Need some clarification with torque or force and gear ratio

Click For Summary

Discussion Overview

The discussion revolves around the concepts of torque, force, and gear ratios in the context of using a motor to pull a load with sprockets and a cylindrical object. Participants explore how changing the radius of the sprocket and an additional cylindrical object affects the pulling force and torque generated.

Discussion Character

  • Technical explanation
  • Conceptual clarification
  • Debate/contested

Main Points Raised

  • One participant describes a scenario involving a motor connected to a small sprocket and a larger sprocket to increase torque while reducing RPM.
  • Another participant suggests that using a smaller radius cylindrical object connected to the load would increase the pulling force, comparing it to a winch mechanism.
  • There is a discussion about the relationship between torque, force, and radius, with participants noting that torque remains constant across connected gears on a common axle.
  • Participants mention that the tangential force remains the same for the chain and sprocket, but the larger sprocket provides more torque due to its greater radius.
  • One participant provides a basic equation relating torque, force, and distance, indicating how changes in radius affect force.

Areas of Agreement / Disagreement

Participants generally agree on the relationships between torque, force, and radius, but there is some uncertainty regarding terminology and the implications of these relationships in practical applications.

Contextual Notes

Some participants express uncertainty about the correct terminology to use when discussing torque and force, which may affect clarity in the discussion. The implications of using different radii in practical scenarios remain somewhat unresolved.

qpham26
Messages
53
Reaction score
0
Hi guys, I have a question about gear ratio, sprocket or wheel ratio.

So let's say I have a motor with connect to a small output sprocket, and I want to use this motor to pull some load, so in order to do this I need to connect the chain with a larger sprocket, let's say 2 time bigger than the other. So this increase my torque by 2x while the RPM is 2x less.

Ok, now I want to generate more torque (not sure if I should say force), I don't know how to say this, but I want to stick a cylindrical object, concentric with the larger sprocket, but this cylinder will have a smaller radius (lets say 2x smaller), and a string that will connect this cylinder to the load (like an inner pulley). Would this increase the pulling force 2x as much as just using the larger sprocket?


Thanks and sorry for my lack of terminology.
This is why I can't find the thing I need by searching google =(
 
Physics news on Phys.org
I want to stick a cylindrical object, concentric with the larger sprocket, but this cylinder will have a smaller radius (lets say 2x smaller), and a string that will connect this cylinder to the load (like an inner pulley). Would this increase the pulling force 2x as much as just using the larger sprocket?

Yes. Consider a winch... The smaller the radius of the drum the greater the pulling force but the slower the wire is wound in.
 
CWatters said:
Yes. Consider a winch... The smaller the radius of the drum the greater the pulling force but the slower the wire is wound in.

Thanks, and the reason that I get a greater force is because they spin together with the same ω the torque is also the same on both, but the radius is difference right?

and for chain and sprocket, what do they both have? The tangential force is the same right? but the larger sprocket have a bigger radius so it give more torque and slower rpm?
 
Yes. The basic equation is..

torque = force * distance (eg radius)

Gears on a common axle have same torque so treat that as a constant and you can rearrange it to give..

force = torque/distance

Change the distance (radius of the winch drum) and the force changes.

For sprockets connected by a chain...The chain tension (force) is the same so treat that as a constant..

torque = force * distance

As you change distance (radius of the sprocket) the torque changes.
 

Similar threads

Undergrad Calculate acceleration from power/torque graphs
  • · Replies 17 ·
Replies
17
Views
1K
Undergrad Why do bicycle gears make pedaling easier or harder?
  • · Replies 19 ·
Replies
19
Views
10K
Undergrad Increasing the output torque of a DC motor with gears
  • · Replies 16 ·
Replies
16
Views
4K
Undergrad Gravity machine force calculations assistance needed
  • · Replies 13 ·
Replies
13
Views
2K
Automotive Ratios, sprocket diameter, and acceleration
  • · Replies 7 ·
Replies
7
Views
3K
High School What is the formula for calculating RPM of a gear with a known force?
  • · Replies 13 ·
Replies
13
Views
4K
Undergrad What is the Torque at the rear wheel in this gear setup ?
  • · Replies 2 ·
Replies
2
Views
2K
How to select a stepper motor and gear ratio?
  • · Replies 2 ·
Replies
2
Views
5K
High School Why do gear forces need to be balanced at the pitch circle radius?
  • · Replies 4 ·
Replies
4
Views
2K
Undergrad Calculating the propulsive force acting on a car's wheels
  • · Replies 4 ·
Replies
4
Views
4K