Brake System Descriptions; Mechanical Drum Brake; Single Leading Shoe Type (Or, Leading-Trailing Shoe Type); Dual Leading Shoe Type - Honda Motorcycle Service Manual

BRAKES
BRAKE SYSTEM DESCRIPTIONS
Braking systems on motorcycles, like virtually all braking
systems, dissipate the vehicles kinetic energy by transforming
it into heat energy-known as friction heat.
Two basic types of braking systems are used on Honda motor-
cycles and scooters; the drum-type and the disc type. Both the
drum and the disc rotate together with the wheel. Each is
slowed by the friction of either shoes or pads that press
against them.
DRUM BRAKE
Single Leading Shoe Type
(Or, Leading-Trailing Shoe Type)
Force applied against the brake lever or pedal activates a cable
or rod attached t o the brake mechanism. A threaded adjuster
on the end of the brake actuating cable or rod offers one Of
t w o adjustments t o control the precise brake actuation point.
The adjuster acts against a pivot on the end of the brake arm.
which is clamped onto and turns a brake activating cam.
DISC BRAKE
MECHANICAL DRUM BRAKE
As shown in the illustration t o the right, this cam transfers a
rotating force from the outside of the drum, through the pro-
tective brake panel to the inside of the drum. Here the cam
spreads one end of t w o crescent-shaped shoes. The other end
of the shoes pivot against a common pin set into the brake
panel. Both shoes press against the inside surface of the drum,
creating friction and slowing the rotation of the wheel. The
first shoe t o act upon the drum beyond the cam, in relation t o
the rotating direction of the drum, is called the leading shoe.
The second shoe, arcing out against the drum from the com-
mon pivot pin, is called the trailing shoe.
BRAKE CAM
Due t o its position within the system, the leading shoe creates
more force against the drum than that which is applied to it.
This increased force capability is called a self-energizing ef-
fect. In contrast, the trailing shoe, again, because of its posi-
tion within the system based on the rotating direction of the
drum, is pushed back by the rotating drum and creates less
force than that which is applied t o it.
Dual Leading Shoe Type
Dual leading shoe brakes differ from single leading shoe types
i n that they use t w o shoe-activating cams, each at opposite
ends of the brake panel, to simultaneously press the shoes
against the drum (see illustration at the right). Because both
shoes are leading in relation to the rotating direction of the
drum and therefore operate against the drum in same way, the
effective braking force is noticably greater than a similarly siz-
ed single leading shoe unit with an identical amount of ac-
tuating force applied to the brake lever or pedal.
BRAKE CAM
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BRAKE CAM
Date o f Issue: Sep.,
1988
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HONDA MOTOR CO., LTD.