Arrow-Hart & Hegeman electric panels

Anyone know when Arrow-Hart & Hegeman went out of business or were bought by another company?

Arrow-Hart & Hegeman was the successor (merged in 1929) of a holding company formed in 1927 that owned two original companies (Arrow Electric and the Hart & Hegeman Mfg. Co.). They got into trouble with the FTC for the way they chose to organize but were eventually exonerated (I think) by the Supreme Court in about 1935.
http://wyomcases.courts.state.wy.us/applications/oscn/deliverdocument.asp?citeid=422382
I skimmed through all that but didn’t find and absolute answer, but I am pretty sure the company eventually became just Arrow-Hart, the remnants of which are a part of Cooper Industried today.