120 



THE CIVIL ENGINEER AND ARCHITECTS JOURNAL. 



[A.. 



DETERIORATION OF RAILU^VY AXLES. 



(inth Engravings, Plate IV.) 



On the Deteriorntion of lidilvai/ A.r/e.^, S;p. By Mr. .7. E. McCon- 

 NKi.L. — (Paper read at the Institution of Mechanical Kniriiieeis.) 



Having been re<|npsted at the last meetinf^ to furnish further 

 proofs of the ciian^e from tiie fibrous to the crystalline character 

 produced in railway axles, and feelinj^ convinced that a strict and 

 careful examination of this important subject is a necexxity in this 

 age of railway practice, the iiujuiry has been resumed in the hope 

 that the further infornuiticm and experience gained may tend to a 

 more perfect knowled^ie of the subject. 



Before stating the results of the different experiments which 

 have been made with the view of ascertaining the cause and extent 

 of the change from the fibrous to the crystalline appearance in 

 railway axle iron, it must be observed tliat in this, as in some other 

 matters of controversy, it is most difficult to produce full and con- 

 clusive proof that tlie iron which is i>roduced of a crystalline cha- 

 racter was once fibrous, as we cannot by any experiment show the 

 change visibly taking place; but surely it is fair and reasonable to 

 admit the fiict of a change, when we find railway axles when new, 

 fi'om the particular mode of manufacture, present through every 

 )iart of their substance a tough, strong, fibrous ajipearance, yet, 

 after several years' use, we find axles of the same description, 

 owing to tlie various deteriorating causes in action, break short 

 at tIiL» back of the wlieel, and then present an appearance totally 

 difterent from the original structure of the iron, as described abo\e. 



It has so happened, in stromr confirmation of the views stated by 

 the writer at the former meeting, that a very remarkalile instance 

 of this change was brought under his notice shortly after the dis- 

 cussion; and he thought the evidence wliich this case furnishes so 

 important and conclusive (alth<mgh produced without any design, 

 and in the ordinary course of business), that the axle has been 

 brought for the inspection of the present meeting. 



This axle was fixed in cast-iron wheels, of tlie pattern in use on 

 several lines of railway, having the H-form of spoke, and, as this 

 wheel is perfectly rigid, experience has proved that the axles are 

 much more liable to deterioration when working in these kind of 

 wheels than in those wheels made partly of wood or other con- 

 struction of wroiight-iron, &c., which may have a certain amount 

 of elasticity. 



The axle now under consideration broke, in ordinary working, 

 close at the back of the wheel, as is usually found ; and the frac- 

 tured ends, which are now produced to the meeting, afford the 

 most distinct proof of the annular sp.ace which was stated on the 

 former occasion to be observable all round the surface of the frac- 

 ture; and this is not only short-grained and crystalline, but there 

 is also, in the writer's opinion, an evident distinct separation to the 

 extent of the annular space, which it would appear takes place 

 some time before the final fracture, .as if each successive blow, 

 heavy or light, lateral or vertical, received or transmitted through 

 the wheels, had each tended to destroy its proportion of cohesiim 

 of the previously crystallised substance of the a.vle at that parti- 

 cular place where the fracture occurs. 



On receiving this axle in the workshops, with one wheel still 

 attached, it was allowed by accident to fall a short distance from 

 the wagon to the ground; and so brittle had it become next the 

 wheel that the other end snapped off simply from the effect of the 

 fall, and shows, as will be observed, a precisely similar apjiearauce 

 to the original fracture. 



I he w riter w as anxious to ascertain how far the theory which he 

 held was correct, that the deterioration <if the axle was principallv 

 local at that point (tlie back of the wheel), and for this purpose he 

 caused the centre of the axle between the two fractures to be laid 

 on supports, with the view <if breaking it. A weight of cast-iron 

 weighing 17 cwt. was then allowed to fall upon it through a space 

 of 1+ feet, but after several attempts it was found to make no 

 impression u|>on this centre part of the axle towards effecting a 

 fract>ire, although it was a frosty day, which would of course ren- 

 der the iron miu-e brittle. Finding'ail efforts to break it bv blows 

 fruitless, the axle was then, in order to test its fibrous character, 

 taken to the hydraulic press, and it has l>eeu bent to the form of 

 the letter U, until the two ends met, witliout showing more than 

 the slightest appearance of the skin of its surface breaking, as will 

 be seen, proving still to be of a strong fibrous iron in tlie centre 

 of the axle. See fig. 9, Plate IV. 



Following up his proposition, the writer wishes to lay consider- 

 able stress on the view he previously stated, respecting the effect 

 of the blows or vibrating- action given tlirough the wheels to the 



axle; he attributes the crystallisation of the axle at that point 

 close behind the wheel, to the sudden stoppage or reaction of the 

 vibratory wave at that place, owing' to the check which it meets 

 from the mass of matter consisting of the wheel, &c., presenting a 

 break of surface, and acting more as an anvil, causing tlie vibra- 

 tion to react like a blow on the neck of the axle (the nearest 

 weakest point), thereby destroying its fibrous character. 



Cast-iron wheels, therefore, are objectionable from their rigidity 

 and non-absorption of the lateral and vertical concussion with 

 other strains formerly enumerated, received in course of working, 

 and transmitted to be w holly expended on the axle; and the writer 

 endeavoured to illustrate this by a comparative e.xperiment witii 

 two different axles of the same description and age, one being 

 fixed in cast-iron, and the other in wooden wheels, those known as 

 the Pimlico make. 



1st Experiment was made on the axle with wooden wheels placed 

 horizontally resting upon the rails : a weight of 1 7 cwt. was allowed 

 to fall through a distance of 13 ft. Sin. upon the axle, immediately 

 within the wheel, by which the axle was slightly bent at the point 

 where the blow came, and a portion of the tyre resting on the rail 

 was broken clear out. This experiment was repeated four times 

 on the other end of the axle, which was bent but vei-y slightly, and 

 the wheel was rendered completely useless. 



2nd Experiment was made upcm the axle with cast-iron wheals, 

 placed as in the former case, and the same weiglit was allowed to 

 fall the same distance at the back of the wheel, when the effect of 

 the first blow was to break the axle at the other end, at the back of 

 the wheel; thus proving that in the former case the axle was saved 

 from fracture by the woi>den wheel absorbing its full share of the 

 effect of the b.low, and the tyre of the wheel breaking proved tliat 

 in course of working it would receive a portion of the deteriorating 

 forces tending to crystallise, the wheel acting like a cushion to 

 soften the blows before they reached the axle; in the latter case 

 the rail supporting the cast-iron wheel was fractured in three 

 places. 



A 3rd Experiment was tried with another a.xle with cast-iron 

 wheels placed as before, and received four blows on each end of the 

 axle within the wheels, which caused it to bend, but produced no 

 fractui'e. This axle had not been much used, and was of a stronger 

 fibrous character. 



In order to ascertain the relative appearances of axles which had 

 been in use, and determine the position of the crystalline change, 

 both at the centre and outer surface of the :ixle, the writer caused 

 four axles which had been condemned as too small from wear in the 

 bearings, to have a groove cut in two cases on each side, to within 

 an inch of the centie, and in the other two, grooved through to 

 within an inch of the outer surface; these were sj lit asunder with 

 wedges, and their appearances will show that a certain change has 

 been going on, and this is more observable in one end of the axle 

 than the other, attributable, he believes, to the break being applied 

 to the wheel wliich was on the end where the greatest crystalline 

 change is visible. 



He has made a number of other experiments in the presence of 

 several of the members of the Institution, with the view of deter- 

 mining the effect produced on the fibre of iron by the cold ham- 

 mering process. The following are the principal results: — 



No. 1. A piece of ordinary bar-iron 2i inches wide and l| inch 

 thick, received 20 blows to nick it across, and was broken with 21 

 blows of a 1 + lb. hammer, showing a fracture part fibrous and part 

 crystalline. 



No. 2. The same bar received 52 blows on one side, and 65 on 

 the other, from the 1 lib. hammer, with 20 to nick it as before, 

 and it broke with H blows, showing different layers of fibre and 

 crystal. 



No. 3. The same bar received 50 similar blows on each side as 

 No. 2, but each blow on alternate sides successively, and 20 in 

 nicking, and 9 l)lows broke it. 



No. 4. The same bar was not cold-hammered, but received 20 

 blows in nicking, and required 28 blows to break it, showing a 

 good fracture. 



No. 5. Was a |-inch square bar, received 50 blows on each of two 

 opposite sides, and 25 on each of the other sides, with + blows in 

 nicking, and 5 broke it. 



No. 6. AV'ithout any cold-hammering and the same bar, after 

 receiving + blows to nick, required 6 to break it. 



No. 7. The same as in the case of No. (>, had no cold-hammering, 

 with 4 blows to nick it, and required 30 blows to break; in this 

 case it was broken the flat way of the pile of the iron, but in No. 6 

 it was broken the edge way of the pile. 



No. 8 Exjieriment was made on a shaft 3| inches diameter. 



