Knex Touch-Sensitive Automatic Transmission

This k'nex transmission is connected to a spinning wheel composed of 4 gray rods. If the wheel is forced to stop turning, the transmission detects the rotational force and automatically reverses the direction of the wheel to avoid stressing the motor. The transmission is adjustable and can be calibrated to switch directions at different levels of force.

This mechanism was not built for any purpose, I just had the idea and wanted to test it. The best practical application I can think of at the moment would be for building pendulum-style carnival rides. This transmission would be able to gradually accelerate a pendulum from rest to nearly vertical just like the actual rides.


How it works:
The wheel on top of the transmission is connected to the drive gear by a long, winding chain. If any force counter to the rotation of the drive shaft is applied, the chain will be pulled tight on only one side. The chain loops around tension gears on either side of the machine, so when one side of the chain is tightened, the tension gear specific to that side will be forced to tighten. When this gear reaches the top, it flips a lever arm with the drive gear attached to it, causing it to engage a gear spinning in the opposite direction, hence, changing the direction of the wheel itself.

Design / Build Time: 3 hours (+ 3 extra hours of fine tuning)
Pieces: about 500
Gears: 33
Non K'nex pieces: 2 rubber bands

To see more of my K'nex projects, and to follow the design and construction of new ones check out http://knexdesigns.blogspot.com

Category:

Science & Technology

Tags:

• knex
• k'nex
• automatic
• transmission
• touch
• sensitive
• sensor
• gears
• chain
• drive
• mechanism
• mechanical
• engineering
• device
• gadget
• cool
• ride

[Sorunome]

I know that this is very long ago but I'm building something similar but I'm having some problems with it so here are a few questions (I hope that you can still answer them).

First of all, what are the rubber bands used for?

And second, that thing in 0:33, how do you make that it just jumps between that two positions? Mine stays often directly between these two gears and thus it all stops :(

[austron]

@Sorunome What I did was to put a horizontal bar at the fulcrum, perpendicular to the gear pendulum. The rubber bands connect the sliding chain gears to this bar, so when the tension increases in one, it begins to pull up on one of the bars, so when the slider gets high enough and knocks the pendulum out of place, the tension in the rubber band is enough to push it over to the other side. Also, make sure the gears spin in the right direction so they try to pull the pendulum inwards.

[Sorunome]

It's so col! Do you have any more pics??

[austron]

@Sorunome I have some more pictures on my blog (archive -> 2010 -> may). There is a link in the description.

[ThriceDog]

just a few more years before this guy builds walking knex crabs that shoot red pieces at tachyon speeds which will doom humanity

[austron]

@ThriceDog This device was actually meant to be a prototype for an inverse tachyon emitter array, but I had a problem with fluctuations in the quantum filament which lead to a decay in the alignment of the plasma fusion coils in the warp core, but fortunately I was able to fix it by re-routing the encryptions through a triple-redundant hysenphram ramastat, so the k'nex doom crabs are still on schedule for a 2012 completion!

[funlearning9]

very interesting. Any chance you can post instructions either here or on your blog?

Thanks,

[looney1023]

so whenever your about to hit something, your car just puts itself in reverse and drives away!

[ChuffChuffWoo]

Great device - hope you like my Knex CVT variable speed transmission - or better still, improve on my design!

[MrWapenv]

nice!

[TheJeremyrussell]

Can you build me a robot that will live my life for me? I lack the enthusiasm to leave my home most days, and often wish I had a robotic pal to do the things I can not be bothered with, like bathing, communication and masturbation.

[dogcatto]

So cool

[DJSI3434]

CCOOOOOOOOLLLLLLLLLLLLLLLLLL