This web site is designed to answer some common questions about precision shaft couplings and related products. If your question is not answered here, please use the contact form at the bottom of this page and we will do our best to find the answer. The information on this site relates to coupling product imported to Australia by Miniature Bearings Australia.
INDEX
The purpose of this web site is not to instruct on how to select a coupling, but rather to offer some basic information on coupling styles and the properties of those styles.
We suggest you consult an engineer for advice on any critical application.
The basic criteria for selecting a shaft coupling are as follows
The required torque can sometimes be found in an application handbook. If no handbook is available then the calculation of required torque is best left to an engineer. Once the required torque is known, the data tables for a prospective coupling selection can be consulted to determine whether the coupling will be able to achieve the required torque transmission. At this stage of any selection process it is important to realise that you should not rely solely on the data shown in product tables, especially in any critical application. A good engineer may be able to tell whether a coupling will be suitable for the job simply by knowing the coupling material, style and size, but for any critical application we recommend testing.
Angular and Parallel misalignment and shaft axial movement needs to be factored into all coupling selections. Some couplings can accommodate very little or no misalignment whilst other styles are quite tolerant. Generally couplings with rubber or plastic inserts will allow for more misalignment than full metal couplings, although some full metal designs can be very tolerant of misalignment.
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In determining the material compatibility a number of criteria need to be examined, including but not limited to...
If the application has a lot of vibration it may be necessary to use a coupling that incorporates rubber in the design. Full metal couplings are best suited to smooth running applications. Another consideration in vibratory applications is the locking method. You may need to consider how you are going to prevent the coupling from vibrating loose from it's attachment to the shafts.
It almost goes without saying that physical space available within the application should be taken into consideration when choosing a coupling, but it is surprising just how often this factor is overlooked.
Ball Type |
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Bantam |
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Bellows |
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BoWex® - Junior |
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BoWex® Tooth Driven |
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Clutch Type |
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Control Flex™ |
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Cross Joint |
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Crowned Tooth |
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Double Disk |
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Flexible Shaft |
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Gear Grip |
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Helical |
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Jaw Type |
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K Type |
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Multi Jaw |
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Neo Flex |
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Oldham |
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Rigid |
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Rotex® |
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Single Disk |
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Sleeve Type |
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Slip |
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Slit |
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Spider |
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Spline |
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Spring |
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Torque Tube |
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Uniflex |
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Uni-Lat |
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Universal Joints |
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Never rely entirely on one set of data for critical applications. Always re-check your figures with another source.
| To get the following units - multiply by the amount in the corresponding box. | ||||||||
| lb.ft | lb.in | oz.in | dyne.cm | N.m | N.cm | kg.m | g.cm | |
| lb.ft | - | 12 | 192 | 13,558,180 | 1.355818 | 135.5818 | 0.1383 | 13,825 |
| lb.in | 0.08333 | - | 16 | 1,129,848 | 0.11298 | 11.2985 | 0.01152 | 1.152 |
| oz.in | 0.005208 | 0.0625 | - | 70,615 | 0.007062 | 0.7062 | 0.0007201 | 72.01 |
| dyne.cm | 0.00000007376 | 0.0000008851 | 0.00001416 | - | 0.0000001 | 0.00001 | 0.000000010197 | 0.0010197 |
| N.m | 0.7376 | 8.8509 | 141.61 | 10,000,000 | - | 100 | 0.10197 | 10,197 |
| N.cm | 0.007376 | 0.08851 | 1.4161 | 100,000 | 0.01 | - | 0.0010197 | 101.97 |
| kg.m | 7.233 | 86.796 | 1,389 | 98,067,000 | 9.8066 | 980.66 | - | 100,000 |
| g.cm | 0.00007233 | 0.000868 | 0.01389 | 980.67 | 0.000098 | 0.0098 | 0.00001 | - |
Never rely entirely on one set of data for critical applications. Always re-check your figures with another source.
Distributors and Resellers please contact Miniature Bearings Australia for information on distributing the MBA product range.
Small Parts and Bearings online store. Small Parts and Bearings distribute the entire range of MBA product with a "help yourself" online store.
Hobby Engineering Supplies counter sales. Hobby Engineering Supplies is based in the MBA building and offer the full range of MBA product via a counter service.
John Crane Couplings John Crane offer their own range of power transmission couplings for larger applications.
Deanquip Deanquip are the Australian agents for Rotex® and Bowex® couplings.
Austenitic - Austenitic stainless steels are effectively nonmagnetic in the annealed condition and can be hardened only by cold working. Some ferromagnetism may be noticed due to cold working or welding. They typically have reasonable cryogenic and high temperature strength properties. Chromium content typically is in the range of 16 to 26%; nickel content is commonly less than 35%.
Chamfered - Chamfered edges refer to a small bevel on the edges of a product. Chamfered edges on the bore edge of a coupling and/or the edges of a shaft assist with the location of the shaft within the coupling.
DIN - Standards for materials as set by Deutsches Institut für Normung E.V. DIN Specifications can be purchased from www.nssn.org/
Fit - The degree of contact between two mating surfaces such as a coupling bore and a shaft. A slip fit is one where there is a small amount of clearance between the two mating parts allowing them to slide together quite easily. An interference fit is one where the actual sizes of the two mating parts overlap requiring a certain amount of pressure to assemble (eg. A shaft of around 7.994mm and a coupling of around 7.992mm bore).
Galvanic Corrosion - Corrosion caused by the mismatching of dissimilar metals.
Inertia - The tendency of a body to remain in it's current state of motion or rest unless acted upon by an external force.
Locking Method - The way that the coupling is held on the shaft. Common methods are by use of a grub screw, a bore reducer or any of a number of proprietary designed locking sleeves such as Shaftloc(r) or Fairloc(r).
Martensitic - Martensitic stainless steels are alloys of chromium and carbon. They are ferromagnetic, hardenable by heat treatments, and are usually less resistant to corrosion than some other grades of stainless steel. Chromium content usually does not exceed 18%, while carbon content may exceed 1.0 %.
Pilot Bore - A small bore usually drilled without regard to tolerances. This bore is used as a starting bore for the machinist to machine to their desired finished bore size.
Power Transmission - The transfer of power from a drive (motor) to a driven shaft.
Tolerance - The permissible limit of variation from the nominal size. For example an 8mm coupling bore may be represented as 8.000 mm +0.002 / +0.005 which would mean that the actual coupling bore may be anywhere between 8.002mm and 8.005. This would create a slip fit on an 8mm shaft and the coupling would then require some form of locking method to hold it firmly on the shaft.
Torque - Turning force. The force applied to cause rotation.
µm - Micron or thousandth of a millimeter (0.001mm).
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A detailed online catalogue is available by following the link to the Miniature Bearings Australia Online Catalogue. Downloadable PDF catalogues are available from the Miniature Bearings Australia FTP Site. The catalogue includes a large range of couplings, shafting, gears, belts, pulleys, bearings, springs, dowel pins, gearboxes, motors and much more. Miniature Bearings Australia are a wholesale only company and their product is available worldwide through a network of distributors. Hobby Engineering Supplies have negotiated for office and warehouse space within the MBA building and have direct access to all of the MBA product for counter sales. If you prefer to order online, you may like to visit the Small Parts and Bearings online store. Small Parts and Bearings offer the entire MBA product range through a "help yourself" online store.
Don't be caught out by unfair and biased terms in contracts. The Unfair Contracts web site highlights Australia's need for government regulation of the terms and conditions that may be included in consumer contracts. The Cleanaway Brisbane contract terms shown on the site are of particular interest. This site alerts us to just how much a company can get away with - legally.
For a great Trivia game see the online interactive trivia with over 1700 questions on the Coldrick web site.
