Motor Wheel at the Heart of Briggs & Stratton History

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Derek Watt, Glenmont, Md., with his two Motor Wheels: at left, a Briggs & Stratton Model D, and at right, a Smith Motor Wheel Model C.
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Motor Wheels were used to power "flyers" like this one.
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A Briggs & Stratton Motor Wheel on a scooter (owned by Sam Breeden).
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Missing its wheel, this restored Smith Motor Wheel engine has been fixed to a frame for display.
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Smith Motor Wheel assembly.

Briggs & Stratton engines are well-known for their role as an early source of power on the farm.

What’s less well-known is the fact that the Briggs & Stratton engine is a direct descendant of a 1 hp gas engine used to power early bicycles and scooters.

It began with the Wall Auto Wheel, invented in England in about 1910. The Auto Wheel consisted of a 20-inch wire-spoke wheel in a tubular frame that held a 1 hp air-cooled engine. The Auto Wheel was a sensation in England, and was equally well received in the U.S. after the A.O. Smith Company, Milwaukee, acquired U.S. manufacturing rights in 1914. The first Smith Motor Wheel, modified from its British cousin and painted a brilliant red, was produced and advertised for sale in October 1914.

According to a 1971 article in Antique Automobile by Jim Altman, when Smith began manufacture of its Motor Wheel, technology of the unit took a jump forward: “The chain drive and wire spoke wheel were eliminated. By using a four-lobe camshaft to lift the exhaust valve, the gearing was 8-to-1, thereby attaching a 20-inch disc wheel directly to the camshaft. The main frame structure consisted of two ‘horns’ attached to the crankshaft, which held the fender and gas tank.”

Smith produced thousands of Motor Wheel units until 1919, when the manufacturing rights were acquired by Briggs & Stratton, also of Milwaukee. Briggs made several significant modifications, including a larger bore cylinder, all-steel connecting rod with bronze inserts and a flywheel magneto. Upgraded to a 2 hp unit, the Briggs & Stratton Motor Wheel continued in production until 1924, when manufacturing rights were acquired by Automotive Electric Service Corporation. Using fundamental concepts from the Motor Wheel, Briggs & Stratton began manufacture of stationary engines for use on cultivators and other small farm equipment.

At the peak of its popularity, the Motor Wheel was a versatile unit used to power bicycles, scooters, “flyers” (a small, two-seat, low-slung wooden buckboard with steering wheel and four wheels) and railway inspection cars. A photograph in the Briggs & Stratton archives even shows an ice skater using a Motor Wheel to tow her around the rink.

“On the two-seater,” says collector Derek Watt, Glenmont, Md., “the Motor Wheel was mounted on the back. On a bike, it was installed next to the rear wheel, and on a scooter, it was installed as the rear wheel.”

Derek’s collection includes a 1918 A.O. Smith Model C Motor Wheel (rated at 1 1/2 hp) and a 1920 Briggs & Stratton Model D Motor Wheel (rated at 2 hp). The Model C was the final Motor Wheel produced by Smith before selling out to Briggs & Stratton.

When Derek found his Smith Motor Wheel, it was barn fresh: “The magneto didn’t have any spark, and it had the original tire [which Derek did not retain in his restoration because the tire was in poor condition], but otherwise it was original. I just cleaned and painted it, and a friend charged the magneto.”

The Briggs, on the other hand, was closer to a basket case. “When I got the Briggs, it had no gas tank, no fender and no drive wheel,” Derek recalls. “It was just an engine.” Now fully restored, it sports a reproduction tank, fender and a homemade drive wheel.

Derek is intrigued by the differences between the Smith and Briggs models. “The biggest technological change between the two was that the Smith Motor Wheel has an external magneto, but the Briggs has a flywheel magneto,” he notes. “The ‘horn’ on the Briggs is hollow, but the Smith ‘horn’ [which is removable] houses the muffler and oil reservoir. Both used the same carburetor, but they had two different pressure release valves. The Smith drive wheel is attached to the camshaft with five bolts; the Briggs drive wheel is attached to the camshaft with three bolts. And the Smith is rated at 1-1/2 hp; the Briggs is rated at 2 hp.”

Derek’s collection was inspired by friends who collect Briggs & Stratton engines. “They had all the usual ones,” he says, “but I really like having the Motor Wheels. I’m looking for a period bike to put the Smith on.” Motor Wheels are rarely found complete, he says, but in one form or another, they turn up at auctions, motorcycle swap meets and on eBay, where Derek found his. “I had some discretionary funds at the right time,” he explains, “and a wonderful wife who encourages my involvement in this hobby.

The hobby, Derek said, has been a pleasure in every way. “You get to meet all kinds of great people,” he says. “I’ve made lasting friendships in this hobby.” FC

For more information on the Motor Wheel, visit the A.O. Smith website:
For more information: e-mail Derek Watt at
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