Hi
This is a 1938 "film noir" by excellence, extracted from the Emile Zola book, La Bête Humaine is about human nature polluted by excessive drinking upon generation makes a man to kill the woman he loves. (Not a very funny subject but still great because of the social description of the rail world in those days
One attractive aspect of la bête humaine is the detailed description of the train environment, of the train practices.

2:12 into the video you can see the water scooping operation.

A water reservoir located between the rails is emptied into the tender by way of a scoop lowered at the appropriate time and removed (raised) before the end of the "bac". This is the large lever Gabin is instructing to lower and pulling the chain himself to raise it.
This allowed the train to continue without stopping for longer train raides and was also common practice in the UK.

The movie also describes lubricating responsibility on friction bearings of the distribution gear. When a bearing is heating then there is a financial penalty to the driving team to pay for its replacement
The movie is also great (at least to me) because I know both extremity stations (Paris Saint Lazare and Le Havre) and seeing them 90 years ago is fascinating.
Cheers
Jean