Pneumatic stepper motors are useful in actuating magnetic resonance (MR) safe robotics. A novel design is presented, which consists of two pistons in cross-configuration, one hoop gear and one rotor composed of a cycloid gear on a shaft. Realizations are presented in two different sizes, both employing 13 teeth and a step size of 6.9 \(^{\circ }\) . The larger motor, RC-80, delivers 6.3 N m torque and 24 W output power. The smaller motor, RC-45, delivers 0.47 N m and 3.0 W. Both motors can continuously operate at approximately 50% of the maximum load for 60 min without breaking down. The presented motors provide highest torque among all state-of-art MR safe pneumatic stepper motors of comparable size, and are significantly more robust. Especially RC-45 is suitable for actuating the joints of compact MR safe surgical robots.