MG Magnette KA Instruction Manual page 93

Previous reference has been made t o t h e in-put and out-put shafts. They can
be seen in lllustration
E,
wherein t h e in-put shaft registers in a spigot bush inside
t h e out-put shaft. The train o f gears, brake bands and drums have been removed
so as t o show the shafts and t o afford a view o f those parts o f t h e gearbox which
otherwise could not be seen.
The first question asked was, W h a t does the camshaft d o ? The camshaft does
n o t have cams similar t o those employed in operating engine valves, but they consist
o f nicks in circular discs permitting any one of the series
of
five selector springs
t o fall i n t o t h e notch in t h e cam depending upon t h e position o f t h e selector lever.
W h e n t h e lever is put i n t o position of 1st gear selection the camshaft rotates,
allowing the notch in N o .
I
cam t o let the selector spring N o . I stand proud o f
all t h e others, and it is the action of this spring which w i l l cause t h e brake band of
No.
I
train
of
gears t o come i n t o operation through t h e action o f t h e operating
struts.
A
number o f small levers w i l l be seen below t h e camshaft which act as gear
interlocks, making
it
impossible for t w o gears t o be engaged at once. Their action is
entirely automatic, and t h e manner in which they are worked w i l l be described later.
The second question which was asked earlier was, W h a t is t h e action o f the
clutch pedal inside the gearbox? lllustration
E
answers this question in so far that
it shows that t h e "clutch" pedal causes a lever inside t h e box t o move up and down.
I N T E R
LOCK
/TpPL,GLECTOR
\SLOT A
,
CAMSHAFT
l l l u s t r a t i o n E.-Interior of t h e gearbox, showing t h e i n p u t and o u t p u t shafts, b u t w i t h o u t the
actual gears and bands.
T o understand the gearbox properly, i t is necessary t o read t h e t e x t .
The action of t h e
pedal is t o cause t h e busbar rocking lever t o rise and fall. O n referring t o illustration F t h e
r o l l e r o n t h e end of t h e rocking lever comes i n contact w i t h t h e boss
(2) o n t h e busbar.
lllustration
B shows t h e external view o f t h e interlock and tail-plate bolts.
In this illustration t h e following parts can be seen: t h e camshaft, t h e selector springs and t h e
gear locks. These t h r e e parts c o n t r o l the actual gear t o be engaged. Rotating t h e camshaft by
moving t h e selector c o n t r o l lever t o and f r o permits t h e selector springs engaging w i t h t h e
operating struts shown i n lllustration
F, and t h e action of t h e gear interlock device prevents m o r e
than one gear being engaged at once.
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