This is a towed light artillery piece, like the Gatling, not a heavy small firearm: https://es.wikipedia.org/wiki/Ametralladora_Maxim#/media/Arc...

Later versions did become more portable, but the Maxim was always a crew-served weapon. The advent of the fully automatic small firearm was really the Kalashnikov 60 atrocity-filled years later.

It's true that the Gatling required an operator to turn the crank and was significantly slower than the Maxim gun.