Train Deviates !!!

 So someone once asked me if there were Train deviates out there. he asked because on the side of a rail car he saw the phrase "DO NOT HUMP"

Well there maybe some deviates out there...

But...that is not the reason for the term. 

For a number of years all yards were flat and they used switch engines to move the cars around. This was a time consuming and costly system. What they came up with to take care of this is a "Hump" yard. That is a freight yard with a man made hump in it. When a train arrives in the yard it drops it's consist. 

The power then heads to the maintenance area. A Hump set (engines or engine and slug) connect to the cars that the train brought in. 

This is because the train requires Classifying. When a train arrives it will have cars from all over heading to all different locations. The Hump set starts pushing on the cars at a slow speed, shoving the consist up the hump.

As the train goes over the top the cars are separated by destination and roll down the opposite side of the hump into the classification yard. The hump tower then sets the switches so that each car rolls down onto the tracks it needs to to go in the correct direction for the rest of it's trip. To control the speed of the cars the hump tower 
operates what is referred to as retarders, these are hydraulic beams that tighten against the wheels and slow the cars decent.

  Each of the classification yard tracks now hold cars heading to destinations in specific directions. This has built multiple out going trains awaiting for engines to attach and take them on their way.

Once done, the hump power heads back down the hump to pick up the next  string of cars.