GagiMunjiza Posted March 6, 2012 Author Report Posted March 6, 2012 Ok so I put tape on the axle between the wheels and now the wheels spin at the same speed :D. Unfortunately there is still 1 problem. :(. The video below will explain more but I basically have made a frame from which a 1kg mass will be suspended held by the fishing line.The fishing line is then connected to the axle of the back wheels and is held together firmly. The 1kg mass is then dropped pulling down the string and turning the axle. the problem is that the axle does not turn when the string is pulled. I have tried many times but it still doesn't work.http://youtu.be/7NY3NDocXLo Quote
Turtle Posted March 6, 2012 Report Posted March 6, 2012 Ok so I put tape on the axle between the wheels and now the wheels spin at the same speed :D. Unfortunately there is still 1 problem. :(. The video below will explain more but I basically have made a frame from which a 1kg mass will be suspended held by the fishing line.The fishing line is then connected to the axle of the back wheels and is held together firmly. The 1kg mass is then dropped pulling down the string and turning the axle. the problem is that the axle does not turn when the string is pulled. I have tried many times but it still doesn't work.http://youtu.be/7NY3NDocXLo i'm having trouble loading the vid. 'til then, i suspect the axle is too skinny. in car lingo, it is lugging out. so, without the new video, i see in the first video you have the axle on the top but in your photo still it is underneath. i suggest on top if you aren't doing it that way. to have room for a thicker axle part for the string to wind on you need to get a gap in the frame for it. i have attached a rough (very rough) drawering to get the idea across. :paint: you can build up the axle with tape & cardboard a bit at a time until you get to a diameter that gets it to go. Quote
Turtle Posted March 6, 2012 Report Posted March 6, 2012 (edited) ok. saw the vid. so first, i would turn the car upside down from what you have so the string does not drag on the frame & pulls directly on the axle. your question about "why this is happening is the "axle too small" business i mentioned earlier. i made another rough drawing to try & explain why. look at the red lines as if they are levers, like in 1 side of a teeter totter. now, when you have someone heavier than you on the other end, you move back from the center, the fulcrum, out to the end of the seat. doing this amplifies your force; it gives a mechanical advantage. having the string wrapped around a fatter axle is like moving out to the end of the see-saw. just how fat it has to be is a matter of experimenting with different sizes 'til she goes. :steering: hope that helps. ps here is an article with diagrams and formulas on torque. >> Introduction to Torque Edited March 6, 2012 by Turtle Quote
GagiMunjiza Posted March 6, 2012 Author Report Posted March 6, 2012 Thank you. You have saved me :lol: Quote
GagiMunjiza Posted March 8, 2012 Author Report Posted March 8, 2012 So I have made a completely new design that I believe is better except there is still 1 problem similar to the last. The video will explain. Sorry to bother you it's just that I need to finish and you are my greatest support. :D http://youtu.be/Q49Xrbc37FY Quote
Turtle Posted March 8, 2012 Report Posted March 8, 2012 So I have made a completely new design that I believe is better except there is still 1 problem similar to the last. The video will explain. Sorry to bother you it's just that I need to finish and you are my greatest support. :D http://youtu.be/Q49Xrbc37FY Looks good. :thumbs_up The problem is still that the part of the axle that the string is pulling on is too skinny; the diameter is too small. leverage too small. Not enough torque. On my earlier drawing I have re-colored in red the "fatter" axle part you need. You probably need to move your back axle all the way to the end of the frame to make room for the "fatter axle part". Only problem then is that I have never built one of these so I don't know how fat fat-enough-to-go is. my bad. Anyway, looks like with the axle moved back you have room to fatten the axle to at least 2" diameter. You can do that just by taping a strip of cardboard to the axle and winding it on until fat and then taping it. Then try your pull on the string & see if it goes. If it still doesn't then you will need even a fatter fat-part. Quote
GagiMunjiza Posted March 10, 2012 Author Report Posted March 10, 2012 THANK YOU for all the help and support over the past week. The car worked great and I am very happy with my results. :lol: Thank you very much for assisting me with this project. I am not such a "project" person and I am more of a pencil & paper person. :). I also used the cone axle and it worked perfectly. THANK YOU! :D Turtle 2 Quote
Turtle Posted March 10, 2012 Report Posted March 10, 2012 THANK YOU for all the help and support over the past week. The car worked great and I am very happy with my results. :lol: Thank you very much for assisting me with this project. I am not such a "project" person and I am more of a pencil & paper person. :). I also used the cone axle and it worked perfectly. THANK YOU! :D yay! you're welcome bob. i'm glad it worked out. Quote
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