Appendix
37
Standard
Service limit
16.992mm
16.954mm
c) Piston-cylinder clearance
The difference between the maximum diameter of the cylinder and the diameter of the piston skirt is the
piston-cylinder clearance.
This clearance must be inspected before and after repair.
During inspection, put the piston upside down in the cylinder, put a thickness gauge with appropriate
thickness between the pressure bearing surface of the piston skirt and the cylinder wall, and then pull out
the thickness gauge. If you feel some resistance, but you can pull it out smoothly, the thickness of the gauge
at this time is the clearance between the cylinder and the piston.
Standard
Service limit
0.015-0.05mm
0.12mm
d) Clearance of piston ring side
During inspection, place each ring in its respective
piston ring groove. Piston rings shall rotate freely,
to be neither loose nor sluggish. Then measure by
inserting a thickness gauge into the clearance
between upper and lower planes of the ring and
slot.
Standard
Service limit
0.015-0.045mm
0.15mm
e) Piston ring closing clearance
Put piston ring horizontally into the cylinder, push the ring
to working position with piston head, and then measure its
opening clearance by thickness gauge. This clearance shall
be neither too great, nor too small. Too great clearance
may make cylinder sealing performance get bad, while, too
small clearance will cause the piston ring to be stuck in the
cylinder due to thermal expansion during operation,
causing piston ring breaking or even "cylinder scraping".
Ring opening clearance is small, the opening can be filed
by thin flat file. It shall be placed into the cylinder for
Piston ring
