Login
or
Register
Home
»
Trains Magazine
»
Forums
»
General Discussion
»
Hunting Prevention of High Speed Intermodals
Edit post
Edit your reply below.
Post Body
Enter your post below.
I guess I started my reasoning with the thought "what if a wheel had no taper?" <br /> <br />A perfectly flat tread perfectly parrellel to a perfectly flat rail head, what would limit lateral motion of the wheel in relation to the rail other than contact by the flange? A truck would definately hunt all the time under these conditions, the leading axel would make contact on one side, then the trailing axel, then the leading axel would make contact on the other side, then the trailing axel, because there would be no natural balance point in the center of the tread. I imagine the period of this ocillation would be set by the distance between the axels. <br /> <br />The pendulum is the "arm" between the the center of rotation at the bolster and the point of wheel rail contact. The "arm" swinging in a horizontal plane as the truck wanders then corrects and returns. <br /> <br />It feels safe enough to say gravity acting on the taper of the wheel is a correcting force to maintain contact in the center of the tread, because for the flange to contact the rail head, the point of contact would have to climb the taper. <br /> <br />This is why I feel a pendulum is a good analogy, because for this model I assume a truck has a natural non destructive hunting, an ocillation with a corrective force from gravity, this pendulum having a very small amount of motion. <br /> <br />I think what Oltmand says makes sense, if for some reason the track of a truck is upset and the lateral path of the wheels across the width of the rail head were tracked as a wave would the wave have a decreasing amplitude and increasing period eventually returning to stability? or an increasing amplitude and decreasing period of an unstable system? <br /> <br />This would mean an unstable system doesn't necessarily hunt, but can if provoked. <br /> <br />I was not thinking of electronics when I mentioned clipping, I was thinking of clipping like when the peak of a wave exceedes the limit of a system. If a wave increases in amplitude to infinity beyond the limit of a system the resault is a square wave. <br /> <br />In the system of a rail/flanged wheel, the limit is the flange. <br /> <br />The lateral ocillation of a hunting wheel across the face of the rail being traced as a curve on a graph. <br /> <br />The length of the wave would be the period or frequency and the hight of the wave the amplitude. <br /> <br />The amount of movement provided by the guage width vs. flange width is the vertical limit of the system. <br /> <br />Such a curve should be long and smooth as long as the line stays within the limits (vertical limit of the graph) of the flange, and if the line meets the flange's limit at a very narrow angle be returned gently. <br /> <br />When I mentioned clipping, I meant the amplitude of the line representing the track of the wheel exceedes the vertical limit of the line representing the limit of motion from the flange. Because the wheel cannot actually track this curve, the peak is in effect "clipped". And if the amplitude continues to increase, the angle of the wheel's line and the flange's line intersection will increase, which in reality will mean the flange is hitting the side of the rail's head in a shorter distance and with greater force.
Tags (Optional)
Tags are keywords that get attached to your post. They are used to categorize your submission and make it easier to search for. To add tags to your post type a tag into the box below and click the "Add Tag" button.
Add Tag
Update Reply
Join our Community!
Our community is
FREE
to join. To participate you must either login or register for an account.
Login »
Register »
Search the Community
Newsletter Sign-Up
By signing up you may also receive occasional reader surveys and special offers from Trains magazine.Please view our
privacy policy
More great sites from Kalmbach Media
Terms Of Use
|
Privacy Policy
|
Copyright Policy