Shafts are generally subjected to bending moment, torsion and axial force or a. Further details available from page 14 the fluid coupling with outer wheel drive is driven via the outer shell of the coupling. Find bending moments from gears, pulleys, or sprockets that are transmitting loads to or from other devices. Therefore a coupling with 5 inch shaft separation should be aligned to be within 0. Note that, when dimensioning the mating hub, the dimension into the keyway is taken across the maximum bore diameter. Key dimensions were standardized about 150 years ago. Metric standard parallel keyway and key sizes shaft diameter mm keyway mm key mm. The force transformation takes place from driving shaft to key then from key to sleeve and then to the driven shaft by means of key. For ensuring correct alignment, a cylindrical projection may be provided on one.
The hub is slightly larger than the shaft and key to allow it to slide over the shaft during assembly. Chapter 10 keys and couplings machine design, mechanical. Mount sleeves, seals lightly coated with grease, end plates, and. In order to have a greater length, it becomes necessary to join two or more pieces of the shaft by means of a coupling 3. The hub is slide over the key to provide the interface.
The shaft usually has a slot running its full length to accommodate the key, or a slot longer than the key starting at the shaft end. Shaft design objectives compute forces acting on shafts from gears, pulleys, and sprockets. The sunk keys are provided half in the keyway of the shaft and half in the keyway of the hub or boss of the pulley or gear. Installation involves lining up keyslots in the shaft and. F tangential force acting at the circumference of the shaft. The reducer low speed shaft diameter is 215 mm, the conveyor head shaft is 225 mm. As a rule, coupling hubs must be installed on shafts with a certain amount of interference. Design of shafts couplings ppt linkedin slideshare. The sunk keys are provided half in the keyway of the shaft and half in the. Flexible couplings are used to transmit torque from one shaft to another when the two shafts are slightly misaligned. A slight clearance should be present from top to bottom when the hub is on the shaft.
Shaft is a common machine element which is used to transmit rotary motion or torque. Rigid taper lock couplings in 8 sizes up to 10,500nm section 5. Keys and keyways 51 introduction university of babylon. The fluid coupling with inner wheel drive is driven via the hollow shaft and the internal impeller. Using this formula the toque acting on the shaft is calculated. Based on the usage of the coupling a keyway in made in the bore in order to transmit the torque by means of the key. The key prevents relative rotation between the two parts and may enable torque transmission. Size check select a gear coupling to connect a 500 hp, 1170 rpm electric motor to a drive high speed shaft of a maneuvering winch. The 350 kw, 1 440 rmin electric motor is driving the reducer with an output speed of 38 rmin. Normally sunk keys are used and in order to transmit the torque safely it is important to. If direction is regularly reversed, determine length of square key required for a sf 2. Be sure to check that the key fits tightly in the shaft keyway. Design a bushed pin type of flexible coupling to connect a pump shaft to a motor shaft transmitting 32 kw at 960 rpm the overall torque is 20 percent more than mean torque.
The design of shafts in some cases, such as those for turbopumps, is dictated by shaft. Install coupling assembly on drive shaft, it may be necessary to free the slotted adapter by pushing on loosened center capscrew. Note that a 5 inch spacer is the minimum allowed by api 610 1995 for process pumps. Troubleshooting power transmission couplings introduction power transmission couplings are used to connect two shafts that turn in the same direction on the same centerline. The common specification dimension, key size, is highlighted. Excessive amount of grease or oil inside coupling guards.
Indicate required length taking face pressure of key into consideration. The key and keyway dimensions were sized according to din standard 6885. Shaft keys are important machine components designed to transmit torque and rotative force. The outer shell of the coupling is linked with the driven side. At the same time jaw couplings have good misalignment characteristics and can transmit high torque. Access to both ends of tapered keys are required so that the key can be inserted and driven out when the key is being removed. Shafts are supported on the bearings and transmit torque with the help of gears, belts and pulleys etc. See the table below for the enlarged hubextended hub dimensions. Design of shafts, keys and couplings, design the diameter of a shaft on the basis of equivalent twistingbending moment and allowable shear stress, design the. Shaftcouplings ho w to select your flexible shaft couplings sizecalculation hp n.
Shaft couplings shaft couplings are used to connecetwo shafts in such away that when both shafts rotate, they act as one unit and transmit power from one shaft to other shafts to be coupled may have collinear axes, intersecting axes or parallel axes at a small distance. The key should fit snugly against the sides of keyway. A practical guide to shaft alignment plant services. Where of is the overload or service factor, for example if the maximum torque is 20% more than mean torque then of should be taken as 1. Sureflex plus couplings have exceptional torsional flexibility, with the 4way flexing action absorbing virtually all types of shock, vibration, misalignment and end float. Keyless shaft the torque transmitted through a keyless coupling without slipping or damage is. Do not use floating shaft couplings with long, overhanging shafts. Generally sunk key is used in muff coupling which makes it simplest coupling among all. It generally has circular crosssection and can be solid or hollow.
Rigid sleeve or muff couplings this is the basic type of coupling. Select a coupling to connect the low speed shaft of an ore conveyor drive to a speed reducer. Keys, couplings and seals material taken for mott, 2003, machine elements in mechanical design keys za key is a machinery component that provides a torque transmitting link between two powertransmitting elements. Good shaft alignment practice should be a key strategy in the. For a key to function, the shaft and rotating machine element must have a. Gearboxes contain a gear lubricant, are sealed, and usually operate maintenance free. In this case, the shaft of the coupling is supported with a single bearing, arranged as closely as possible to the outer sprocket or pulley. Twin shaft coupling a semifloating shaft coupling is combined with a. Highspeed shafts require not only higher shaft stiffness but also stiff bearing supports, machine housings, etc. The output shafts may be located on the sides or at the back of the gearbox. A reference for the usage of these couplings is shown in the left illustraion. The fit of the key is critical in assuring sufficient capacity of the shaft to coupling hub interface.
A key is a machine element used on shafts to secure the rotating elements like gears, pulleys or. Key is a machine element which is used to connect the transmission shaft to rotating machine elements like pulley, gear, sprocket or flywheel. Shaft keys, shaft key design, rectangular keys, square keys, woodruff keys, gib keys, taper keys. Links to pdf outline drawings, dxf drawings and 3d cad. Dimensions comply with din 68851 requires use of chamfered keys. It features a dropout center assembly for easy equipment maintenance.
Square and rectangular keys may be made with a taper of 1 in 100 along the length of the key. In this example, the test fixture is using torque transducer as torque senor for measuring torque. There are several types of shaft keys, each with their own particular role and application. In rotating machinery, torque is transmitted from shafts to coupling hubs or vice versa through keys, friction, or a combina tion of the two. Shaft design introduction standard diameters of shafts torsion. However keys also serve the purpose of protecting the parts against damage in case of excessive torque or load. This consists of a pipe whose bore is finished to the required tolerance based on the shaft size. The key is inserted into the bore of the hub, and the assembly is then fed on to the shaft, thus locking the key in position.
Friction will help transmit torque and provide resistance to axial motion of the hub relative to the shaft. A2a keys are use to provide a positive engagement between two members whose relative motion need to be restricted. Standard inch series bores and keyways data sheet ds103. Sureflex plus couplings are an excellent choice when low cost, high flexibility, low vibration. Shaft keys that reduce manufacturing costs and machine. Shafts are breaking or cracking at or close to the inboard bearings or coupling hubs.
Type s couplings are offered with epdm, neoprene, or hytrel sleeves. The basic dimensions width and length remain the same jijr all types. Design of shaft exam revisions important question,part1. Commonly keyed components include gears, pulleys, couplings, and. Couplings are normally furnished with an average interference fit of. Note that metric keys are rectangular in shape, and not square as in the english system. A machine properly aligned will be a reliable asset to the plant, it will be there when it is needed and. Rigid couplings are used in applications where misalignment is not a factor. Highspeed shafts must be carefully checked for static and dynamic unbalance and for firstand secondorder critical speeds. In mechanical engineering, a key is a machine element used to connect a rotating machine element to a shaft. Unit 6 keys and couplings keys and couplings structure 6.
The resulting friction is used to provide resistance to axial motion. Connected to the input shaft is a high speed power source such as a motor andconnected to the output shafts. Standard contains tables of recommended key sizes versus shaft diameter. A keyway is a slot or recess in a shaft and hub of the pulley to. Pdf a textbook of machine design keys and coupling.
Machine elements, power transmission devices kdk college of. Shafts are usually available up to 7 meters length due to inconvenience in transport. A list of the standard key sizes and corresponding keyways for metric shafts are listed below in table 2. Each cardan shaft size has a specifi c hole pattern. Mechanical engineering notes edurev pdf from edurev by using. Hrc, resilient couplings from 30 to 3,150nm, available in taper lock and pilot bore variants jaw couplings from 0. The hollow shaft with integrated impeller is linked. Shaft keys types and their design bright hub engineering. Make sure slotted adapter does not ride up on any radius or shoulder on the drive shaft. Determine torque in shafts from gears, pulleys, sprockets, clutches, and couplings. Clearance and interference coupling fits efficient plant. Coupling torque speed ofbores torsionally torsionally backlash.