Abstract: A self-locking device for a table elevating screw includes a rotatable disk disposed on a screw having a nut thereon, a wedged body disposed on the rotatable disk, an outer cover moveably disposed on the rotatable disk and the wedged body and a stop plate disposed on the outer cover. When the rotatable disk rotates in relation to the screw in a direction or a reverse direction, the wedged body ascends or descends in relation to the rotatable disk, maintaining a gap between the stop plate and the outer cover or generating a frictional force therebetween. By means of the frictional force occurred when the screw rotates in a single direction, the self-locking device can achieve a precise self-locking device for the screw in a lifting/lowering positioning task.

Abstract: A pedalling vehicle includes a main body, two control handles, two drive links, and a transmission link. The main body includes a front frame a front wheel, a rear frame, two rotation devices, two rear wheels, two cranks, and two connecting members. The rotation devices are connected by the transmission link through connection of the connecting members so that the rotation devices are rotatable synchronously and the rear wheels are movable with the rotation devices synchronously. Thus, the two rear wheels are turned synchronously by connection of the transmission link so as to turn and change the travel direction of the pedalling vehicle exactly.