Railroad dining cars were operated and staffed by the railroad (the company that owned the tracks and operated the trains). African Americans who were cooks and waiters on dining cars therefore worked for the railroad company, not for Pullman. (See Pullman-related objects and graphics throughout the 'Salisbury, N.C.' section of "America On The Move.") Most parlor cars and lounge/observation cars were also railroad-owned.
A dining car in the 1920s was staffed by a steward (in charge of the dining car and the one who seated patrons), usually three cooks working in the galley, and two or more waiters. On trains throughout the country, the steward was white and the other staff African American.
Meals were prepared entirely on-board, from fresh ingredients. Meats and vegetables were fresh; fruit might be fresh or canned. Pies and cakes were made on-board if the train traveled long-distance or overnight. Roasts, steaks, fish, chops, etc., were cut and prepared on-board. Storage lockers for china, cutlery, and glasses; ice boxes for perishables; stove and ovens; and storage for food supplies all fit into the galley. Cooks had a division of labor as in any restaurant kitchen, under the head cook. To adequately accommodate all this activity, the galley was about 1/3 of the length of the whole dining car. With patrons' seating in just 2/3 of the car, seating was limited, and thus there were usually two to three 'seating times' for lunch and supper. A passenger in a sleeping car could ask the porter to make a reservation for a given seating time.
Three customs were universal in dining cars: (1) For each seating, the steward seated patrons in first-come, first-served order as they appeared for the seating (if a passenger missed his reserved time, he missed the seating);
(2) the steward seated patrons at his sole discretion, filling tables entirely, without empty chairs (thus couples and singles almost always sat down with strangers -- but since that was the custom, most people enjoyed meeting their co-travelers in this way); and
(3) patrons themselves filled out their own meal-order cards, to ensure no mistakes in the galley; at a given table, the waiter verified patrons' completed cards before taking them to the galley (a container of little pencils on each table for passengers to use in filling out the cards was standard).
Waiters were skilled at carrying their laden trays down the center aisle of a swaying dining car and distributing food orders without mistake. Because of the tight quarters and limited seating times, high efficiency in order-taking, meal preparation, and serving was utterly essential.