"HARTMAN SPECIAL V"

I have a vintage treadle sewing machine that has the words "HARTMAN SPECIAL V" on both sides of the arm, that I'm trying to get some information on with regards to who the manufacturer was and the date it was produced. In searching the Internet, I found that it is a "badged" sewing machine made by either National, Standard or White sewing machine company. Would anyone have any information on this particular sewing machine? And if so, anything would be greatly appreciated.
Thank you.