Motor Sizing for Wheel Endurance Testing

Click For Summary

Discussion Overview

The discussion revolves around sizing a motor for a wheel endurance testing application, specifically addressing the calculation of torque in relation to the drum and wheel radii. Participants explore the implications of different forces applied during testing and the necessary adjustments for motor specifications.

Discussion Character

  • Technical explanation
  • Debate/contested
  • Mathematical reasoning

Main Points Raised

  • One participant questions whether to use the radius of the drum or the wheel for torque calculations, noting that using the drum radius results in excessively high torque values due to the applied force.
  • Another participant suggests that the radius used depends on the motor's position relative to the drum and wheel, indicating that torque and angular velocity will differ based on this choice, but power remains constant.
  • A different participant raises concerns about the relevance of the radius in the context of force alignment and leverage, suggesting that the motor sizing should focus on overcoming friction rather than solely on torque calculations.
  • One participant provides a reference for calculating rolling friction resistance, offering a method to estimate minimum needed torque based on the weight of the wheels and the coefficient of rolling resistance.
  • A recommendation is made for a variable velocity connection between the motor and drum to accommodate the different wheel sizes and specified angular velocities during testing.

Areas of Agreement / Disagreement

Participants express differing views on the appropriate radius to use for torque calculations and the factors that should be considered in motor sizing. There is no consensus on the best approach, and multiple competing perspectives remain unresolved.

Contextual Notes

Participants highlight the complexity of the problem, including the need to account for friction from bearings and wheel deformation, as well as the implications of varying wheel sizes on motor performance.

SR71
Messages
1
Reaction score
0
TL;DR
Motor sizing for wheel endurance testing
I am working with a wheel endurance testing application. I am trying to size a motor for the system. Basically, I have a drum which has to be rotated by the motor. I have different size wheels that I have to test. The motor is supposed to rotate the drum and then the wheel is pushed onto the drum with a force.

My question is when I want to find the torque (Fx perpendicular distance) do I use the radius of the drum or the radius of the wheel being tested? Currently, I am using the radius of the drum as the wheel is being pushed onto the drum but this gives me huge numbers as the wheel is pushing with 1000-2500 lbs of force.

Thank you in advance.

Link:
Wheel Endurance FBD.png
 
Last edited by a moderator:
Engineering news on Phys.org
If the motor is on the drum then use the drum radius. If it is on the wheel then use the wheel radius.

Torque will be different in both cases but so will be the angular velocity. In both cases, the power will always be the same.
 
Reply
  • Like
Likes   Reactions: SR71
SR71 said:
My question is when I want to find the torque (Fx perpendicular distance) do I use the radius of the drum or the radius of the wheel being tested? Currently, I am using the radius of the drum as the wheel is being pushed onto the drum but this gives me huge numbers as the wheel is pushing with 1000-2500 lbs of force.
How is the radius of the drum or wheel relevant for this? The force is aligned with the axles so it's got no leverage. Am I misunderstanding the drawing? Or are you obtaining the tangential component due to the friction?

Since the angular velocity is constant during the test (or so I think from the video), I would say to size the motor you just need it to have enough torque to overcome the friction from the bearings and the friction due to the deformed wheel rolling.
I guess the second one should be the greatest one but I don't know how to derive it yet.
 

Attachments

  • 1690647772315.png
    1690647772315.png
    14 KB · Views: 141
Reply
  • Like
Likes   Reactions: Juanda and Lnewqban
Welcome, @SR71 !

Due to the different diameters of wheels to be tested, I recommend to engineer a variable velocity connection between motor and drum.
It could be a variable pulley-belt system, or a VFD (variable frequency drive), for example.
I assume each test has one or several specified angular velocities for the wheel.
 
Reply
  • Like
Likes   Reactions: Juanda and Tom.G

Similar threads

Can an axle connected to a wheel transmit momentum to the plate to which it is attached?
  • · Replies 11 ·
Replies
11
Views
2K
How to spec a motor for this floor testing system?
  • · Replies 10 ·
Replies
10
Views
2K
Maximum torque required to turn the wheel along the vertical axis
  • · Replies 9 ·
Replies
9
Views
2K
Design problem with a constant torque motor
  • · Replies 24 ·
Replies
24
Views
4K
Help Walk Me Thru Motor Sizing Calculations Please
  • · Replies 14 ·
Replies
14
Views
3K
Help with wheels, stopping forces and possibly Simpack
  • · Replies 24 ·
Replies
24
Views
4K
Hydraulic winch torque questions
  • · Replies 4 ·
Replies
4
Views
4K
Selecting hydraulic motors and a pump for hydrostatic transmission
  • · Replies 58 ·
2
Replies
58
Views
8K
Torque requirements for launching a soccer ball
  • · Replies 4 ·
Replies
4
Views
4K
Automotive Mechanism to drive a wheel from an internal motor allowing suspension?
  • · Replies 9 ·
Replies
9
Views
3K