How were aircraft moved on Béarn's rails?

Was there a locomotive to move aircraft along Béarn's hangar rails?

No. The aircraft were moved along the rails by hand.

Béarn's overhead system had no powered locomotive to move aircraft through the hangars. Deck crews pushed the suspended loads by hand from one stage of the transfer chain to the next. That labor requirement compounded the delay already created by lifts that did not reach the lower hangar. In rough water, the same crews also had to control aircraft swaying from the rails as the ship rolled.