Tire pressure is registered through a glass lens in the top:
I hope to refurbish it and put it back into use.
The Druge Brothers Manufacturing Company of Oakland, California seems to have specialized in air pressure tools, making pressure gauges that were used by the U.S. military among others. Their "Tru-Flate" trademark was registered in the U.S. in 1948.
They also seemed to have manufactured pinions for post-war Garand rifles. The only other reference I can find to the company is on a site featuring two toy "straddle carriers" otherwise known as "hysters, " "lumber carriers" or "lumber loaders." Daniel O. Druge et al. were awarded U.S. Patent No. 2601930 for this toy in 1952. Apparently, in their ads they pictured both the toy and the actual machine on which it was based, and their toys were dead ringers for the real thing. A remarkably whimsical product departure for the Druge Bros. firm.
"Tru-Flate" is now a trademark of Plews & Edelmann, a company with roots back into the early decades of the last century. They continue to sell window-style inflator gauges. My guess would be that they acquired Druge Bros. sometime along the way.