Panduan Lengkap Jenis Coupling: Definisi, Aplikasi, dan Konstruksi
In this article we are going to discuss about Coupling, Types of coupling, Shaft Coupling, Working and construction with Images. Let’s start with defining What is coupling?
What is coupling ?
A coupling is device that connects two shafts at their ends in order to transmit power. Couplings’ primary function is to connect two pieces of rotating equipment while allowing for some degree of misalignment, end movement, or both.
What is Shaft Coupling ?
A shaft coupling is mechanical component that connects two shafts in order to accurately transmit power from drive side to driven side while absorbing mounting error (misalignment), etc. of two shafts.
Shaft coupling is mechanical component that connects two rotating shafts, such as driving and driven shafts, for purpose of power transmission. It is found in motors, pumps, generators, and compressors, among other things.
Shaft coupling connects electric motor and pump hydraulic system. Slip-free shaft couplings for centrifugal pumps are classified as rigid or flexible.
Functions of Coupling ( Shaft Coupling )
1. Transmission power :- Transmission of power from driving side (turning side) to driven side (turned side).
Main purpose of coupling is to connect drive shaft to driven shaft. It is difficult to manufacture machine that is connected with one-piece shaft rather than coupling. It causes issues in terms of cost and accuracy, but it also makes transportation and assembly difficult, necessitating additional man-hours. In addition, if either drive or driven side of one-piece shaft is broken, it must be replaced in entirety.
2. Absorb misalignment :- Mounting errors between axes of driving side (turning side) and driven side are absorbed (turning side).
It takes long time to precisely align drive shaft to driven shaft. If axes of two shafts are misaligned, extra force is applied to surrounding parts as it rotates, causing vibration and noise. Furthermore, even though same parts are used to manufacture units, there are errors such as machining accuracy, making it very difficult to assemble every unit with accuracy because dimensions differ one by one. As result, coupling should be used to absorb such mounting errors.
Coupling’s role is to transmit power dynamically and accurately even if two shafts are misaligned (eccentricity / declination angle, axial displacement, etc.).
3. Absorb vibrations to protect surrounding products :- Absorbs vibration from driving side (turning side) and protects surrounding products.
When using machine, vibration and shock may be transferred to surrounding parts. For example, if vibration of motor, etc. in driving side is transmitted to ball screw, etc., it causes machine to deviate from prescribed position and makes good use of machine’s performance impossible.
In addition, if machine with no coupling is hit from outside, impact may be transmitted directly to motor, causing damage to motor. Solution to this problem is coupling. It absorbs vibration in order to move driven side with high accuracy, and/or shock in order to protect expensive motors and other components.
4. Do not transfer heat of motor, etc. to driven side :- Does not transfer heat from motor on drive side (turning side), etc. to driven side (turned side).
When motor is used, it generates lot of heat. When transmitted to driven side, ball screw and other components expand due to heat and their lengths change. As result, positioning accuracy suffers, and expected machine precision is not met. However, by using coupling, it is possible to prevent heat transfer from motor, etc., so parts are not deformed or shifted from proper position.
How does Shaft Coupling Works ?
As shown in diagram above, coupling can be used to connect two shafts. It is not problem if shaft diameters differ.
According to diagram above, motor is on driving side and propeller is on driven side.
Coupling does not transfer heat etc. of motor to driven side.
Coupling did work of absorbing shock and vibration from transferring, this will help to protect surrounding components from damage.
Types of Coupling
1. Rigid Coupling
Rigid couplings are used to connect two shafts when they are in perfect rigid axial alignment.
Rigid couplings are types of coupling that should be used only when shafts are perfectly aligned. Rigid coupling is only appropriate for shafts that are in close alignment or are held in alignment. Torque will be transferred to shafts and bearings if they are not aligned, resulting in premature failure.
There are two principal types of rigid coupling :
A. Muff coupling, and B. Flange coupling
2. Muff coupling
A muff coupling / Sleeve Coupling is simplest type of rigid coupling, consisting of hollow cylinder with same inner diameter as shaft. It is fitted over ends of two shafts by means of gib head key. Power is transmitted from one shaft to other shaft by means of key and sleeve or muff.
It is simple type of rigid coupling ,made up of cast iron. It consists of hollow cylinder whose inner diameter is same as shaft. It is fitted over ends of two shafts by sunk key.
Simply, A muff coupling or box coupling, consists of solid box or muff made of cast iron, bored out to fit shafts whose ends are made to butt together inside box. Box may be secured to shaft by means of sunk key which extends whole length of box. Sometimes two keys are used to fit muff on shafts.
Power is transmitted from from one shaft (drive ) to other shaft (Driven) by means of key and sleeve.
3. Split Muff or Compression Coupling
Split muff couplings are also known as compression couplings or clamp couplings. It is type of rigid coupling.
Sleeve in this coupling is made of two halves. Muff’s halves are made of cast iron. Muff is attached from below, and other half is attached from above. Mild steel studs or bolts and nuts hold two halves of sleeve together. Number of bolts can range between four and eight. They are always divisible by four. Bolts are inserted into recesses cut into sleeve halves.
Advantage of these types of coupling is that position of shafts does not need to be changed when coupling is assembled or disassembled. This coupling is suitable for both heavy duty and moderate speeds. It is cheaper than other types of coupling. It has compact construction with small radial dimensions. It has no projecting parts except key head.
4. Flange Coupling
Flange coupling is type of connector that connects two turning clutches with different flange arrangements. At ends of shafts, flanges are fitted or provided. Number of nuts and bolts are used to secure flanges together. At end of each shaft, one of these flanges or chutes is fixed.
What types of coupling is flange coupling ?
Flange coupling is type of shaft coupling having two separate flanges which are mounted on shaft end and both flanges are bolted together by means of nuts and bolts
Parts of flange coupling
The “Flange Coupling” is very simple to describe. It is made up of two hubs (that fit on equipment shafts), with those hubs being machined with multi-bolt flange on one end. When equipment is “coupled”, flanges are bolted together and basically become ONE LARGE MASS!
Construction
It is made up of two cast iron flanges that are attached to ends of each shaft. To complete drive, two flanges are bolted together with bolts. Flange coupling connects two tubes in sealed manner.
One of flanges has projected portion part, and other has similar recess. Each flange end is joined together to ensure they are correctly aligned without causing resistance in material being passed through them.
It aids in aligning shaft and bringing it into same line. Nuts and bolts connect two flanges. These couplings are commonly used in pressurized piping systems. It is also used for heavy loads, so it is very useful for large shafting.
Different type of flange coupling are following
Unprotected type flange coupling
Protected type flange coupling
Marine type flange coupling
5. Flexible Coupling
Flexible coupling are used to protect driving and driven machinery from detrimental effects, which may arise from misalignment of shafts, vibration, sudden shocks loads, end float, or shaft Expansion. Most extensively used of all types of flexible coupling is probably crown-pin type coupling is shown in figure.
One or both half of coupling are provided with studs engaging in holes in other half. Studs have insulating and renewable flexible driving surfaces built up of leather washers or similar materials. This construction permits some axial movement and take care of starting shock or slight misalignment. Another advantage is that it can quickly be disconnected by removing driving pins.
Other types of flexible couplings are : belt-type flexible coupling used to transmit medium power at low speeds ; internal gear type flexible coupling used for heavy drives such as in rolling mills, cement Mills, etc. and Bibley coupling applied universally to machinery and shafting drives upto largest powers.
6. Bushed Pin Type Coupling
A Flexible Pin Bush Coupling is type of Power Transmission Mechanical Coupling used to connect two shafts together at their ends for purpose of transmitting power.
Bush pin type flexible coupling is alteration on flange coupling described above. In place of nuts and bolts in flange coupling, Bush coupling has rubber bush and pins and nuts.
Rubber bush allows flange coupling to be flexible.
Flexible flange coupling is made up of two flanges, one keyed to input shaft and other to output shaft. Depending on diameter of shaft, two flanges are joined together with 4 to 6 bush and pins.
Nut is used to secure pins to flange. To prevent rubber bush wear, inner surface of rubber bush is lined with brass.
Key is used to secure flange hub to shaft.
In general, 5 mm clearance is maintained between coupling’s two flanges. For starters, there is no rigid connection between two flanges, and power is transmitted via rubber bushes.
Coupling becomes more flexible as result of this.
Advantages
Its construction is simple
It absorbs shock and vibration during power transmission.
These types of coupling can handle misalignment of 0.5 mm laterally and 1.5 degree angular misalignment.
Disadvantages
It is not economical i.e. its cost is high due to more components.
Radial space required by coupling is more as compared to other couplings.
7. Universal Coupling
Hooke’s coupling is another name for universal coupling. It is used when axes of two shafts intersect at small angle. In theory, inclination of two shafts can be constant, but in practice, this changes when motion is transferred from one shaft to another.
When it comes to connecting shafts at angle, universal coupling is one of most versatile couplings. It can be used for shafts that are 90 degrees apart.
Figure above depicts universal joint. These types of coupling are widely used in power transmission. Universal coupling is found in transmission of automobile from gearbox to differential. Two universal joints are used on each end in these cases. One at propeller shaft’s end to gearbox and one on differential to opposite end.
Universal coupling is also used to transmit power to various spindles on multiple drilling and milling machines.
It also enables efficient power and torque transmission between misaligned shafts at any angle, hence name universal coupling.
8. Oldham Coupling
Oldham coupling is another types of coupling designed to join two shafts having lateral misalignment. It was invented by John Oldham in Ireland in year 1821.
Jaw couplings are being replaced by Oldham’s coupling. Oldham’s coupling is inversion of double slider crank chain mechanism.
Coupling is made up of three parts: two flanges and central disc. Keys connect two flanges to shafts. Flanges have inner grooves, as shown in figure.
Center disc, on other hand, has projections made onto it. These projections fit into grooves cut into flanges. As result, center disc is sandwiched between two flanges, and it is also free to slide in grooves as shown below.
Flanges are made of stainless steel or aluminum alloy. Central disc, on other hand, is made of polymers or plastics. This reduces friction between flange and center disc while sliding. It also adds flexibility to coupling.
Advantages
Its size is compact.
Easy to assemble.
In case of excessive load, center disc will be one to break first. Thus preventing failure of other important machine components.
Center disc can be replaced easily and is inexpensive.
It can effectively absorb shocks and vibrations.
It can tolerate misalignment in shafts.
Due to presence of plastic center disc, coupling becomes electrically insulated.
It is economical.
Disadvantages
It cannot tolerate angular misalignment.
It cannot tolerate high torque.
Due to sliding movement, center disc is subjected to wear, thus after particular time period, it has to be replaced.
Applications
It is used in stepper motor.
In robotics.
Servo motor applications.
In printers and xerox machines.
9. Gear Coupling
A gear coupling is device that connects two shafts at their ends in order to transmit power. Couplings do not normally disconnect or allow couplings to disconnect from shafts while in operation; however, there are few torque limiting couplings that slip or disconnect when torque limit is exceeded or problem arises.
Gear coupling is variant of flange coupling. Because of large size of teeth, gear couplings can transmit lot of torque. In this type of shaft coupling, flange and hub are assembled separately rather than as single part as in flange coupling.
Coupling Gears Each joint is built with 1:1 gear ratio internal and external gear pair. Furthermore, gear coupling is limited to angular misalignments of approximately 0.01-0.02 inch in parallel and 2 degrees in angular.
For similar applications, gear couplings and universal joints are used. These are typically used in heavy-duty applications where high torque transmission is required.
What is functions of gear coupling
Basic function of Gear coupling is to provide mechanical connection between two rotating shafts. They use gear mesh for transmitting power and torque between connected shafts. Hence, gear Coupling is mechanical device that transmits torque between two shafts by using gears.
Types of gear coupling
Gear couplings customarily come in two varieties, flanged sleeve and continuous sleeve
Where are gear coupling are used ?
Gear couplings are commonly employed on large, industrial machines such as pumps, blowers, compressors, mixers, etc. They can be used in smaller motion control systems, mostly with polymer sleeve as means of reducing backlash but other zero-backlash coupling designs are usually better suited to these applications.
10. Bellow Coupling
Bellows couplings are type of flexible coupling that has twin coupling ends called hubs that cap precision-engineered corrugated tube that serves as coupling body. Bellows couplings are well-known for exceptional torsional rigidity, which allows them to accurately transmit velocity, angular position, and torque.
What are below coupling are used for ?
Bellows couplings are single-piece flexible shaft connectors used to couple driving and driven shafts in mechanical power transmission assemblies. Flexible shaft couplings are used to counter inevitable misalignment that occurs between connected shafts and, in some cases, to absorb shock.
Bellows couplings are types of coupling with twin coupling ends known as hubs. These couplings have high torsional rigidity and can transmit velocity, angular position, and torque accurately. They are typically constructed of stainless steel. These couplings are used in applications requiring high precision positioning.
Bellows couplings have thin walls and are only slightly flexible in case of angular, axial, or parallel misalignment. Coupling bellows are welded to hubs. Torsional stiffness of these couplings is highest of any servo motor coupling.
11. Jaw Coupling
A jaw coupling is type of power transmission coupling that can also be used in motion control applications. It is intended to transmit torque while dampening system vibrations and accommodating misalignment, thereby preventing damage to other components.
What is jaw coupling used for ?
Jaw and Spider Couplings. Jaw & Spider (or Jaw-Type) couplings are common type of shaft coupling in industry. They are designed to transmit torque and rotation between two shafts, accept shaft misalignment, and help protect components from damage by damping shock and vibrations.
How does jaw coupling work ?
Element in jaw couplings is loaded in compression between jaws of mating hubs. Driving hub jaws push toward driven hub jaws as they operate in same plane. By being compressed between driving and driven jaws, elastomeric spider’s legs transmit and cushion force between them.
This coupling is used for general-purpose power transmission as well as motion control applications. Jaw coupling is intended to transmit torque while reducing system vibrations and adjusting misalignment, thereby protecting other components from damage.
Jaw coupling is made up of two metallic hubs and Elastoplast insert known as element, also known as “spider.”
Advantages
This system is capable of handling angular misalignment as well as reactionary loads caused by misalignment.
Has good torque to outside diameter capability.
Excellent chemical resistance and dampening capability.
12. Diaphragm Coupling
Diaphragm couplings are one type of nonlubricated coupling used in high-performance turbomachinery for torque transmission and misalignment of equipment shafts.
This coupling transmits torque from outside to inside diameter, and then from inside diameter to outside diameter.
Flexible members in diaphragm couplings are made up of single or series of plates. Misalignment of diaphragm can be angular, axial, or parallel. These types of coupling are used when high torque and speed are required.
Diaphragm coupling is made up of one or more metallic membranes that are attached to outside diameter of drive flange and transfer torque radially through diaphragm to attachment on inside diameter. Disk coupling is another type of metallic membrane coupling.
How does diaphragm coupling work ?
Diaphragm couplings have flexible members that are made up of single or multiple plates or diaphragms. It transmits torque from outside to inside diameter of flexible plate, across spool or spacer piece, and then from inside to outside diameter.
13. Fluid Coupling
A fluid coupling, also known as hydraulic coupling, is hydrodynamic or ‘hydrokinetic’ device used to transmit rotating mechanical power. It has been used as alternative to mechanical clutch in automobile transmissions.
Functions of fluid coupling
Fluid coupling, also known as hydraulic coupling, is hydrodynamic device that uses transmission fluid to transfer rotational power from one shaft to another. It is used in automotive transmission systems, marine propulsion systems, and power transmission in industries.
Working principle of fluid coupling
Fluid coupling or hydraulic coupling is device used for transmitting power from one shaft to another shaft by means of acceleration and deceleration of hydraulic fluid. Fluid coupling is based on hydro-Kinetic principles and requires that output speed be less than input.
It is made up of impeller mounted on driving shaft (input) and runner mounted on driven shaft (output). Impeller functions as pump, while runner functions as turbine.
Tangential component of absolute velocity is low in impellers near their axes. Where tangential component of absolute velocity is high near impeller’s periphery, fluid velocity increases as impeller accelerates.
As velocity increases, so does kinetic energy. Fluid exits impeller at high velocity, strikes runner blades, transfers energy, and exits runner at low velocity.
Why Shaft Coupling is Used ?
Following are some most common reasons for using shaft coupling:
Used to connect shafts of separate units, such as motor and generator.
For misalignment of shafts.
For mechanical flexibility
Absorbs shock loads transmitted from one shaft to another.
Protections from overload.
Applications of Coupling
1. Sleeve and Muff Coupling Line shafts are used in power transmission.
2. Clamp or split-muff or compression coupling line shaft are used in transmission of power.
3. Flange coupling used for alignment accuracy . For example : In marine.
4. Bushed Pin Flexible Coupling which are Used for connecting which have small parallel misalignment, angular misalignment, or axial misalignment.
5. Universal Coupling which are Used for transmitting rotary motion or power, e.g., aircraft, driveshafts, etc.
6. Oldham’s Coupling are Useful in applications where parallel misalignment exists, e.g., Printing Application.
We have tried to provide you with complete details about different types of coupling available and what are their advantages and disadvantages along with proper Images. Hope you loved this article. Please let us know about feedback in comment below.
