Engine Lubrication System; Lubrication Maintenance; Engine - Triumph SPEED TWIN 1945 Workshop Instruction Manual

The d r y sump lubric3tion system i s employed on
a l l
Triumph engines.
The o i l is
fed by gravity from the o i l tank via a filter and pipe t o t h e pressure side o f t h e o i l
pump.
The pump i s a double plunger type, fitted w i t h t w o non-return valves.
From this point t h e o i l i s forced through drilled passageways t o the crankshaft, and
f r o m the big end the o i l issues i n t h e form of a fog t o lubricate the pistons and t h e
other internal engine parts.
The o i l pressure is controlled by means o f a release valve situated i n the timing cover.
This valve serves t w o purposes, f i r s t t o release excessive o i l pressure and secondly
t o indicate t h e pressure by visible means. The valve consists of a piston, main spring.
secondary spring, o i l seal and b u t t o n indicator. W h e n t h e engine is running t h e valve
is forced back by o i l pressure o n t h e secondary spring, this being indicated by t h e
button projecting through t h e cover nut. Excessive pressure w i l l move t h e piston
back still further o n the main spring and allow o i l t o be by-passed through the release
valve body t o the crankcase, f r o m there t o be scavenged t o t h e oil rank.
A f t e r lubricating t h e engine, oil h l l s t o the bottom of the crankcase where it is
filtered. T h e crankcase o i l r e t u r n pipe which can be seen protruding through the
filter after the sump plate has been removed, then returns t h e o i l t o the suction side
o f t h e o i l pump t o be returned co the o i l tank. The suction o i l pump plunger has
t w i c e the capacity of the pressure side, i n order t o make certain that n o surplus o i l
remains o n the floor of t h e crankcase. T o lubricate the valve rockers, o i l i s taken
f r o m the return scavenge pipe by tapping the supply just below the o i l tank. The
oil, after being forced through t h e rocker spindles, lubricates the valve stems and
push rod cups. O n all models, external drain pipes are fitted. These pipes collect
t h e o i l f r o m the valve wells i n the cylinder head and transfer
it
t o the push r o d cover
tubes, where it then lubricates t h e tappets and finally drains i n t o the sump.
LUBRICATION M A I N T E N A N C E
E N G I N E
The system employed i s simple and w i l l function over a long period of t i m e w i t h o u t
attention t o the actual pumping mechanism. O n the other hand, failure t o observe
t h e eleinentary precaution o f changing the o i l and cleaning the filters at regular
intervals, may cause a complete breakdown due t o foreign matter entering the system.
If the oil tank cap i s removed after the engine has been started, it w i l l be noted that
t h e r e t u r n of oil t o the tank via t h e stack pipe (seen just inside the filler aperture) is
intermittent. The reason f o r this is that the scavenge side of the o i l pump has a
greater capacity than t h e feed side. Therefore, the crankcase sump is kept free o f
o i l under normal running conditions and the scavenge pump w i l l draw
a i r
u n t i l the
crankcase scavenge pipe is again submerged i n oil. The air which
is
forced i n t o the
o i l tank is vented out via an outlet pipe i n t o the primary chaincase.