It should have no projecting parts. Following types of rigid coupling are important from the subject point of view:. Following types of flexible coupling are important from the subject point of view:. It consists of a hollow cylinder whose inner diameter is the same as that of the shaft. It is fitted over the ends of the two shafts utilizing a gib head key, as shown in Fig.
The power is transmitted from one shaft to the other shaft utilizing a key and a sleeve. It is, therefore, necessary that all the elements must be strong enough to transmit the torque. In this case, the muff or sleeve is made into two halves and is bolted together as shown in Fig.
The halves of the muff are made of cast iron. The shaft ends are made to about each other and a single key is fitted directly in the keyways of both the shafts. One-half of the muff is fixed from below and the other half is placed from above. Both the halves are held together utilizing mild steel studs or bolts and nuts. The number of bolts may be two, four, or six. The nuts are recessed into the bodies of the muff castings. This coupling may be used for heavy-duty and moderate speeds.
The advantage of this coupling is that the position of the shafts need not be changed for assembling or disassembling of the coupling. Each flange is mounted on the shaft end and keyed to it. The faces are turned up at the right angle to the axis of the shaft. One of the flange has a projected portion and the other flange has a corresponding recess.
The two flanges are coupled together utilizing bolts and nuts. The flange coupling is adopted to heavy loads and hence it is used on large shafting. The flange couplings are of the following three types :. Unprotected type flange coupling. Generally, three, four, or six bolts are used. The keys are staggered at a right angle along the circumference of the shafts to divide the weakening effect caused by keyways.
Protected type flange coupling. Marine type flange coupling. The flanges are held together utilizing tapered headless bolts, numbering from four to twelve depending upon the diameter of the shaft.
In such a case and many others, as in a direct electric drive from an electric motor to a machine tool, a flexible coupling is used to permit an axial misalignment of the shaft without undue absorption of the power which the shaft is transmitting. Following are the different types of flexible couplings : 1.
Bushed pin flexible coupling, 2. Universal coupling. Two flanges, each having a rectangular slot, are keyed, one on each shaft. The two flanges are positioned such that, the slot in one is at the right angle to the slot in the other. To make the coupling, a circular disc with two rectangular projections on either side and at the right angle to each other is placed between the two flanges.
During motion, the central disc, while turning, slides in the slots of the flanges. Power transmission takes place between the shafts, because of the positive connection between the flanges and the central disc. The inclination of the two shafts may be constant, but in actual practice, it varies when the motion is transmitted from one shaft to another. It is used as a knee joint in milling machines.
Application of Couplings : Advertisement. Slightly thick rubber bushings are designed so that the studs or bolts perfectly fit inside it and bushing fits perfectly inside the holes provided. The major advantage of using this coupling is that it can be used for slightly misaligned shafts.
The rubber bushings add a certain amount of flexibility to the coupling which also helps to absorb shocks and vibrations. Application- Bush pin-type couplings are used where there is a little amount of angular, parallel or axial misalignment.
The gear coupling is another modified version of the flange coupling. In gear coupling, the flange and hub are different parts assembled together instead of a single part as in flange coupling. The hubs are externally splined but they are so thick and deep that you can regard them as gear teeth. Also the flanges have internal teeth. The gear ratio is and are meshed together.
The single joint gear couplings are limited to lower angular misalignments. Application- Gear couplings are used for heavy-duty applications where the requirement of torque transmission is higher. Both of these have blades mounted inside at a certain angle. The pump is mounted on the end of driver shaft while the turbine on the driven shaft.
The fluid enters into the pump through its centre and when the drive shaft rotates, due to centrifugal force it is pushed outwards.
The casing is such that it diverts the motion of fluid into the turbine and the turbine blades along with the turbine start rotating. This way the pump and the turbine both make a coupling. When an extra part called a reactor is introduced between the pump and the turbine, surprisingly the device becomes a torque converter which is an alternative to manual clutch in automatic transmission systems in cars! Application- It is widely used in marine and industrial applications where controlled start-up of the power transmission is very essential.
This is sooo cool! Also it is able to transmit power through variable angles. The joint is protected by applying grease on it and is covered by rubber boots. Application- Rzeppa joint is used in vehicles with independent rear suspension. In India, if you notice, you can see these joints near the rear wheels of rickshaws and tuk-tuks or chhakdas. As the name suggests, this type of coupling can be used anywhere.
The universal joint can transmit power even at high parallel or angular misalignments. These couplings are typically used in pressurized piping systems. Also, it is employed to heavy loads hence, it is very beneficial on large shafting. It is used to connect two shafts that have both lateral and angular misalignment.
Bushed pin-type coupling, Universal coupling, Oldham coupling, Gear coupling, Bellow coupling, Jaw couplings, Diaphragm couplings. This is used for slightly parallel misalignment, angular misalignment, or axial misalignment of the two shafts. It is a modification of the rigid flange coupling. It consists of two halves that are dissimilar in construction and bolts known as pins, rubber bushes which are used over pins. There is a clearance of 5 mm between the faces of the two halves of the coupling.
There is no rigid connection between them and the drive done through compressed rubber or leather bushes. It is used when two shafts axis intersects at a small angle. The inclination of two shafts can be constant, but in actual practice, this changes when the motion is transferred from one shaft to another. A universal joint is shown in the above figure.
These couplings are widely used in the transmission of power. Universal coupling is found in the transmission from the gearbox to the differential of the automobile. In these cases, two universal joints are used on each end. One at the end of the propeller shaft to the gearbox and one on the differential to another end. Universal coupling is also used for the transmission of power to different spindles of multiple drilling machines and milling machines.
Oldham coupling used where two shafts have a lateral misalignment. The below figure shows the schematic diagram of Oldham coupling. As a figure, it consists of two flanges A and B with slots and a middle floating part E with two tongues T1 and T2. The middle part is fixed by means of pins which are fitted to flanges and floating parts. The T1 tongue fits into flange A allows back and forth motion and T2 is fitted into flange B and allows for vertical motion of the parts.
These two components of speed will result in the lateral misalignment of the shaft being adjusted as they rotate. The gear coupling is a modified version of the flange coupling. Gear couplings can transmit high torque because of the large size of the teeth. In this types of shaft coupling, the flange and hub are separately assembled together instead of a single part as flange coupling.
In construction, each joint has a gear ratio internal and external gear pair. And gear coupling is limited to angular misalignments about 0. Gear couplings and universal joints are used for similar applications. These are mostly used in heavy-duty applications where the torque transmission is required to be high. Bellows couplings are flexible coupling with twin coupling ends called hubs. These couplings have excellent torsional rigidity to accurately transmit velocity, angular position, and torque.
They are usually made up of stainless steel. These couplings are used where high precision positioning is required. Bellows coupling consists of thin walls and has minor flexibility angular, axial, or parallel misalignment. The hubs are welded to coupling bellow.
These couplings have the highest torsional stiffness of any servo motor coupling. This coupling is used for general purpose power transmission it is also used in motion control applications.
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