ENGINE
Camshaft and timing gears
The camshaft
is
a high-carbon steel forging
having three journals by which
it
is
fitted
into
and held by
the
cylinder block. Its journal and
cam faces are induction-hardened for increased
resistance
to
wear. Lube oil
is
pressure-fed from
cylinder block
to
each camshaft journal. By a
recess or
notch
provided in the rear journal, lube
oil
is
intermittently supplied through
the
cylinder
head in order
to
lubricate the rocker arms and
related parts
of
the valve mechanism. An oil
hole which permits an excess
of
the oil
to
return
to
the oil pan
is
drilled in the rear
end
of
the
shaft.
Camshaft
Valve timing
Intake
valve
opens 18° Before Top Dead Center
Exhaust
valve
closes 18° After Top Dead Center
Intake
valve
closes
46° After
Bottom
Dead Center
Exhaust
valve
opens
46° Before
Bottom
Dead Center
Fuel injection lining
21
0
Before Top Dead Center
Top
dead
center
Intake valve
opens
Exhaust valve closes
Exhaust
stroke
Bottom
dead
center
Valve timing diagram
\
Direc~ion
of
f
rotation
The valvetirning data, listed above, presuppose
that
the
valve clearance has been accurately set
to
meet the specification for each valve.
2·8
Helical gears, finished by shaving and crown-
ing for greater durability and quieter running,
are used for the timing gears.
Hydraulic
pump gear
The gear for driving
the
hydraulic
pump
is
located at the left-hand end part
of
the gear
case. The rear end face
of
the shaft
of
this gear
has a groove for Oldham coupling. The pump
is
connected to
the
bearing housing directly.
Tappets and pushrods
The tappet, pot-like in shape,
is
heat-treated
in a carburizing
gas
furnace and has its
bottom
face hardened by chilling. Thus, it
is
highly
resistant
to
wear. Relative to
the
center
of
its
cam,
the
center
of
the
tappet
is
slightly offset
in order
to
avoid uneven wear
of
its
bottom
face riding on
the
cam.
The pushrod
is
a steel bar, whose end portions
are flame-hardened.
Offset between tappet and cam
Fuel-injection-pump camshaft
This injection
pump
is
of
"in-line" type and
is
driven by
the
camshaft built in
the
engine
side. Its material
is
a high-carbon steel, the cam
faces being induction-hardened.
A ball bearing
is
used
to
support
the front
part
of
this camshaft; the tip
of
the
front part
is
shaped
to
admit the governor shaft. The rear end
face has a groove for Oldham coupling.
It
is
through this coupling
that
the oil
pump
is
driven.
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