Adiriron: Power-house Angel of the Merkavah
[Wheel of Life Angel by Elizabeth Frank, found at http://www.lanninggallery.com/]
on protective amulets. The name is frequently mentioned, yet I have not had a clear sense of its nature or function. At times, it is used as a divine name . Some argue it is a substitute for the Tetragrammaton. Other times, Adiriron is treated as an angel. So I am trying to get a handle on this elusive entity. While the name is used in amulets and herem [spirit ban] texts, it is most often mentioned in association with some aspect of the merkavah, the divine chariot. Thus it appears in Hekhalot Rabbati 14:
When a person seeks to descend to the Chariot he will call upon Surya, the Prince of the Countenance, and make him swear one hundred and twelve times in the name of Tutrusyiyah [with many titles]...and Adiriron-YHWH, Lord of Israel...
This could be a divine name or an angel, but either way it gives the adept access to highest levels of the celestial order. Perhaps we can split the difference; this indicates Adiriron is more than an angel, for he is a Malakh Adonai, a super-angelic entity with the "name" of God in it . As such he is either akin to, or another name for, Akatriel-Yah [see T.B. Berachot 7a]. Can we get any more clarity?
In Sefer Hekhalot, he is listed as one of three high angels that personify a divine attribute. In the case of Adiriron, that attribute is God's koach, "power."  This association of Adiriron with "power" is repeated elsewhere - Michael receives some of his angelic power from Adiriron! He commands every Saraf angel. Later he is described as the rokeiv ("rider") upon the wheels [of the divine chariot], perhaps this means he is a cherub, but by any account Adiriron is a driving force in the divine superstructure. 
My best interpretation is that he is a personification of the "dynamos," the attribute of power within the Godhead, and the reason that the name/entity fades from use is that later Kabbalah would refer to this same divine phenomenon as Gevurah.
Zal g'mor - to own the Encyclopedia of Jewish Myth, Magic, and Mysticism, go to: http://www.amazon.com/Encyclopedia-Jewish-Myth-Magic-Mysticism/dp/0738709050
 Meaning, in quasi-Hebrew, is "Mighty One." The odd -ron ending resembles the morphology of Metatron. Sometimes the name is divided into Adir Yiron.
 Scholem, Major Trends in Jewish Mysticism, p. 56, 363.
 Margoliot, Malachei-Elyon, p. 2 [translation is the author's]
ha-Kamia ha-Yehudi presents it as a divine name, noting that it has the same gematria value as the 42-letter name (p. 3).
 Dan, Unique Cherub Circle, p. 113.
 Sefer Temunah 17b-18a.