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Subject: 
Re: 2 speed automatic transmission
Newsgroups: 
lugnet.robotics
Date: 
Tue, 24 Nov 1998 15:58:31 GMT
Original-From: 
Andrew Carol <AECAROL@IX.spamcakeNETCOM.COM>
Viewed: 
1883 times
  
2 speed automatic transmission challenge
Based on this design, http://www.sonic.net/~rci/transmission.htm
can you come up with a 2 speed automatic transmission.
I did.

* RCX based solution to the automatic transmission challenge snipped. *

When it goes uphil, the weighted pendulum makes contact with
the sensor, this causes the motor to reverse direction and
shift the transmission to low gear. when it reaches level ground,
the pendulum swings forware, moving off the sensor, and this
causes the motor to change directions, thus shifting to HIGH.



I almost have one working which is truly automatic.  I modified the device
at the link given to have a spring on the same axle as the screw which
pushes to keep the screw in high gear.  When the load is increased the screw
pushes against the spring until it grabs the second gear.  As long as second
gear also has a load it will stay there.  If second gear 'lightens' up, it
will be pushed back by the spring into first gear.

My problem is how to combine the two drive axles into one.  I tried direct
gearing, but have a problem.  It will start in first gear, then switch to
second when loaded, but won't shift back to first (it gets hung up between
gears).  This is because I directly connected the gears and they try to spin
at different rates. (which the screw doesn't like)

I will next try to use a limited slip differential to combine the axles and
share the load.

My goal is a fully automatic transmission (not needing a RCX to change
gears!).

Anybody got any advice?

--- Andrew



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