Surplus pressure is obtained from a difference between a hydraulic pressure value detected by a hydraulic pressure sensor and a target supplied hydraulic pressure. Each pixel 8-bit byte is converted to a difference byte representing the difference between the pixel and its immediate predecessor in a serialized stream of the pixel bytes. Both the first and second flanges include a at least one first aperture and at least one second aperture designed to receive a means for securing the car cover to the rail car.