- #1
hooleydooley
- 1
- 0
Homework Statement
Hi, this is not homework or course work, I am a layman and I am just trying to understand an article I have regarding drawbar pull, in particular the pull coefficient (dimensionless) P/W where P is described as "pull (drawbar pull), lb" and W is described as "wheel load; weight, lb".
I should point out that this article is regarding traction and not power.
Homework Equations
The equation seems simple enough but the problem arises when the P (drawbar pull) seems to be measured in horizontal force and the W (wheel load; weight, lb) seems to be measured in weight, then it makes no sense to me.
The Attempt at a Solution
There are 3 solutions I can think of:
1) The carriage attached to the wheel in the test is measuring weight, although at one point n the paper it says "horizontal force"
2) The "lb" in "W wheel load; weight, lb" refers to the horizontal force required to propel the wheel at a given speed/acceleration.
3) A pull coefficent of .5 does not mean that the wheel can only tow 50% more weight*, or with 50% more force than it takes to dive the wheel, before traction is lost.
*assuming the same rolling resistance as the wheel.I have searched the net extensively but because most drawbar pull formulas are related to locomotve power they don't help to clear things up for me, and I need to be sure that the pull coeffcient is representative of a pulling power or traction in relation to the wheel (ie: pull coefficient of 0.5 equals 50% towng capacity above either the wheel weight, or the horizontal force require to drive the wheel).
There's a big difference between a wheel with 1000kgs of weight being able to pull 500kgs of weight (assuming the same rolling resistance as the wheel), or being able to pull with a horizontal force of 500kgs, before traction is lost.
I realize this question is very lowbrow for this forum but I am hoping a definitive answer can be given to help me out.