A hydraulic cylinder assembly includes a cylinder and a piston rod. The cylinder has an opening and upper and lower inner walls formed by a bore. An end of the piston rod is received in the bore through the opening and travels reciprocally through the opening in response to volume change of a hydraulic fluid in the cylinder. The cylinder has a first section adjacent the opening provided with a narrow passage of the piston rod close to the cylinder upper inner wall. The cylinder has further a second section spaced apart from the opening and provided with a clearance between the piston rod and the lower inner wall forming a chamber for the hydraulic fluid. The inner upper wall at the first section is provided with circumferential camberings.