How many of you have seen an accident involving a tractor trailer which has jackknifed on the roadway?  Did you ever stop to think about why this happens?

Generally speaking, jackknife accidents can be caused by a sudden braking event with a tractor-trailer. However, in many circumstances the cause is not so innocent. Brake failures or improperly adjusted brakes can cause an imbalance in the braking force applied to the trucks wheels, and can cause the trailer to become angled vis-a-vis the direction of the tractor’s motion.  When the trailer’s angle exceeds fifteen degrees off of the centerline under braking, the truck can jackknife and may cause an accident. Statistics show that brake failures or improper brake adjustment are amongst the most common causes of accidents involving heavy trucks.