Hand Brake?

What would be the reason some hand brakes (I’m guessing thats their purpose) are found at the bottom of some boxcars…

and others at the top…

as shown on a couple of mine?
Is it something to do with the time period, or the type car, or do different mfgs just do things differently?

see this thread[:D]

http://www.trains.com/community/forum/topic.asp?page=-1&TOPIC_ID=22829&REPLY_ID=220982#220982

Thanks DSchmitt. Now all I need to know is how ‘automatic retarders’ work. Thanks for the information!

Automatic retarders in a hump yard are connected to a computer that weighs and measures the speed of a car or cars as they roll down the throat. Pneumatic cylinders pu***he retarders against both sides of the wheels, thus slowing them to a pre-computed speed so they will reach their destination track with exactly the right amount of intertia to couple to the number of cars that are already on that track without damaging the couplers or stopping short of coupling. Computers have replaced many personnel in a hump yard over the years, because previously a brakeman had to ride each car down the hump and apply manual brakes, while other brakemen set the turnouts to route each car to the correct track. Today, everything is automatic and controlled by one operator in the hump tower, with one brakeman on the ground to uncouple the cars as they move over the crest of the hump and begin to roll down hill.

Thanks Cacole…