Battery Buggy

[John2019]

Dear Friends:

As a part of my middle school science Olympiad competition I built a battery buggy using Lego pieces like axels, gears, motor, battery etc but this project requires motorized vehicle to stop automatically after going for certain distance (9 to 12 meters) and I am unable to make any progress on stopping part. Does you guys have recommendations please?

 

Thanks,

John D

[ukbajadave]

How about string that winds up around a driven axle and pulls a lever connected to the battery box switch?

[John2019]

Thanks for your response. I tried that that by tying a string to front and back axels to wind up around axles based on direction of the vehicle but the problems that I am facing are it's very hard to keep the string knot tight and if it's tight then string is breaking. Do you recommend any specific string?

 

[samurai-turtle]

3 hours ago, John2019 said:

Thanks for your response. I tried that that by tying a string to front and back axels to wind up around axles based on direction of the vehicle but the problems that I am facing are it's very hard to keep the string knot tight and if it's tight then string is breaking. Do you recommend any specific string?

 

Have you tried fishing line or even dental floss? I heard dental floss is fairly strong. 

[John2019]

I tried the dental floss but no luck, let me try the fishing line. Thanks for the tip.

[ukbajadave]

Are you tying the string directly around the axle? I would think it is very hard to get it tight enough.

 When I built a winch I tied the string onto a pulley first, then drove the pulley with an axle.