MG Magnette KA Instruction Manual page 94

AUTO ADJUSTER
/ ADJUSTER NUT
ADJUSTING SET
REVERSE
T H R U S T PAD
BRAKE ANCHORAGE
BOSS ENGAGES
W I T H BUS
E A R
ROCKING LEVER
BUS BAR S U P P
lllustration F.-This is a view of the base of the gearbox on t o which the brake band assembly
is mounted on anchorage links. Operating struts are caused t o rise and fall by the action of a busbar
which is under the control of the spring 6 ; the busbar terminates at (I), making knife-edge contact
on the bracket (3) when the clutch pedal is in its normal position.
Expansion of the clutch spring
pulls on the point (4), causing the busbar t o rise with
it
and contract the selector brake band. The
mechanism on the top of the anchorage link consists of an automatic adjusting device, t o take care
of any wear in the bands and give uniform pressure. When the clutch pedal is pressed down, the
busbar rocking lever forces the busbar outwards, thus freeing the brake band until the pedal is let
up again.
This lever is known as the busbar rocking lever. It will be noted that at the inner
extremity o f this lever there is a steel roller let into the fork end o f the lever.
Before passing t o the next illustration
it
will be remembered that lllustration E
is the view o f the gearbox taken from below, and is really, so far as the reader is
concerned, upside down. W i t h this in mind pass t o lllustration
F
and first o f all
look at the part marked I Busbar, and then carry the eye along t o the point marked
2, which is a raised track on the busbar which engages w i t h the busbar rocking
lever shown in lllustration E.
W h e n the pedal is pushed down the rocking lever moves downwards,
pressing upon the point of the busbar marked 2. The busbar pivots on supports
(3), and
it
will be noted that the point o f support has a knife edge.
The outer
extremity o f the busbar, at the point
4,
is coupled by means o f a link t o the
spring compression lever
5,
which is clearly under the action o f the spring 6.
I t follows, therefore, that when the pedal i s pressed down the busbar is forced
downwards, thereby compressing the spring, and when the pedal is let up
o r back, the spring 6 causes the busbar t o rise, carrying w i t h it one o f the
operating struts which through the action o f the various linkages at the t o p w i l l
cause one o f the brake bands t o contract. The busbar has a groove running the
complete length, and when the selector lever is in neutral the 1st and reverse struts
are engaged, and owing t o the action o f the gear interlock neither s t r u t can reach
the engaged position and the busbar w i l l remain partly depressed.
Page Seventy-nine