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4-4 PISTON RINGS
The piston rings are made of special cast iron. The top ring is a barrel face type, the second ring is a
tapered one, and the oil ring consists of three pieces, so as to reduce the oil consumption.
4-5 CAM GEAR
The cam gear consists of the combination of the
cam and the gear. The cam is a sintered compo-
nent, widely used in this kind of application. The
gear is made of synthetic resin to reduce both
weight and gear noise.
4-6 COOLING SYSTEM
This engine adopts the forced air-cooled system, where cooling air is sent to the cylinder block by an
even-pitched cooling fan that works as a flywheel as well. This cooling air is guided properly to the
cylinder block by the baffle plate.
4-7 LUBRICATION SYSTEM
The rotary parts and the sliding parts of the engine are lubricated by lubricant oil, which is forcibly sup-
plied by utilizing the pressure generated by the up-down movement of the piston. Moreover, the oil
compartment is provided separately in order to prevent lubricant oil from flowing directly into the cylinder.
Fig. 4-5
Fig. 4-4
TAPER
1
2
3
1
2
3
TOP
RING
SECOND
RING
OIL RING
BARREL
THREE-PIECE
ASSEMBLY
