Herlin gained experience by studying and working abroad, before he inherited his father's position as manager of the lift producer Kone Oy in 1932.

Harald Herlin was a water piping specialist and he managed plumbing company Oy Vesijohtoliike Ab until 1920.

The production in the Helsinki-located factory had grown steadily during Harald Herlin's leadership, but now the company started to develop rapid.

Finland was in an economical upswing after the 1930s recession was overcome, and number of new buildings, equipped with Kone lifts, were constructed.

Prior to the Winter War, the company employed 300–400 people and the annual production reached 250 lifts.

When the war reparations were finally paid off in the early 1950s, Herlin continued the export within normal trade agreements.

[1][2] While Herlin had strong background and expertise in engineering industry, he had broad knowledge in other areas as well.

He met there his future wife Anna Oittinen at the turn of the 1930s; she had come there as a nurse to take care of his mother Hanna Herlin.

[2] During 1931–1936 the couple got three daughters and one son, Pekka Herlin, who inherited his father's position as Kone leader.