The Depression and Harley Davidson

The Great Depression began a few months after the introduction of their 45 cubic inch model. Harley-Davidson's sales plummeted from 21,000 in 1929 to less than 4,000 in 1933. In order to survive, the company manufactured industrial powerplants based on their motorcycle engines. They also designed and built a three-wheeled delivery vehicle called the Servi-Car, which remained in production until 1973.
In the mid-'30s, Alfred Rich Child opened a production line in Japan with the 74ci VL, which became Rikuo after the parent company severed its business relations with Harley-Davidson.
An 80 cubic inch flathead engine was added to the line in 1935, by which time the single cylinder motorcycles had been discontinued.
By 1937, all the flathead engines were equipped with the dry-sump oil recirculation system that had been initially introduced on the 61E and 61EL "Knucklehead" OHV models. This prompted the 74 cubic inch V and VL models to be renamed U and UL, the 80 cubic inch VH and VLH to be renamed UL and ULH, and the 45 cubic inch RL to be renamed WL.
In 1941, the 74 cubic inch "Knucklehead" was introduced as the F and the FL, replacing the 80 cubic inch flathead UH and ULH models.