The way I read it they were turning the manual brakes on the car (the big wheel) that sets individual brakes.
>>>>I'm puzzled, though--wouldn't uncoupling cars on a moving train cause all the brakes along the entire train to get automatically thrown pretty quickly? Or did whoever uncoupled the cars cap the brake lines to prevent that from happening?
Had the angle cocks NOT been closed, the brakes would have set up on the entire train as soon as the "glad hands" on the air hoses uncoupled. Since the trespassers/vandals closed BOTH angle cocks, the train line was kept intact and no "emergenty application" of the brakes occured.
The hand brakes (big wheel) does set up the brakes on an individual car but did not come into the play at any time during this event.