A ram cylinder control system for a wheel type hydraulic comprises a pilot hydraulic pump , pilot-opened check valves for normally prohibiting discharge of working fluid from the ram cylinders to lockthe ram cylinders, a ram cylinder control valve adapted to shift from a home position to an operating position in response to a valve control signal for allowing the hydraulic oil from the pilot hydraulic pump to open the check valves so that the hydraulic oil can be discharged from the ram cylinders, brake pressure sensor for detecting hydraulic oil pressure supplied to the brakes, joystick position detector for detecting position of the joystick to generate one of a forward position signal, a backward position signal and a neutral signal, and a controller for applying the valve control signal to the ram cylinder control valve if the forward position signal or the backward position signal is received and if the brake pressure is no greater than a set pressure, and for cutting off the valve control signal applied to the ram cylinder control valve if the neutral signal is received and if the brake pressure exceeds the set pressure.