@big train posted:I think the item is an empty/load adjuster. If the car is loaded, the truck springs compress and the bolster will drop in relationship to the sideframe. As it drops the arm pivots as it makes contact with the top of the frame, activating something in the brake system to reflect the weight of the car.
Jim
And you are correct! You receive a tip of my hat.
The actual purpose is to provide higher brake cylinder pressure when the car is loaded, and to provide reduced brake cylinder pressure when the car is empty. You will see these devices on cars which are very heavy when loaded and very light when empty -- coal hoppers, double-stack container cars, etc.
This prevents sliding the wheels and causing flat spots when train brakes are applied and the cars are empty. It is possible to have both empty and loaded cars that are equipped with load/empty devices, in the same train
