Abstract: A stabilizer for a multi-trailer rig has a cylinder assembly including a cylinder A and a piston rod E pivotally mounted between a front trailer on one end and a wheeled dolly at H exerting a force which at all times is in a direction tending to bring the dolly into alignment and thereby bring a rear trailer which follows the dolly into alignment. A pair of such cylinder assemblies may be provided with each having a central stop member B carried internally of a cylinder with pistons C and D on each respective side for effectively moving to pull or to push until such action may be reversed following engagement of a piston with the central stop member. Exerting control over alignment of the dolly stabilizes the trailers and continues to exert a force to maintain alignment, yet permits turning. A locking clutch member I may be manually fixed to limit movement of the cylinder and piston rod thereby preventing the dolly from coming out of alignment during backing.