Society of Robots - Robot Forum

Mechanics and Construction => Mechanics and Construction => Topic started by: cjholloway on September 18, 2012, 08:26:49 PM

Title: Gears, Sprockets, and Chain confusion
Post by: cjholloway on September 18, 2012, 08:26:49 PM

In the Gears, Sprockets, and Chains section of this web site at:  http://www.societyofrobots.com/mechanics_gears.shtml#compoundgears (http://www.societyofrobots.com/mechanics_gears.shtml#compoundgears),
it states:
torque_gear3 * radius_gear3 = weight * radius_gear3
something is not correct here since the units on both sides of the equation are not the same - can anyone help?
 
 

Title: Re: Gears, Sprockets, and Chain confusion
Post by: fridgid on September 20, 2012, 10:37:16 PM

I assume they're trying to state that the force from the motor torque (N or lbs) times the radius is equal to the weight force (again N or lbs) times the radius.
This equation might better be stated as:
r x F = r x F

If you are using spec motor torque from a sheet, the units would be in N-m or lb-ft (or some derivative of those two) and would be equal to r x F (meters or feet times newtons or lbs)

The motor torque is:
T = r x F

Motor torque in those equations is a force not a torque, so you are correct.