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Subject: 
Re: single motor pneumatic pump and switch
Newsgroups: 
lugnet.robotics
Date: 
Tue, 24 Oct 2000 20:38:41 GMT
Original-From: 
Ben Gracewood <gracewoodben@hotmail.{saynotospam}com>
Viewed: 
681 times
  
I think the key is that the differential has a lot less resisitance than the
white slip gear.
Your idea would work, but if I understand you, the slip gear would be
slipping the whole time the pump is pumping, meaning the motor has to
overcome the slip friction AND turn the pump.
In the original design, the nice low-friction diff spins freely once the
switch is thrown, and the slip gear is only used to prevent the motor
stalling when max pressure is reached.

Maybe someone needs to invent (or has invented?) a variable-torque slip
gear.  This switching application would only need a tiny amount of torque so
a near-freewheeling slip gear would allow a Mike's nice minature version to
work.

Late nights ahead methinks.

Ben.


mike mcfarlane wrote:

Does this mechanism actually need the differential? If you used a 24 tooth
crown (the horrible bendy one) on the motor and this turned the white slip
gear for the switch and also a standard 24 tooth for the pump, the diff
isn't
needed, or is it just too late at night for me to think clearly? (The white
gear and the standard gear aren't connected with a central shaft as shown
in
the pics. The rest of the layout is similar.) So when you run the motor in
one
direction the white gear moves the switch until the end of travel then it
slips and the pump gear, well, pumps. Reverse the motor to move the switch
again.

Tis a good idea though and a neat design.

Mike

In lugnet.robotics, John Barnes writes:
A truely ingenious little mechanism. I wonder if mechanical engineers
in the real world ever get jealous of how easy it is for us Lego world
engineers to do such rapid prototyping.

... and in reply to Ralph's comment, who was the famous figure who
proposed closing the patent office a hundred or so years ago on the
grounds that everything had been invented?

JB


Ralph Hempel wrote:

This is a really interesting twist on pneumatic switching! And
we thought it was all done already!

Nice work.

Pneumatic pump and switch using a single motor:

Have a look at:
http://www.t-online.de/~sibylle.eddy/pneswit.html


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