow for flexibility and efficiency at high speeds or at low speeds with high torque. Grid couplings can operate up to 400 hp/100 rpm. Being more rigid, their misalignment capabilities are not as great as elastomeric couplings, so alignment of the motor and pump shafts is more critical.
Disc couplings are extremely uniform in design and can rotate at high speeds. Pumps operating at high RPMs are good applications for these well-balanced, smooth operating devices that, like elastomeric couplings, require no lubrication. Disc couplings, however, are quite complex designs and are extremely sensitive to misalignment and axial movement. Flexing of a disc or metallic component beyond its yield point can cause fatigue, and axial movement can cause failure.
With coupling selection, pump users should beware of the trap that “more is better.” Oversizing a coupling can result in a reduction in needed flexibility or misalignment compensation, and a coupling that is too large can put additional stresses on the pumps and motors being coupled. On the other hand, a coupling with too much misalignment capacity may be too soft or compliant, which can cause vibration or an unbalanced condition in rotation.
“For turbine-driven equipment running at 3,000 rpm or higher, you may want a disc coupling,” Konkol said. “For high torque, a gear or grid coupling may be the right choice.
“It is all about putting the right coupling in the right application, so that is where the manufacturer can be a valuable asset in the selection process. That engineering knowledge base can be a real value-added service to the user.”
Types of Mechanical Coupling
Types of Mechanical Coupling :- Coupling is used to connect two shafts belonging to different machines. For example, connecting shafts of Motor and Wheel. Simply it connects the Driving shaft and Driven shaft. Sometimes we need a shaft of length more than 7 or 8 meters. At that time to reduce the shock effect, we simply couple 2 shafts and get the required length of the shaft. The basic purpose is to join two different shafts but every time we don’t have similar conditions like sometimes we have a co-linear shaft, sometimes we have shafts having eccentricity. So, we need different types of coupling. Today we will talk about types of coupling. ( Shaft Coupling )
To connect two different machines.
To transfer power from drive shaft to driven shaft.
To reduce the shock effect on the equipment.
To eliminate overload problems to equipment.
:
Muff or Sleeve Coupling
Split-Muff Coupling
Flanged Coupling
Flexible Coupling
Oldham Coupling
Universal Coupling
Gear Coupling
Fluid Coupling
1. Muff or Sleeve Coupling
: ( Types of Coupling )
Sleeve Coupling
This is the simplest type of coupling. It consists of a simple hollow cylindrical part called a muff or sleeve. The diameter of the muff is manufactured by keeping the diameter of the shaft in mind. Here, two shafts (Driver and Driven) are fitted on both sides of the sleeve. Two threaded holes are also provided for bolts to keep shafts in their position and eliminate longitudinal motion. The key and keyway confirm no slip between muff and shaft. It is used to transmit low to medium torque. All the elements must be strong enough to work properly.
Advantages:
Cheap compare to other couplings.
Very simple construction.
It has only two parts sleeve and key.
Disadvantages:
Can’t use when shafts are misaligned.
Difficult to assemble and dismantle.
It can not absorb shock and vibration due to the rigid design.
: ( Types of Coupling )
Split Muff Coupling
In this type of coupling muff or sleeve is not a single part. It is made of two semi-cylindrical parts. Two semi cylindrical parts are made of cast iron. Here one part is fitted from above and the other from below the shaft. Both the parts are joined together by bolts or studs. Here two, four, or six holes are provided to fit the muff.
Advantages:
The main advantage is that don’t need to change shaft position while assembling and dismantling.
: ( Types of Coupling )
Flange Coupling
In flanged type coupling two flanges are kept together and fitted. Both the flanges have the same number of threaded holes. Both flanges are taken together and using the nut and bolt it is fitted. The gasket is used to eliminate leakage. It is widely used in a type of coupling. It is used for medium and heavy-duty applications. To ensure no-slip condition tapered key is used.
: ( Types of Coupling )
Flexible Coupling
It is the same as Flanged coupling only difference is that we use rubber bushing with nut and bolt. Here we simply design rubber bushing of hole size which will provide extra strength to absorb shock and vibration more easily than flanged coupling. Due to the use of rubber bushing little misalignment of shafts is also taken care of. It is used in medium-duty applications.
: ( Types of Coupling )
Oldham Coupling
Oldham coupling consists of two flanges with one middle plate. It is used when two shafts are misaligned and having distance between them. The middle plate is joined with two flanges via tongue and groove. Here grooves are perpendicular to each other. The main advantage is it used even there is high parallel misalignment.
: ( Types of Coupling )
Universal Coupling
This is used when two shafts are at an angle. The angle may be constant but while in motion angle may change. The most important use of Universal coupling is in heavy vehicles where the shaft from the gearbox is connected to the axel.
: ( Types of Coupling )
Gear Coupling
A gear coupling is a subcategory of Flange coupling. It has flange and hub as a separate part which is different from flange coupling. It is used in very heavy applications. Two shafts are connected at fixed holes and connected by the third spindle. They are also used when the angular displacement of the shaft is 4 to 5 degrees. Generally, it has a 1:1 gear ratio of internal to external pair.
: ( Types of Coupling )
Fluid Coupling
In this coupling, we connect the power supply to one shaft and the other to the power generator shaft. Here the pump is connected to the shaft and the turbine is connected to the second shaft. As time goes the speed of the pump impeller and turbine matches each other.
:
Used in the marine propulsion system.
Used in various industries for power transmission.
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