Reasons for Rupture of Flywheel Housing

Causes of a cracked flywheel housing may include:

The flywheel housing fastening bolts are loose. If the flywheel housing fastening bolts are not tightened in the specified order and torque, or the bolt spring washers fail, the bolts may loosen under the combined effects of the locomotive bumps and engine and clutch vibrations, resulting in a gap between the body and the flywheel housing and an impact. The load causes uneven stress on the flywheel shell under the action of gravity and vibration, causing cracks.

Crankshaft axial or radial clearance is too large. When the crankshaft main bearing clearance is too large, the high-speed rotating crankshaft may deviate from the original axis, causing large radial runout and knocking vibration; if the thrust plate is damaged, the axial movement of the crankshaft may cause impact, and these conditions may cause The flywheel housing is cracked.

The coaxiality of the crankshaft and flywheel housing is out of tolerance. If the rear end face of the machine body is not perpendicular to the crankshaft centerline, the end face of the flywheel housing will not be perpendicular to the crankshaft axis, which will cause the distance between the flywheel centerline and the electric starter axis to change. When using an electric starter, the flywheel ring gear will be in contact with the electric starter. Additional forces may occur between the engine drive gears, causing stress concentration on the flywheel housing.

The balance of transmission components is out of tolerance. The crankshaft, flywheel, clutch, and transmission shaft should all undergo a dynamic balance test before assembly. If the dynamic balance of these transmission components is out of tolerance or the technical condition is poor, large centrifugal force may be generated during operation, resulting in unstable operation and vibration, thereby causing the flywheel to Shell fatigue crack damage.

Improper manufacturing or assembly. If the positioning reference on the flywheel housing is incorrect and is skewed after installation; the front and rear end surfaces of the flywheel housing are not parallel, etc., and the coaxiality between the first shaft of the transmission and the crankshaft is out of tolerance, it is easy to damage the clutch driven plate and produce a gap on the flywheel housing. The additional bending moment accelerates the cracking of the flywheel housing.

Engine mounting failure. If the front and rear ends of the engine fail to be supported on the frame using bolts or soft pads, it may not be able to effectively absorb vibration and impact, thereby increasing the risk of the flywheel housing rupturing.

Improper use. Such as frame deformation or improper use, etc.