|Bill Molony posted|
Pennsylvania Railroad class Q1 4-6-4-4 Duplex-type #6130 at the PRR's 59th Street engine house on the southwest side of Chicago. The 6130 was built at the PRR's Altoona Shops in 1942, and was the only 4-6-4-4 ever constructed.
Penssy also built the duplex locomotives S1 and T1.
Bob Lalich Only one Q1 was built. The Q2, with 4-4-6-4 wheel arrangement, was a follow on. They were used regularly on the Panhandle line out of Chicago.
Richard Mead www.crestlineprr.com/duplexexperimentals.html
|1938 Aerial Photo from ILHAP|
|Bill Molony: The Pennsy's designers dressed up the 6130|
with all that streamlined shrouding,
but their maintenance men took it all off
shortly after it went into revenue service.
Here's the before & after views.
|Stuart Pearson NO GUESSING WHERE THE S2's STYLE/DESIGN CAME FROM! My attachment show both the Q1, and the Q2. Supposedly the Q2 produced 7900+ HP which made it the most Powerful Steam Locomotive ever built.|
[Note the Q1 was 4-6-4-4 whereas the Q2 was 4-4-6-4.]
|Tyler Mathis posted|
PRR 6130 class Q-1 duplex 4-6-4-4 at Chicago in 1950. The only one of its class, the Q-1 was a failed design due to slippery handling and placement of rear engine behind the drivers, which led to maintenance issues. But they paved the way for the Q-2, a more successful design that unfortunately came too late. Photographer unknown.
|Bev Smith commented on Tyler's post|
Q-2, designed to outperform Pennsy's wartime copies of C&O 2-10-4. It did, but that was offset by maintenance costs and huge appetites for coal and water.
Richard C. Leonard The same photo is in my Random Steam Collection, where I give credit as follows: "this image (from a Flickr site discontinued in 2008) reveals the locomotive later received a more conventional front end appearance and also lost its side skirting. Taken in Chicago in 1948 by an unnamed photographer, this image belonged to the Harold Vollrath collection and also appears on the North East Rails site."
Boyd Walker Did the wheel sets articulate?
Tyler Mathis No, all duplexes were rigid-frame.
Jim Angel Essentially you have two engines controlled by one throttle. Almost impossible to get them to work together!
Scott Gwynn The engines constantly worked in and out of step. No attempt was made to keep them in step. The B&O actually had different sized driver sets on one of their duplexes in order to make sure the engines stayed out of step. One set was 80", the other 79". They felt the engine ran more smoothly that way.
Stephen Phillips The idea of the duplex drive , was developed to lessen the effect of "Dynamic Augment" … the effect of the mass of the weight of side rods and main rods slamming down on the track , first one side then the other … by spitting the drive in two the pounding force on the rails would be lessened , and the number of power strokes for each wheel rotation would be doubled when the engines were out of sync..... The engineering dept. at Altoona embraced the Duplex Drive …. after the engineers at Mt. Clare Shops of the B&O had their kick at the can … In 1937 the B&O built No.5600, a 4-4-4-4 duplex drive with a water tube firebox … and a layout similar to the PRR's Q1 4-6-4-4 … both had their rear cylinders next to the firebox …. This cylinder placement was the fatal flaw in both design , as heat from the firebox lessened the lubrication in the rear cylinders …. When George Emerson , Chief of Motive Power on the B&O left for retirement , the B&O dropped all their experimental designs …. Only the PRR designers were left to develop the Duplex … the S1 of 1939 , the T1 experimentals of 1942 and the (50) production T1's of 1945-46 , the Q1 of 1942 , and the(26) Q2's of 1944-45 …. It's my opinion that the T1's and Q2's were good engines that have gotten a great deal of bad press … the PRR didn't provide the training for engine crews and maintenance crews necessary to operate these new locomotives , so very different from those they replaced ….
Jim Angel Box Pok Drivers were one of the real additions to the problem of Overcoming balance problem on locomotives. I fired on the CNW and we had the JS class Mikes and the JA class Mikes. There was a big difference in how they rode at speed.
[There are a lot more interesting comments about steam locomotive development.]
Raymond Storey shared
Matthew Hurst Actually new info has come to light that has said the locomotive was actually very well built and handled well... unfortunately some conjecture artists placed the brand of failure on it because it wasn’t reproduced. Remember ww2 was going on and the PRR needed locomotives and the war production board wasn’t backing novel ideas... they wanted tried and true designs. Also slippery?... I have stood trackside and have seen articulated slipping uncontrollably... think about that.
Christopher DiCianna Agreed. Good point. I think when the discussion of wheel slip is mentioned on a ridged frame duplex the assumption is that the cause of wheel slip is the rigid frame itself. ALL steam locomotives slip. I have witnessed the N&W J slip and stall and I watched Reading T-1 loose its traction and the wheels looked and sounded like it was going 120 MPH! I think the problem with duplexes (and articulated) is that once one engine slips the engine that is still 'biting the rails" now has to deliver nearly twice the tractive effort. That engine then starts to slip or may stall.....had to be a nightmare to control these on a very heavy train! As for handling I bet this loco did handle and ride well. Again, it's back to the reduction in dynamic augment and pounding of the rails due to less rotating mass. When the ACE was on the drawing boards in the early 1980's it was designed with this in mind. It would have had opposed cylinders.
|Bev Smith commented on Tyler's post|
It looked good on paper. The B&O built a similar locomotive with a water-tube firebox https://www.american-rails.com/n-1.html