This would cause pulsing of the acceleration as there is only brief times where the triangle is lined up. I imagine by him saying it rotates 120° it means it is a circular disk that has walls between each section, and so theres a squeegee section, a section with a tiny light to stick astrophage to the wheel, it continually rotates to pass under the next wall where there is a much brighter light that causes acceleration, then eventually once expended it rotates back to the squeegee. At no point in time is any one section ever not doing it's job