red mushroom n.— «A preliminary investigation also found that the train’s braking system was not defective and that the operator did not press the “red mushroom”—Muni parlance for the bright red button on the operator’s...
J-bar n.— «Install a mechanical device that locks to the steering wheel, column, or brake to prevent the wheel from being turned more than a few degrees. Commonly called clubs, collars or J-bars, these devices can act as a deterrent if...