Howe do I find complex gear ratios?
For example, say I have two high-speed motors on different axles turning one 12-tooth metal pinion each. Both of these pinions mesh and power a 60-tooth gear that’s on the same axle as a 36-tooth gear. This 36-tooth gear finally meshes and powers an 84-tooth gear.
What’s the gear ratio?
Also, for future reference, how do I find complex gear ratios like these for myself?
Lastly, do the high-speed motors make a difference in the gear ratios?
Please do not refrain from going into excessive detail. In fact, I would rather you do so than not.
Okay, so basically, when calculating a gear ratio, you do the output/input * the output/input. So if the 12 tooth gear is driving the 60 tooth gear, then the 36 tooth gear, that is on the same axle as the 60 tooth hear is driving the 84 tooth gear, your ration is equivalent to 60/12 * 84/36 which is equal to 11.67:1. Technically, the gear ratio does not change for the internal gearing, but the gears will move faster is if you were adding gears to the outside, but with normal gearing. Attached is a picture of the outputs for all of the internal gearing. The normal versus high speed is 100 RPM vs 160 RPM, so multiple the 11.67 by 1.6 and you get a total of 18.67 turns of the final output gear, to one turn of your original input gear.
This is on the assumption that your gearing goes 12-60, these meshing, then 36 on the same shaft as the 60, which then meshes with the 84. If you have 12-60-12, but the same condition with the 36 and 84, the 60 acts as an idler gear, so get rid of the 5:1 and divide the 18.67 by 5.
Looks pretty correct to me. However, HS is a 1.6:1 for speed, as the RPM is higher than your standard internals. That would reduce the torque ratio - which means that you need to do the reverse operation that you used to include the HS gearing. Thus, 11.65/1.6 = 1:7.225 for torque.
Perhaps I’m thinking this through incorrectly - bit tired.
@g_sawchuk
Yeah, you are right, I was thinking for speed, not torque, so 1:7.225 would be correct. But question, what are you using the torque ratio for? If it is for your arm, it shouldn’t be necessary, we actually have ours geared for speed and it is working really well
Don’t want to de-rail main purpose of this thread too much - however, using a high torque ratio enables a hang, and you can still keep it fairly quick with a solid elastic assist. Also makes it easier on your arm for lifting heavy loads.
