Re: O/T why does a skidding tractor trailer jackni

Posted by jmixigo on October 13, 2006 at 17:23:36 from (69.73.54.156):

In Reply to: O/T why does a skidding tractor trailer jacknife?? posted by baffling question on October 13, 2006 at 14:41:16:

A sliding tire has lost all traction. A rolling tire ,even when force is applied has tractive force to resist. When the tires lock up they have lost not only most of their resistance to forward motion, but resistance to sliding in any direction. The towing unit, in most instances, has not lost traction to as great a degree as the unit being towed. The situation is exacerbated by the length to weight and length to length ratios of the truck and trailer.
Added to the equation is the fact that the RELATIVE weight of the tractor truck unit changes very little whether loaded or empty while the RELATIVE weight of the trailer changes greatly.
Most old truckers will tell you that a "medium" load, where the weight of the trailer roughly matches that of the tractor, stops MUCH better under any condition than an empty trailer.
A drag car enters the bleach box with COLD tires and does a burn out to heat the tires to their operating temprature (whether the driver actually knows that or not). They then perform as designed. The truck has all ready traveled miles getting to the scene of the accident so his tires are done warmed up. Sliding around on pavement is just gonna over heat the tire and make it act "greasey".
All of the above was taught me by folks that were supposed to be smart. What I learned on my own is that a tractor trailer jack knife happens damned quick. And seeing yore own trailer just outside the driver's side window is right spooky. I only did it once an strangely enough on a Friday the 13 th.
Sorry bout the length of all this.

Replies:

• Re: O/T why does a skidding tractor trailer jackni Kent in NB 17:30:32 10/13/06 (1)
  • Re: O/T why does a skidding tractor trailer jackni jmixigo 17:48:32 10/13/06 (0)

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