I was reading a book on SP passenger service. Within the book there was a segment on the Shasta Daylight and the power that hauled it. It stated that it was originally intended that the power for the train would be EMD E-7’s however shortly after the train started operating the power was switched to Alco PA’s because the PA’s had dynamic braking and the E units didn’t.
Did EMD offer dynamic braking as a option on any of their E units?
Dynamic braking was first introduced as an option on the E8.
If I recall correctly SP had only one E8 but they had a number of E9s which indeed had dynamic brakes, indicated by a 48" fan in the centre of the units between the radiators.
Peter
Only four railroads apparently had E8s with DB (a fifth, Rock Island, bought a demonstrator but may never have used its installed dynamic). Early ones had a 36" fan, later ones a 48" as on E9s.
I am not a SP expert but I think they used that field loop setup on the E8 dynamic and this was only changed going through the GRIP rebuild program later…
The Rock Island didn’t (officially) use dynamic brakes. Their train handling rules forbid engineers from using them when foriegn power happened to be on RI trains. The dynamics on engines they bought used were disconnected and on some that were eventually rebuilt, removed entirely.
Jeff
Why would using dynamic brakes be banned? Lack of training on proper usage or something else?
Until about the 1970’s, dynamic braking was considered an expensive option useful for long and heavy grades and not much else. Many Midwestern roads such as IC, RI, MP and C&NW did not equip their locomotives with dynamic brakes since there was no perceived need for them.
Until the development of effective blended braking, which really inherently depended on developments in practical electronics, many of the principal uses of ‘cost-effective’ dynamics on E units (and other passenger power) would be severely limited and perhaps even dangerous. About the only ‘good’ use would be retarding heavy passenger consists down long or severe grades – there was a dramatic Steinheimer picture accompanying a poem in an early-'70s issue of Trains that shows a good example of a situation that would likely benefit from good dynamic. But the fun involved with jockeying throttle and contemporary EMD dynamic in, say, repeated commuter stops while modulating the train brake is not something I suspect most commuter engineers would enjoy.
Railroads also used to allow Power Braking for smooth stops. Now it is forbidden on freight trains at least.
Main reason why caused issues and accidents if not properly used.
On a train controlled with standard dynamic braking, the engineer applied the independent brake and shut down the dynamic brakes as the amperage dropped between 250 and 200 amps, which usually occurred at 10 to 13 mph. Failure to make this change from standard dynamic brakes to air brakes could result in the head-end of the train running out ahead of the train as the dynamic brakes faded. The ensuing slack could cause a broken knuckle and a train separation.
I could be very mistaken - in a book I have dedicated to the B&O’s E units from the Box cab #50 through the 4 E9’s that were their final purchase in the middle 1950’s which included the EA’s, E6’s, E7’s and E8’s in the intervening years - the only diagram that showed any reference to dynamic braking was a diagram of the E9. There was no reference to Dynamic Braking in the prose in the book, so I don’t know, factually, if any of the B&O’s E units actually had Dynamic Braking.
Descending the grades crossing the Alleghenies where were one would expect Dynamic Braking to benefit train handling as there were serious grades on both the routes to Chicago and St.Louis.
Canadian National was very similar. While a lot of our older power was delivered with dynamics they soured on it pretty quickly, and it was disconnected or removed on most if not all units. They continued buying new units without DB until the final order of SD40-2Ws were delivered in 1980 (the HR-616s might have been later, I’m not sure if they had DB or not). The only exceptions were a small number of SD40s and SD40-2Ws that were purchased with both DB and pacesetters, and specifically assigned to coal and ore trains on certain branchlines in western Ontario and Alberta.
I don’t think CN ever prohibited engineers from using DB if power with it happened to show up somewhere else.
GO Transit also followed CN practice in this regard, the F59s were their first units with DB.
Apparently when DB was an extra-cost option CN figured that they could buy an additional few units for the same price by not getting it, of course this doesn’t account for all the brake shoes and fuel that would be saved down the road…
Modern extended range DC dynamics start to peter out around 5 or 6 mph.
ACs are a completely different animal, you can bring a train to a complete stop and hold it stopped on a grade with just the DB.
No B&O or C&O E8 locomotives had dynamic braking. Only three railroads purchased E8 or E9 locomotives new with dynamic braking. The Milw Rd purchasedd E9 units for the UP’s Streamliner pool operation that had dynamic brakes, but the six E9 units purchased specifically for commuter service lacked dynamic brakes. The UP and SP purchased all their E8 and E9 locomotives with dynamic brakes, plus the previously mentioned EMD demonstrator locomotive sold used to Rock Island also was equipped with dynamic brakes.
A review of EMD Product Data and Extra 2200 South issue #43, the E8 and E9 roster, shows that four road ordered dynamic brake equipped E units. The four railroads are Milwaukee, Southern, Southern Pacific and Union Pacific. The fifth railroad had former demonstrator #952 sold to Rock Island #643 shows as dynamic brake equipped in the Product Data. The twin 12-567Bs installed in the demonstrator date to January/February 1949.
Ed in Kentucky
Funny that you mention this. I used to live in Petersburg, Illinois on the old C&IM line between Springfield and Pekin. The small fleet of EMD locos that the G&W’s Illinois & Midland subsidiary inherited from the C&IM did not have dynamic brakes. Whenever the I&M would run a local down the famous Petersburg Hill, the engineer would make a hefty set with the train brakes and PULL the train downhill at a high notch setting. Watching an SD18 working hard going downhill was very disorienting to say the least!
Even with dynamics it was more sometimes more convienent to use power braking. On the B&O line between Pittsburgh and Wheeling there are eight grades - all but one fairly short. It was a pain to keep bunching up the slack to use the dynamics just to have to stretch it out again to go uphill.
At other locations with longer or steeper down grades such as Sandpatch or Bakerstown I found it better to make a light air brake application while cresting the grade and add dynamics as more of the train comes over the crest. Having the air brakes applied allows the slack to be bunched more smoothly and slows the speed increase if the dynamics don’t work as expected. Once the entire train is over the crest the air brakes and dynamics can be adjusted to maintain the desired speed.
Since freight air brakes cannot be partially released if they are applied too much the only recourse is to use power to keep the train moving or stop and recharge the brakes. In some cases it is possible to make a running release and reapply the air brakes but this is usually prohibited on the steepr grades due to the possibility of runaways.
Mark Vinski
One thing to note - many mountainous lines preferred F units after trying E units in the hills (GN, NP, ATSF come to mind) because they liked the idea of all locomotive weight being on the driving wheels. So the E unit became a flat land railroad’s unit (CB&Q jointty owned by GN & NP continued to buy E’s. SP&S, the other GN/NP serf was almost all Alco, not sure about whether the grades down the Columbia River Gorge would have led to E’s or F’s). As mentioned, as long as D/B was an extra-cost option, these lines figured they didn’t need it and could save some money by not ordering it. Of the two biggest E8 owners, PRR stayed out of the D/B club because they figured whether they had E’s or F’s leading, they’d still need helpers over Horse Shoe and didn;t need it east of Altoona or west of Pittsburgh (I don’t think the Buffalo Line (Keating Summit) ever saw E’s on a regular basis). NYC? They were the Water Level Route, man…The same logic as the PRR might have applied to the B&O over Sand Patch, but why C&O didn’t apply it to its 31 E8’s, I must admit is beyond me
B&O E units originally got steam helpers ascending Sand Patch westbound. DB would have been useful for the eastbound down grade run, although I remember a rule prohibiting its use on passenger trains even if it was available. I did use the DB on Amtrak trains.