While Sheldon is quite correct to point out that most computer search algorithms effectively ignore the specifics of punctuation such as a hyphen, I believe that the discrepancy between the number of hits resulting from entering "Dura-Ace" versus "Dura Ace" into either Google or the CR Archive is quite easily explained. When one searches upon the term "Dura Ace" without any hyphen and delimited in quotes (...to do so without quotation would in effect request results based upon the presence of the individual words "Dura" and "Ace" wherein they need not be symbiotically paired) will render a subset based upon the appearance of those words where a blank space AND ONLY A BLANK SPACE separates the two. On the other hand, to search either database using the term "Dura-Ace" with the hyphen present will beget results not only where, indeed, there is a hyphen existent (...unlike the previous search) but also those instances where the two words "Dura" and "Ace" are juxtaposed with an intervening blank space (...and this is because, as we said earlier, most search algorithms are built to essentially "ignore" punctuation marks). The bottom line here is that searches based upon the term "Dura-Ace" should provide all of the same hits as one would get had they chosen to search using "Dura Ace" as well as those instances where a hyphen is present (i.e. the superset of the two distinct subsets).
As is most often the case, Sheldon is further accurate in pointing out the fact that "...the infamous Delta brake was Campagnolo" and decidedly not a Shimano product. And while we are in the mode of handing out accolades, Chuck is right on target with his assessment that the D-A (...oops, yet another shorthand notation that one might consider searching upon in their quest for the utmost inclusive construct) Parapul brakes were "...all about the aerodynamics".
And finally, Jerry is correct in pointing out the fact that the original Dura-Ace brakeset was a center pull configuration which predates the 1973 introduction of the official Dura-Ace line of components, which at that time actually included the Crane derailleur (...and just for the sake - pun intended - of playing a little Trivial Pursuit here, how many folks out there knew that Shimano initially chose the term Crane for its premier derailleur due to the fact that the majestic bird has a special place in Japanese society wherein it is closely associated with strength and longevity - excellent virtues for any derailleur to be sure, but a translation that was unfortunately lost on the American and European markets which is why the Crane name was eventually dropped in favor of the term Dura-Ace).
With respect to various vintage configurations of their center pull brakes, in addition to the original Dura-Ace calipers, Shimano also offered the model BB-500 having an integral quick release mechanism, the model BB-400 Shimano 600 center pull link type (...and yes, their 600 series also included two different versions of side pull brakes as well as a cantilever edition), as well as the model BB-100 Tourney center pull and model BB-120 Tourney center pull with quick release (...although the Tourney grouping did at one time or another also include no less than five distinct variants of side pull calipers).
For the benefit of those who are consumed by such details, as well as those who have only a very specific need to know things of this nature due to their immediate circumstance, I have been quietly working on digitizing what reference material I have on hand. True enough, I have had available to the public for quite some time now a select grouping of period literature within my Wool Jersey album. But in actuality, I have something on the order of one hundred more pieces of vintage literature of this nature yet to digitize and post - and the vast majority of same fall squarely within the CR List timeframe. Rather than release things in piecemeal fashion only to invite debate based upon the lack of some forthcoming document which might well address the very issue in question, it had been my intention to make MUCH further progress with respect to scanning these materials before releasing everything en masse. However, given the circumstance of this thread, I think it perhaps appropriate at this time to share yet a few more of those catalogs that I have already completed for the immediate benefit of others. Any interested parties are invited to review said materials using the following link:
Please understand that it will take a considerable amount of time for me to complete digitizing all of this literature and that time is not always a luxury that I have in great abundance. However, I will endeavor to move forward with my little project and promise to provide an appropriate notification to the List upon its ultimate completion.
Robert "a man of many words - arguably too many" Broderick ...the "Frozen Flatlands" of South Dakota
P.S. A HUGE debt of gratitude is owed Morgan Fletcher for his incredible generosity in providing the Wool Jersey venue for the benefit of the all vintage cycling enthusiasts. Without his patronage, I would likely have never considered such an undertaking. Thank you, Morgan.