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Description of an improved railway switch
On an Improved Railway Switch.
289
consist in the adjustment given to the wheels, but in the perfect fit at all times maintained between the sliding surfaces ; the elasticity of the india rubber also f~)rms an elastic cushion to receive the shocks of the machinery. A small strip of leather prevents the oil from gaining admission to the india rubber. The perfect freedom of motion, the small wear of the axle-box, in consequence of the case-hardening of the slides, the ease with which the engine passes curves, and the diminished wear of the wheel-flanches, are important advantages, which have been derived, in practice, from this construction of axle-box. A similar application of an india rubber spring to the outside coupling-rods of an engine had also been made. In this construction of rods, the use of cotters for tightening the brasses was dispensed with, by employing a set-screw at the end of the rod, secured by a lock nut, from risk of working loose. Mr. W. FAIRBAIR~¢ showed a specimen of the india-rubber lining from an axle-box that had run 17,000 miles in a locomotive engine ; also, a model of the axle-box fitted up with india rubber, and a specimen of one of the connecting-rod ends. He stated that it was requisite to take great care to keep oil away from the india-rubber ; as in one trial, the india rubber had lasted only a month, from neglect of this precaution ; but when properly protected from oil, its durability was found to be very great. A cap was now fixed over the india rubber, as a more complete protection for this purpose. These axle-boxes and connecting-rods were working in several locomotives on the Chester and Birkinhead Railway, and they were found to be now as good and perfect as when first put in, though some had run as much as 17,000 miles ; they were considered quite satisfactory, and the result of the axle-boxes was an improvement in reducing the wear of the wheel fianches. The connecting rods were screwed up at the ends, instead of being cottered as in the usual manner; and this mode of construction he considered an improvement as regarded convenience and security from accident.
Description of an ImTroved Railway Switch.* By Mr. J o l ~ A. HASW~LL. [Read before the Institution of Mechanical Engineers.]
In the various kinds of switches now used on railways, the moving tongue slides upon the chairs, rubbing upon them throughout the extent of its motion ; and the switches are made self-acting by a balance weight, hanging from the lever, and constantly pressing the tongue home to the side of the main rail. But in practice this plan is found defective ; for although a weight is employed as heavy as can be conveniently Worked, its action is uncertain,--being frequently impeded by the friction of the sliding tongue, from the chairs having become dry, or the oil becoming adhesive or mixed with sand and ashes. The tongue-rails are then liable to remain on the wrong side, or only partially reversed,--thus presenting both tongues open, and causing dang~r of accident, from wheels running off the rails, by the flanehes * From Newton's London Journal of AI~S~February, 1859.
240
Civil Engineering.
entering between the tongues and main rails at both sides. TO lessen this defect, a raised strip has been used upon the rubbing part of the chairs, which reduces the surface for holding sand ; but this plan involves the objection of the oil being sooner rubbed off by the motion of the tongue, from the increased pressure between the rubbing surfaces. The large consumption of oil that takes place with the ordinary switches, forms a serious item of expense,--most of the oil that is applied being unavoidably wasted. The new construction of switches described in the following paper, which is the invention of Mr. Edwin Thompson and Mr. William Nieholson, of York, is designed to remove this difficulty, by avoiding the sliding of the tongue-rails upon the chairs, and so dispensing entirely with the use of lubrication. The tongues are of the ordinary form ; but a short iron strut or link is jointed to the thin end of each tongue-rail and to the end chair, so that, when the tongue-rail is opening, this strut causes the end of the tongue to rise off the chairs, and the other tong.ue at the same time descends upon the chairs,--the short strut acting as a radius link. The elevation of the tongue-rail, when open, is two inches above the level of the main rails, which is found to insure the tongue-rail being properly put down upon the chairs, and closed to the main rail, and being also entirely clear from any low portions of the engines, &c. In this construction of switches, on account of the sliding motion and friction of the tongue-rails being entirely avoided, oil is not required, and no danger can arise from sand or ashes lodging on the chairs ; also, the remow~l of any larger fl'agments of coke or ballast is, to a certain extent, provided for by the altered form of the chairs, which this manner of opening the tongue-rails admits of. As the tongue-rails require no larger surface to rest upon than is actually in contact with the chairs, when they are closed to the main rail, advantage is taken of this by increasing the thickness of the chairs at the particular part upon which the rails rest, forming a raised step, which is completely covered wllen the tongue-rail is closed; and on the open side, the width of the tongue-rail only is exposed to the reception of rubbish,--the larger pieces thus falling off, and the smaller ones being crushed or removed by the descent of the tongue. The accomplishment of this object has been satisfactorily shown by the working of one of these switches, which has been put down in a situation where sand was constantly used for the engine-wheels, and has continued to work well, although sometimes nearly buried by the accumulation of sand. In these switches, the ends of the tongue-rails are extended a foot beyond the sharp edge that fits against the top of the main rail ; and the extended ends are curved inwards, like a check-rail end, and reduced in height 1~ inch, to allow the wheel-fianches to pass over the top, when the tongue rall is closed to the main rail; and in any case of the tongue not being properly closed, the pressure of the wheel-flaneh will tend to crush an~r obstructing substance upon the chairs. This action is aided by the check-rail end of the tongue on the opposite side, which in such a case will not be opened to the full extent, but
On Bridge Gonstruction.
241
sufficiently so to guide the wheel-flanches in the proper course~ and, by drawing them from the other imperfectly-closed side, prevent the wheels from taking both lines. Some of these switches are now in constant use at the York and Newcastle stations, where they can be seen in operation. Sir. J. A. Haswell exhibited a large working model of the new switch. Mr. J. Bourne had had one of the switches in operation at the Newcastle station for a month, and some others had been tried for about six months at the York station. These had been working very satisfactorily, and were found to have a decided advantage over the other switches in use. The others required constant oiling and attention to keep them in working order; and the oil, collecting the dust and grit, caused frequent cleaning to be necessary, to prevent risk of accident, from the switch sticking partly open. In winter, great difficulty was experienced with ordinary switches from the snow, which partially melted in the day-time, and then froze again in the evening,-causing the switch-tongue to be choked up by ice, and prevented from shutting close ; and the men had to be continually using salt, to thaw the ice and keep the switches working. But these new switches were completely free from those defects, and appeared very successful in meeting the requirements of self-acting switches. No oil was used, and this effeeted an important saving in annual expense; andfrom the switch-tongues not having any sliding motion on the chairs, no inconvenience was experienced from sand and dust; and the risk of their sticking partly open was effectually prevented, as they must fall on one side or the other. For the Journal of the Franklin Institute.
_P~Ters on Bridge C~onstruetion. By JOHN W. I~IURPHY,Civ. Eng. Philadelphia, Pennsylvania. (Continued from page 147..)
THE ARCH.--In the construction of arch bridges, some definiteline is assumed for the intrude--and some other definite line also assumed for the extrude. These lines are dependant upon either the taste of the engineer, or upon some necessity. In some cases it may be imperative that the extrude shall be a horizontal line, while the intrude may be any curve, according to taste. Sometimes imperative that the intrude shall be of that character such as will give the greatest possible area of waterway, at others, so that the greatest architectural effect may be produced upon the eye. In all cases where these lines are fixed agreeably to the judgment, foresight, and discretion of the engineer, the weight of the superstructure may be approximately determined. It then only remains to give such dimensions to the ring-stones or ribs, to cut their joints in such direction as shall best satisfy the conditions of the line of resultant Tres~ures. VoL. X,~XVI[.--T~mD SERIES.~NO. 4.--APRIL, 1859.
21
289
consist in the adjustment given to the wheels, but in the perfect fit at all times maintained between the sliding surfaces ; the elasticity of the india rubber also f~)rms an elastic cushion to receive the shocks of the machinery. A small strip of leather prevents the oil from gaining admission to the india rubber. The perfect freedom of motion, the small wear of the axle-box, in consequence of the case-hardening of the slides, the ease with which the engine passes curves, and the diminished wear of the wheel-flanches, are important advantages, which have been derived, in practice, from this construction of axle-box. A similar application of an india rubber spring to the outside coupling-rods of an engine had also been made. In this construction of rods, the use of cotters for tightening the brasses was dispensed with, by employing a set-screw at the end of the rod, secured by a lock nut, from risk of working loose. Mr. W. FAIRBAIR~¢ showed a specimen of the india-rubber lining from an axle-box that had run 17,000 miles in a locomotive engine ; also, a model of the axle-box fitted up with india rubber, and a specimen of one of the connecting-rod ends. He stated that it was requisite to take great care to keep oil away from the india-rubber ; as in one trial, the india rubber had lasted only a month, from neglect of this precaution ; but when properly protected from oil, its durability was found to be very great. A cap was now fixed over the india rubber, as a more complete protection for this purpose. These axle-boxes and connecting-rods were working in several locomotives on the Chester and Birkinhead Railway, and they were found to be now as good and perfect as when first put in, though some had run as much as 17,000 miles ; they were considered quite satisfactory, and the result of the axle-boxes was an improvement in reducing the wear of the wheel fianches. The connecting rods were screwed up at the ends, instead of being cottered as in the usual manner; and this mode of construction he considered an improvement as regarded convenience and security from accident.
Description of an ImTroved Railway Switch.* By Mr. J o l ~ A. HASW~LL. [Read before the Institution of Mechanical Engineers.]
In the various kinds of switches now used on railways, the moving tongue slides upon the chairs, rubbing upon them throughout the extent of its motion ; and the switches are made self-acting by a balance weight, hanging from the lever, and constantly pressing the tongue home to the side of the main rail. But in practice this plan is found defective ; for although a weight is employed as heavy as can be conveniently Worked, its action is uncertain,--being frequently impeded by the friction of the sliding tongue, from the chairs having become dry, or the oil becoming adhesive or mixed with sand and ashes. The tongue-rails are then liable to remain on the wrong side, or only partially reversed,--thus presenting both tongues open, and causing dang~r of accident, from wheels running off the rails, by the flanehes * From Newton's London Journal of AI~S~February, 1859.
240
Civil Engineering.
entering between the tongues and main rails at both sides. TO lessen this defect, a raised strip has been used upon the rubbing part of the chairs, which reduces the surface for holding sand ; but this plan involves the objection of the oil being sooner rubbed off by the motion of the tongue, from the increased pressure between the rubbing surfaces. The large consumption of oil that takes place with the ordinary switches, forms a serious item of expense,--most of the oil that is applied being unavoidably wasted. The new construction of switches described in the following paper, which is the invention of Mr. Edwin Thompson and Mr. William Nieholson, of York, is designed to remove this difficulty, by avoiding the sliding of the tongue-rails upon the chairs, and so dispensing entirely with the use of lubrication. The tongues are of the ordinary form ; but a short iron strut or link is jointed to the thin end of each tongue-rail and to the end chair, so that, when the tongue-rail is opening, this strut causes the end of the tongue to rise off the chairs, and the other tong.ue at the same time descends upon the chairs,--the short strut acting as a radius link. The elevation of the tongue-rail, when open, is two inches above the level of the main rails, which is found to insure the tongue-rail being properly put down upon the chairs, and closed to the main rail, and being also entirely clear from any low portions of the engines, &c. In this construction of switches, on account of the sliding motion and friction of the tongue-rails being entirely avoided, oil is not required, and no danger can arise from sand or ashes lodging on the chairs ; also, the remow~l of any larger fl'agments of coke or ballast is, to a certain extent, provided for by the altered form of the chairs, which this manner of opening the tongue-rails admits of. As the tongue-rails require no larger surface to rest upon than is actually in contact with the chairs, when they are closed to the main rail, advantage is taken of this by increasing the thickness of the chairs at the particular part upon which the rails rest, forming a raised step, which is completely covered wllen the tongue-rail is closed; and on the open side, the width of the tongue-rail only is exposed to the reception of rubbish,--the larger pieces thus falling off, and the smaller ones being crushed or removed by the descent of the tongue. The accomplishment of this object has been satisfactorily shown by the working of one of these switches, which has been put down in a situation where sand was constantly used for the engine-wheels, and has continued to work well, although sometimes nearly buried by the accumulation of sand. In these switches, the ends of the tongue-rails are extended a foot beyond the sharp edge that fits against the top of the main rail ; and the extended ends are curved inwards, like a check-rail end, and reduced in height 1~ inch, to allow the wheel-fianches to pass over the top, when the tongue rall is closed to the main rail; and in any case of the tongue not being properly closed, the pressure of the wheel-flaneh will tend to crush an~r obstructing substance upon the chairs. This action is aided by the check-rail end of the tongue on the opposite side, which in such a case will not be opened to the full extent, but
On Bridge Gonstruction.
241
sufficiently so to guide the wheel-flanches in the proper course~ and, by drawing them from the other imperfectly-closed side, prevent the wheels from taking both lines. Some of these switches are now in constant use at the York and Newcastle stations, where they can be seen in operation. Sir. J. A. Haswell exhibited a large working model of the new switch. Mr. J. Bourne had had one of the switches in operation at the Newcastle station for a month, and some others had been tried for about six months at the York station. These had been working very satisfactorily, and were found to have a decided advantage over the other switches in use. The others required constant oiling and attention to keep them in working order; and the oil, collecting the dust and grit, caused frequent cleaning to be necessary, to prevent risk of accident, from the switch sticking partly open. In winter, great difficulty was experienced with ordinary switches from the snow, which partially melted in the day-time, and then froze again in the evening,-causing the switch-tongue to be choked up by ice, and prevented from shutting close ; and the men had to be continually using salt, to thaw the ice and keep the switches working. But these new switches were completely free from those defects, and appeared very successful in meeting the requirements of self-acting switches. No oil was used, and this effeeted an important saving in annual expense; andfrom the switch-tongues not having any sliding motion on the chairs, no inconvenience was experienced from sand and dust; and the risk of their sticking partly open was effectually prevented, as they must fall on one side or the other. For the Journal of the Franklin Institute.
_P~Ters on Bridge C~onstruetion. By JOHN W. I~IURPHY,Civ. Eng. Philadelphia, Pennsylvania. (Continued from page 147..)
THE ARCH.--In the construction of arch bridges, some definiteline is assumed for the intrude--and some other definite line also assumed for the extrude. These lines are dependant upon either the taste of the engineer, or upon some necessity. In some cases it may be imperative that the extrude shall be a horizontal line, while the intrude may be any curve, according to taste. Sometimes imperative that the intrude shall be of that character such as will give the greatest possible area of waterway, at others, so that the greatest architectural effect may be produced upon the eye. In all cases where these lines are fixed agreeably to the judgment, foresight, and discretion of the engineer, the weight of the superstructure may be approximately determined. It then only remains to give such dimensions to the ring-stones or ribs, to cut their joints in such direction as shall best satisfy the conditions of the line of resultant Tres~ures. VoL. X,~XVI[.--T~mD SERIES.~NO. 4.--APRIL, 1859.
21