MG Magnette KA Instruction Manual page 62

Oil that is forced t o t h e main bearings finds its way under pressure t o t h e big-
end bearings through holes drilled i n t h e crankshaft, whence in t h e usual course it
is t h r o w n o u t by centrifugal force finding its way upwards t o lubricate t h e pistons
and gudgeon pins.
The path o f t h e o i l can better be followed if t h e dismantling o f
t h e engine is n o w continued.
Before proceeding w i t h the details o f the o i l circulation it is as well t o examine
t h e i n t e r i o r o f t h e sump, f r o m which
it
w i l l be seen t h a t there are a number o f
baffles t o take care o f o i l surging, and also the manner i n which t h e suction filter
registers i n a boss i n t h e centre o f t h e sump.
lllustration No. 46 shows a view o f t h e crankshaft i n position after the sump
has been removed. The crankshaft runs i n four main bearings, the f r o n t and rear
bearings being w h i t e metal lined bushes and t h e t w o centre bearings being o f w h i t e
metal cast direct in t h e split steel housings. Examine f o r a moment t h e crankshaft
after removal. O w i n g t o t h e size o f t h e balance webs o f t h e crankshaft
it
is
necessary t o employ split housings t o accommodate t h e t w o centre main bearings
and t o register these i n the barrel t y p e crankcase. These housings are held i n
position by long bolts which pass through them, and a view o f t h e crankshaft after
it
has been removed is shown i n lllustration No. 47, which shows the crankshaft,
f r o n t end housing w i t h its bush f o r t h e f r o n t main bearing, the rear end housing
o f t h e crankcase and the split centre main bearings, and t h e manner i n which t h e
bolts pass through them.
lllustration 46.-View o f t h e base chamber after t h e sump has been removed, showing t h e
crankshaft in position i n t h e main bearings. T h e o i l feed pipe t o t h e t h r e e main bearings can be
seen and also t h e heads o f t h e bolts 1 , 2, 3 and 4, w h i c h pass t h r o u g h t h e centre supports o f t h e
crankcase i n which t h e main bearing housings are f i t t e d and l o c k these i n position.
As has been stated already, t h e f r o n t main bearing is fed w i t h o i l by an external
pipe, and
it
is n o w possible o n examining lllustration N o . 46 t o see h o w t h e o i l
feed holes o n t h e side o f the base chamber correspond w i t h t h e large f r o n t cross
web coupling up the t w o halves o f t h e crankcase and, o f course, integral therewith.
The t w o centre and rear main bearings receive t h e i r supply f r o m the o i l pipe t h a t
can be seen i n t h e illustration.
The crankshaft centre main bearings are fitted i n t o housings which w i l l be
shown later, and these housings are held i n the crankcase by means o f long bolts,
Nos.
1, 2, 3
and 4, t h e bolts being prevented f r o m t u r n i n g by t h e use o f tab washers.
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