Reply With QuoteCan't you just cut some popsicle sticks to see how length effects throw (ie., 1/2 length = 1/2 throw)?
Need a hand here.
I am trying to reduce the ratio on a control by one third. The Marine Machine controller we are using is designed for an outdrive and has a 3" stroke for the cable. Jet drives have a 2" stroke. I am trying to convert using a bellcrank.
Logic has basically told me that if I run an arm that is 2/3 the length of the top arm on the bottom, I will have a 1/3 reduction in throw. For some reason none of the smart people I know believe this to be true or not true. It is stumping them.
Bottom line is this... I am going to make a bellcrank arm that is the exact same pivot length as the MM control. This should get me an exact replication of the movement and remove any included angle from the question. I am not asking for how long the arm needs to be... I am interested if there is a ratio for reduction like you have on gears. I know that the number of teeth, which is essentially the diameter of the gear is how you reduce the ratio, and that it is a linear difference. I.E. a 4" gear working on a 2" gear will spin the 2" gear twice for every revolution???
Does this work the same way? Is this even right? I have been burning the candle at both ends for quite some time now and am admittedly not thinking straight, but want to build this linkage without a bunch of trial and error.
Any help???
Can't you just cut some popsicle sticks to see how length effects throw (ie., 1/2 length = 1/2 throw)?
Can't you just cut some popsicle sticks to see how length effects throw (ie., 1/2 length = 1/2 throw)?
Yeah, but now I want to know if there is a ratio, or if I am smoking crack.
Bottom line is, I want to do this once, have a template for future use and know WHY it is x length. There has to be a rule somewhere....
I am seeing if a changed title will help my views...
Froggystyle, your intuition is correct. The length of the throw is directly related to the distance from the pivot point. The lever will travel X number of degrees. The farther out on the arm that you make the connection, the greater the throw. The calculation is length times the sine of the angle traveled. If you want to do it in ratio, the formula is travel above the pivot / distance from pivot = travel below the pivot / distance below the pivot. If you know how much travel you want, you can calculate how far you should be from the pivot. I hope that this helps.
Thanks, I was just going to get off this thing, and now you have me researching the mechaical advantage of a lever in relation to throw. If you were talking about a pulley system, and how a change in mechanical advantage effects length of pull I could tell you the effects.
on a 4" bar you would need to have you second point at 4-5/8" from the pivot point
Thanks Eliminator89, by the time I pecked out my response, you came up with the answer. Now I can get off. :sleeping:
man you can draw this shit out in like 30 seconds
man you can draw this shit out in like 30 seconds
I can't draw and post at the same time!! Geeez.
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