A working machine includes a braking assembly and a throttle assembly. A controller is operatively connected to the braking assembly and the throttle assembly. A proximity sensor is operatively connected to the controller and is adapted to emit radiation away from the rear of the working machine, and to receive reflected radiation indicating the presence of a person or object within a danger zone adjacent to the rear of the working machine and within a warning zone that extends beyond the danger zone. The proximity sensor is adapted to send a signal to the controller when it detects a person or object in the danger zone to cause the braking assembly to brake the working machine, and to send a signal to the controller when it detects a person or object in the warning zone to cause the throttle assembly to reduce the speed of the working machine.