1850.] 



THE CIVIL ENGINEER AND ARCHITECT'S JOURNAL. 



119 



pressed. Practically the writer is not well acquainted witli the use 

 of these sjirings, hut presumes that the ftdlowing uhjectioiis have 

 been found in practice: the spring hears upon the sole-liar at one 

 point, viz. over the centre of the a.\le-hox, instead of at two points 

 some 3 ft. apart. There is a much greater uncertainty in the 

 decree of elasticity and supporting povver than in Hat springs com- 

 posed of many plates, partly from the greater thickness of steel 

 causing uncertainty in the tempering, and from the greater angular 

 strain on tlie particles of the steel; the sudden hlows experienced 

 bv railway springs requiring the thickness of the steel to be within 

 a'certain limit, say of |-in. or ^-in. 



linfffr (inil Draw Spriihyx. — The ordinary Laminated Buffer and 

 Draw Spring is 5 ft. 4|-in. long, 5/5 in. thick, and 3 in. broad, 

 consisting of 17 plates, the outside plates f-in. thick and the re- 

 mainder J.-in.; the camber when at rest being 13 in. The same 

 principles of construction apply to this spring as to the laminated 

 bearing spring in fig. 1. These springs are generally fixed in the 

 centre of the carriage, sliding between four bars of iron, ordinarily 

 termed the " buffer spring cradle." The ends are acted u])on by 

 the four buifer rods, ;md the draw bar is cottered to tlie centre of 

 the spring. The same methods Ijave lieen tried to obviate friction 

 at the ends as have been already mentioned with respect to bearing 

 springs, but these plans are now obsolete In fixing tlie springs on 

 carriages they are generally compressed one inch, and in wagons 

 to the extent of aliout one-third of the stroke. The stroke of the 

 buffer rod is limited to such an extent as will not deflect the spring 

 beyond a straight line. The sustaining power of this spring is 

 etpial to about 2 tons 11 cwt., or equal in all including both ends 

 of carriage to about 2| tons, developed through a stroke of 2 ft. 

 As yet this method of buffing has not been surpassed or equalled, 

 as none of the modern substitutes will give this moderate amount 

 of resisting power developed through so great a space as 2 ft.; also 

 the weight of the buffer springs being in the centre of the carriage, 

 and the springs acted upon by long buffer rods, cause the action to 

 be very steady. 



The Double Draw Spi-iiigx, with a check bar to limit the action 

 within the straining point, make probably the only truly effective 

 metliod yet adopted. It is to he observed that the springs when 

 drawn liome are limited in their action by the check bar A A, thus 

 forming a continuous rigid draw bar (see fig. 7, Plate IV). The 

 springs are each 2 ft. long, S-pj^ in. thick, and 3 in. wide, consisting 

 of II plates, of which 2 are f-in. thick and the remainder Y^-inch; 

 the camber is 3| in. before fixing; the springs are each compressed 

 5-in. in fixing. The method of fixing is the same as already 

 described for the laminated buffer spring. 



E.i'teninl Buffers. "Within the last few years a considerable 

 numher of external buffers have been introduced, consisting of a 

 cylinder and piston packed with nearly every available elastic 

 substance, and practically varying only in the material of the 

 packing. 



De Bergiie's Buffer Spring is packed with rings of vulcanised 

 india-rubber; there are 4 rings 52 in. diameter, and l| in. thick- 

 ness each. 



In the opinion of the writer this is the least effective of any yet 

 produced, as the stroke is very short, and then only moderately 

 developed under enormous pressure. It is questionable whether in 

 the event of a collision, the train would not collapse and leave the 

 rails, before the immense sustaining power of these springs was 

 fully developed. This buffer has an apparent stroke of about 

 3 in.; l)ut it appears that to drive up the pair of huffei's lA in. 

 would require a force of 3 tons. By reference to the description of 

 the ordinary laminated spring it will be observed that the sti-oke is 

 12 in. with a force of 2| tons; being 8 times the length of stroke, 

 with a rather less force. It is also questionable whether the vul- 

 canised india-rublier is of that imperishable nature originally 

 supposed. The writer has had in his possession a considerable 

 quantity of vulcanised elastic bands for papers, that have become 

 completely rotten. 



Todtl s Coric Buffer is as nearly as possible the same as De Ber- 

 gue's, excepting that the packing is cork; there are 5 plates of 

 cork 7^ in. diameter and f-in. thick each. This spring appears to 

 be superior to De Bergue's inasmuch as the cork is more compres- 

 sible than the vulcanised india-rubber, but it is questionable 

 wliether the cork is not liable to a permanent set. 



Adams's Disc Bvffer has the packing, consisting of 16 disc springs, 

 made from flat circular plates of steel 8 in. diameter and i-in. 

 thick, with a radiating i)iece AA, cut out to enable the plates to be 

 press^'d to a conical form (see fig. 8, Plate IV.) This buffer spring 

 is superior to the foregoing inasmuch as the total amount of stroke 



is wholly developed, and the power can he properly adjusted by tlie 

 thickness of the plates; the total length of stroke is 5i in. 



Webster's Air Buffer exhibits considerable ingenuity, but is more 

 complicated than the other plans. The air jiiston is 6 in. diameter, 

 and the leather packing is distended by a vulcanised india-rubber 

 ring; the length of stroke is 1 in. In' the event of leakage during 

 the stroke, the piston would not return to its original position, and 

 to effect this a small spiral spring is employed which drives back 

 the piston. A small valve admits air at the time that the piston is 

 recovering its position to compensate for leakage during the stroke. 



Spiral Buff'er and Draw Springs are used to some extent, but 

 they are liable to the same objections already described with refer- 

 ence to the spiral bearing springs. 



Brown's Conical Spiral Spring Buffer appears to be the least 

 objectionable of these (see the annexed woodcut). The resisting 

 power is that of a spiral spring 

 made in the form of a cone 73 

 in. diameter at the base, and 

 the spring has the advantage 

 of rotating at the point of the 

 cone, thereby considerably eas- 

 ing the tendency to fracture or 

 strain the particles of the steel; 

 the steel is 1 in. wide and g-in. 

 thick at the base of the conical 

 spiral, and is tapered for the 

 last three coils to ^-in. diameter 

 at the ]ioint of the cone. AVlien 

 driven home the spring forms a 

 complete flat volute. The sus- 

 taining power of the spring is 

 about eipial for the space ])assed 

 through to that of the ordinary 

 laminated buffer spring, but 

 with a shorter stroke, the length 

 of stroke being only 3g inches, 

 instead of 12 in. From its compactness and comparatively mode- 

 rate price, it is in the writer's opinion, should the springs be found 

 to stand their work, the most eligible of the external buffers; but 

 yet far from equalling the result obtained by the use of the lami- 

 nated buffer spring and buffer rods. 



The whole of the cylinder and piston buffers are liable to the 

 defect of the piston being guided through only a short length, and 

 consequently they cannot work with the smoothness of the long 

 buffer rod guided in several places. Tliis more particularly applies 

 in the event of an oblique blow upon the buffer. 



In conclusion, it is suggested that it would be desirable for a 

 correct table to be formed of the sizes, weight, sustaining power, 

 and deflection of laminated bearing and buffing springs, as a uni- 

 form guide in their practical application. 



Mr. MiDDLETON remarked, that the conical spiral-spring buffer bad liecn 

 mentioned in the paper as the most advantageous of the external bufTers in 

 respect of the length of stroke, but that a still greater length of stroke was 

 required ; and he wished to mention one that be had introduced, consisting 

 of a double-coned spiral spring, which bad the advantage of giving n greater 

 length of stroke, and he thought would form a very satisfactory bulftr- They 

 had been applied for the purpose of making a long buffer of 7 feet stroke, 

 by using 6 of these springs, 4 in the middle aud 1 at each end of the 

 buffer rod. 



Mr. Adams observed, that an objection to the double-coned spring would 

 be that it was not free to revolve on its axis like the single-coned spring 

 whilst it was being compressed, because it rested on the large base of the 

 cone at each end, and the friction would be too great to allow of its revolv- 

 ing, but the single-coned spring bad so little friction at the small end tliat it 

 was capable of revolving when compressed. The strain on the steel was 

 mufh increased if a spiral spring was prevented from revolving when com- 

 pressed, and it was consequently more liable to break. 



Mr. Fuller wished to state (for Mr. De Cergue in his absence), with 

 respect to the vulcanised india-rubber in buffer springs, that upwards of 

 100,000 of the rings had been sent out, and many of tliem had been in use 

 for tvpo or three years; and as far as he had ascertained, the cases of failure 

 had been very few indeed. In some cases where the material had been used 

 for bearing springs, it h.ad failed in consequence of not having a sufticicnt 

 aniouut of bearing surface, but in the application to butVer springs he was 

 not aware of any instance of failure excepting in a few cases where the rings 

 had been over vulcanised. 



Mr. Adams n-plied, that he had not had any experience of the durability of 

 the vulcanised india-rubber applied to buffers, and he had therefore only 

 stated the circumstance he was acquainted with of the bands for papers. 



17* 



