Sariel's Studless Transverse Subtractor

[Andy D]

I have been experimenting with Sariel's Studless Transverse Subtractor from pages 291 and 292 of his book. It went together really easily, very straight forward design. I am using two (2) M motors like in his design.

My observations:

1. When I turn on the motor connected to the differential connected to the 6 l axels (the normal output of the Subtractor) I can make the outputs go forward or reverse.

2. When I turn on the other motor the outputs are reverse of each other.

3. When I turn on both motors (both forward or both reverse) only one output is driven.

4. When I turn on both motors and select one forward and the other reverse, the other output is driven.

I have changed the motors to account for one motor being stronger tha the other and I get the same results.

I just want to make sure that this behavior is normal before I continue. If it is, great! I can use this, if not I want to correct it before I continue.

Overall I really like it, it is a compact and useful design!

Thanks,

Andy D

Edited January 4, 2016 by Andy D

[pgplay]

I might be wrong, but from what I understand, the thing you are trying to build is a transverse subtractor and if I understood what Sariel wrote correctly, the idea behind the contraption is to drive and turn a threaded vehicle

[Andy D]

I might be wrong, but from what I understand, the thing you are trying to build is a transverse subtractor and if I understood what Sariel wrote correctly, the idea behind the contraption is to drive and turn a threaded vehicle

Yep, that is correct. I am just trying to make sure that the Subtractor is functioning correctly. I have another MOC that I use a longtitudional Subtractor in, and the transverse Subtractor works slightly different than the longtitudional Subtractor.

Andy D

Edited January 4, 2016 by Andy D

[Andy D]

I went back and looked at the Subtractor again. This time I decided to look at it as drive inputs and steered inputs (per Sariel's description) then I looked at the outputs as left and right outputs and made a table with different input descriptions and I examined all the conditions and found that the Subtractor functions as I would expect and most importantly I recorded what happened for different conditions. It has been a long time since I examined something this closely from an engineering/scientific perspective.

1. With the drive input selected as forward or reverse and the steering output off, both outputs go forward or reverse.

2. With the drive input selected as forward and the steering input selected as forward, the right output spins forward and the left output is stopped (or in a coast mode).

3. With the drive input selected as forward and the steering input selected as reverse the left output spins forward and the right output is stopped (or coasts).

4. When the drive input is off and the steering input is forward the outputs spin counter to each other one direction.

5. When the drive input is off and the steering input is reverse the outputs spin counter to each other in the the other directions.

Upon closer examination, this is what would be expected from a Subtractor. I guess I just needed to examine it as drive and steering inputs and left and right outputs. Making the table and recording the results really helped.

I hope all this makes sense. It really made a difference when I looked at it differently and more scientifically.

Andy D

Edited January 5, 2016 by Andy D

[lcvisser]

Isn't it great to learn something new?

I'm always excited when I find out how some mechanisms work and always amazed at what other people come up with.