Did you know that Mack Truck at one time built trailers? I didn't until last week when, along with other truck writers, I toured the Mack Museum in its recently established Customer Center in Allentown, Pa.

This complex was the company's technical center until its headquarters and engineering staff were moved several years ago to Greensboro, N.C., the home of Mack's corporate sister, Volvo Trucks.

One of the vehicles displayed at the museum is a model 12-16S trailer built in 1938. It's a semitrailer with a single rear axle and Westinghouse air brakes, says a nearby placard. It was delivered to a fleet in New Jersey in May of '38.

The placard explains that Mack made 6,201 similar semi- and full trailers from 1929 to 1944, and some were bi-directional four-wheel wagons that could be towed from either end.

As you can see in the photo, the display trailer totes a Caterpillar industrial diesel, another relic from those Great Depression-era days. My memory didn't record the Cat engine's particulars, but its weight is probably well within the trailer's capacity of 12 to 16 tons.

The trailer, presented to the museum by Nuss Truck & Equipment, a Mack-Volvo-Isuzu-UD dealer headquartered in Rochester, Minn., is hitched to a '39 Mack BX tractor. It has a 151-horsepower Thermodyne gasoline engine and a TR-12 five-speed transmission. It was built with tandem rear axles but now has a single rear axle. It's on loan from Paul Nuss of St. Paul.

All the display trucks run and got onto the floor under their own power, except of course for the trailer, a curator said. Vehicles of 70-plus years ago look almost crude by today's standards, but they and the men and women who ran them did a lot of hauling that supported the continuous building of our country. Here's to 'em all!