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Subject: 
Re: Motors in parallel and stuff...
Newsgroups: 
lugnet.technic
Date: 
Thu, 1 Aug 2002 02:18:06 GMT
Viewed: 
607 times
  
In lugnet.technic, Bram Lambrecht writes:
Hi all,
I'm sure many of you have much more experience working
with drive trains than I have, so I'd like your advice.

I'm working on a six wheel (well, actually, six wheg[1])
drive robot with two points of articulation (for steering).
Thus, I basically need to power a drive shaft that runs
through the hinges with universal joints, and then at
three points along the drive shaft, I need to drive axles
perpendicular to the shaft.  The problem is, the output
has to be high torque, and high speed (no less than 40 rpm,
preferably over 100 rpm). I have a bunch of geared motors
thanks to ZNAP, and i also have 5 old ungeared 9V motors.

With how many motors do I get the best power to weight?

Hi Bram,

I'd use the new geared motors. They draw less power that the non-geared ones
(old style) and their internal gear reduction seems more efficient than one
built from normal Lego gears.

Good motor reference:
http://web.mit.edu/sp.742/www/motor.html

As for how many, that's a function of the overal weight and desired
performace of the model. I guess start with two, and then see how it works.

How many batteries do I need to add when I use extra motors?

Jennifer Clark can advise better on this, but I think if you've got one or
two of the geared motors, the small 9V battery box works okay. If you have
three or four, I'd go with the larger box (6 AA's). If you're brave and into
non-Lego solutions, hook up 8 AA batteries and watch your model fly!

What's the best or most durable way to change direction from
the shaft to the axle?

A set of 12-toothed bevel gears, perhaps. Or you could have a reducing set
of bevels, and use 12t and 20t bevel gears. I'd stay away from using worm
gears, they are too inefficient.

Any suggestions on gearing?

The geared 9V motors should turn (unloaded) at about 350 RPM. A 1:3 gear
ratio would be a good choice. You could use a set of 8t & 24t gears at the
motors, and have the rest of the gear train 1:1.

Alternatively, you could use a 8t to 16t at the motors, and then a reducing
set of bevel gears at the 90 degree connection (12t to 20t). This would give
you a 1:3.333 reduction.

Hope that helps!

TJ



Message has 1 Reply:
  Re: Motors in parallel and stuff...
 
"Thomas Avery" <thomas.avery@intec-hou.com> wrote in message news:H057q6.Mrp@lugnet.com... extra motors? (...) into (...) I think the small 9V battery box is ok with one motor, but you can really see the difference with two or more motors under (...) (22 years ago, 1-Aug-02, to lugnet.technic)

Message is in Reply To:
  Motors in parallel and stuff...
 
Hi all, I'm sure many of you have much more experience working with drive trains than I have, so I'd like your advice. I'm working on a six wheel (well, actually, six wheg[1]) drive robot with two points of articulation (for steering). Thus, I (...) (22 years ago, 1-Aug-02, to lugnet.technic)

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