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Pennsylvania S2

Posted: Thu Feb 01, 2018 7:39 pm
by Notch 8
The S2 steam turbine locomotive built for the Pennsylvania Railroad was the only one ever to use this wheel arrangement 6-8-6 and weighing in at almost one million pounds. The engine built in 1944, used a direct-drive steam turbine, which ensured a smooth uniform power flow (torque or tractive effort) at all speeds. As the locomotive did not use cylinders, there was no rail hammering as with reciprocating engines, so that the wheels did not require counter-balances. Consequently, the wheel diameter was small at 68 inches.
The locomotive was to be a 4-8-4, but wartime restrictions on light steel alloys increased weight until six-wheel leading and trailing trucks were needed. Two turbines were fitted, one for forward travel and a smaller one for reversing at speeds up to 22 mph (35 km/h). A large boiler with a Belpaire firebox and long combustion chamber was fitted. The turbine exhaust was piped through a set of four nozzles in the smokebox, providing an even draft for the fire and exiting through a unique quadruple stack. A Worthington-pattern feedwater heater was fitted for increased efficiency. Twin air pumps for train braking were fitted below the running boards beside the smokebox front, and a large radiator assembly at the nose cooled the compressed air.
The large 16-wheel tender was similar to that used on the PRR's other large passenger locomotives, the T1 and S1. The turbines drove the two middle axles via a series of reduction gears, however high pressure steam hits the blades at speeds up to 2,000 "miles per hour" which in turn generated about 6,900 horsepower (5.1 megawatts). The output exceeded all conventional steam locomotives as well as diesels rated at 6,000 hp (4,500 kW), above 40 mph. At speeds less than 30 mph steam consumption was high, but above that speed, its steam consumption was well below normal locomotives. Turbine maintenance was a major problem and the engine only ran until 1949.
Some of its impressive attributes included; boiler pressure 310 psi but at low speed the pressure could drop as low as 85 psi (0.59 MPa). The increased fuel usage at low speeds caused the firebox to run hotter, which sometimes caused stay bolts to break.A grate area 120 ft², tractive force 70,500 lbf; engine weight 589,920 lb. Although it ran well on fast passenger and freight runs, monstrous fuel consumption at low speed and high maintenance costs brought an early retirement to Pennsy’s unorthodox experiment. The locomotive's problems and the advantages of the emerging Diesel locomotive ensured #6200 would never be duplicated. The locomotive was withdrawn from service in 1949 and scrapped in 1953.

Re: Pennsylvania S2

Posted: Fri Feb 02, 2018 12:26 pm
by rrnut282
And best of all, pretty sure it came through Fort Wayne while it was still in regular usage.

Re: Pennsylvania S2

Posted: Sun Feb 04, 2018 8:56 am
by cjberndt
This photo was taken when PRR was showing off its newest locomotive in Chicago in Dec. 1944, three weeks after S2 was delivered to PRR and before it was placed in service. The model has her hand on the throttle.

Craig

Re: Pennsylvania S2

Posted: Sun Feb 04, 2018 10:26 am
by Steve Bryan
The top two photos were used in our (Three Rivers RR Heritage) early calendars. One time at a show, a man stopped by our table and said he was that little boy sitting in the grass next to the locomotive. I do not have his name.

Re: Pennsylvania S2

Posted: Mon Feb 05, 2018 6:10 am
by Notch 8
The Pennsylvania Railroad had to be the Greatest Show in Town ! Hard to believe that it's been 50 years since the last curtain call.. Almost 20 since Conrail..