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XII Cylinder Block and Piston
Preparatory data 12.1
Fault diagnosis 12.2
Cylinder block 12.3
Piston 12.4
12.1 Preparatory Data
Function of cylinder block:
Cylinder block provides the space for gas compression, combustion and expansion and guides piston
movement. It also transfers part of heat in the cylinder to surrounding coolant.
Function of piston:
1. Piston can bear the pressure generated by combustion of mixed combustible gas in the cylinder and transmit
the pressure to connecting rod to drive crankshaft to rotate.
2. It forms a combustion chamber with cylinder head.
Precautions on Operation
All the components shall be cleaned before inspection and test, and purged with high-pressure air.
Table of standard values of baseline projects and allowable limit
Item Standard Value Service Limit
Cylinder
ID
60-60.013 60.063
Cylindricity
0.005 0.025
Roundness
0.004 0.025
Flatness
0.03 0.05
Piston OD(measuring point)
59.94-59.95 -
Piston pin hole ID
15.002-15.008 15.04
Piston pin OD
14.994-14.999 14.976
Clearance between piston and piston pin
0.003-0.014 0.064
Clearance between piston
ring and ring groove
Top ring
0.03-0.07 0.12
Second ring
0.03-0.07 0.12
Joint clearance of piston
rings
Top ring
0.15-0.3 0.4
Second ring
0.25-0.4 0.5
Oil ring
0.15-0.6 -
Connecting rod small end ID
15.01-15.018 15.068
Clearance between linkage rod and piston
pin
0.011-0.024 0.092
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