Piston And Piston Ring - Kubota WG972-E2 Workshop Manual

WG972-E2, DF972-E2, WSM

[5] PISTON AND PISTON RING

■ Piston
Expansion Control Piston:
The thermal expansion is suppressed to the minimum
by the adoption of the strut (5). The piston head has the
combustion chamber (1) with the concave of bathtub
shaped type.
■ Piston Ring
Top Ring:
Barrel-faced type has an ideal shape in terms of
lubrication theory in order to prevent abnormal wear due
to edge loading at the time of initial running-in, and it is
very effective in prevention of blow-by.
Second Ring:
Barrel-faced type has an ideal shape in terms of
lubrication theory in order to prevent abnormal wear due
to edge loading at the time of initial running-in, and it is
very effective in prevention of blow-by.
Oil Ring:
Oil ring consists of three steel components, that is
upper and lower rails and one spacer being held between
two rails. This function is particularly effective in
preventing oil-up because of high boost at the time of
engine coasting.
(1) Combustion Chamber
(2) Top Ring
(3) Second Ring
■ Piston Skirt
Piston's skirt is coated with molybdenum isulfide ★,
which reduces the piston slap noise and thus the entire
operating noise.
★ Molybdenum disulfide (MoS
The molybdenum disulfide serves as a solid lubricant,
like a Graphite or Teflon. This material helps resist metal
wears even with little lube oil.
(1) Molybdenum Disulfide
M-4
GASOLINE / LPG ENGINE
(4) Oil Ring
(5) Strut
W1015665
)
2
W1017255
KiSC issued 01, 2006 A