semi-cylindrical
supports
and
spring
seats is a t t a c h e d t o t h e b l o w e r d r i v e
gear (42), and prevent the transfer of
torque fluctuations to the blower.
Since the lower rotor (timing) gear (14)
is also splined to the lower rotor shaft,
it drives the upper rotor (timing) gear
(13).
The blower rotors are timed by the two
rotor (timing) gears (13 and 14) at the
read end of the rotor shafts. This tim-
ing must be correct, otherwise the re-
quired clearance between the rotor lobes
w i l l not be maintained.
Figure 11D-2. Air Flow Through
Normal gear wear causes a decrease in
T u r b o c h a r g e r and Blower
the rotor-to-rotor clearance between the
leading edge of the upper rotor lobe and
lobe rotors
r e v o l v e s w i t h v e r y close
the trailing edge of the tower rotor
c l e a r a n c e s in a housing bolted to the cyl-
lobes.
inder block. To provide continuous and
uniform displacement of air, the rotor
While the rotor lobe clearance may be ad-
lobes are made with a helical (spiral)
form (see Figure 11D-3 on page 11D-3).
justed by the use of shims behind the
gears,
backlash
gear
cannot be
Two timing gears, located on the drive
corrected. When gears have worn to the
p o i n t where the backlash exceeds 0.004",
end of the rotor shafts, space the rotor
lobes with a close tolerance; therefore,
the gears must be replaced.
as the lobes of the upper and lower ro-
tors do not touch at any time, no lubri-
cation is required.
Lubrication
Oil seals located in the blower end plates
Oil drains from the valve operating me-
prevent air leakage and also keep the oil
c h a n i s m on the cylinder head into the ba-
used for lubricating the timing gears and
lance shaft pocket in the cylinder block;
rotor shaft bearings from entering the
then, when it reaches a certain level,
the oil flows from the pocket into the
rotor compartment.
cavities a t t h e u p p e r c o r n e r s o f t h e
Metal ring type oil seals are installed in
blower and through passages in the
the blower end plates.
blower and end plates to lubricate the
Each ring type
oil seal consists of a carrier pressed into
bearings,
governor and water pump
drives at the front end, and bearings
the rotor shaft, a collar pressed into the
e n d p l a t e , a n d a seal ring contained in a
and gears at the read end of the blower.
groove of the carrier. The outside diam-
A slinger attached to the front end of
the lower rotor shaft throws oil onto the
eter of the seal ring seals against the
collar to prevent leakage of air or oil.
front
roller
and
governor
w e i g h t s . A dam in the blower end plates
maintains oil at a level adequate to sub-
Each rotor is supported in the doweled
end plates of the blower housing by a
merge t h e l o w e r p o r t i o n o f t h e s l i n g e r
roller bearing at the front end and two
and driven gear.
row pre-loaded radial and thrust ball
bearing at the gear end.
S u r p l u s oil overflows the dams in the end
plates and returns through two drilled
The blower upper rotor is driven by the
holes in the cylinder block in the engine
blower drive shaft which is coupled to
the upper rotor timing gear by means of
a flexible drive hub (20, Figure 11D-3
on page 11D-3).
I n s p e c t i o n of Blower
The blower may be inspected for any of
A flexible coupling, formed by an ellip-
the following conditions without being
tical cam driven by two bundles of leaf
four
which
ride
on
springs
11D-2
