Trolley for a slidable cantilever gate comprising two L-shaped plates, each provided with a load-bearing wall and a base wall which is extended without interruption from the load-bearing wall by means of a substantially orthogonal fold. The load-bearing walls are rigidly connected by means of screws or rivets with the two base walls oriented in opposite directions so as to form a support base on ground. Each load-bearing wall is provided with two first through openings aligned with respective corresponding first openings of the other load-bearing wall so to jointly define two first seats adapted to house first rotatable support means for two pairs of support wheels; and with a second through opening aligned with that corresponding on the other load-bearing wall so to jointly define a second seat for receiving a guide wheel, rotatably supported by second rotatably support means. The load-bearing walls, moreover, are each provided with a first shape with concavity facing that of the other load-bearing wall in order to jointly define a first housing adapted to receive a fixing screw of the pin of the guide wheel, and a second shape with concavity facing that of the other load-bearing wall in order to jointly define a second housing, which communicates with a vertical guide defined in one of the first seats, and houses adjustment means operating on a slide which bears, pivoted, a pair of adjustable wheels, in order to adjust its vertical height.