Abstract: A transmission for a multi-blade mower has a belt trained around a driving pulley and successively around driven pulleys for the blades. For driving, an idler pulley of a tensioner engages a portion of the belt that is "downstream" from the last driven pulley and "upstream" from the first one. When the tensioner idler is disengaged from the belt for slippage of the driving pulley relative to it, blade braking is effected by opposing stationary and movable brake members mounted at opposite sides of the belt at a normally straight stretch of it that is "downstream" from the tensioner and driving pulley and "upstream" from the first driven pulley, the movable brake member then cooperating with the stationary one to clampwise engage the belt and confine it in a groove in one of those members. Manual shifting of an actuator towards an "on" position tensions a spring that engages the tensioner with the belt, and such tension, through a toggle connection, tends to maintain the actuator in that position.