The crankshaft is made of wear-resistant cast iron, it is the role of the rectilinear motion of the piston into rotary motion of the piston, the linear power into rotary power, and the power to transmit through the rear end of the flywheel, which mainly comprises a belt pulley, crankshaft, flywheel and output flange etc., there are a total of six crankshaft crank and each adjacent crankshaft is 120 degrees space angle, among them, one, six cylinder, two cylinder, three or four cylinder, five crank respectively in three different planes.
Crankshaft is the most important part of the engine, the engine overhaul, we must pay attention to the crankshaft from several aspects of inspection and repair.
The appearance of a scratch check and Baotou beiben parts of the crankshaft, the crankshaft and the connecting rod with the surface precision of tile and body tile is very high, the appearance must be carefully checked for ablation, carbon removal, scratches, severe erosion of crankshaft removing carbon scratches too deep should be scrapped for the shaft; the crankshaft size requirements are quite high, roundness and cylindricity measurement must be carried out by qualified precise micrometer crankpin the loss of loss through the large circular and cylindrical for crankshaft in size within a specified range of grinding, and increase the level of crank bearing and connecting rod, the supporting bearing with.
Two, the crankshaft bending inspection for crankshaft, bear the movement of shock wave is more frequent, because of the difference between each cylinder combustion condition also makes easier the crankshaft bending deformation, so tiny, dressing in the engine must pay attention to the crankshaft bending inspections, the shaft is placed in a special flat on the table. A crankshaft bending both ends with precise magnetic seat dial indicator check qualified in the middle of the crank shaft neck, crankshaft, observation indicator changes, if the maximum and minimum readings exceed 0.20 mm said crankshaft bending has exceeded the standard, thus to crankshaft bending correction, correction by cold pressing correction.
Three, running inspection parts of crankshaft on the north of Baotou, as an important engine crankshaft transmission bearing torque, the fatigue stress is some wounds is as can be imagined, visible to the eye, but also need the help of the special inspection of the detector, if does not have the condition, can use the lime powder hammer click the inspection method, namely with lime powder and spread evenly on the crankshaft stress of the key, such as crankshaft, shaft neck surface, and then gently hammer hammer everywhere, if it is found that the surface of lime powder crankshaft small break mark that the crankshaft fatigue crack, the need to replace the crankshaft.
Four, the crankshaft assembly method, the crankshaft installed to ensure shaft neck cleaning, the bearing and shaft cap should be in strict accordance with the mark installation, installation should pay attention to the direction of the bearing cover, there is usually a arrow. In order to remove when the crankshaft is removed from both ends to the middle of the bolt, when installing crankshaft bearing cap bolt tightening from the middle to both ends alternately tighten, and the cylinder head bolt tightening method is similar, not a place to tighten, several times, not too much force, to prevent warping deformation of crankshaft. In the process of tightening the hand wheel to move the crankshaft to see whether the rotation is not stuck, the rotation is flexible, if the rotation with the card blocking phenomenon, should promptly identify the cause. Finally, tighten the bolts with the torque wrench to the repair value.
Five, check the axial clearance of the crankshaft, completed the installation and check the crankshaft, at last the crankshaft axial clearance check, axial clearance is too small, prone to burning phenomenon, the axial gap is too large, prone to excessive movement of the crankshaft phenomenon, affect the engine running smoothly and increase the body’s impact. The axial clearance checking the magnetic base indicator inspection method, the axial clearance of the engine is not a standard, but the general control in 0.15-0.30 mm.
General repair points of crankshaft is to ensure the smooth movement of the crankshaft without block, we need first to Baotou beiben parts of crankshaft in all aspects of the inspection correction, every step has to be taken seriously and carefully operating rules again, after all, an engine overhaul is not easy, although the trouble spots, but if some repairs out of the engine is the engine of our hearts the most assured.