Vous êtes connecté sur le site www.liennard.com                       

Vous pouvez nous écrire par : alain@liennard.com

Volver :                        N&W           

A traduire !

The Norfolk and Western
Steam Turbine Locomotive

Brotherhood of Locomotive Firemen and Enginemen's Magazine; July, 1954.
Reprinted with permission.


The Norfolk and Western steam turbine locomotive is slightly over 161 feet long and weighs 586 tons complete with fuel and water. Designed for a maximum speed of sixty miles per hour, the unit is capable of exerting a maximum tractive effort of 175,000 pounds, and a continuous tractive effort of 144,000 pounds at nine miles per hour.


Railroad operators will follow with considerable interest the performance of the Norfolk and Western's new experimental coal-burning, steam turbine-electric drive locomotive which has recently been delivered. Rated at 4500 horsepower, the Baldwin - Westinghouse unit incorporates a Babcock and Wilcox high-pressure water tube boiler with Westinghouse steam turbine and electric drive. This steam locomotive embodies the best designs from modern stationary and marine power plant practice that can be adapted to the restricted space and requirements of railroad service. It is designed to utilize coal and operates at about double the efficiency of the average coal-burning reciprocating steam locomotive. Its economy in comparison with the diesel-electric depends upon the relative costs of coal and diesel fuel oil at the location where the fuel is used, and within the coal-producing industrial areas it can compete favorably. The locomotive has a 6-6-6-6 wheel arrangement and the locomotive and tender complete with fuel and water weighs approximately 586 tons. The separate tender holds 22,000 gallons of water. Twenty tons of coal can be carried in a hopper in the nose of the locomotive. Over-all length is 161 feet, 1 l/2 inches. Designed for a maximum speed of sixty miles per hour, the unit is capable of exerting a maximun tractive effort of 175,000 pounds, and a continuous tractive effort of 144,000 pounds at nine miles per hour. The design of this steam locomotive includes the combination of several features which, while proved satisfactory in Navy and stationary practice, are new to the locomotive field; and they have been incorporated for the first time in locomotive practice in this unit. For example, the use of steam at high pressure and high temperature (600 pounds per square inch, 900 degrees F), in a Westinghouse geared turbine unit developing 4500 horsepower at the electric generator supplying power for the traction motors, contributes to the high thermal efficiency.

Boiler

The Babcock and Wilcox water tube boiler in which the high pressure high-temperature steam is generated is of a construction that eliminates water legs and staybolts, which in the conventional steam locomotive not only limit the possible steam pressure but cause outage and high cost of maintenance. The weight and space occupied by this water tube boiler is considerably less than for the older fire tube type. Coal is fired to the boiler furnace by an improved design of locomotive stoker. The self-cleaning traveling grate on which the coal is burned is entirely new to locomotive practice. This feature is one of the most important improvements over previous practices as it prevents the accumulation of ash and clinkers which interfere greatly with the uniformity of the fuel bed which is so necessary for prevention of smoke and for efficient combustion. The area of the grate and the smaller amount of coal required have reduced the rate of combustion per square foot of grate surface and have greatly reduced the cinder discharge from the stack, with a corresponding improvement in efficiency. The air for combustion is supplied under pressure by an efficient steam-turbine driven axial blower through an air preheater, both of which are new features in locomotive practice. By these means the flue gas temperature is reduced and the efficiency increased. This method of supplying combustion air eliminates the exhaust nozzle and the resulting inefficiency of back pressure on the main steam turbine. Most previously designed steam turbine locomotives, as well as the conventional reciprocating steam locomotives, have been affected by the high back pressure caused by the exhaust nozzle.

Boiler Feedwater System

Water is pumped from the tender by a cold water pump through a zeolite softener located on the tender, then through the turbine oil cooler and into an open type deaerating feedwater heater. From here a booster pump delivers the softened, deaerated and heated water to the main feed pump, which delivers it through an economizer (for additional heating) to the boiler drum. An automatic feed supplies sodium sulfite in proportion to water flow. A continuous boiler blowdown maintains proper boiler water concentration. The high pressure emergency pump can deliver cold water from the tender directly to the boiler drum if required.

Boiler Controls

Another outstanding feature of this locomotive is the complete automatic control of fuel and air to the furnace as well as the feedwater to the boiler in exact proportion to the demand for steam. The engineman runs the train as usual with control of electric power to twelve axle-hung traction motors. The turbine governor maintains the turbine speed by supplying more or less steam flow as required. The automatic control responds instantly to maintain boiler pressure by changing the coal supply and proportioning the air flow to the steam flow; also the boiler feedwater supply to keep the correct water level in the bolier drum. The automatism of the complete unit keeps the proper relation between coal and air for the best combustion efficiency, and also prevents loss of steam and nuisance from the popping of safety valves.

Power Plant

The Westinghouse power plant consists of an impulse type noncondensing steam turbine which delivers 4500 horsepower at 8000 rpm to the generator for traction. The turbine drives the generator through an 8.9 to l ratio single-helical reduction gear. The generator has two armatures on a single shaft, each of which is electrically connected to two parallel groups of three series-connected traction motors (one motor on each axle).

The reduction-gear housing containing the lubricating oil reservoir is rigidly attached to the generator stator, and the turbine is mounted on the, gear housing. The entire power plant is thus assembled as a single self-contained unit that is supported on the locomotive frame at three points so that alignment cannot be affected by distortions of the frame.

Cab

The cab and its equipment are supported by two side trusses, with liberal crossties for box strength. The side truss with no cab underframe construction was dictated by the fact that the boiler takes up the entire locomotive cross section between the side trusses for a length of 34 f eet. The boiler is 102 1/2 inches wide with its roof sheet conforming to and forming the cab roof over the boiler. The ashpan clears the rail by only eight inches.

Running Gear

Two swivel-type motor trucks at each end of the locomotive are spanned by a bolster. The bolsters are loaded by body center pins and by spring-plunger loading pads at each corner. The front-span bolster carries the cast-steel pilot and swing-type coupler. Traction and buff loads are carried through the body center pin to the side trusses and to the rear center pin. The rear span bolster carries M-380 rubber draft gear and a tightlock coupler, also the cold and emergency feedwater pumps.

Equipment Arrangement

The locomotive, from front to back includes: (1) Electric control and dynamic braking equipment (for forward trucks), (2) coal bunker, and stoker, (3) operator's cab, (4) boiler, (5) turbine and boiler-feed equipment, (6) generator, and (7) electric control and dynamic braking equipment (for rear trucks).

Sandboxes are located beside the coal bunker, ahead of operator's cab, in the turbine and generator compartments. Each truck is sanded front and back. Sandboxes are filled from the top.

The operating brake (schedule 24-RL) is located under the operator's cab, with the air pumps and reservoirs under the coal-bunker side slope sheets. Axial-flow traction motor blowers are located in the electrical compartments, each blower supplying air to six traction motors. Fans for ventilating the dynamic braking resistors are driven by motors connected across the resistors. The braking effort varies from 35,000 pounds at fifty miles per hour to 130,000 pounds at fourteen miles per hour.

Locomotive Controls

All manual controls are located in the engineman's compartment. The master controller is equipped with a throttle and reverse lever, the throttle having twelve notches in addition to the "off " and "idle" positions. It actuates the turbine speed changer pneumatically and also controls the excitation of the main generators. Power and braking are applied smoothly, without transition. The reverse lever has five positions: Brake, forward, off, reverse and brake.

Turbine Stopping Controls

A flexible shaft with a handwheel in the operator's cab provides a means for opening and closing the turbine stop valve.

A push-pull type trip lever with the handle in the operator's cab can be used to shut down the turbine in an emergency.

General

Among the old and established features are included the steam driven air compressors and the whistle. The trucks, including the Westinghouse type 370-DZ traction motors, are standard for diesel locomotives. The main turbine, generators, turbine driven combustion air blower, and electrical control are all adapted from existing practice in railroad, marine and other power fields. In general, the new locomotive has all the desirable characteristics inherent in electric drive units such as (1) high starting tractive effort, and (2) no reciprocating parts, plus the advantage of being able to use coal-a plentiful low-cost fuel.

Baldwin-Lima-Hamilton, designer and builder of running gear, cab, tender and other mechanical parts, was also responsible for the erection and assembly in the locomotive of all component parts including the , Westinghotise steam turbine, generator, traction motors, forced draft blower, electrical control equipment and the Babcock and Wilcox Cornpany's high pressure boiler. 

Las fotos