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Subject: 
Re: Two Design Problems
Newsgroups: 
lugnet.build
Date: 
Thu, 9 Nov 2000 01:09:19 GMT
Viewed: 
412 times
  
Jason J. Railton <j.j.railton@cwcom.net> wrote in message
news:G3nots.9z9@lugnet.com...
In lugnet.build, Doug Dropeskey writes:
I am having a hard time solving two design problems related to the base I
am

First off, thanks for the input.  I appreciate it.

Problem 1:
I would mount your rotating axle on an upright micro-motor.  Then, stand • the
micro-motor on a base which you raise and lower.  The axle could go up
through a hole in a technic plate if you want to hide the mechanism
underground.  This brings us on to problem 2, raising and lowering.

The only problem with this is that, assuming I power both motors
simultaneously, the axel will begin rotating before the platform fully
ascends, causing the mass on top of the axel to knock against the sides of
the housing in which everything is contained.  If I can keep the micromotor
unpowered until the platform clears the housing, this strategy should work.
I'll play with it.

Problem 2:
Three possible solutions here.  The first is to use several vertical • technic
beams with racks fitted, then use pinion gears to wind them up and down.
Gear them from a motor using a worm gear at some point to prevent • slippage.
The drawback to this is that you either have these beams sticking up from
your moving platform, or they have to go underneath, making for a very • bulky
mechanism below the surface.

The second is to use a scissor-lift.  Arrange technic beams to form two • Xs,
side by side.  Between the tops of two of the beams fit wheels or some • type
of sliding mechanism, so that they can slide along the underside of your
platform.  At the base of the other two beams put a rack mechanism, so • that
you can squeeze the scissors together and force the platform up.
The drawback to this is that the higher the scissors go, the less stable • the
platform is.  But, you could build one at each end of your platform and • gear
them together.  Again, use a worm gear off your motor to prevent slippage.

The third is the method used in the second-generation fork-lift truck - a
pneumatic lift.  Put a pair of 16-tooth gears at the top of a pnematic
cylinder, and loop a chain over the top and down the other side.  Anchor • the
ends of the chain with wide track-links pushed into the holes of a technic
beam.  Now when you extend the cylinder, the chains lift the platform by
twice the amount, bringing it up level with the top of the cylinder when
fully extended.
The drawback to this is that you will need several cylinders, and they're
unlikely to all move together.

Of course, you could use beams with racks on in place of the cylinders, • and
loop chains (or string!) over the tops - a combination of the first and
third ones.

As for your hatches, just add racks to them and drive them back and forth
with a motor.  You could use the same drive as raises and lowers the
platform, if you can time them right.

These are all fruitful ideas.  I had trouble with the scissor lift method
but I think the third option may suit my project best.  I'll pull up the
plans for that forklift to see exactly how it works.

Thanks again,

  -Doug

^V^^V^
I am:  Damraska@Excite.com
Minifig Suns:  http://pages.prodigy.net/damraska/



Message is in Reply To:
  Re: Two Design Problems
 
(...) I would mount your rotating axle on an upright micro-motor. Then, stand the micro-motor on a base which you raise and lower. The axle could go up through a hole in a technic plate if you want to hide the mechanism underground. This brings us (...) (24 years ago, 7-Nov-00, to lugnet.build)

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