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The Working Principle of Crankshaft and Its Precautions

Pulished on Apr. 21, 2021

The crankshaft is one of the key components of an automobile engine, and its performance directly affects the life of the automobile. The crankshaft is subjected to large loads and changing bending moments and torques, and the common forms of failure are bending fatigue fracture and journal wear. The following is the Crankshaft Supplier to share the working principle of the crankshaft as well as precautions.



The working principle of crankshaft.

The Crankshaft is one of the most typical and important parts of the engine, its function is to transform the gas pressure transmitted by the piston connecting rod into torque, as power and output to do work, drive other work mechanism, and drive the internal combustion engine auxiliary equipment work. 

Engine main stress parts crankshaft fatigue damage is the most common metal fatigue damage, namely bending fatigue damage and torsional fatigue damage, the former is more likely to occur than the latter. Bending fatigue cracks are first produced in the connecting rod journal or main journal rounding, and then to the crank arm development. Torsional fatigue cracks occur in poorly machined oil holes or rounded corners, and then develop in the direction of the axis. Metal fatigue damage is the result of variable stresses that vary periodically with time. Statistical analysis of crankshaft damage shows that about 80% is produced by bending fatigue.

The main causes of crankshaft fracture.

(1) long-term use of oil deterioration; serious overload, over hanging, resulting in long-term overload operation of the engine and burning tile accident. As the engine burns tile, the crankshaft is subject to severe wear.

(2) After the engine is repaired, loaded without a break-in period, that is, overload over-hang, the engine long-term overload operation, so that the crankshaft load exceeds the allowable limit.

(3) in the repair of the crankshaft using the overlay welding, destroyed the crankshaft power balance, and did not do the balance calibration, the unevenness exceeds the standard, causing greater engine vibration, resulting in the crankshaft fracture.

(4) Due to poor road conditions, the vehicle is seriously overloaded and over-hung, the engine is often in the torsional vibration critical speed line, damper failure, will also cause the crankshaft torsional vibration fatigue damage and fracture.

Crankshaft maintenance considerations.

(1) in the crankshaft repair process, the crankshaft should be carefully checked for cracks, bending, twisting and other defects, and the wear of the main shaft tile and connecting rod shaft tile, to ensure that the main journal and main shaft tile, connecting rod journal and connecting rod shaft tile fit clearance between within the allowable range.

(2) crankshaft cracks mostly occur at the transition corners between the crank arm and the journal, as well as the oil hole in the journal.

(3) Repair and reinstallation of the crankshaft should ensure the running balance of the flywheel.

(4) internal combustion engine occurred after a major accident such as burning tile, pounding cylinder, to carry out a comprehensive overhaul of the crankshaft.

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