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Why do locomotives have discrete throttle settings?

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Posted by Overmod on Saturday, April 17, 2021 8:03 PM

Former Car Maintainer
https://patents.google.com/patent/US2311285A/en?oq=Us2311285a

This may more accurately show the throttle/load regulation scheme, and 1941 would better date it.

I have to wonder whether this is a way to get around the EMD load-regulator system (which uses rotary control of generator field excitation) by using linear pressure on a Carbonstat to accomplish a similar purpose.  He seems to be unaware of the way EMD uses the Woodward governor; he seems to think that primary field excitation is the way locomotives avoid being 'bogged down' (as with gas engines in the '20s) not realizing that homeostatic control over engine speed once selected as governor speed input is the way EMD's successful locomotive control helps assure this.

It would be interesting to see how engineer Stamm would rig this for effective multiple-unit control, let alone compatibility with 8-notch AAR MU -- I think it might be difficult to do it effectively with contemporary technology.  Thinking about the PCC accelerator, though, leads me to wonder if progressive position of the 'wiper arm' around the circle of progressive resistances in the accelerator could toggle different combinations of solenoids just as they do different contactor combinations in electric-car acceleration, to give proportional engine speed and hence HP range as governed (that could be sent through AAR-compatible MU wires and pins) with the Carbonstat then performing appropriate duty comparable to an EMD load regulator...

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Posted by Former Car Maintainer on Sunday, April 18, 2021 2:32 AM

The technology of the air throttle is a reminder of the pneumatic player piano/orchestrions or calculators built from decatron tubes....

 

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Posted by Overmod on Sunday, April 18, 2021 7:22 PM

Not that I have anything but serious respect for Welte-Mignon, or the technology of fluidic amplification used by the Air Force in the '50s, or the Honeywell proportional control in the A-12.  There's a lot to be said for full proportional control; we have it in most drive-by-wire automobiles, and as noted this 'could' be made multiple-unit compliant with a comparatively small amount of technology (strain gages trainlined with some kind of high-rate multiplexing).  All you really have to do is equilibrate the strain-gage readings among the engines in the consist, with simple feedback control of the throttle positions when necessary to develop more power at rpm and of the load regulators...

Now, decatrons I'll grant you are as pointless as EBCDIC ... base 10 is sooooo much less useful than base 16.

I think one of the chief attractions of the air throttle (aside from getting around EMD patent coverage) is that most of the components would be familiar to existing shops.  One of Westing's books, I believe, mentions the culture shock involved in putting injector-rebuild facilities for Baldwin engines in one of the PRR shops -- the idea of very clean, essentially controlled-atmosphere facilities being alien to their general practice.  We might conclude that their working on EMD 567 unit injectors -- where a fingerprint on some of the components precludes assembly -- would be more difficult still...

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Posted by Former Car Maintainer on Sunday, April 18, 2021 10:21 PM

Which makes me think....if locomotives had to be built to MIL specs?

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Posted by Overmod on Sunday, April 18, 2021 10:37 PM

Former Car Maintainer
Which makes me think....if locomotives had to be built to MIL specs?

They would cost $172 million and change apiece, be design-frozen with flat-pack electronics and 'EMP-resistant' Ignitrons, and not be reliable for several more years...

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Posted by Former Car Maintainer on Sunday, April 18, 2021 11:13 PM

Speaking of ignitrons, weren't they used in Budd's shotwelding machine , along with precision timing charge networks, for controlling spot weld time while constructing the Burlington Zephyrs? And back to throttle settings...guess enough has been said...

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Posted by Overmod on Monday, April 19, 2021 12:09 AM

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Posted by Overmod on Monday, April 19, 2021 12:20 AM

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Posted by Overmod on Monday, April 19, 2021 12:23 AM

Former Car Maintainer
Speaking of ignitrons, weren't they used in Budd's shotwelding machine , along with precision timing charge networks, for controlling spot weld time while constructing the Burlington Zephyrs?

You raise a highly interesting point.  The original Shotwelding (as used up to construction of the Silver Slipper and the "Michelines") used a mechanical timer.  Meanwhile Westinghouse introduced the Ignitron-tube timer sometime in 1934... but I don't know precisely when.

Both were described in this article (from 1937):

https://worldradiohistory.com/hd2/IDX-Site-Early-Radio/Archive-Radio-Engineering-IDX/IDX/37/Radio-Engineering-1937-04-OCR-Page-0012.pdf

The way this was written appears to indicate that the Budd Company was preferring to use the mechanical timer system for much of its heavier work later than the time the Zephyrs were built, but I don't know. 

Closely associated with the practical development of Shotwelding was a system that could quickly assess weld quality.  The original version of this to be patented was 2093932, which was filed in 1932 but not granted until 1937, not being improved in process; this shows only the mechanical timer.  Heitman's improved version, 2138790 (filed 1935 and granted 1938) clearly references a "Thyratron timer" as an essential component. 

Have to do more reading!

(The posts on October 21 and 22, 2008 really answered the original poster's question regarding 'why the eight-notch throttle', so I think you're right about letting what's left of the horse find surcease... Wink)

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Posted by Overmod on Monday, April 19, 2021 12:23 AM

.

I see Kalmbach is trying to quadruple my posts again.  At least I caught it myself this time.

 

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Posted by blue streak 1 on Friday, April 23, 2021 8:59 PM

Many years ago in Pannama City,Fl there was a bay line Alcoa in a park.  Opened the MU connector and it had fewer than 27 points.  Maybe 18?.

Cab ride on Amtrak on NYP - PHL commuter train with 2 AEMs  train performance terrible. Head unit 95x ? Maintenance went back at stop and cut second unit out.  Ran much better. Much later read somewhere that early AEMs did not have notches but used something called "P"  control..  Not compatible with later 8 notch AEMs. Also read "P" was later eliminated ? Anyone know more ?  

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Posted by Former Car Maintainer on Friday, April 23, 2021 10:19 PM

blue streak 1

Many years ago in Pannama City,Fl there was a bay line Alcoa in a park.  Opened the MU connector and it had fewer than 27 points.  Maybe 18?.

Cab ride on Amtrak on NYP - PHL commuter train with 2 AEMs  train performance terrible. Head unit 95x ? Maintenance went back at stop and cut second unit out.  Ran much better. Much later read somewhere that early AEMs did not have notches but used something called "P"  control..  Not compatible with later 8 notch AEMs. Also read "P" was later eliminated ? Anyone know more ?  

 

https://railroad.net/p-wire-question-t77859.html

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Posted by CSSHEGEWISCH on Saturday, April 24, 2021 9:56 AM

The Bay Line RS1 may have been equipped with the old Alco standard of two connectors with 12 and 21 pins.

The daily commute is part of everyday life but I get two rides a day out of it. Paul

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