THRUSH AIRCRAFT, INC – MODEL S2R-R1340
AIRCRAFT MAINTENANCE MANUAL
Effective: 01/01/2008
4-9
position on the wire. Bend the
strands back over the lead opening
in a radial pattern. Do not solder the
lead.
OIL SYSTEM
Oil is circulated through the engine by a
three section gear pump mounted in the
lower right hand side of the rear case.
Oil from the tank enters the oil inlet at the
bottom of the pump and is directed to the
pressure (lower) section of the pump,
where it is forced to the oil strainer
chamber through a cored passage in the
rear case. The oil passes through the
strainer assembly and the pressure of
the oil opens the spring-loaded check
valve. When the engine is not operating,
the check valve prevents oil from seeping
into the engine. When the oil emerges
from the check valve, it is diverted into
two main branches. In the first branch,
the oil is directed through a passage to
an annulus around the right magneto
drive gear shaft rear bushing. Part of the
oil from this annulus is carried by drilled
passages to the right accessory drive
gear bushing. Here the oil enters the
hollow accessory drive gear shaft and
flows upward to the starter shaft bushing.
Part of the oil from this annulus flows
upward through a drilled passage to
lubricate the accessory, and another part
enter the magneto drive gear shaft and
flows forward to lubricate the front
bushing.
Another passage carries the oil from the
annulus encircling the right magneto
drive gear shaft bushing to the oil
pressure relief valve, which regulates the
engine oil pressure. By-passed oil is
returned to the inlet side of the oil pump
pressure section.
In the second branch, oil is directed to
the left side of the rear case where the oil
flow divides. Part of the oil enters the
annulus which encircles the left magneto
drive gear shaft rear bushing. Drilled
passages from this annulus carry oil to
the left accessory drive gear bushing.
Here the oil enters the hollow accessory
drive gear shaft and flows upward to the
started shaft bushing. Other drilled
passages and tubes carry oil to the
vacuum pump, tachometer and starter
gear. Oil from the annulus around the
left magneto drive gear shaft rear
bushing flows upward through a drilled
passage to lubricate the accessory
section, oil also enters the shaft and
flows forward to an annulus around the
front bushing where it is directed by a
drilled passage to the front of the
supercharger case. Here the oil provides
lubrication for the impeller shaft bearings.
Oil from the crankcase and front sections
is carried from the left side of the rear
case through the rear and supercharger
case by a tube. The supercharger case
oil pressure tube bracket supports a tube
assembly that transfers the oil to the
crankcase and also provides spray
lubrication for the floating gear and
impeller intermediate drive gear. The oil
is then directed to a tube in the top of the
sump and then to the cam oil-feed
bracket.
At this point the oil is introduced into the
crankshaft by means of the cam oil-feed
bracket, where a drilled passage in the
crankshaft directs it to the crankpin for
lubrication of the master rod bearing,
linkpins, piston pins and cylinder walls.
The cylinder walls and piston pins are
lubricated by spray from the oil nozzles,
one in the rear of the front crankshaft and
the other at the top of the rear cheek,
and also from oil that passes the master
rod bearing and linkpin bushings. Part of
the oil at the cam oil-feed bracket is
routed to the cam bearing and cam
reduction gear bushing to provide
lubrication at these points. Oil is also
distributed from the cam oil-feed bracket
to the tappets through a groove around
the front crankcase section to internal
