MG Magnette KA Instruction Manual page 75

The principal point t o note i n this illustration is t h e gear on the lower o r layshaft,
which is indicated i n t h e illustration as
"
floating t h i r d gear," which is always i n
constant mesh w i t h t h e t h i r d speed pinion o n t h e mainshaft.
T o p gear is obtained i n t h e ordinary way by sliding t h e t h i r d gear on the
mainshaft forward, so t h a t t h e splines o n t h e hub o f t h e gear mesh internally w i t h
t h e constant mesh pinion o n t h e first motion shaft, and
it
w i l l be noted that t h e
spigot bearing is o f t h e r o l l e r type. W h e n , through t h e movement o f t h e change
speed lever, t h e t h i r d speed gear o n t h e mainshaft is caused t o slide rearwards, t h e
nature o f the t o o t h engagement w i l l automatically cause t h e t h i r d speed gear o n
t h e layshaft t o move backwards i n unison
; it
is then t h a t t h e gear o n t h e layshaft,
which has internal c u t teeth, engages w i t h a set o f teeth o n t h e f r o n t o f t h e second
speed pinion. W h e n any o t h e r gear is engaged except t h i r d gear this t h i r d gear
o n t h e layshaft simply rotates o n its sleeve.
In o r d e r t o make t h e matter clearer, t h e user should n o w refer t o Illustration
N o .
59,
which shows t h e layshaft train o f gears locked up o n a t u b e removed f r o m
t h e layshaft itself. The layshaft is fitted w i t h roller bearings at either end and over
these roller bearings t h e complete layshaft is fitted.
The internal mesh dog engagements o f t h e direct drive on t h e mainshaft and
t h e t h i r d speed free sliding gear o n t h e layshaft should be examined.
If
momentary reference is made t o Illustration No.
56
it
w i l l be noticed t h a t
the mainshaft protrudes through t h e gearbox, passing through the gearbox f r o n t
end cover.
,INTERNAL M E S H DOG
M
\S1
2""
3""
/
ENGAGEMENT
C O N S T A N T
MESH
M A I N S H A F T
GEAR BOX
FITS
B E H I N D
END
o c a D l h r r .
COVER
B E A R I N G S
-
AYSHAFT C O N S T A N T
GEAR
G E A R 5
/
3 ' \ M E S H
STRlhrrn
NOTE
I N T E R N A L
FREE T O
M E S H
S L I D E
ci
U
BALL
.-
I l l u s t r a t i o n 59.-Another view of the gearbox components. The complete layshaft gears
have been removed from the layshaft. Note the internal mesh engagement of the top gear on the
mainshaft and the third gear on the layshaft.
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