Crankshaft cracks often occur at the crankshaft and crankshaft and crankshaft and main journal junction (dangerous section). A repair shop with better equipment conditions is inspected with a magnetic particle flaw detector or an ultrasonic flaw detector. During the inspection, the crankshaft is magnetized with a flaw detector, and then the dry fine scraps are sprinkled on the parts to be inspected. At the same time, a small hammer is used to gently strike the crankshaft. Observe at this time that the scrap iron is accumulated in the middle. Cracks.

In the absence of such equipment, it can also be checked by hammering. Before the inspection, remove the oil adhering to the crankshaft surface, then dip the entire crankshaft with kerosene, and then support both ends of the crankshaft on the wooden frame and gently tap each crank with a small hammer. If the crankshaft has no cracks, the metal sound of the “squeaky metal” will often occur; if the crankshaft is cracked, “waves and waves” (metals will not be connected and the sound will be short) will occur, and then it will be easy to produce near the crankshaft. The cracked area is carefully inspected with a magnifier. If there is a place where the oil stains a black line, it is the crack.

There is also an inspection method. After the crankshaft is cleaned, a layer of talc powder is evenly coated on the surface of the crankshaft, and then the crankshaft is used to gently tap the crankshaft. If the crank is cracked, the oil will seep out of the crack and make the crankshaft. The talc on the surface turns yellow-brown.