Just over a month ago, we posted a well-received article titled "Active Coupling Bore and Keyway Standards - What Are They & Where Can I Find Them?" While this well researched article covered and provided direct links to over a dozen standards pertaining to bores and keyways, the article begged the question "What other coupling standards are out there?"
While the question does seem daunting, fortunately, much of the work has already been completed by a fantastic team (which we may or may not have been a part of) working on behalf of the Mechanical Power Transmission Association. (Quick shout out to Dan F., Lovejoy VP of Operations, who is currently sitting as President of this organization!)
The MPTA document lists no less than twenty one distinct standards organizations that have a role in coupling regulations, and in most cases has an active link to each organization's website. From the American Bureau of Shipping to the American Petroleum Institute to the Mine Safety and Health Administration, a wide range of industries and interests are included in this list.
Where the MPTA document does fall a bit short on this herculean task is that they do not link to specific regulations themselves. (This is unfortunately left up to you and me to explore and discover.)
Without further delay, the following is the so described MPTA document: Standards and Regulations Affecting Couplings (MPTA C9-2014).
Bonus Offer: If you are the overly ambitious type, and would like to meticulously research these 21 organizations (plus possibly more) and provide direct links and a summary to all of their relevant standards (similar to our prior article narrowly focused on coupling bore & keyway standards)... we will be more than happy to post your research, give you a shout out, and send you some corporate swag from our highly guarded "prize closet". Ready, set, go!
The first thing to know about coupling bore and keyway standards is that there are quite a few currently active and available. Given your application and the origin of the product/shaft in question, you should be able to quickly determine what standard applies to you. (If not, call an application engineer at a coupling company you trust... and they will quickly point you in the right direction.)
Active Standards include:
In North America...
- API STD 610 - Centrifugal Pumps for Petroleum, Petrochemical and Natural Gas Industries
- API STD 671 - Special Purpose Couplings for Petroleum, Chemical and Gas Industry Services
- AIA/NAS NA0139 - Keyway and Key Slot Dimensions Metric (an Aerospace standard)
In Germany...
- DIN 6885-1 - Drive Type Fastenings without Taper Action; Parallel Keys, Keyways, Deep Pattern
- DIN 7172 - Tolerances and limit deviations for sizes above 3150 mm up to 10000 mm; principles, standard tolerances and limit deviations (ISO 286 Addendum for larger sizes)
In Japan...
And Globally (ISO)...
- ISO 286-2:2010 - Geometrical product specifications (GPS) -- ISO
code system for tolerances on linear sizes (Part 1: Basis of tolerances, deviations and fits & Part 2: Tables of standard tolerance classes and limit deviations for holes and shafts)
- ISO 3912:1977 - Woodruff keys and keyways
- ISO 3117:1977 - Tangential keys and keyways
In addition to these active standards, the Mechanical Power Transmission Association's excellent (and free) 18 page "Frequently Asked Questions on Metric Bores and Keyways in Couplings" PDF can be used to discover a number of no longer active (expired or withdrawn) bore and keyway standards. (Note: Unfortunately, the MPTA document does not provide a route to secure these documents... but at least they can confirm the standard you seek did in fact exist at one time.)
To broadly and briefly touch on bore and keyway standards, the North American (inch/imperial) standards tend to be more straight forward with limited variation (derived off the shaft)... while the metric options tend to be much more diverse (and were largely derived off the bore hole and were fragmented by various national approaches). Case in point, the metric standard (ISO 286), calls out over 100 different shaft and bore tolerances! Fortunately, great strides have been made to popularize a much smaller subset of these metric possibilities... and, today, many coupling manufacturers default to using just a few metric tolerances as their standard (with Js9 keyways, and H7 clearance fit or P7 interference tolerances for the bore being a very popular default).
And as a final (also free) reference: Lovejoy's Engineering Data PDF catalog, which covers both inch and metric shaft tolerances in great detail on pages ED-10 through ED-20.
(Bonus Hint: Lovejoy's Engineering Data catalog does comply with and specifically reference ANSI/AGMA 9002-B04 and ANSI/AMGA 9112-A04...and does use Js9 keyways as well as both H7 & P7 as default metric tolerances... so, if your need is narrow in scope, you might possibly consider saving a few bucks by pulling the data you seek directly from Lovejoy.)
