Sand Patch Grade. Cumberland Yard West. Engine SD40-2 YN2 Y110-NonStopSwitching Approaching cars to be coupled, applying Brakes. Increasing speed, not able to stop! Get a message saying damage has accrued. Sent back to beginning, have to Start over. What’s wrong? Rich
Forgive me for starting with the obvious, but are you cutting the throttle before braking? Or worse, accidentally increasing the throttle instead of applying the brakes? Another possibility would be using the air brakes (slower to react and cut, need to recharge) instead of the independent (locomotive) brakes.
Another possibility: did you set the brake cut-out and MU2A valves? Until you do that, your brake handles are strictly ornamental.