Hatsudoki Seizo Co. “Daihatsu SB-7” motortrike, ca. 1938.

Hatsudoki Seizo Co. “Daihatsu SB-7” motortrike, ca. 1938, with a mounted spare tire. used here by a shoyu [soy sauce] brewer for deliveries. Founded in 1907, Hatsudoki Seizo manufactured some of the first internal combustion engines produced in Japan, later branching out into marine steam engine and electric power generation engine manufacturing. After developing a four-cycle air-cooled 500cc motorcycle engine in 1930, the company also moved into the manufacturing of three-wheeled vehicles at which time Hatsudoki Seizo began using “Daihatsu” as a marketing brand. (“Daihatsu” is a contraction of “Osaka Hatsudoki” [“Osaka Engine”], the first kanji for Osaka – 大 – having two contextual pronunciations, “oh” and “dai”.) The company would formally adopt “Daihatsu” as its corporate name in 1951.

“Hatsudoki Seizo Co. Ltd. was founded in 1907, starting out as an engine maker, building stout, well-engineered diesel, electric, and gas-powered mills for industrial and agricultural applications. They even got into making marine engines for a while.

“Building engines and selling them to other companies was all well and good for the first twenty-or-so years, but by the late-20s the company figured that it’d have a go at producing its own complete vehicle, and the Tsubasa [“Wings”] was born. It was also at this time Hatsudoki began using ‘Daihatsu’ (short for ‘Osaka Engine’) as a brand name.

“The first ‘Model HA Daihatsu Vehicle’ debuted in 1930, followed soon thereafter by the improved Model HB, the Tsubasa, the company’s first consumer vehicle which entered the market in March 1931. It was powered by the company’s 500cc, air-cooled single — an engine HSC had been selling to other companies — mated to a three-speed, hand-shifted trans.

“From about the seat post forward, the Tsubasa was a pretty normal-looking late-20s/early-30s-era bike (tear-drop gas tank, forked front tire, handlebars). From the seat back the Tsubasa was, essentially, a tiny pick-up truck. It had a broad cargo bed that sat on two wheels with an automotive-style differential. Twin frame spars ran forward from the cargo box providing cover for the rider’s feet and a convenient place to mount some shin guards. Given its relative size, the Tsubasa was remarkably nimble navigating Japan’s narrow streets. By all accounts, it was well received and quite popular.

“The SA-6 model was first introduced in 1937 and used as a blueprint for further work. The SB-7 model was built from 1938-1940, with many purchased by the Japanese military. While nearly identical in appearance, there were subtle differences between the two – most noticeably in engine displacement. The SA-6 was powered by a 630cc engine while the SB-7 boasted a 736cc engine.

“In the mid-30s motor tricycles were also popular in Italy, but the Japanese version had undeniable advantages: an increased engine displacement, a more durable chassis, and a stronger frame.”

– Wikipedia