42 



THE CIVIL ENGINEER AND ARCHITECT'S JOURNAL. 



[Feb. 



There are three (lilTerent systems of switches employed upon railways ; 

 the first— that of moveable rails, which art by pressing upon the inside of 

 the carriaRe wheels, so as to force them to run in the required direction. 

 This plan possesses the disadvantage of loosening the wheels and wearing 

 them away quickly. The second system is, that of the moveable rails, 

 which may, by turning on a pivot, be moved in the direction in which the 

 train is required to run. In this plan, there is no pressure on the inside of 

 the wheels ; but. if by chance, the moveable rail is badly placed, the en- 

 gine will run oil' the rails. And, lastly, the third plan, which is generally 

 adopted at pri'scni, is one that unites the advantages of the first two. It 

 13 composed of duuble switches, arranged in such a manner that there may 

 be always a moveable rail opposite each road ; and the switches being 

 always brought back to their original position, by a counterbalance weight, 

 there is no danger of running oil' the rails. This latter plan is much pre- 

 ferable, as regards public safety. 



Independently of the changes and crossings in a level, the Commission 

 has given its ailenlion to some questions which are of i^reat importance as 

 regards security in travelling. For instance, when a railroad is curried 

 across a deep valley, which can only be traversed by means of lofiy via- 

 ducts, or through deep cuttings, or across rivers, of greater or less w idth, it 

 will be understood that it would be much moredangerous to run olTthe rails 

 at suchjlplaces than when travelling on a level road, although attended at 

 all times with much danger. In order to prevent this, as much as possible, 

 counter rails are generally employed, placed either inside or outside the 

 line of rails, and more or less elevated above the ground. The Commission 

 has thought, that in certain cases, the couuter-rails may be useful, adding 

 besides, that when used, it is advisable to place them inside the ordinary 

 rails. In fact, by this means, the height of the flange of the wheels is 

 gained ; and, besides, if an axle were to break, the wheel, instead of being 

 dragged outside the rails, would have a tendency to run inside, which is 

 an evident advantage as regards safety. 



Lastly, — the Commission has had to examine whether, as regards safety 

 of transit, there should not be a limit to the radius of the curves, and what 

 this limit should be ; but it was not long in perceiving that nothing positive 

 could be decided on this point, and that it should be left to the government 

 to determine, in each particular case, the limit to be adopted. This limit, 

 as at present stated in the railway books, appears suitable and sufficient 

 for preventing accidents. 



II. Oh the influence of the state of the mnterials, as regards safety of transit, 

 and the precautions to be taken for that purpose. 



If the stale of the rails, and the materials of which the railway is com- 

 posed, have great influence upon the security of railway transit, the ma- 

 chinery employed in working it, viz. — the locomotive engines and carriages, 

 is also worthy of serious attention. 



Experience has proved, that by forming the upper surface of the rails of 

 a slightly convex form, the oscillation may be much diminished, and the 

 friction of the flanges of the wheels upon the rails will be reduced in pro- 

 portion. They are, in fact, scarcely in contact, and consequently, the rails 

 may be made about a third of an inch wider, which greatly facilitates the 

 progress upon curves. These slight improvements need not increase the 

 expense of the railway, but by their adoption the chances of accidents will 

 be greatly diminished. 



The next question to be discussed relates to the axles. This subject is 

 one that has greatly occupied public attention, from most of the serious 

 railway accidents having been accompanied, if not caused, by the breaking 

 ofau axle. The Commission has examined the axle, successively, in all 

 possible positions : — Urst, in the process of manufacture, and in their form 

 and adjustment; and, afterwards, in the different kinds of work to which 

 they might be adapted. As regards the manufacture of axles, the Com- 

 missiou is of opinion, that this manufacture is now conducted on as perfect 

 a plan as possible, as well for straight as cranked axles. The former are 

 wrought by the hammer; and the cranked axles, which are always larger, 

 are also nia<le of fagotted iron ; but in order to give them the desired form, 

 only one method appears to have been thought worthy of being employed. 

 This method consists in putting a number of iron bars together to form a 

 parcel of about two feel square ; and these, having been heated in a rever- 

 beratory furnace, are submitlec! to the action of a powerful hammer, and 

 beaten on all sides, in order to weld the bars together : the bar thus made, 

 is afterwards reduced to a thickness somewhat more than the diameter of 

 the intended axle, keeping a sufficient width for the cranked part. Those 

 parts of the axle which are to receive the wheels, are first wrought into the 

 required form, and then the cranks (which do not require to be rounded) 

 are brought to their proper shape. 



The form to be given to the axles is not material. It has been proved 

 by experience that axles nearly always break inside the wheels, and at or 

 near the nave. It is therefore advisable to make this part much thicker 

 than the others ; and this is generally done by manufacturers ; but they do 

 not always pay great attention to the levelling of these parts wilh the body 

 of the axle, as the incline is generally too abrupt. This mode of manufac- 

 ture being very defective, and likely to decrease the strength of the axle, 

 it is indispensably necessary to make the thick parts taper gradually down 

 to the smaller ones, or in the form of a truncated cone, the apex of which 

 would be equal to the diameter of the body of the axle. 



The Commission had to inquire whether it was advisable, before em- 

 ploying the axles, to test their strength ; and their opinion was, that this 

 trial w as not desirable, but that there might be certain modes of trial which 

 would not injure the metal, aud which would nevertheless expose the de- 



fects : such, for instance, as re-heating to a cherry red — an examination of 

 the portions detached from the ends of the axles, &c. 



In a word, the especial attention of the Companies should becalled to 

 this question, the importance of which may be easily understood ; and 

 they ought to be also obliged to keep registers, in which all tlie axles re- 

 ceived should be carefully noted, together with all the circumstances of 

 their reception, and a statement of the proofs to which they had been sub- 

 mittcd. 



When working on railways, the axles are subjected to strains of dilTerent 

 kinds, and to shocks and vibrations, sometimes of a very violent nature, 

 which may cause them to break. Accidents of this nature have frequeutly 

 happened upon railways ; but, in most instances, the circumstances have 

 not been truly investigated, nor the appearance of the fracture considered ; 

 except in some cases (fortunately very few) in which the breaking of the 

 axles occasioned serious injury or death, lint in these cases, the two 

 broken portions of the axle had been so twisted, that no conclusion could 

 be arrived at from the appearance of the fracture. It is, besides, generally 

 impossible to determine whether the breaking of the axle was the cause of 

 the accident, or merely the effect. 



From these circumstances, the Commission has been nnable to discover 

 any documents of a nature sufficiently conclusive to determine the probable 

 time that axles would last; but it has no hesitation in declaring that ihey 

 are deteriorated in quality by use. It may be concluded, from isolated 

 but well-verified facts, thai, after a certain time, depending upon the effec- 

 tive work accomplished by each, the axles will break. — Is this owing to 

 any molecular change in the material? It is impossible to determine this 

 from what we know at present; but it will be readily conceived that this 

 is matter of serious consideration, and, consequently, the Commission 

 thinks that every Company ought to be obliged to keep a register, in which 

 should be entered, independently of the particulars of the time of receiving 

 the axles, ixc, the number of miles run over by each. 



The documents extracted from these registers would doubtless be of great 

 utility for solving the important questions reUtive to the duration of axles; 

 bul the fact cannot be denied that this will furnish no result until after a 

 number of years ; and, therefore, the Commission is of opinion that it would 

 be advisable to make some experiments as to the means of ascertaining, at 

 anytime, the amount of alteration which has taken place in the axles'; 

 and either to restore them to their former stale, or limit the period of their 

 working. 



After ascertaining the average weight which axles have to support, and 

 the strain they undergo, the following experiments were proposed to be 

 made : — On analysing the strain upon axles, it was found to consist, 1st, — 

 Of a vertical strain, due either to that portion of the weight of the engine 

 bearing upon that poiul, in consequence of the position of the centre of 

 gravity, or to the action of the springs of the hinder axle in the six-wheel 

 engines. This strain being thus defined, even supposing that the parts 

 upon which it acts are as near as possible to the point d'appui formed by 

 the wheels, tends, nevertheless, to bend the axle in a vertical direction. 



2nd. — A twist or strain, arising from the conoidal form of the peripheries 

 of the wheels, and inequality in the inclination of the rails; from which it 

 happens that the peripheries of two wheels, fixed upon one axle, never 

 touch the rails at the same part at the same time, and consequently, each 

 of the wheels slip alternately on the rail : if the twist resulting therefrom 

 is not too violent, it keeps all the molecules in a permanent stale of vibra- 

 tion. 



3rd. — The shocks arising from inequalities in the road, caused by the 

 undulations of the rails, and the momentary depression of the rails at their 

 point of junction when a train passes. These shocks increase in violence 

 in proportion to the speed of the train, and act in a direction at right 

 angles to the axis of the axle. 



4lh. — Another kind of shock, arising from the oscillation of the train, 

 which acts on the axles both in the direction of their knglh and at right 

 angles thereto, increasing in force in proportion to the diameter of the 

 wheels on the axles. 



In order to appreciate the eflfects of these four kinds of strain, the Coni- 

 missioa is of opinion, that the first series of experiments to be undertaken, 

 should be to inspect a certain number of axles whioh have already worked 

 for a given time upon railways, aud minutely examine their interior tex- 

 ture. As, however, these experiments could not lead to perfectly satisfac- 

 tory conclusions, from the want of points of comparison, the Cimunissiun is 

 of opinion that it would be advisable, at the same time, to commence ex- 

 periments upon axles. 



These experiments might be made by taking an ordinary locomotive 

 axle, furnished with the two wheels, loading it as it would be if adapted 

 to an engine, and giving to it a rotary movement, similar to that which it 

 would acquire if employed upon a railway. By placing the wheels of 

 this axle upon a frame, consisting of another axle, furuislied with w heels, 

 to which motion is commuuicatfid by a steam engine, the first class of uo- 

 tion to be observed will be obtained. 



All the other motions might be obtained by this means ; and also, by a 

 suitable construction of the wheels of the frame, the twisting of the axles, 

 the shocks arising from the bending of the rails, ami the shucks arising 

 from the oscillation, liy this method of proceeding, the axle submitted to 

 esperiment will be exposed as nearly as possible to the same injurious ac- 

 tion as when in use ; only, instead of advancing upon a railway, the rail- 

 way will present itself to the wheels. The Commission, wishing to ascer- 

 tain the expense of the above experiments, arrived at Uie following re- 

 sults :— 



