Maintenance manual for sunray hfc4da1-2c china-IV diesel engines
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Section IV Piston and Connecting Rod Group
z The piston crown is of ω type combustion chamber;
Depending on the performance and reliability requirements, the piston
profile designed can guarantee the normal working of engine under high
speed, high temperature, and high pressure conditions. The good skirt sizes
can reduce the frictional power consumption of piston and improve the
economic performance of the engine.
z The HFC4DA1-2C piston rings include two compression rings and one
oil control ring:
The first ring adopts the trapezoid tubbish ring, which can effective reduce
the consumption of engine oil.
The second compression ring adopts the torsional trapezoid ring to increase
the flexibility of piston ring and improve the capability of piston ring for
adapting to deformation of cylinder sleeve.
The oil control ring is of coil spring expander type and adopts the combined oil ring composed of two side guide rings
(upper and lower) and the middle expander, featuring the advantages of low mass and outstanding oil scraping effect.
It can reduce the consumption of engine oil and the grain emission while meeting the Euro-IV emission standard.
40~50% of the frictional power consumption of the engine is attributed to the pistons and piston rings. The piston
rings of 4DA1 engine can effectively arrange the engine oil, reduce the friction power of piston subassembly, and
improve the fuel economy.
z The piston is stamped with mark, which shall
face upward during assembly. During assembly, take
caution to position the spring connector 180º away
from the opening of oil control ring. Notice the
opening direction of the ring while installing the
cylinder sleeve. The openings of the piston rings shall
separate 120º from each other and the ring opening
shall not face towards the piston pin. Apply an
appropriate amount of lubricating oil during the
assembly. The piston rings shall rotate flexibly after
being installed in the ring grooves.
a. The arrow on the piston crown shall point to the
front of the engine.
b. It adopts variable section connecting rod to effectively reduce the force applied onto the connecting rod.
c. The piston pin is of full-floating structure and adopts retainer ring for limiting. The piston pin can be directly
assembled during installation.
d. The body of connecting rod adopts H-shaped cross section, featuring good bending strength and light weight.
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