The New Zealand Railways Magazine, Volume 2, Issue 4 (August 1, 1927)
The following extracts from a paper read by Lieut.-Col. E. Kitson Clark, T. D., M. A., before the Institute of Mechanical Engineers in April last, describe an interesting experiment in the adoption of the internal-combustion principle to locomotive development. The subject is of particular moment in view of the revolutionary advances which may occur in locomotive and train operating practice, should the experiment prove successful.
Annihilation of time and space and efficient production of power have been accepted as symptoms and reputed as advantages of Western Civilisation. For the last hundred years the steam-locomotive has been a prime minister in these services. Its day is not yet over. Where reliability, versatility, and flexibility are required, where loyalty in lonely places is looked for, there will still be the steam-locomotive; but verstality and flexibility are not necessarily partners with rigid economy. A more complete use of nature's heat units is now called for, together with less human exertion in their application. Under certain circumstances, electricity presents the ideal. An electrical machine demands no physical effort from the operator. Its controls are simple, its power supply is not exhausted at speed, but it requires a land over-flowing with water and crowded with traffic, and postulates for the region thus richly endowed a clientele as abundant in capital.
Where any member of this trinity is absent, designers in all parts of the world who look beyond the steam-engine are turning to the internal-combustion engine for the next step in locomotive development. Oil atomised and expanded by combustion is a more economical vehicle of energy than evaporated water; its machinery-power for power-is less bulky. Its manipulation is a matter of mind rather than muscle and its effort can be maintained at high speeds without exhaustion. So far internal-combustion has merit, but in its usual form it is devoid of flexibility and presents great difficulty in starting against a load.
Therefore, when the Still system came before the author, he was impressed by its unique combination of internal-combustion and steam-power; internal combustion for continuous work, steam for starting, for overload and for auxiliaries, such as brakes, train heating, etc. The problem has been to obtain a machine of moderate cost with all these qualities and at the same time capable of facing the rough usage of a life on the open road.
In a few words the Still system is as follows:-The engine is double acting with internal-combustion at one end of the cylinder and steam at the other end through which the piston rod works. The water in the jacket is in connection with the boiler, and the excess heat from products of combustion assists in the production of steam in the boiler. The boiler is primarily heated by oil burners, and the steam generated is used for starting the engine. The two-stroke experimental engine which has been installed for ten years at the Chiswick Laboratory of the Still Engine Company develops 400 indicated horse-power with the expenditure of 0.345lb. of oil per b. h. p. hour. To obtain such a result on a locomotive would be to save 60 per cent. of the fuel bill, and towards such a result the designs which follow are aimed, but until the final tests with the locomotive are carried out, it is not proposed to make any higher claim than a saving of 10 per cent. on the fuel bill alone.
The locomotive to be described has three coupled axles, is designed to undertake the most ordinary regular work on main line service, and its axle load is 17 tons. The outside dimensions of the locomotive conform to the requirements of the great railways of the country. It is calculated to exert a tractive effort of 24,500lb. from starting to a speed of 6 miles per hour, dropping to 7,000lb. at 45 miles per hour. Its cylinders are disposed horizontally.
The transmission of force is in the first instance via a crank-shaft, mounted in rigid bearings to rotating gearing protected by a page 31 spring and damping device. From this the transmission is by connecting rods which provide the toleration required by the relative movement between the spring-carried superstructure and the driving wheels.
The gearing consists of two pinions incorporated in an engine crank-shaft.
For the fuel supply to the cylinders airless injection has been adopted.
In the course of experiment heavy Diesel oil of 0.95 specific gravity was used, but a lighter oil of 0.86 specific gravity was substituted; an improvement of 5 lb. per sq. in. mean indicated pressure resulted.
Main Particulars of Locomotive.
Internal Combustion Engine, 8-cyls., 4-stroke Cycle.
Cyls: 13 1/2 in. dia. × 15 1/2 in. stroke.
Gear Ratio: 1.878 to 1.
Designed Engine Speed: 450 r. p. m.
Loco Speed at 450 r. p. m.: 45 m. p. h.
Max. i. h. p. on Combustion only: 1,000.
Max. i. p. h. available, 1,200.
Starting Tractive Force: 25,450 lb.
T. F. at 45 m. p. h.: 7,000 lb. (assuming 80 per cent. overall Mech. Efficy.).
Boiler and Tanks.
119 Tubes 1 3/4 in. dia. outside × 9 ft. long; 490.6 sq. ft.
Firebox: 72.0 sq. ft.
Total Evaporating Surface: 562.6 sq. ft.
36 Tubes 2 3/4 in. dia. outside × 17 ft. 4 in.: 448.7 sq. ft.
2 Tubes 6 1/2 in. dia. outside × 17 ft. 4 in.: 59.0 sq. ft.
Total Regenerative Surface: 507.7 sq. ft.
Firebox Volume: 39 cu. ft.
Water Capacity: 1,000 gallons.
Fuel Oil: 400 gallons.
Lubricating Oil: 85 gallons.
The boiler which supplies the steam is a simple structure. Its functions are to provide steam by oil firing for starting, to act as partner with the combustion-cylinder jacket in the regeneration of steam, by absorbing the heat of the exhaust gases, and at the same time to act as a silencer.
Full advantage has been taken of the loading gauge width for the cab and footplate, seats are provided for the operator and his assistant: the controls are so placed that the driver need not leave his seat to perform any of the manipulations required, and the fireman, having no arduous task in maintaining steam, can assist in any duties demanded by routine. Due to the absence of coal dust and firing tools, a neat, clean, well-lighted compartment for the crew is provided.
The small diameter of the boiler enables large windows to be provided in the cab front, whilst the disposition of the tanks permits a generous look-out for running in reverse.
Under normal conditions of load and grade the process of starting the engine is as follows:-Having put the steam gear over to full gear position (which ensures the combustion gear being set correctly) and having opened the oil regulator to “start” position, the steam regulator is opened and the engine moves away. Within a few revolutions of the driving wheels the oil side fires at a low power, the first combustions being also imperceptible because in the “start” position the spill valve returns most of the oil to the tank. As the speed increases, the steam gear is notched up, and the oil regulator is advanced to running position. At any speed above about 6 miles per hour the steam regulator may be closed entirely and the oil engine relied upon.
To stop, the oil regulator is moved round to the “off” position, and if steam is being used its regulator is closed and the brakes applied in the usual way. In case of emergency stops, the steam gear could be reversed and the steam regulator opened. In the case of special need for acceleration, steam will be used to judgment according to the circumstances.
For starting, brakes and train heating, steam is the source of energy. By its essential flexibility it replaces for starting and low-speed work a clutch and gear box, electric or fluid transmission, and enables a unit complete in itself to accomplish the extraordinary requirements demanded by rail traction. It enables also a staff trained for the maintenance of any ordinary reciprocating engines to adjust or repair or inspect the entire mechanism of the locomotive with very little special training. The controls and operations will be familiar to the driver of steam-locomotives and the general appearance reminiscent of his usual charge.page 32
Shunting, backing on to a train, or moving about the yard and sheds, can be done on steam alone by the controls familiar to all.
It is safe to assume that an overall figure including oil burnt whilst firing the boiler for starts, will not exceed 0.4 lb. per i. h. p.-hr.
The Kitson-Still locomotive, burning fuel at 80s. per ton, would cost roughly £500 per annum. For a comparative steam-locomotive, using coal at 21s. 6d. per ton the fuel bill would be approximately £1,000 per annum.
In a review of the various points in the design of this engine probably the most important is the symmetrical disposition of details about the central shaft and gears. By this means, accessibility is made very real, the main driving gears operate under the best conditions, a simple and stiff crank-shaft is possible, latitude for wheel position is obtained, and cam-shaft and pump operations are effectively synchronised.
Such is the engine which in a few months will be submitted to the chances and changes of the open road.
Egyptian Railway Enterprise
One of the most notable attractions to tourists to Egypt is the enterprise of the Egyptian Government, who have changed the old narrowgauge railway between Luxor and Assuan into a standard one, allowing, therefore, of a continuous run from Cairo to the wharf at Shellal for those who are either staying at the Great Dam or proceeding by Soudan Government steamer farther south. In the past passengers have caught the night mail at Cairo so as to arrive at Luxor next morning, when they had to change into another coach for a day's journey through the grit and glare for Assuan. Now they will be saved all that discomfort, and be readier for that night-long experience of the desert between Wadi Halfa and Abu Hammed, where the river makes a 400-mile bend, and the stations have no names, but only numbers, on their way to Atbara, Khartoum, and beyond.