-3
$\begingroup$

There is something wrong with the way we describe how a cornering vehicle wheel creates a cornering force. I think a rolling wheel must first rotate on a vertical axis to then create the cornering force. This is fundamentally different than what we think about cornering wheels. Can anyone else see this?

$\endgroup$
1
  • $\begingroup$ Comments are not for extended discussion; this conversation has been moved to chat. $\endgroup$
    – Wasabi
    Jan 24 '19 at 17:15
1
$\begingroup$

Your understanding is missing substantial information regarding statics and equilibrium. Think for a minute:

The instantaneous forces acting in the wheel system are radial velocity, momentum, inertia, kinetic energy and friction. Above all there is also gravity. When the wheel changes direction, its centroid remains constant but its centre of gravity changes. It is possible for a body in motion to have its centre of gravity outside itself. This occurs because of a constant resistance force applied to the control arm which exceeds the losing radial velocity gyroscopic forces. In addition there is the moment of inertia imbalance that is corrected by asked force through the control arm. The axle or more correctly, constant velocity joint (cvj), transmits force to the issuing wheel which also provides resistance to direction change observing by steering control arm. This is why wheel bearings are often the conical thrust type or specially designed ball race type instead of rod type bearings.

The lateral forces are the result of radial inertia change with an equal and opposite force in the directing of steering. Newton's third law of motion...

$\endgroup$
10
  • 1
    $\begingroup$ perpetual motion does not exist, but perpetual discussion does - just a heads up... $\endgroup$
    – Solar Mike
    Jan 20 '19 at 6:06
  • $\begingroup$ Thanks Rhodie. I left out the obvious because there is only so much I can fit. The answer is not in the details. It is in the fundamental rules established by Newton. I purposely did not focus on CoG location because we only need to know that when the mass velocity is parallel to the travel direction of the wheel you have no cornering/lateral force. When the mass velocity and wheel travel direction are different directions there IS a force. I show how to cause this force in two examples. But in the steady state turn, we mistakenly believe that a wheel cornering force occurs without a cause. $\endgroup$
    – Matt Zusy
    Jan 20 '19 at 15:30
  • $\begingroup$ Now, if we say the force is a centripetal force I say that it can’t be because a wheel is limited to straight path travel and centripetal force only occurs to bodies experiencing angular motion. We observe what we believe is angular motion, but this is no different than saying I experience a centripetal force when my foot pushes me laterally when I’m walking. If I do it enough times I am traveling a circular path and rotating around a center point. Not the case. Laws of motion are very specific for a reason. $\endgroup$
    – Matt Zusy
    Jan 20 '19 at 15:30
  • $\begingroup$ Consider a wheel with its plane perpendicular to the plane of the surface it rolls along. From a stop we roll it forward. ANY motion forward is linear motion. There is no change in direction until the wheel rotates around a vertical axis. When does the cornering force occur? AFTER the vertical axis rotation. Cause and effect. $\endgroup$
    – Matt Zusy
    Jan 20 '19 at 15:40
  • $\begingroup$ Sure but equilibrium is maintained due to the continued applied force that induces change. The wheel is part of a system not the system itself. Newton's second law of motion is in play $\endgroup$
    – Rhodie
    Jan 20 '19 at 15:57

Not the answer you're looking for? Browse other questions tagged or ask your own question.