Assuming an RPM-increase gear-train, if more gears are added to the gear train, without changing the step-up ratio of the total train, and without changing the desired output torque, will the first gear require more torque to turn it? Less torque? Or no change?
For example, compare:
1:64
vs
1:4:4:4
Will there be any difference in the torque required to turn the first gear? If not, will there be a reduction in the amount of torque required at the intermediate stages?
In a theoretically perfect world no. But we live in a worlds were friction is a thinkg. so more moving parts = more friction. more friction means its takes more motor power to turn the system.
In an ideal world, no, but since there is an increase in friction everytime another gear is added, then generally longer gear trains will require more torque to turn. Hope this answers your question.
if they’re all in a line, it’s just 1:4
Yeah. Im assuming that the OP meant that it was a 1:4, the ngeared down again 1:4 then agian geared 1:4. like a compound gear ratio. so it goes 1:4 → 1:16 → 1:64
The overall gear ratio is based on the first and last gear in the geartrain. So five gears in a single train 84:36:12:36:60 still results in an 84:60 (first : last) ratio.
The required torque stays the same in theory, but slightly increases with each gear you add due to friction in practice.
Torque at intermediate gears depends on the gear ratios at each stage. In a step-up train, each gear closer to the output typically carries more torque. So yes, torque varies across the stages, and it’s not evenly distributed.
I think my ratio-notation is wrong. In my example, i intended to show that RPM increases by 4x at each gear.
RPM: 1x4x4x4
So i think that means, assuming same tooth size, that number of teeth is divided by 4 at each gear.
256T - 64T - 16T - 4T
well vex doesn’t have a 256t gear, ig you could use compound. but im wondering why do you need this gear ratio?
I’m trying to understand the theory. if one were to use compound gears then you could step up RPM with identical gears at each stage , correct?
Correct. because the small gear spins at the same RP as the large gear it shares a shaft with. and then you can drive another big gear with that small gear reducing the ratio again and so on and so forth. heres a decent article explaing and showing some examples
https://woodgears.ca/gear/ratio.html
In my scenario, i’m going in the other direction - Driving the small gears with large gears.
