JJ Keller Entry Level Driver Training For CDL (Commercial Driver’s License) Practice Test

A tractor jackknife occurs when the rear of the tractor swings out to the side, typically due to the drive wheels losing traction and consequently causing the trailer to swing uncontrollably. This situation is often heightened by factors such as improper weight distribution, slick road surfaces, or sudden braking. When the drive wheels lose grip, they cannot maintain control of the vehicle, leading to the trailer moving independently and creating the jackknife effect. The other conditions mentioned, while they can contribute to various driving hazards, do not directly result in a jackknife situation in the same manner. For instance, uneven tire pressure or excessive speed on turns can affect vehicle handling, and a heavy load can create challenges, but it is primarily the loss of control from the drive wheels that initiates a jackknife scenario.