This paper presents the experimental study of the lubricated oil film pressure of the connecting-rod big end bearing in the special device for lubricating condition of the connecting-rod big end bearing. A connecting-rod model of photoelastic material is subjected to simulated load as in an engine. The oil film pressure is measured at different positions in the circumferential direction and at the mid-section in length by a pressure sensor located on the shaft. The measured results show that, the oil film pressure corresponds to the load acting on the connecting-rod. At the position 0° of the bearing, the oil film pressure reach a maximum value around the 360° of crank angle, zone of explosion, and the oil pressure is at minimum at 720 (0°) angle of the crankshaft, corresponding to the minimum load zone to the connecting-rod. In the opposite position, at the 180° of the housing bearing, the oil film pressure is at minimum when an explosion occurs and is at maximum in the neighborhoods of 0° of the crank angle. At other position of the connecting-rod, the oil film pressure is also corresponding to the load acting on the connecting-rod. The maximum value of oil film pressure decreases when the rotational speed of the crankshaft increases, the minimum pressure of the oil film slightly varies.
