|A Chabad "tank" in India|
The next day Rabbi Krinsky came to 770 and told the boys the Rebbe called their vehicles "tanks". This news spread quickly and from then on these vehicles became known as "tanks".
|... in Manhattan|
A few days later, the Rebbe held a "farbrengen" (chassidic get-together) in 770 in honor of the 12th of Tammuz, and mentioned the "tanks".
He said, that before tanks existed, they only had vehicles on wheels. As such, these vehicles could not traverse terrain that was hilly, ploughed, strewn with rocks or crevices. A tank, however, can handle these landscapes. So, if anyone felt he could not reach some Jews or influence them because of apparent barriers, the "tank" now lets him reach Jews to successfully influence them with sanctity.
He added, that the letters for Tank, in Hebrew, טנק, stand for 3 books by the Rambam, טהרה, נזיקין, קנין
which implies that 1) the boys must be of pure thought, and not think they can gain something from their reachout campaigns, like money, career, honor or "connections" of some kind; and 2) by doing their tasks solely for the sake of the Jew, all "harmful" or negative aspects of that Jew will more easily be eliminated, 3) which will allow the Jew to "buy" or "earn" all things involved with sanctity and Torah.