MONO-RAIL TRANSPORT

New Zealand Times, Volume XXXII, Issue 7025, 13 January 1910, Page 3

MONO-RAIL TRANSPORT

THE BRENNAN SYSTEM. (By ‘'Civil Engineer,” in the "Spectator.") In May, 1207, Mr Louis Brennan exhibited at the Royal Society a working model of a railway truck illustrating the principal features Of his mono-rail system Considerable interest was awakened in the invention by this demonstration before the loading British scientific society of the possibility bv this demonstration of running carriages on a single line of rail laid on tho ground, of keeping them upright by means or gyroscopic control —although, apart from that control, the vehicles would have been unstable and toppled over—of turning sharp curves and climbing stoop gradients. A popular description. of the mechanical devices by which these extraordinary results were obtained was given in the “Spectator” of May 18th, IS-07, and at that time it was un-derstood-that Mr Brennan, with the aid and encouragement of certain Government Departments, was engaged in the construction of a full-sized railway truck for 'experimental purposes. This vehicle has now been completed, and a public trial of its capability was made on November .10th at Mr'Brennan's factory near Chatham. In view of the novelty of tho system and its future applications, a brief description of tho truck and its performances may not be unwelcome. ~ Tho railway-truck was of considerable size and weight, being forty feet long and ten feet wide, weighing when empty twenty-two tons.. It ran upon four wheels- three feet in diameter, placed below tho centre-line of tho truck.,, each pair of wheels being attached to a “bogie carriage"■similar to those fitted under the long vehicles now . commonly used on ordinary railways. -Inordinary practice, of course, four wheels instead of two are attached to each “bogie/ and the arrangement is adopted chiefly in order to permit long vehicles to-pass readily and safely around the curves of the railway-line. The centres of- the bogies in the ,Brennan vehicle were twenty feet .apart, and curves only thirty-five-feet in radius were 'traversed in the* course of the trials. The wheels are double-flanged so as to fit over the upper part of the rail, and the experimental track was laid with seventy-pound Yignole section rails, carried by transverse sleepers three feet six inches long. The carriage was self-propelled, and was electrically driven by two motors of forty to fifty horse-power, a speed of about seven miles an hour being maintained when running on a circular track of a hundred and five feet radius. From the track the carriage ran on a straight piece of line, and was subsequently driven oyer sharp reverse curves, keeping practically upright throughout. When some forty people stood on one side of the car, it remained almost level. This .stability, as was explained previously, was due to gyroscopic control. There are two gyroscopic wheels, each three feet six inches in diameter weighing three-quarters of a ton, which are driven by an electric motor a-t a speed of three thousand revolutions per minute, within an air-tight case in .-winch a high vacuum is maintained. Mr Bren-; nan would have preferred a still higher rate of revolution and it may be obtained hereafter, in which case smaller and lighter wheel’s would give equal stability. It will be seen, therefore, that Mr Brennan has succeeded in reproducing on full scale in this large carriage, which can carry a load of from, ten to fifteen tons, results corresponding to that, obtained in bis model truck of 1907, which was only six feet in length.

Certain features of the new carriage deserve special notice. It has been said that it is self-propelled, the electric energy required for that purpose, for driving the gyroscopic wheels, actuating the Wcstinghouse brake, and other purposes, being generated by dynamos driven by petrol engines. There are two genera-_ ting sets, one of eighty horse-power and ono of twenty horse-power; and their .veight is included in the twenty-two tons. Steam power could, if preferred, be used for propulsion, but electricity is greatly superior for driving the gyroscopic wheels. If electric energy could be obtained from a central ‘station and conveyed by an overhead wire to the motors driving the carriage-wheels and the gyroscopes, tho .weight on the truck could, of course, be correspondingly reduced and its load increased. If the mono-rail system cam©. into general use, no doubt this would be the course usually adopted. Tho 'speed attained on the recent trial was low. but there is no reason,-to doubt that the mono-rail system could be,used at much higher speeds —indeed, its advocates maintain that it is better adapted than tho ordinary, system for extraordinary high speeds. Very steep gradients were ascended and .descended in tho £oursb of the trials, grades of one in thirteen being traversed, Mr Brennan being- of opinioA that one in six and a half emild be mastered if another generating ' set (weighing about four tons) were fitted. On this and all other points his gtateraents are entitled to respect, as he has fulfilled ‘ his ' estimates hitherto.

A German inventor has now entered into, competition with Mr Brennan, and it. is reported that excellent results have been obtained with models of considerable size. To what extent the monorail system may find favour and practical use Ht is net possible to predict at present. Originally it is understood that Mr Brennan contemplated its employment for military purposes, or in new and sparsely peopled countries, on ! the ground that railway-lines could thus be mado much more cheaply and rapidly than on the ordinary system. Reports ,on The Brennan system have, it is believed, been made—by eminent engineers having export knowledge of railway construction and electric traction—to the Government Departments specially interested in the subject. The nature of these' reports has not transpired, but it is reasonable to suppose that exhaustive trials with the vehicle now available will be made before an - final decision is reached. Within the limits originally contemplated by Mr Brennan, it may well happen that use will be made of the system; but its large appli'cation to railway traffic generally is not probable until further experience has been gained under conditions of an ordinary character. It cannot be .overlooked that with a single rail laid on the ground vehicles must depend absoultely Tor their stability upon the continuance of gyroscopic control, Mr Brennan recognises this, and lias designed simple means of preventing the “toppling ox'er" of carriages when the gyroscopes are out of action; but there are obviously circumstances in which certain risks would arise. The question of cost of constructing and operating railways on the rival systems also requires serious examination, and unless very substantial economies can be ensured the new system will not bo used generally. The Kashmir Government has joined the India Office and the War Office in providing the sum of <£15,000. said to have been on the experiment, and it is regarded as probable that the first mono-

rail line constructed on. the new system will be made in Kashmir. In that case, the results .obtained will bo of great interest, and must .influence the fur-, ther application of the system, especially in mountainous countries.