During the 1905 general strike, he joined the national railroad workers union and was later selected it's executive committee.

In the 1918 Civil War, Kulo was the commissar of Tampere station and a member of the Red Guards general staff of the Tavastia Front.

He was injured in the explosion accident that killed the commander-in-chief Hugo Salmela.

During his sentence Kulo distanced from communism and joined the democratic socialist Left Group of Finnish Workers.

[2] After the war, Kulo was the chairman of Socialist Unity Party 1947-1948 and People's Democratic League 1948–1966.