Inbound trains are shoved slowly up an artificial rise, the hump, where a pin puller uncouples each car or group of cars at the crest. The cars roll downhill through automatically lined switches and through retarders that grip the wheels to control speed, landing on the correct track in the classification bowl. A large hump yard sorts thousands of cars a day, far more than flat switching with a locomotive can manage.
We're a humper, so yard us on the receiving tracks at the hump yard and we'll tie up at the shanty.
Trains bound for a hump yard are called humpers, and a yard that is behind on trims is struggling to pull sorted cars out of the bowl into outbound trains.
Also heard as
- hump
- gravity yard
Related terms
Bowl
The set of classification tracks at the bottom of a hump yard where sorted cars collect.
Block
A group of cars bound for the same destination, kept together so they can be handled as one unit.
Pull the pin
To uncouple cars by lifting the coupler's pin with the cut lever; also, to retire from the railroad.
Switch list
The list telling a yard or local crew which cars to move and where each one goes.