1) Main Oil Pump (Engine Lubrication Circuit) - Rotax 914 F Maintenance Manual

9.3.1) Main oil pump (Engine lubrication circuit)
See Pic. 19.
The oil flow, forced by a trochoid type pump starts at the oil tank Q and oil
cooler E on suction side of pump via oil lines W and R and enters pump rotor
T of main oil pump engaging in oil pump shaft Y and driven by the cam shaft.
The pump forces oil through filter cartridge from the outside to inside of filter
U. The oil pressure from 1,5 to 5 bar (22 to 72 p.s.i.) is controlled by the
pressure relief valve I. The surplus oil returns back to the pump rotor via the
duct O. If the filter cartridge is completely clogged up, the excess-pressure
valve P opens and oil will flow unfiltered to the points of lubrication. Prevent
this situation by all means, using oil and filter as specified and punctual
change of oil filter.
Consequently the oil is pumped through the oil duct { located in the left
crankcase half with direct supply to the 4 hydraulic tappets } for the cylinder
2 and 4. Via the hollow pushrod q and oil duct w oil flows to the rocker arm
bearing. The oil emerging from passage e lubricates valve mechanism, and
flows back to crankcase via oil return tube r to passage t.
Forced oil supply from oil duct { also to camshaft bearing y N3, crankshaft
main bearing u H3, conrod big end bearing i of cylinder 4 and bronze bush
o of the crankshaft backing bearing S2 in ignition cover.
Through crankcase joint p oil enters the right crankcase half. From the oil
duct [ the camshaft bearing ] N2, the centre bearing of crankshaft A H2 and
the two conrod bearings S and D of cylinder 3 and 2 are lubricated. This oil
duct serves also the hydraulic tappets and valve mechanism for cylinder 1
and 3.
In further course oil is forced to flow to camshaft bearing F N1, to crankshaft
main bearing G H1, to conrod bearing H of cylinder 1 and to the backing
bearing J S1 in gear box cover. Electric terminal for oil pressure gauge on
pressure sensor K.
At engine version with hydraulic governor, ROTAX 914 F3, the hydraulic
governor a is supplied with oil at adequate pressure via the oil line L. From
the governor flange : oil flows to gear pump of governor which raises the
pressure to approx. 23 bar (333 p.s.i.). According to lever position of governor
more or less oil passes via oil duct s and through oil inlet flange d and hollow
propeller shaft f to variable pitch propeller, thus changing pitch accordingly.
The surplus oil returns back to the crankcase via the duct g. Oil escaping from
every point of lubrication accumulates on the bottom of the crankcase h and
is forced back to the oil tank by the blow by gases via hose nipple j and oil
return hose k.
Owing to the tangential entering of the oil return, separation of air from oil
takes place at the baffle insert l, thus establishing an oil supply nearly free
of air in the suction line W.
Date Main
Page Reference Modification no.
1997 02 01 914 F
44 - 0 -