PRR K4 Top Speed

There are likely instances that PRR steam ran at speeds much higher than the official top speeds. Supposedly between 900-100 mph when double headed on the Fort Wayne Division where the 7002 hit its alleged record, but the reality is the normal top speed for the K4s's or the Atlantics would be 80 mph.  Typically top speed is a function of driver diameter.  Yes there are recorded instances of higher speeds but these were not sustained.  Likely the fastest of the PRR locomotives was the S1 with its 84" diameter drivers when it was actually running.  It regularly ran 100 mph and allegedly ran as fast as 134 mph but that is unofficial.  The A4 Mallard still holds the official record at 126 MPH.

For most steam, the top speed was about 1.1 times the driving wheel diameter, or 90 mph for the K-4s.  The E6's, with less reciprocating mass were a little faster, but that claim of 127 mph was a wild exaggeration.  I don't know about the S-1, but there are apocryphal tales of T-1s with their highly advanced valve gear eclipsing 130 mph, trying to make up time in flatland Ohio after a slippery start.  They had much, much more horsepower than the A4 Mallard, but there's no official proof.  I just read an account in Bill Withuhn's book of how difficult it was to measure the speed of a locomotive without special equipment, once you get above 100 mph.  That being said, I'm pretty sure that the duplex passenger locos were the fastest steam locos on the Pennsy.

Some late steam with disk drivers, lightweight roller-bearing rods, etc., had exceptional balancing and could exceed the rule of 1.1.  The N&W 'J' could reportedly run 110 mph with 70" drivers!

The J class Northerns are freaks of nature.   Amazing machines.

Maximum authorized speeds for different classes of locomotives were listed either in the employee timetable or in a special instruction.  There was some variance on where the information was posted.  Some railroads (Santa Fe) put this in the timetable.  Other railroads (and I think Pennsy was one) issued employees a book like the timetable, containing only System Special Instructions, thereby putting only the Division information in the timetable.  The reason for this is that the timetable would have to be re-issued more than once a year, to reflect schedule changes of regular trains, while the System Special Instructions only had certain pages amended throughout a year.  Printing costs were reduced by not reprinting everything with each new Division timetable.

If anyone on this Forum has a Pennsylvania Railroad publication from the late 1940s or early 1950s, listing the maximum authorized speed for locomotives, it would be interesting to know what was allowed some of Pennsy's more commonly modeled locomotives, such as 4-6-2, 4-4-2, 2-8-0, 2-8-2, 2-10-0, 4-8-2, the duplex steam engines, and EMD E7's.

Without doubt, on every railroad, the maximum authorized speeds were sometimes exceeded by individual Engineers.  The maximum authorized speed was the speed authorized by the Mechanical Department, mainly to optimize locomotive maintenance.  The maximum safe speed was another matter, and was normally quite a bit higher than the authorized speed, but at the price of increased wear and tear on the equipment, especially the crank pins, rods, and bearings.  And, at some speed beyond good sense on the part of the Engineer, every steam locomotive could kink rails.

On my home road, an Engineer with no common sense ran an ancient 2-8-0 (which was allowed 30 MPH) so fast that thirty miles of 90 MPH railroad was placed under a 20 MPH temporary speed restriction while hundreds of rails were replaced over a period of several days.

Regarding the speeds of PRR 460 and 7002, weren't those extrapolated from the time difference between reported signal tower passings? Not the most reliable, especially against an engine-based speedometer or modern radar gun.

I think the speeds as mentioned above were calculated from the time between towers.     Actually I think it is a fairly reliable way to calculate an average speed.     the distance between towers was accurate and well known.    If the operators  in the towers were paying close attention, they could record the time the loco passed the tower.    remember railroads had very strict standards for time and watches, so the operator watches should have been identical to within a few minutes a week.

It does give an average speed, however, not the maximum attained at any point.    

As a note on speeds, articles I have read state that PRR ordered the designers of the T1 to deliver a locomotive capable of pulling 10 steel (heavyweight) cars at 100 MPH.    From this I assume many locos were specified with speed according to load.   Unfortunately I have not seen this information for a K4.

I have to look for the book, but IIRC the PRR had speed recorders on their locomotives and upon arrival the recorder discs/tapes were sent to the locations supervisor where each engine's route was analyzed for speed, braking and other operationally collected data which directly affected the performance evaluation of the respective locomotive crew.

Keystone posted:

I have to look for the book, but IIRC the PRR had speed recorders on their locomotives and upon arrival the recorder discs/tapes were sent to the locations supervisor where each engine's route was analyzed for speed, braking and other operationally collected data which directly affected the performance evaluation of the respective locomotive crew.

Maybe on the early diesel units, but I don't recall seeing ANY speed recorders on their steam locomotives, especially the K4s locomotives.

I would concur with Ted above about the T1 possible being the fastest that PRR had if not  THE fastest anyone had. Trains Magazine had a short piece back in the 1970's (1973?) on a last run of one from Crestview OH to Ft Wayne. It was pulling a lengthy mail train that had 2 K4's when one of them went down. The engineer had to make up time so on the flat stretch coming into Ft Wayne, they may have hit well above 130 mph according to estimates that day. A great story and one that started my fascination with the amazing Duplex.

Slugger posted:

Regarding the speeds of PRR 460 and 7002, weren't those extrapolated from the time difference between reported signal tower passings? Not the most reliable, especially against an engine-based speedometer or modern radar gun.

Most steam locomotives did not have speed indicators.  The engine crew was expected to regulate speed based on elapsed time per mile, and the employee timetable and special instructions listed maximum authorized speeds in minutes and seconds, not miles per hour.  We were well into the diesel era when timetables began to list speed in miles per hour.

Once the Engineer had timed a few miles, he could tell the speed by listening to the exhaust.  It was a skill, not a science.

Beginning in the 1930's, some of the last and most modern steam locomotives began to be built with Valve Pilot and Speed indicator/Recorder devices from Chicago Pneumatic.  Barco and Chicago Pneumatic Speed Indicator/Recorder devices began to be applied to road diesels beginning in the 1930's.  Retrofitting of older steam locomotives was uncommon.

I have read somewhere in the late 1930's ARR conducted speed tests. PRR and the UP both participated . The UP mechanical engineers first went to the PRR to observe the K4 pulling a train. The best the K4 could muster was a little over 90 MPH.  Then the PRR mechanical engineers went to the UP. The PRR men said no way a 4 coupled locomotive could generate any speed (The UP used a early FEF1 4-8-4.) The PRR men were blown away. For the same tonnage, the 4-8-4 ran at 110 MPH!

Chuck Sartor posted:

I have read somewhere in the late 1930's ARR conducted speed tests. PRR and the UP both participated . The UP mechanical engineers first went to the PRR to observate the K4 pulling a train. The best the K4 could muster was a little over 90 MPH.  Then the PRR mechanical engineers went to the UP. The PRR men said no way a 4 coupled locomotive could generate any speed (The UP used a early FEF1 4-8-4.) The PRR men were blown away. For the same tonnage, the 4-8-4 ran at 110 MPH!

Just another example of the "not invented here" mindset of the PRR Mechanical Dept.. The same thing happened when the PRR "tested" an N&W J Class 4-8-4, and with its 72 inch diameter drive wheels, the PRR folks didn't believe it could ever exceed something like 75 MPH. Again, in the 1940s, the PRR folks were "blown away" by the 110 MPH performance of the big N&W locomotive with the "little drivers"!

                    Barco speed indicator- NYS&W F45 #6370, Maybrook, NY Jan. 87' 

PAUL ROMANO posted:

                    Barco speed indicator- NYS&W F45 #6370, Maybrook, NY Jan. 87' 

Nice, but this has nothing to do with the discussion about the speeds of PRR K4s steam locomotives, which did NOT have speed indicators, nor speed recorders.

70 inch drivers on  J class, not 72.

Standard Gauge posted:

70 inch drivers on  J class, not 72.

Thanks for the correction. I knew they were REALLY small for a 4-8-4. Thus truly mind boggling for those PRR Mechanical Dept. folks.

In the book, Set Up Running: The Life of a Pennsylvania Railroad Engineman, 1904-1949, the author tells the stories of his father who was an esteemed PRR Engineer out of the Williamsport division.  One of the train assignments he had in the book was a passenger consist that went south from Williamsport through Northumberland, and into Harrisburg. The story references that when the train was running behind the timetable, a K4 would run 110+ MPH on the final portion of the line in approach to Harrisburg to make up the time.  And, that when he was sometimes assigned the K2 or K3 clocomotive for the same run, that there simply wasn't the same power that the K4 had, and the lessor locomotives would top out in the 90-100mph range. 

And, another story describes how he ran light in a K4 to aid the rescue of a stranded express passenger train. Since he was on a time sensitive rescue run, running light, the stories reference was that his speed was well in excess of 100mph.

So, I would make the suggestion that not only could the K4 run at speeds well in excess of 100 mph, but also that they would do so in certain occasions in regular service. I would also suggest that the K4 was capable of speeds in excess of the 126 mph record, and probably ran that speed in service in unrecorded situations. Of course we never really know but in the case I believe in the power of the Pennsy.

I would take that book with a grain of salt. I have never heard of a K4 running in excess of 100 MPH. Maybe possibly at the Altoona test plant under controlled conditions. 

Obviously without modern speed tracking equipment there is no way to know how fast these engines could go and I suspect the railroads didn't exactly encourage engineers to set records, for obvious reasons. You have to wonder if they builders ever did any kind of speed trials to see, but I suspect they were more concerned  with the engine being able to meet the needs of the railroad buying the engines and things like reliability, fuel and water usage and so forth. Sadly, unless someone is willing to submit  running engines for speed tests, whether restored older engines or one like the group is trying to recreate from scratch and they can find a place that will allow it, we likely will never know. Maybe given that British rail seems to be more steam friendly, we can ship engines over there  and do testing there. 

As far as measuring speed, when they were filming "The Great Train Robbery" in Ireland, there was a scene where Sean Connery goes on top of the train doing his own stunts, while being filmed by a helicopter chasing the train, the train was supposed to go relatively slowly. They got going filming, and pretty soon it was obvious that Connery was having problems on the top of the train and they told the engineer to stop the train. Connery was, shall we say indignant, and asked the engineer (or yelled at him, I am sure with plenty of 4 and 5 letter words we can't use here), how fast they were going, and the engineer replied that  they were doing no more than 15-20 miles an hour, as they were told. Connery then asked them how the **** they knew that was the speed, when the engine didn't have any kind of speed indicator (it was a pre WWI engine), and they said they calculated it using the number of telegraph poles that came buy in a given minute, and Connery exploded, saying they were a horses (south end) if they relied on bloody Irish telegraph pole distances being regular to check train speed, he was livid, cast aspersions on the engineer and the labor that put the poles up in the first place (he said things that I won't repeat here, not politically correct). The helicopter crew later confirmed  that the train was going well over 40 mph at the time.......

prrjim posted:

... If the operators  in the towers were paying close attention, they could record the time the loco passed the tower.    remember railroads had very strict standards for time and watches, so the operator watches should have been identical to within a few minutes a week. ...

 

A nice description of how time was synchronized across the nation/railroad system using telegraph:

http://www.telegraph-office.com/pages/time.html

With synchronized messages daily and regulated clocks and watches, any error would be low or even sub seconds.  Or, perhaps better than the error of the human to measure exactly when a train passed by just looking out the window.

Interesting to note in the article that Western Union sold, as a service, time keeping signals to banks and other businesses on which time is important.  Today, milliseconds are worth billions to the stock market.

Bob-

hmmm, i wonder how fast these K4's were goin on this video between 2:35 and 3:10?

Penn-Pacific posted:

hmmm, i wonder how fast these K4's were goin on this video between 2:35 and 3:10?

 

 Looks to me like about 60 to 70 MPH.

Chuck Sartor posted:

I would take that book with a grain of salt. I have never heard of a K4 running in excess of 100 MPH. Maybe possibly at the Altoona test plant under controlled conditions. 

Be that as it may, it's still a great read. I love that book! 

It seems this discussion comes up every now and then; regardless of the actual "top speed" of the K4, I think it's safe to say it was a magnificent piece of motive power, especially when you take in to account it was developed what, 10-15 years before "Super Power" was introduced? 

Mark in Oregon

The Railroads and builders had dynometer cars that could give horsepower, speed, fuel consumption, etc. Pennsy finally 'caved' and starting to experiment with 'expanded' 4-8-4's with their duplex series of engines and famous turbine 6-8-6 locomotive.

Chuck Sartor posted:

I would take that book with a grain of salt. I have never heard of a K4 running in excess of 100 MPH. Maybe possibly at the Altoona test plant under controlled conditions. 

I have a hard time believing those numbers and suspect some very partial and biased rounding in them.

If we were to take some other, more modern steam locomotives that we have a good top speed record of.....and reverse engineer back to the K4....I don't think we get there. 

I've been wrong plenty of times....but I just don't see this being feasible.

Penn-Pacific posted:

hmmm, i wonder how fast these K4's were goin on this video between 2:35 and 3:10?

 

Turn the sound off, get to 2:37 or 2:38, and fixate on one of the poles....which are stationery while the CAMERA is also stationery.  Then watch the cars go by.  It's not going as fast as you may think/hear.

That said, this is a neat video.

The biggest limiting factor to train speed is wind resistance.  The horsepower required to overcome aerodynamic drag is proportional to the SQUARE of the velocity.  Downhill, with a tailwind, a lot of things might be possible.  The record-holding Mallard had a fairing that was designed in a wind tunnel, and it set the 126 mph world record on a slight downhill run.  The German loco which held the previous record of 124 mph was also streamlined.  This might be one case where that cowl wasn't just for looks.  In the years just before WWII, the pride of England and Germany were at stake!  Even so, neither of these locos ever claimed more than 4000 HP.

A couple of other considerations... Above a certain speed an unbalanced machine will shake itself apart.  The valve events and exhaust passages have limits too.  The K-4 just wasn't as advanced as an FEF, Niagara, or Milwaukee F7 Hudson in these respects.

Now, the T1 duplex had precision valve gear and a streamlined shroud.  It was dyno tested at 6500 HP, much more than Mallard or the German class 05.  I would believe the T1 could break 130 mph before I would believe the K4 could break 110, especially pulling tonnage on the level.  I'm not sure why the Pennsy never attempted a record with the T1;  they were built after WWII and I guess by then no one cared about steam technology  .  Since there is a group of enthusiasts who are trying to build a 'new' T1 based on the old design, I guess it's remotely possible that we could find whether it's really a record-breaker.  Doubtful, but I never thought we'd see an operational Big Boy either!!

Quick addendum to the brief discussion of the N&W Class J's 70" drivers.  The Western Maryland modern 4-8-4's built in 1947 had 69" drivers. Perhaps the lowest applied to a 4-8-4 design?  They were not designed for high speed passenger work, rather fast freight, which probably translated to 50 mph, and occaisional spurts up to 60. They were described as very comfortable riding engines and were designed for quick turn-around at terminals.

The Mallard and the German Class O5 were relatively small locomotives. The German O5 had a grate area of 50 sq. ft, which would put the draw bar horsepower somewhere in the neighborhood of 2000. Presume the Mallard was similar in size and power potential. What allowed their impressive performance was the small size of the cars they were pulling.

Given the modest size of those locomotives and the speeds they hit, it doesn't strike me as a stretch for the 80" drivered T1, as well as the Santa Fe 3460 class 4-6-4, the CNW 4-6-4 and Milw 4-6-4, all with 300 psi boilers and 84" drivers relatively easily achieving 130 mph.  As someone noted, the T1 would go as fast as the engineer's nerves would allow!

The K4 had 80" drivers, 69.89 sq ft grate and was quoted as having 3286 horsepower (presume indicated, not drawbar - - - which would come in at about 2800/2900). Again, think 100 mph would be achievable, but, per Ted's comment, would the valves keep up with the power demand at that speed, or higher?  

Hot Water posted:

Penn-Pacific posted:

hmmm, i wonder how fast these K4's were goin on this video between 2:35 and 3:10?

 

 Looks to me like about 60 to 70 MPH.

 

Yea, thats sounds about right to me. 

mark s posted:

 

The K4 had 80" drivers, 69.89 sq ft grate and was quoted as having 3286 horsepower (presume indicated, not drawbar - - - which would come in at about 2800/2900). Again, think 100 mph would be achievable, but per Ted's comment, would the valves keep up with the power demand at that speed, or higher?  

Only one way to find out for sure, rebuild one and let it haul an Acela train up the NE corridor. 

I'd buy a ticket

Seriously though I did read that the 20th Century Ltd. and the the Broadway Ltd. would occasionally race on the New York to Chicago runs. Each, of course, trying to best the other and sometimes reaching speeds of 100+ mph. I honestly don't know if it's true or not.

I'll call, "Calf rope", and settle for "pretty fast,"  That's good enough for me.

They were passenger engines and -- despite any shortcomings -- were fast enough to make up some time when a train fell behind schedule.

This discussion may go on for a hundred pages without a specific answer to the root inquiry.

Maybe if and when the #1361 gets re-built we will find out.....

After 1957 the average high speed of the K4s as a class of locomotives was 0 mph.

Double-headed K4's would produce something like 5600-5800 draw bar horsepower. Per the Baldwin Locomotive formula, the T1 would produce 5100 DBH - - - The T1 more or less replaced the power output of the k4's (well, except for the occaisional wild slipping drivers !)

PAUL ROMANO posted:

Maybe if and when the #1361 gets re-built we will find out.....

I seriously doubt THAT.

Hot Water posted:

PAUL ROMANO posted:

Maybe if and when the #1361 gets re-built we will find out.....

I seriously doubt THAT.

Allow me to interject:  "Umm.....ain't gonna happen!!"   

I know you were just joking Paul. IF it ever sees the rails again, There is really no place to run it, much less anywhere near 90!

Did the PRR K4’s have stokers?