• Switching yard control computerr

  • General discussion about railroad operations, related facilities, maps, and other resources.
General discussion about railroad operations, related facilities, maps, and other resources.

Moderator: Robert Paniagua

  by abacus
Looking for info about a unique control system for a switching yard. I think this would have been in the 1950s, possibly mid-continent.

A standard switching yard with a hump. As cars coasted downhill they’d be switched to end on a track for cars with a common destination.

What was unique was the computer control system. It was digital but ferociously non-electronic. A command word consisted of eight balls, each either steel or glass. The word was assembled to designate the outgoing track on which a car was to end up. The balls of the word were allowed to fall through parallel glass tubes. Coils were wound around the tubes; a set of coils corresponded to each of the sorting track switches in the yard. As the balls fell and passed through the coils, steel balls
generated electromagnetic pulses; glass balls did not. So the eight-bit command word triggered control signals to the track switches.

This system, though you might be skeptical, really was in regular service...
Given the racket it made it was labelled, of course, 'Hailstorm.'


  by David Benton
A binary system . say glass balls zero , metal balls one .
it is fascinating to see that the binary system was in widespread use , before computers came along , and made it so much easier .
I once saw a exhibition on early mechanical control systems . alot of them were based on punched cards . hole = 0 , no hole = 1 for e.g . some machinery , like sewing machines were very complex , but all based on this system .
  by abacus
Hi David,

Glad to see your post. The early history has quite a few tales of ingenious kind of off-beat designs...I guess you know the early 19 cen Jacquard looms used punched hole systems...

But did you know that New Zealand is prominent in one story?


[Monetary National Income Automatic Computer] was created in 1949 by William Phillips [1914-1975] to model the national economic processes of the United Kingdom. At the time Phillips was a student at the London School of Economics [LSE], The MONIAC was an analogue computer which used hydraulics to model the workings of an economy. The MONIAC name may have been suggested by an association of money and ENIAC, an early electronic digital computer.The device was also known as the FINANCEPHALOGRAPH, or as the Phillips Hydraulic Computer.

Phillips scrounged a variety of materials to create his prototype computer, including bits and pieces from war surplus such as parts from old Lancaster bombers. The first MONIAC was created in his landlady’s garage in Croydon at a cost of £400.

Phillips first demonstrated the MONIAC to a number of leading economists at the LSE in 1949. It was very well received and Phillips was soon offered a teaching position at the LSE.

...A MONIAC was donated to the New Zealand Institute of Economic Research in Wellington, New Zealand. This machine formed part of the New Zealand Exhibition at the Venice Biennale in 2003. The MONIAC was set to model the New Zealand economy.

The wikipedia entry has more details...