Thank you very much for the information! I've found a few additional pictures of locomotives that appear to match the model, and I'm hoping to nail down a number soon and get the locomotive painted.
Regretably, my collection of TKM only goes back to 2012, so I'll have to buy a copy of the back issues CD to read the article.
My appologies for taking so long to reply - life has been crazy.
Modeling the Pennsy and loving it!
Hi,
Since no one else has chimed in I thought I'd take a stab at a few observations.
First, if you're interested in Pennsy's cab signal and Automatic Train Control tests and conclusions you might want to pick up a back issue of The Keystone, Volume 39, No. 3. Autumn 2006, which has a pretty extensive article by Michael Savchak, P.E. covering the history of the system.
Yes, there were early experiments going back even before 1923. Two PRR engineers had patented a system in 1880 relying on a glass tube that would be smashed when hit by a lever "trip device" actuated by a restricting signal. (Wood & Vogt System).
U.S. & S. began, as you mention, in late 1922/23 with the three speed loop system tested on the Lewistown Branch. Cost of the installation to wayside and locomotive apparatus was $330,000. This test installation was taken out of service on Jan. 17, 1926. The system was installed on twelve locomotives and problems were encountered with false brake applications and other air brake interference.
The "coded system" was being developed further and testing began in July, 1926 between Bryn Mawr and St. Davids, on the Main Line, using a pair of MB62 M-U baggage cars. Right away the PRR found clear advantages to the coded system.
All the while this testing was going on, the ICC was writing up "orders" for minimum requirement mandates so the railroad was trying to work these mandates into the mechanics of the system while still integrating it into the existing wayside signal system. A pretty tall order for a road the size of the PRR. Additional testing and installations were being done on the Long Island and the NY & LB and PRSL, too.
Through the 1930s additional segments and branch lines of the Pennsy and subsidiary companies installed cab signals at a cost of about $4,000 per double-track mile and $2,260 per locomotive with only the whistle and acknowledger. The 1929 depression slowed down investment in further expansion of the system.
I can not find specific lists of which of the 598 I1s and sa's were equipped with cab signals but each terminal had specific engine assignments and I would guess that by the late 1930s some of these engines were going on twenty years old and some were probably assigned to puller, hump or transfer duties and the tight-fisted Pennsy wasn't going to spend $2500 on a locomotive that was nearing the end of its career.
According to the article the total cost of installation was $9.4 million for equipping 1,492 track-miles and 1,019 locomotives with cab signal/train stop apparatus. It is unclear in the article but I believe this is the cost up to the completion of the coded system, November, 1932.
On June 17, 1947 the ICC issued another order requiring railroads that operated passenger trains at speeds of 60 MPH or above to have automatic block signal systems and if operated at 80 MPH or above the line had to be equipped with cab signals with train control or automatic train stop features.
I've been in the same spot trying to figure out exactly which locomotive I have a model of, based on the number and location of various appliances. About all you can do is keep looking at the photos and taking notes. Often times the train phone and cab signal equipment was changed around at shoppings and salvaged for use on other locomotives. Stokers, boosters, feedwater heaters and, of course, tenders were changed out all the time. Makes it real interesting!
Hope that helps, Ed
I recently purchased a Sunset Models brass I1. It appears to be a model of an I1s (or I1sa) with dual air compressors, but no train control box on the driver's side running board. Or anywhere on the locomotive, for that matter. This brings up the interesting question of if such a locomotive existed and where it would be used.
From this angle, #4245 appears to match the model.
However, on the driver's side the absence of a train control box is readily apparent. Similarly, #4230 has a second air compressor but no train control box on the driver's side.
Now as I understand it, the PRR installed pulse code cab signalling starting in 1923, and eventually installed it over most of the eastern portion of the system. I've seen a lot of photos of I1s and I1sa class locomotives with train control boxes - mostly on the driver's side, but a few with the boxes on the fireman's side. While it is difficult to find pictures of both sides of a locomotive, I have found a few, and in every case the locomotive was equipped with cab signals.
Were there any I1s or I1sa locomotives that were never equipped with cab signals? And where would a locomotive without cab signals be used?