Conventional fluid motors require high-pressure fluid (15∿20Mpa) and rotation speeds of thesemotors are extremely high (10,000∿20,000rpm or more). Therefore it is difficult to apply these motors to mobile robots. This paper describes a new fluid motor named "Crown Motor" using a new mechanism that consists of two crown gears. Torque of this motor is high with a high gear ratio of 77 : 11 while rotation speed is slow enough to allow for mobile robotic applications. The motor is able to control its torque and rotation speed independently when it is controlled by electric valve. Moreover, it can drive with a low-pressure fluid like tap water (2∿7MPa). To use water fluid practically, it is necessary to introduce mechanical valve system. Last section describes the fundamental mechanism of the system and how to build a test model.