"John Rumm" wrote in message
...
Doctor Drivel wrote:

The ratio is continously variable


.....oh no! failure. The planetary cluster is referred to as a
power-splitter. A normal gearbox/CVT lowers and raises ratios. No
ratios
are raised and lowered.

Nonsense.

"CVTs have been around for a while and at first it doesn't seem that Toyota
has broken new ground here. This, however, is entirely false, because the
ECVT in the Prius works in a completely different manner from any other CVT
put into a production car. It is so different, that calling it a CVT is
misleading. However, using this semi-familiar term at least explains why
the pitch of the engine sound doesn't rise as you accelerate."

Note: "calling it a CVT is misleading"

"The Prius transmission produces one of the effects of a CVT but not the
other. The spin rate of the engine can be selected to produce the required
power but otherwise to spin no faster than is necessary to maintain fuel
efficiency. The Prius engine tone therefore sounds as if the car has a CVT
because it does not rise as the car picks up speed. Instead, it rises and
falls with power demand, in other words, how hard you press on the
accelerator pedal."

Note: "it rises and falls with power demand", not raises and lowers ratios.

" The Prius transmission does not, however, multiply up engine torque at low
vehicle speed."

Note: No raising or lowering of ratios, as rasing and lowering torque is
what gearboxes/CVTS do.

"This is because it has only one gear ratio".

Note: so no gearbox/CVT to lower and raise ratios as there is only one.

" Effectively, the engine is coupled to the wheels as if the car is always
in top gear. This would be a crippling limitation, if not for the presence
of a powerful electric motor in addition to the gasoline engine. With this
motor adding its considerable torque, people have said that the car feels as
if it's always in bottom gear!"

http://home.earthlink.net/~graham1/M.../ContinuouslyV
ariableTransmission.htm