This paper proposes trot pattern generation and online control methods for a legged robot to carry heavy-loads and move fast on the uneven terrain. The trot pattern is generated from the frequency modulated pattern generation method based on the frequency modulated oscillator in order for the legged robots to operate outdoors with the static and dynamic mobility. The efficiency and performance of the proposed are verified through the computer simulation and experiments using qRT-1/-2. In experiments, qRT which is a 2-legged and 2-wheeled robot and a front drive system vehicle with hydraulic linear actuators is used. The robot has trotted gaits at speeds up to 1.3 m/s on the even surface, walked up and down the 20 degree inclines, and walked at 0.7 m/s on the uneven surface. Also it has carried over 100 kg of the total weights including over 40 kg of the payload.