"Rolling Resistance" made clear | Basics 

Glad that it helped you and other students ☺

Thanks Dhruv !

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Thanks Rishabh :)

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Thank you very much ! Next video is coming soon :)

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I didn't quite understand that as well

It is not introduced, rather it comes as a result to satisfy the condition of equilibrium for opposite moment caused by Fz. There should be the only moment in direction of rolling or motion by driving force on roller.

Please go ahead, since there is no proprietary information in this presentation you can use it in your school presentation, but pls quote reference. So the ultimate aim is to spread knowledge 👍

@Chris: In this particular situation, you can see an anti clockwise moment is introduced to the system due to the shift of Fz towards front. Only way to balance this moment is to have a clockwise moment introduced by the rolling resistance force. Here steady state is assumed, so no transients such as slip are not considered. Note that rolling resistance can exist even if slip ratio is existing or not (anywhere in the range 0-100%). Hope it helps!

@@AutomotiveInsights I understand how the moment by the offset vertical force is produced, but what actually produces the resistive force at contact patch (orange arrow) if not a negative slip ratio? Surely something has to apple this force?

@@chrisc9608 : This resistive force (orange arrow) should be present to provide the clockwise moment and is supplied by friction available at the road-tire interface. You can also imagine a situation of friction at the road-tire interface as zero then it becomes another interesting problem. But as I mentioned in my last comment, slip may be assumed as zero.

@@AutomotiveInsights Is this rearwards resistive force at TCP the same as what some textbook show where there is net rearwards longitudinal force due to the stretching of the tyre elements (like brush model), where in the front half there is a force facing the front, and in the rear half, there is a slightly bigger force facing rear, hence net rear. Is this what balances it?

@@chrisc9608 : I agree that there are forces on the front half of the tire due to deformation of treads as in brush model towards forward direction and in the rear half towards backward direction. But these two forces balance each other in the brush model because the concept of hysteresis and thus rolling resistance is not considered in the brush model. So these forces are equal and opposite in the brush model. However in the actual testing or in the models in which hysteresis is considered, surely the backward force should be higher than the forward force and thus this difference accounts for the rolling resistance. Also please keep in mind that the rolling resistance force need not be balanced. If no propelling force is given at the axle, ultimately the tire is going to stop. But if an equal magnitude force is applied in the direction of motion, the velocity sustains (this is covered in the video).

Thank you !

Is it the action reaction pair formed by the system of forces?

@@stall_horn The rolling resistance force acts at the ground level. Move it to the centre of the wheel. Then we can see that the rolling resistance force was contributing to a moment also. Recollect the concept of force acting at the end of a candilever beam. When we move the force to support, then we can see a moment was also acting due to that force. Hope it helps!

@@AutomotiveInsights Got it! thanks

There are several excellent books in vehicle dynamics. A couple of them for beginner's would be: Fundamentals of Vehicle Dynamics by Thomas D. Gillespie Vehicle Dynamics - Theory and Application by Reza N. Jazar Theory of Ground Vehicles by Jo Yung Wong

@@SubashMU Thank you for the suggestion