Ashton Crusher <Hello@nowhere.net> wrote:
> dold@XReXXEscap.usenet.us.com wrote:
>>Seems like plenty of power. The engine seems noisy and too quick to jump
>>up to 4000 RPM, but if you ignore that, it's all good.
> Doesn't it have a continuously variable ratio transmission?
Yes, but not like one in the Ford 500, or Freestyle, or Hondas.
Those also bring the engine speed up quickly and hold it there while the
road speed climbs, but it's different in the Escape Hybrid.
It has a planetary gear transmission. Road speed holds a constant ratio
between Engine RPM verses generator RPM. As a load is put on the system,
it moves gas RPM up to the optimum power (and I suppose efficiency) RPM for
a balance of gas + electric power to the wheels. This gives something
around 4000 RPM under moderate load uphill, making the Escape seem
underpowered. It's not. if you step on the gas, there's still more power
available, but 4000 RPM sounds like it's straining. It just takes a while
to get used to.
The transmission is very similar to the Toyota Prius, which I think is
nicely explained by Graham. The ratios and road speeds are not correct for
the Escape, but the overall effect seems in line.
<http://home.earthlink.net/~graham1/MyToyotaPrius/Understanding/PowerSplitDevice.htm>
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Clarence A Dold - Hidden Valley (Lake County) CA USA 38.8,-122.5