柴油发动机备件

The crankshaft is made of high strength alloy steel 42CrMo with four balance weights, one time formed by forging. It has soft nitride treatment after finish machining, so its strength and stiffness and wear-resisting are all good. The main bearing is steel back three elements alloy plated copper lead shell, which has big capacity of bearing, totally 10 pieces. No.3 main bearing shell (down) is different from others, no oil groove on the shell face, dont apply oil on the shell back when assemble the shell. The material of thrust washer is steel back high tin aluminum alloy installed on the fourth bearing and positioned by the lower thrust washer extended tail, keeping the working surface (the side with oil trough) towards crank-web. The crankshaft must be washed carefully before put it into the block, special attention must be paid to the cleanliness on the surface of the journal, opening of the oil passage and the surface of the bearing seat. When the main bearing shell with oil hole fit on the bearing seat of the block, the oil holes should be coincided. No.3 main bearing cover should fit with the main shell (down) without oil hole and groove, apply some lubrication oil on the surface of the journal and working face of the shell when assembling. The main bearing caps and engine block are machined in pairs, there are numbers and serial numbers on the caps. Except positioned by lug, like other caps, the fourth bearing cap also has pin bush for position.The tip of triangle mark of caps is facing the front of engine block, andnumbered begin from the front whenassemble them. Dont make mistake. The main bearing bolts are lubricated with diesel engine oil, the tighten torque is 216 235N·m (22 24 kgf·m), it should start to tight alternatively from the center (no.3 main bearing) towards both sides. After tight, the crankshaft can be rotated smoothly.