[AT] OT: the inch is somewhat metric

[Jim Becker]

Attempting to see if this thread can go so far off topic it ends up back on 
topic.

The locomotive test resistor bank reminds me of the old test equipment at 
the Nebraska test lab.  In the old days, they did a belt horsepower test. 
The dynamometer inside the lab used an electrical generator to put the load 
on a tractor.  The power out of the generator was burned off in a resistor 
bank mounted on the roof of the building.

The modern lab does a PTO horsepower test and the electricity generated by 
those dynamometers is pushed into the electric grid.

Jim Becker

-----Original Message----- 
From: James Peck
Sent: Sunday, May 05, 2019 2:47 PM
To: Antique Tractor Email Discussion Group
Subject: Re: [AT] OT: the inch is somewhat metric

The railroad I trained with was using a paper punched tape “Search Machine”. 
A cable was wired into each of the newer locomotives and a cable with mating 
multipin connector was wired into the “Search Machine”. In phase 1 the 
“Search Machine” checked resistances of components through the wires. In 
phase 2 the leads to the traction motors are tied to a resistor bank and the 
locomotive operated at various loads up to full with the power going into 
the resistor bank. I have seen them glowing cherry red in the winter. Phase 
2 measures voltages at various points.

If a resistance or voltage is out of its range, electricians looked at the 
locomotive electrical schematics and made measurement with meters. They 
might adjust, repair, or replace a component. The idea was to catch a 
problem before it came to a head with the locomotive hundreds of miles away 
from the shop. Moisture in the traction motors was a common problem.

The company, I think, became part of Textron. The locomotive manufacturers 
may have added similar features as an OEM offering.

[Jim Becker] <snip> On the subject of paper tape.  Ask almost any programmer 
how big a program is, he will give you an answer in bytes, kilobytes, or 
these days megabytes.  Ask an NC programmer about the size of a program, he 
will answer in feet, as in how long the paper tape would be if you punched 
it out.  I found that even in the ‘90s, long after paper (or mylar) tape had 
disappeared from the shops, that was still the way they answered. <snip>

[Stephen Offiler ] <snip>The very earliest numerical-control (NC) machines 
had no computer, but rather read instructions from a punched paper tape, and 
these were in the research stage in the 1940's and began to appear in 
practice in the 1950's.  It was not until the 1970's that computers and 
digital displays began to appear on the shop floor.   Conversion from metric 
to inch in the displays was not an issue.  Even if it was, the conversion 
could have been accomplished regardless of the definition, because even 
prior to the universal adoption of 1" = 25.4mm exactly, the errors were on 
the order of 25.39993 to 25.40005 which is well beyond the precision of the 
machines in those days.


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