Norman
No I did not get this from a book it is just the way that epicyclic gear
systems work. This is not easily explained without drawing my own
diagrams but I will try.
First we must understand the normal operation of the overdrive when
engaged and the car moving forward, The drive form the gearbox goes to
the planet wheel cage and the sun gear is held from rotating by
hydraulic pressure. Therefore the output to the prop shaft via the
annulus rotates faster than the input from the gearbox.
Please see http://www.mekanizmalar.com/transmission.shtml and press the
bottom mode button to see this condition. In this animation the annulus
is around the outside. The blue gears are the planet gears that can be
driven around the centre point by a cage; not shown, and the centre
yellow gear is the sun wheel
However when the cone clutch is not fully engaged in either direction
the condition, with the top button of the animation pressed on this WEB
site, exists. The annulus is stationary because the car is not moving,
the blue planet gears are driven via their cage from the gearbox and the
uncontrolled sun wheel spins around at a much higher speed than the
input from the gearbox. However in the forward direction this cannot
happen because the one way clutch locks the gearbox output shaft to the
annulus. In reverse however there is no one way clutch in control and
the sun wheel spins at high speed and this then spins the cone clutch
moving part.
The figure of 8 times may not be accurate and is as I say dependant on
the overall ratio of the overdrive but whatever it works out to be, it
is high enough to cause the system to burst.
I don't understand your point about a uni-drive not working backward?
No doubt this is going to cause some interesting debate?
Regards
>
>PLEASE EXPLAIN , WHAT YOU MEAN 8 times ???
> did you get this info from a book ???
>
>THE uni-drive does not work backwards , it goes BANG
>
--
John Harper
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