The ring bank s broken at transition arc mostly in mian thrust surface of piston :
Bad combustion of engine cause excess coke in ring groove and adhension of piston ring ,the opening of ring is vibrated vertically ,and bumps the ring bank and results in the breakage of teh ring bank.
Unreasonable joint interval between piston ring and ring groove makes the ring flutter during the working and results in breakage of piston ring bank.
Inferior piston materials, its strength is not quliafied for design needs ,the ring bank is easily broken,an obvious casting error is exsited in the broken oarts,but there is no high-temperature color difference on the piston surface.
Abnormal combustion gives rise to over high temperature of engine.The strength of the ring bank is decreased ;the bank is easily broken at main thrust surface under larger force.
When the engine is too hot under overload run,the strength of the ring bank is decreased .The impact force between piston ring and ring groove become stronger ,and results in the breakage of piston ring bank.
The wearing of cylinder sleeve over the step ,the step may bump the first ring and results in the breakage of ring bank.