PRR class FF1
| PRR FF1 | |
|---|---|
 "Big Liz"
|
|
| Number: | 1 |
| Manufacturer: |
Altoona Works of PRR Westinghouse Electric |
| Year of construction (s): | 1917 |
| Retirement: | 1940 |
| Axis formula : | according to UIC (1'C) - (C1 '), according to AAC 1-C + C-1 |
| Gauge : | 1435 mm |
| Length over coupling: | 23,320 mm |
| Service mass: | 234 t |
| Top speed: | 33 km / h |
| Hourly output : | 3680 kW (continuously 2940 kW) |
| Power system : | 11 kV, 25 Hz |
| Power transmission: | Overhead line |
| Number of traction motors: | 2 × 2 (double motors) |
The PRR FF1 was an electric locomotive for the US Pennsylvania Railroad . Compared to the electric locomotives of other railways of its epoch, it held a special position because of its experimental design, its size, the high electrical power rating, the enormous tractive power and the peculiarities of the chassis drive.
Structural features and area of application
The FF1 was procured in 1917 as a test locomotive for the planned electrification and freight train operation on the railway line over the Allegheny Mountains between Altoona (Pennsylvania) and Johnstown (Pennsylvania) 60 kilometers away with gradients between ten and twenty per thousand. With its performance values, it was the most powerful electric locomotive of its time.
Landing gear arrangement
The machine had two close-coupled bogies, each with three coupled wheel sets driven by a jackshaft and a running axle in a common frame. On the bogies there was a locomotive box with the electrical equipment extending over the entire length, the design of which was derived from the PRR passenger coaches with minor changes. The bogies carried the pulling and pushing device, the bridge frame did not transfer any pulling forces. With reference to the fact that there were two bogies under a common main frame, the locomotive could be assigned the wheel arrangement (1'C) (C1 '). From the US point of view, however, it was more relevant that the bogies were not each mounted independently rotatable in the main frame, but were connected to a common central articulated coupling on which the relative movement of the two bogies was based. With this perspective, the US-American AAR classification resulted in the 1-C + C-1 wheel arrangement , which, according to UIC terminology , would indicate a double locomotive .
Axle drive
Each bogie contained two traction motors. They drove a common jackshaft , which was mounted between the running axle and the adjacent driving axle. The rotary movement was transmitted elastically to the jackshaft washers with a kind of spring cup drive , i.e. with damping by several spiral springs. The tensile force was transmitted from the jackshaft via the drive rods to the adjacent drive axle and via the coupling rods to the coupling axles .
Electric motor operation
The traction motors were designed as three-phase motors , the necessary three-phase alternating current was generated by a rotating converter in the machine room. The PRR used a traction current supply with single-phase alternating current of 11,000 volts and 25 Hz. The motors were designed for a total output of 5618 kilowatts (7640 hp), but the converter could only provide a continuous output of 2940 kilowatts (4000 hp) and an hourly output of Provide 3380 kilowatts (4600 hp). All electrical power devices (converters, traction motors, electrolyte resistors (see below) and their liquid pumps) were externally ventilated via their own fan motors.
Electric control
By switching the engine groups, two continuous speed levels could be selected with 16.5 km / h (10.3 mph) and 33 km / h (20.6 mph). This was considered sufficient to move the heavy freight trains over the planned steep sections of the railway company. In addition to the continuous speed changeover, the start-up speed could be controlled using electrolyte resistors for high electrical currents. These consisted of a container with conductive water, the adjustable liquid level of which was used to control the engine power and maintain the pulling force during the switching phases.
business
In test operation on the already electrified line between Philadelphia and Paoli (Pennsylvania) , the machine called "Big Liz" proved to be operational, but with its hourly output of 3680 kilowatts and starting tractive effort of 620 kN, it was far stronger than it was for the time Car stock of the company allowed. The use as a train locomotive led to breaks at the domes and the high pressure forces when pushing them to derailments.
In comparison, the legendary “Big Boy” steam locomotive, built 25 years later, produced just 602 kN of pulling power and the modern DSB EG electric freight locomotive built in 2000 with a continuous output of 6500 kW “only” had a starting pulling force of 400 kN, although the latter was lower Mass was conditioned. A similar experience with too high a pulling force was made in Switzerland around 1933 with the Ae 8/14 - 11852 double locomotive , with the maximum pulling force of 588 kN tearing the wagons' pulling devices. "Big Liz" was shut down after the trial operation and scrapped in 1940.
Individual evidence
- ^ A b "Pennsylvania Electric Locomotive - A Description of Interesting Details in the Running Gear Construction and in the Electrical Equipment". Retrieved April 5, 2020 . Railway Mechanical Engineer 92 (2): pp. 87–90.] (PDF; 509 kB)
- ^ "Pennsylvania Electric Locomotive - Experimental Design for Heavy Trunk Line Service to Operate Over 24 Miles of One Per Cent Grade". Retrieved April 5, 2020 . Railway Mechanical Engineer 91 (7): pp. 389-390. (PDF; 278 kB)
literature
- Alvin Staufer: Pennsy Power. (1962) pp. 248-253. ISBN 0-94451-304-2 .
Web links
- "Pennsylvania Electric Locomotive - Experimental Design for Heavy Trunk Line Service to Operate Over 24 Miles of One Per Cent Grade". Railway Mechanical Engineer 91 (7): pp. 389-390. (PDF; 278 kB)
- "Pennsylvania Electric Locomotive - A Description of Interesting Details in the Running Gear Construction and in the Electrical Equipment". Railway Mechanical Engineer 92 (2): pp. 87-90. (PDF; 509 kB)