Frisco had a passenger model FP7A. Frisco numbers SLSF 5040-5051 Quantity: 12 Delivered: 1950-1951 I have not found any record of Frisco buying FP7B. Very few railroads did. Information from the following web site. https://www.american-rails.com/emd-fp7.html The FP7 already housed all of the components needed for passenger service. The FP7As sales numbers appear very low; only 324 were produced by the time production ended on the model in late 1953. However, the FP7A solved a specific and very important need for railroads operating passenger trains in mountainous terrain. Looking at the locomotive from this angle it was actually a resounding success. The FP7A began production in the early summer of 1949 as a means for railroads to have a streamlined diesel pull passenger trains over stiff grades, a task for which E units were not well suited given their A1A-A1A truck setup that provided relatively poor tractive effort. Realizing this problem and railroads' desire to use the four-axle freight model units in passenger operations EMD cataloged the FP7A. The locomotive was 54-feet in length, four feet longer than the standard 50-foot car body of standard F units thus enabling the engine compartment to hold both the needed water and steam generator. Aside from these added components the FP7A was near identical to the F7A. It featured GM's 16-cylinder model 567B prime mover that could produce 1,500 horsepower and carried the company's D27C traction motors which offered 40,000 pounds of continuous tractive effort and a mighty 64,000 pounds starting, then the most of any F available in EMD's catalog. It did, however, use a slightly upgraded main generator, the model D12D and featured dynamic braking a staple of F units multiple-unit control as also included. FP7 technical data http://www.thedieselshop.us/Data EMD FP7.HTML This sound that it was a pretty neat puller.
SLSF Passenger models FP7A. I have not found any record of Frisco buying FP7B. Very few railroads did within USA. Info from the following web site. https://www.american-rails.com/emd-fp7.html But, F9B SLSF 5140-5152, quantity 13, built 1954-1957. They may of have matched these B units with the FP7A SLSF 5040-5051, quantity 12 and/or which others? The F9B may been more freight like.
The F7Bs SLSF 5126-5134 were the only Frisco B-units to come from EMD with steam and signal connections for use in passenger service. Twenty-one additional B-units, F3s, F7s and F9s, received post-delivery steam and signal line conversions. Neither the Alco FA-1 units nor the FB-1 units were equipped with steam or signal lines. The F-7B diagram notes “for use with FP-7 Locos in passenger service”. The 9, F7B units arrived after the FP7As, and their dual service capability as noted on the diagram seems to be an afterthought. I am not certain what type of consists the Frisco envisioned when this note was added to the diagram. Did management see only an A-B set, or did it envision A-B-A sets as well as A-B-B-A sets? The notation also implies that the Frisco had not thought about splicing one of these B units between two E units. There is ample photographic evidence that shows a B, F-unit spliced between a pair of redbirds, and likewise, a B, F-unit spliced between a pair of FP7As.
FP7A SLSF 5043 Taken at Fort Smith, AR. Charles Lawrence Collection courtesy Fort Smith Trolley Museum. Photograph is undated.
The only two Frisco F cab units that had dynamic brakes were F9A SLSF 5005 and 5007. The F3As were rebuilt at EMD into equivalent F9As in February 1954. This was done so they could better mate with the dynamic brake equipped F9Bs and be used as run-through units for ATSF service out to the west coast. There is a neat picture in Chard Walker's book Cajon showing F9A SLSF 5007 and its three mates bringing Symbol freight CTX into Summit, CA on Cajon Pass, February 1962. K
Those sheets are very interesting. I noted the 62:15 gear ratio, which is normally what freight units got. Some other railroads had their FP7As geared 56:21 for passenger service, and later regeared when switched to freight duty. The weights for both freight and passenger service seem to imply that "switch hitting" was the plan all along. I presume the 65 mph top speed was more than enough for secondary passenger service.
Somewhere I read a statement that indicated when the Frisco F units were used with the E units, the consist was limited to 65 MPH because of the gearing, My assumption is this was true for the GP7s with boilers too. Paul
Karl probably has the sheets for GP7s. Maybe he could be induced to share in the GP7 section. EDIT: Same Gearing. See Below. Already done. Sorry
This is true. When a dual service unit, GP7, FP7A, or covered-wagon B-unit, was used in the same consist with one of the E units, then the 65 mph limit would apply. There are several points to be made here. First of all, an exact match of gear ratios was not a necessity. It would be a concern only at the extremes of the speed range. The maximum speed limit was in place to prevent the motor from turning into a bird’s nest of wire. When operated at low speeds at maximum amperage, the traction motors of locomotives geared for high speeds could get very hot. When operated at speeds in the middle, gear ratios were not so important. Secondly the difference between 70 mph and 65 mph is only 4 seconds per mile. That is in 70 mph territory, one would only lose 4 seconds every mile at 65 mph. If one examines the speed verses time chart, some inferences with regard to our speed-constrained passenger train consist of an E8A/F7B/E8A, verses E8A/E8A, can be drawn. As noted, placing that freight unit in our consist will reduce our top speed, and we will lose at least 4 seconds a mile wherever the speed limit is above 65 mph. On the other hand, the third unit will improve the acceleration, so that the train will get back to its maximum speed more quickly after station stops and speed restrictions. The 3-unit passenger train will spend more time running at its maximum speed even though slower than a 2-unit train. Consequently, I believe that the 3-unit train will have faster average “acceleration speed” on the low end of the spectrum. Depending on the number of station stops and the number and nature of the speed restrictions encountered, this improvement on the “low side” could offset the lost time at the high end of the speed axis. The chart show that we get a lot of bang for our buck at the low end of the speed range. Lastly, even though the Frisco was a 70 mph passenger railroad, the question becomes how often did trains operate at the 70 mph maximum? This map depicts the Frisco passenger speed limits at the time the Frisco was buying passenger units. At first glance it appears that much of the railroad was capable of supporting 70 mph speed limits. A closer examination is in order. The Willow Springs Subdivision had a 70 mph limit, but a look at the speed restrictions in the ETT tell a different story. In order to learn more about the territory, the maximum speed limit map needs to be refined further. Over what portion, of the Subdivision can a passenger train operate at the maximum? The list of speed restrictions on curves covers the entire subdivision. In other words, passenger trains may travel at 70 MPH only on the tangent segments. The determining factor therefore is, the length of tangent, and does that tangent provide enough distance to recover speed from the previous curve before having to brake for the next curve. Even though tangent track comprises approximately 74.3 miles or 54.3% of the total mileage on the Willow Springs Subdivision, the two longest tangents on the subdivision are 2.54 miles and 2.43 miles and are located near MP C221-C224. The average tangent is but .31 miles long. So, there was not much space for acceleration and braking between curves. It would take some real skill to keep the train at the speed limit. The Willow Springs Subdivision also challenged passenger train operation with its rugged topography. Not only are the curves numerous; they are sharp. Nearly 73% of the subdivision is restricted to 55 mph or less. In this setting, a locomotive, which is geared for 85 mph may not be the best performer. I suspect that the Lebanon and Rolla subdivisions were much the same. It is also interesting to look at the passenger speed limit map and note all the places where the Frisco operated the E units at speeds well below their 85 mph max.
I have attached a chart, which depicts the service time-spans of Frisco passenger units. Its focus is on those units, which possess a cab, but I have included the F7B SLSF 5126-5134 covered wagons because they were delivered with steam lines and signal lines. The other B-units were converted post-delivery and conversion dates were unavailable. When steam died on the Frisco, it had 87 passenger-capable diesel units. During a time when its passenger volumes were declining, the Frisco expanded its passenger roster further with the conversion of its B-units.
