First Mack AC Comes Full Circle

Thomas E. Spencer (right), who headed the team that restored the AC, drove the truck into the Mack garage with friend Carolyn Koroluk riding as passenger.

The first Mack AC ever built returned to the company’s Allentown, Pa., headquarters on Oct. 10 so employees could get a glimpse at one of Mack’s most famous early products.

The AC is the famous truck that, in military versions, helped the British fight World War I and caused Mack to adopt the British bulldog symbol afterward. The late Bill Moon, the truckstop entrepreneur who started Iowa 80 and Cat Scale, collected the truck, numbered 7,000 and built in 1915, before his death.

Recently, his widow Carolyn Moon and other members of the family had the spectacular old truck restored by Spencer Restorations of Nesquehoning, Pa., at a cost of about $100,000. Thomas E. Spencer, the restorer, drove the truck into an indoor area to protect it from the rain just before employees were invited to walk around it.

Mack executives who joined employees to admire the beautiful restoration included Mack President Paul Vikner and Mack Chairman Michel Gigou.

The truck’s sharp green and yellow paint job complete with pinstriping was restored to like-new condition, and all mechanical parts were completely overhauled. Spencer said the most difficult part of the restoration job was finding tools and techniques to reinstall the solid rubber tires onto the wooden wheels.

The truck was quite a technical achievement at the time. It featured a 48-horsepower four-cylinder gasoline engine governed at 1,000 rpm, and a three-speed, sliding gear transaxle, a combination transmission and differential much like those used in modern front-wheel-drive cars. The transaxle drove the truck through two chains. The chains linked sprockets mounted at the ends of the transaxle’s two output shafts to larger sprockets on the rear wheels. The service brakes slowed the truck by resisting the rotation of the chain drive sprockets on either side of the transaxle. The parking brake operated on the two rear wheels, using brake drums mounted in the traditional way. The parking brake served as an emergency braking system in the event of a broken chain.

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The engine had to be hand cranked by the driver, a feat made easier by its low 3.5:1 compression ratio. To get the engine to start more easily, the driver would first open four priming valves located on the cylinders and fill them with gasoline. He’d then turn the engine over gently a few times to put gas into the cylinders before closing the valves and cranking vigorously.

The truck featured two radiators, with one mounted on each side of the cowl, and an engine driven fan, but had no thermostat or winter heating system. There was no electrical system, only a magneto for ignition. Lighting was provided by acetylene, which came from a Prestolite-brand tank mounted on the left fender.

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