compound gears formulae
compound gears formulae
(OP)
Hi all,
I needed to go through essentials of gear calculations.
I found nice tutorial here http://www.societyofrobots.com/mechanics_gears.sht...
During my studies I found a possible mistake that it was so obvious that I start to feel that maybe I was thinking wrong?
Please go to compound gear section:
Final formulae for compound gears does not have identical units.
torque_motor=weight*radius_gear3 / radius_gear1 so then Nm = N ???
this mistake (or am I wrong?) comes from wrong basic equation few lines
above in text:
torque_gear3 * radius_gear3 = weight * radius_gear3 so once again N*m =
kg*m so N=kg ? (torque = weight ???)
Am I right?
Anyway if it is correct - could someone explain me why, if not - what is the correct method to determine motor torque there?
I needed to go through essentials of gear calculations.
I found nice tutorial here http://www.societyofrobots.com/mechanics_gears.sht...
During my studies I found a possible mistake that it was so obvious that I start to feel that maybe I was thinking wrong?
Please go to compound gear section:
Final formulae for compound gears does not have identical units.
torque_motor=weight*radius_gear3 / radius_gear1 so then Nm = N ???
this mistake (or am I wrong?) comes from wrong basic equation few lines
above in text:
torque_gear3 * radius_gear3 = weight * radius_gear3 so once again N*m =
kg*m so N=kg ? (torque = weight ???)
Am I right?
Anyway if it is correct - could someone explain me why, if not - what is the correct method to determine motor torque there?





RE: compound gears formulae
Power in = Power out
Torquemotor*rpmmotor=Torquegear*rpmgear
Torquemotor*rpmmotor=Weight*radiusgear*rpmgear
RE: compound gears formulae
RE: compound gears formulae
RE: compound gears formulae
The page is correct.
Weight is a force and is measured in Newtons, mass is measured in kg.
Your mistake is assuming that weight is measured in kg. In English units scales report pounds-force; it's metric scales that are incorrect and report kg. On the moon a person would apply 1/6th their usual weight on a scale, but their mass would be unchanged.
RE: compound gears formulae
I don't think that is the best possible explanation.
If you treat pounds and newtons as units of force, and kilograms and slugs as units of mass, you have a consistent system of equations.
m = w/g
F = ma = w/g × a
If you have a weight hanging from a lever arm...
T = wr = gm × r
If you are not methodical about your units, you need some other way to figure out when and where to insert g in your equations. Good luck!
--
JHG
RE: compound gears formulae
RE: compound gears formulae
"writing down the equations:
torque_motor * radius_gear1 = torque_gear2 * radius_gear2
torque_gear2 * radius_gear2 = torque_gear3 * radius_gear3
torque_gear3 * radius_gear3 = weight * radius_gear3
simplifying, we get:
torque_motor * radius_gear1 = weight * radius_gear3"
the picture of this is torque_motor is driving a gear train to raise a weight. i think the whole set of equations is messed, no? what is "torque_gear3 * radius_gear3" ? = weight * radius_gear3" is wrong. i'd've thought torque =
weightmass*accel*radius3.note, this guy is playing very quick and roughly with units ...
"rps_gear3 * 2*pi*radius_gear3 = velocity_weight" is right for "rps" in rev/sec and "velocity" in ft/sec.
normally v=w*r, with w in rad/sec, so the 2pi corrects rev to radians.
another day in paradise, or is paradise one day closer ?
RE: compound gears formulae
then motor_torque/radius_1 = torque_gear3/radius_3 = weight (because, confusingly, he has radius_2 = radius_3);
motor_torque (for static equilibrium) = weight*radius_1.
another day in paradise, or is paradise one day closer ?