When shoving cars to spot at an industry, what is the preferred method of controlling slack?

Using the charge air brake system on the cars and setting the automatic brakes to minimum or light is the preferred method for controlling slack when shoving cars to a spot in an industry setting. This approach allows for smoother movement and better management of slack in the couplings between cars.

When shoving cars, maintaining control over the slack is crucial to avoid creating excessive tension or compression that could lead to derailments or damage to equipment. By using the charge air brake system and adjusting the automatic brakes to a minimum or light setting, the operator can effectively manage the speed and movement of the cars without inducing sudden changes that could exacerbate slack issues.

The other methods, while they have their uses in certain scenarios, do not offer the same level of efficiency and safety for managing slack. Manual brakes may be less effective in this context, and applying maximum thrust or engaging emergency brakes could lead to abrupt movements that increase the risk of accidents or damage to the train consist.