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Moped Clutch/Trasmission--
How it Works
What is a
Variator? Clutch? Belt? Pulley? Gear
box?
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Mopeds have a
couple of different transmission types used. The
top speed of the moped is determined by how fast the engine can spin,
and what the gear ratio from the engine to the wheel is. You need power
to get started, (low ratio) and high top speed (high gear ratio)
How is this achieved? Several ways, depends on your machine, as
to how fast it is intended to go.
One is a manual gearbox, like
a motorcycle, where you clutch with your hand and shift gears
manually. Another is automatic clutch and manual shift,
where you shift gears with your foot but the clutch action is
automatic. A very common style for mopeds is a single speed
automatic with a centrifugal clutch. This type requires no shifting or
manual clutch operation, and top speed of the moped is determined by
how fast the engine can spin after the centrifugal clutch is fully
engaged. (not slipping).
A better way is with pulleys and a drive
belt, where the pulleys have movable sides so when the pulley halves
come together, the belt moves higher in the pulley, increasing
the diameter of the pulley and changing the gear ratio. As
the belt moves up in the front drive pulley, the halves of the rear
pulley are moving apart and the belt is sliding down. This
makes the rear pulley smaller, further increasing the gear ratio
to the rear wheel. The top speed of
this type system is determined by the ratio produced when the front
pulley is fully compressed and the rear pulley is fully apart, offering
the highest ratio available without making the pulleys a different
diameter or replacing the gears in the rear gear box with a different
size. This type of system uses roller weights
to force the front pulley together, and a spring to keep the rear
pulley from coming together too easily.
Changing the weight of
the rollers will alter the speed at which the engine spins, until the
clutch is fully compressed. The rollers weights are telling the pulleys
when to shift up to the next ratio. Changing them does not
affect top speed at all, just how long it takes to get
there. The rear gear box transfers
power from the rear pulley to the wheel, commonly with two shafts
and two gears. Changing the size of the gears will affect the
overall ratio, having nothing to do with the belts or pulleys.
Although it will affect them, in that more power is needed to pull a
higher ratio.
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Scooter Therapy Inc
12 North Few
Street | Madison,
WI
53703
toll
free
1-800-411-1543
| local
1-608-255-1520
fax
1-608-255-1587 | E-mail
|
Scooter Therapy
Inc
12 N. Few
St
Madison, WI
53703
toll
free 1-800-411-1543
local
1-608-255-1520
fax
1-608-255-1587
E-mail
Hours: M-F,
9-6 Saturday, 10-3 CST
copyright
(c)
2000
Scooter Therapy
inc.
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