1. 
   Jackknifing
   Jackknifing means the folding of an articulated vehicle (such as one towing a trailer) such that it resembles the acute angle of a folding pocket knife. If a vehicle towing a trailer skids, the trailer can push it from behind until it spins round and faces backwards. This may be caused by equipment...
   Found op http://en.wikipedia.org/wiki/Jackknifing
   
   

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