A truckle assembly has a housing, a rotating unit movably mounted on the housing, a limiting unit and a wheel assembly. The housing includes a body and a sleeve. A slope portion is formed inside the body and neighboring the sleeve. The rotating unit includes a central shaft, and a gear ring mounted on the central shaft for corresponding to a first side of the slope portion. The limiting unit includes a pedal, an interferential portion linking an end of the pedal, and an arresting portion linking an end of the interferential portion. The pedal has a first portion extending into the housing, and a second portion extending out of the housing. The interferential portion corresponds to a second side of the slope portion. The wheel assembly includes at least a wheel assembled on sides of the housing, and a shaft pole extending through the wheels and the pedal.