The first apparently dates to the 1880s as a repair shop for saw mill, flour mill and other industrial machinery. The company apparently assembled machinery and crushers to be sold under the brand names of others.
The second apparently was a division of the former that was active from 1937 to 1953. The historical society has a good picture from 1954 with sings for the company prominently on display. I'm not sure that this is the same location, but there is also a good one of Mahr furnaces loaded on a rail car from 1922 and a shop interior from 1926. Today it is K&K metal recycling.