MG Magnette KA Instruction Manual page 25

Brake Anti-squeak Device. The brake-shoes are fitted w i t h an anti-squeak
device, which consists o f lead alloy blocks fitted i n t o t h e channel section o f t h e
brake-shoes and held i n position by means o f clevis pins and l i t t l e coil springs.
W h e n vibrations take place i n t h e brake-drum, they are communicated t o t h e brake-
shoes and t h e shoes vibrate ; t h e lead weights, however, are i n effect
"
left behind
"
by t h e vibrating shoes and energy is wasted i n friction between t h e weights and
t h e shoes.
The conditions under which t h e weights are mounted can i n practice be made
such t h a t they can always waste more energy than t h e squeaking forces can generate
and t h e squeak is prevented.
These are fully illustrated below.
I l l u s t r a t i o n 19.-Sectional view through a
brake-shoe, showing the lead weight attached t o
the brake-shoe, and the various component parts
for same.
Showing diagrammatically how the brakes are applied.