K4s 5399 Clearly , just having a book sometimes isn’t enough – as can be checked in his postings , the user largely lacks understanding of the work of André Chapelon and now even misinterpretes his remarks on 5399 . Since I have inherited and read not just this edition but also the more technically profound 1938 edition of ‘La Locomotive á Vapeur’ – the second part of the 1952 edition was never published , clearly a loss to steam loco tech-history since it was to contain all the technical descriptions, drawings , graphs and calculation – I should herewith make it clear that Chapelon was of course not as naïve and superficial in his knowledge and consideration of valve gear design and it’s influence on specific steam heat consumption as to assume there would be a certain fixed percentage of saving to be attributed to any type of valve gear as such . There is no such fixed saving and there never was because that would violate basic physical laws – full stop . It all depends on the quality of engineering realized in each or any type of valve gear . It’s thermodynamic quality that rules the quantity of steam heat demanded to perform an engery conversion worth the unit of mechanical energy an actual engine can turn out . In a nutshell , you may have pretty good ssc values with good old Walschaerts / Baker and piston valves , especially if you come to think of double exhaust valves or Willoteaux double admission / double exhaust valves or one of the many other types including more recent realizations such as by David Wardale . Or you may have better or worse such ssc with poppet valves . Of course , an engine having a lesser degree of throttling in its steam flow needs a higher degree of superheating as such and also in balance of boiler pressure – this is trivial , I apologize to mention it here .RegardsJuniatha(if you might feel I should sound ever so slightly annoyed – you’re right )
Dreyfusshudson 5399 was a most interesting development, and I have often wondered why the PRR didn't follow it up. I have tried, unsuccessfully to locate the PRR test report on the Altoona plant trials. However Chapelon in his book on the Steam Locomotive gives 4 pages to it. I can let anyone who is interested have copies. He notes that power/efficiency was increased by 16%. Chapelon argues that the increased power comes from the poppet valves. However, whilst it is true that they allow much shorter cut offs for given steam flow, hence an efficiency boost, he also says that inlet steam was raised from 550F to 630F, worth about 8%, and that the blastpipe diameter was increased from 7" to 8", which together with the superheating would easily give the 16% efficiency/power boost at high rates. So a better superheater and exhaust would have made a significant difference to the K4s at low cost.
5399 was a most interesting development, and I have often wondered why the PRR didn't follow it up. I have tried, unsuccessfully to locate the PRR test report on the Altoona plant trials. However Chapelon in his book on the Steam Locomotive gives 4 pages to it. I can let anyone who is interested have copies. He notes that power/efficiency was increased by 16%.
Chapelon argues that the increased power comes from the poppet valves. However, whilst it is true that they allow much shorter cut offs for given steam flow, hence an efficiency boost, he also says that inlet steam was raised from 550F to 630F, worth about 8%, and that the blastpipe diameter was increased from 7" to 8", which together with the superheating would easily give the 16% efficiency/power boost at high rates.
So a better superheater and exhaust would have made a significant difference to the K4s at low cost.
It is amazing that this modification to the 5399 would have eliminated double headed K4's on most trains since the 5399 could handle many of the trains without assistance. The PRR really overlooked a less costly way of eliminating double crews and locomotives on many runs. When we viewed the 5399 at the station stop that evening at at Effingham, the engineer told us it really performed extremely well compared to a regular K4. The eastbound train was pulled that evening by the 5399 without assistance. That was rare on the St. Louis main line since most passenger trains had double headed K4's or T1's. I would guess 70% to 80% of the PRR passenger trains could have been pulled by the 5399 without assistance. The St. Louis main line used K4's on many passenger trains for three more years after the T1's were sidelined.
Just a thought from someone who watched them run.
CZ
Thank You to all, thats what I was looking for!
Tim
5399 was equipped with Type A oscillating poppet valve gear (as were the later T1s). I believe Burlington had a loco equipped with this type of gear and it also had a box on the pilot beam. It housed a set of what could be described as miniature Walschaerts valve gears.
Type B is rotary cam poppet valve gear. It has a cam that looks similar to that used on valves for a car. PRR T1 5500 was rebuilt with this type of gear in the late 1940s. C&O's final 4-6-4's were equipped with Type B gear. The outside drive was much more accessible.
Franklin Types A and B are two distinct types. Hope this not-too-great explanations helps
feltonhill CZ, The box on the pilot beam of 5399 is the valve gear drive mechanism, not train control. This is a common feature of all locomotives equipped with the oscillating cam form of poppet valve gear. The later rotary cam poppet valve gear had a different configuration. Also, DBHP on PRR usually means DBHP at the rear of the locomotive on the Altoona test plant, not at the rear of the tender.
CZ,
The box on the pilot beam of 5399 is the valve gear drive mechanism, not train control. This is a common feature of all locomotives equipped with the oscillating cam form of poppet valve gear. The later rotary cam poppet valve gear had a different configuration.
Also, DBHP on PRR usually means DBHP at the rear of the locomotive on the Altoona test plant, not at the rear of the tender.
Thanks.
Interesting, but still not clear. I googled the Franklin B type poppet valves and it produced some very good pictures of the control box for the rotary valves and drawings. The control box was behind the cylinder chest, not in front at least in the drawings. Google that and take a look at the configuration they show. It is interesting to see the box and how it controlled the valves.
A side note, I got to see the 5399 at Effingham on an eastbound train stopped at the station in early 1951. It was so distinct and it was the lone engine on the train. My dad spoke to the engineer about the modifications and he said he liked the performance of the 5399.
5399 Lima rebuild
In the summer of 1939, engine 5399 was sent to the Lima Locomotive Works where the Franklin system was applied after which she was assigned to the Fort Wayne Division. The 5399 was given a 1000 ton test train similar to the one used the AAR trials of 1938. The results were truly amazing as the 5399 posted a 24.2% increase in DBHP over a stand piston valve K4s at 60 mph and a 32.7% increase a 70 mph with an astounding 44% at 80mph. This K4 single handled trains normally hauled by double headed K4s. The modifications made to the 5399 was assisted by a front end arrangement to lessen pressure and temperature drop of steam between the boiler and cylinders. The 5399 received a larger dry pipe, front end throttle and larger steam and exhaust pipes. After running about 57000 miles after the rebuilding, the 5399 was sent to the Altoona test plant in 1940 for more testing. At speed of 75mph with a 30% cutoff, it developed 3862 B=DBHP as the cylinder HP stood at 4088. These figures were the highest performance ratings every recorded for the K4s ever. Many very good pictures of the 5399 are illustrated in the book “The Many Faces of the Pennsy K4.” It is the Classic Power # 6.
The box on the pilot looks to be the signal train box that was normally on the right hand side running board up near the smoke box. The box on the smoke box is to house the front end thottle.
I recently bought a book titled " The History of North American Steam" by Christopher Chant. Among the many photos I found a pic of K4s 5399( pg. 232). A little reserch found that it was rebuilt by Lima (!) with popet valves operated by osalating(sp) cams and " other modefications" but not what they were. It appears to have a front end throttle but I could find no other info. It has a large square box on the top of the smoke box and what appears to be a cast steel box of some kind on the pilot beam.Anybody know what the "other modefications are? A Google search produced several pictures of the locomotive
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