US 3796160 A
A method of correcting the level of a sleeper of railway track supported on a ballast bed comprises applying a loading, for example, through the sleeper to the ballast beneath the sleeper towards at least one end of the sleeper of an intensity greater than the intensity of normal traffic loading, the loading being applied a number of times sufficient to deform the ballast vertically in order to support the sleeper end at a desired lower level. The loading may be applied directly to a high sleeper end or a low sleeper end may be raised above its desired level and a packing of ballast placed beneath it prior to the application of the loading.
Claims available in
Description (OCR text may contain errors)
United States Patent [191 Waters et al.
[ Mar. 12, 1974 MAINTENANCE OF RAILWAY TRACK  Inventors: John M. Waters; Michael J.
Shenton, both of Derby; Donald L. Heath, London, all of England  I Assignee: British Railways Board, London,
England  Filed: Nov. 29, 1971  Appl. No.: 202,900
 U.S. Cl 104/7 R, 104/2, 104/12  E0lb 27/16, EOlb 33/00  Field of Search 104/5, 6, 12, 7 R, 7 L
 References Cited UNITED STATES PATENTS 3,638,578 2/1972 Helgemeir lO4/12 3,486,461 l2/l969 Plasser et al.... 104/7 R 3,589,298 6/1971 Plasser et al l04/l2 3,651,762 3/]972 Plasser et al l()4/l2 Primary ExaminerGerald M. Forlenza Assistant Examiner-Richard A. Bertsch Attorney, Agent, or FirmGoerge Vande Sande  ABSTRACT A method of correcting the level of a sleeper of railway track supported on a ballast bed comprises applying a loading, for example, through the sleeper to the ballast beneath the sleeper towards at least one end of the sleeper of an intensity greater than the intensity of normal traffic loading, the loading being applied a number of times sufficient to deform the ballast vertically in order to support the sleeper end at a desired lower level. The loading may be applied directly to a high sleeper end or a low sleeper end may be raised above its desired level and a packing of ballast placed beneath it prior to the application of the loading.
15 Claims, 5 Drawing Figures PATENTEUMAR 12 1914 3396160 SHEET 1,: 0F 3 FIGI.
O N OF LOADINGS,
DEFORMATION C I IQ IQ IO \D G.\
DEFORMATION N OF LOADINGS PATENTEUMAR 1 2 I974 smear 2 er 3* WOI PATENTEDMAR 1 2 I974 SHEET 3 [IF 3 MAINTENANCE F RAILWAY TRACK The invention relates to the maintcnance of railway track of the conventional kind in which the rails are fastened to sleepers supported on a ballast bed. In particular, the invention relates to methods of eliminating errors in sleeper levels.
In an ideal length of track, each sleeper is at a predetermined level in relation to the other sleepers and the two ends of each sleeper are at predetermined related levels so that the plane of the track has a desired configuration in order to permit the smooth and safe running of trains at high speeds. Resulting from the continual passage of trains over the track, the relative levels of the sleepers depart from the predetermined values.
' A conventional method of correcting errors in sleeper levels has been to tamp ballast beneath the ends of low sleepers in order to raise them to the correct level. This method is not entirely satisfactory because it has been found that the sleepers or sleeper ends so raised lose their correct level agains relatively quickly, because the loading imparted to them by the passage of trains (hereinafter referred to as traffic loading) causes deformation of the newly tamped ballast.
In research into the behaviour of ballast beds, we have discovered that the vertical deformation of a ballast bed at any given point under a repeated loading of a given intensity follows a predictable curve.
In FIG. 1 of the accompanying drawings, three curves A, B and C are shown of vertical deformation ofa ballast bed at a given point plotted against the number of loadings applied, the curve A being for one loading intensity and the curves B and C being for higher loading intensities. In FIG. 2 are shown the corresponding curves A, B and C with the number of loadings plotted on a logarithmic base (i.e. log From FIG. 2 the predictability of the deformation of the ballast bed can be readily appreciated in that the curves are substantially linear, and consequently as one moves to the right along the curves the rate of deformation becomes very small.
The object of this invention is to make use of this discovery to correct errors in sleeper levels in a manner which will prevent rapid loss of corrected levels upon renewed traffic loading.
According to this invention, a method of correcting the level of a sleeper of a railway track supported on a ballast bed comprises applying loading to the ballast beneath a sleeper towards at least one sleeper end of an intensity greater than the intensity of normal traffic loading, the loading being applied a number of times sufficient to deform the ballast vertically in order to support the sleeper end at a desired lower level.
In carrying the invention into effect, the loading may be applied directly to an incorrectly high sleeper end, or to an incorrectly low sleeper end which is first purposely raised above the desired level and has ballast packed beneath it and is then loaded.
The invention will now be described in more detail by way of examples and with reference to the accompanying drawings in which,
FIG. 1 shows as previously mentioned curves of ballast bed deformation plotted against the number of applied loadings for three loading intensities,
FIG. 2 shows curves corresponding to FIG. 1 but with the number of applied loadings plotted on a logarithmic base,
FIG. 3 is an explanatory diagram of one method of correcting sleeper levels,
FIG. 4 is a side view of one construction of machine for performing the invention, and
FIG. 5-shows a detail of the machine shown in FIG. 4.
Referring to FIGS. 1 and 2, it will be assumed for simplicity that curve A corresponds to the deformation of the ballast bed beneath any sleeper end caused by the normal traffic loading being applied each time a wheel axle of a train passes over the sleeper; the average in tensity of such loading with present-day trains is of the order of 15 to 20 tons. It will be appreciated that for different sleeper ends a slightly different curve corresponding to curve A will be applicable. The curves B and C therefore correspond to the deformation of the ballast bed caused by higher loading intensities applied in a manner to be described; the maximum loading intensity being for example of the order of 40-50 tons. It must be accepted that deformation of a ballast bed under repeated traffic loadings will be a continual process following the curve A but the rate of deformation will decrease to a value which is acceptable-to railway engineers; for example 1mm for the passage of 100,000 axles, since at this rate of deformation the differential deformation rate between sleepers or sleeper ends is acceptable. For convenience in explaining the invention, it will be assumed that the part of curve A to the right of line D in FIGS. -1 and 2 shows an acceptabl rate of deformation.
Basically the method of the invention consists in applying repeated loadings of a predetermined intensity to the ballast beneath both ends of a sleeper which is incorrectly high in relation to other sleepers or to the ballast below one end of a sleeper which is incorrectly high in relation to its other end in order to deform the ballast vertically and thus lower the high sleeper or high sleeper end. As will be described, the loading of the sleeper may be performed directly on a high sleeper or a high sleeper end, or on a sleeper or sleeper end which was previously incorrectly low and which has been over-lifted by packing ballast beneath it.
Referring now to FIGS. 4 and 5, these illustrate a machine for performing the loading operation. The machine comprises a pair of vehicles 1 and 2 running on the track the rails of which are shown at 3 and the sleepers at 4. The vehicle 1 comprises a generator van for providing the necessary electrical power. The vehicle 2 is basically flat and has a very rigid body structure 11 and carries on each side a hydraulic ram 5, only one of which is visible. At their lower end the rams 5 have U shaped loading heads 6 (see FIG 5) which straddle the rail 3 of the track and engage the sleeper ends. The rams 5 are independently controllable so that they can simultaneously apply different loadings to the opposite ends of a sleeper. To prevent the vehicle 2 from lifting off the track when the rams 5 are operating, reaction weights 7 are provided on the vehicle. Also, to prevent vertical movement of the vehicle body 11 relative to bogies 8 the springs 9 of the bogies 8 are rendered inoperative. The operating gear 10 for the hydraulic rams 5 is contained in a cabin 12 which also houses the operators control panel 13. Hydraulic power unit 14 for supplying the necessary hydraulic power for operating the rams 5 is housed in cabin 15. The frequency and magnitude of the loading by the rams 5 will be controlled using known hydraulic control techniques.
The vehicles I and 2 are interconnected by a ram 16 which enables the vehicle 2 to be moved so that the rams 5 are moved from one sleeper to the next whilst the vehicle 1 is held stationary.
In an alternative arrangement of the machine, loading heads of the rams 5 may be designed to engage the rail heads 17 immediately above a sleeper. This can be achieved simply by shortening the arms of the U shaped loading-heads 6. In a further alternative arrangement, eccentric rotating masses could be used to apply the loading instead of hydraulic rams.
Various level errors in sleepers and their method of correcting them will now be considered.
First let it be assumed that from a track surveying operation the relative levels of the two ends ofa certain sleeper are incorrect and that to correct this it is necessary to lower the high end of the sleeper. Since the sleeper in question has already been subjected to traffic loading, it can almost certainly be assumed that the rate of deformation of the sleeper under normal train load ing is already to the right ofline D in FIGS. 1 and 2 and is therefore acceptable.
To prevent lifting of the low end of the sleeper while loading is applied to the high end, a continuous downward force is applied to the low end by the appropriate ram, whilst repeated loadings are applied to the high end by the other ram. Let it be assumed that these repeated loadings are of an intensity in accordance with curve C of FIG. 2 and that the deformation necessary to lower the high sleeper end is between points G and H. This means that the deformation follows curve C in FIG. 2 between points J and K by which time the originally high sleeper end is at its correct level. When the normal traffic loading is renewed, the rate of deformation for the lowered end of the sleeper will be along the curve A starting at point L that of the sleeper end which has remained at its original level is along curve A from point M. Since both the points L and M are at acceptable deformation rates the relative deformation of the two sleeper ends will be acceptable.
'Now let it be assumed that a high sleeper is to be lowcred. Basically, the same operation is carried out but on both sleeper ends by the two rams. This can be performed by operating the rams in phase to apply loadings to both ends of the sleeper simultaneously. Alternatively, the loading can be applied to one sleeper end to lower that end and then to the other in the manner described above. If, while lowering the whole sleeper, it is desired to lower one sleeper end more than the other, then the intensity of the loadings applied by the two rams will be different. For example, the loadings could be such that the deformation of theballast at one end of the sleeper follows curve C while the deformation at the other end of the sleeper follows curve B.
Instead of applying the repeated loadings to the high sleepers or high sleeper ends, it might be more convenient to first over-lift the low sleepers or low sleeper ends and tamp or pack ballast beneath them and then apply the loadings by the hydraulic rams in the manner described above to over-lifted sleepers or sleeper ends. Lifting and tamping or packing operations are well known in the railway art. Suitable lifting and tamping or packing gear could be provided on the vehicle 2.
Since it is necessary to ensure that, when a sleeper end is at its correct level, the rate of deformation of the ballast beneath the sleeper end is acceptable, the overlift has to be at least a certain minimum.
In FIG. 3 we have shown-line R which indicates the desired levelfor a number of the sleepers 4. Their initial incorrect low position is shown at 4 and their overlifted position is shown at 4".
Consider now the loading operation performed on one end of the over-lifted sleepers 4". Because new ballast has been tamped beneath the sleeper end, the rate of deformation will not be acceptable. Assume that the loading intensity is such that curve C is followed, then ideally the overlift should be at least equal to PG so that the deformation follows curve C down to point J. Upon renewed traffic loading, the rate of deformation is then that at the point M just to the right of the line D on the curve A.
Under certain combinations of loading intensity and frequency, it may be possible to induce fluidisation in part of the ballast under the sleepers and/or between the sleepers such that the required deformation of the ballast structure might more easily be achieved. Alternatively, fluidisation might be induced by the introduction of vibrating tines into the ballast, for example, tines similar to those used in conventional tamping machines.
I. A method of correcting the level of the sleepers of a railway track supported on a ballast bed comprising,
repetitively applying to the ballast beneath any one sleeper towards at least one end thereof a vertical load which is greater than the magnitude of normal traffic loading,
repeating said high magnitude loading a sufficient number of times to (a) deform the ballast vertically to support the sleeper end at perdetermined level, and (b) to ensure that further loadings caused by normal traffic will result infurther vertical deformation of the ballast to an extent not exceeding a predetermined value, and
repeating said loading step on each sleeper which is to be lowered.
2. A method as claimed in claim 1 wherein the loading is applied to the sleeper.
3. A method as claimed in claim 1, wherein the loading is applied to the rail head at a position above the sleeper.
4 A method as claimed in claim 1, wherein loading is applied towards both ends of the sleeper to cause the whole sleeper to be supported at a desired lower level.
5. A method as claimed in claim 4, wherein the loading is applied simultaneously to the ballast towards both sleeper ends.
6. A method as claimed in claim 4, wherein the loading applied towards one end of the sleeper is different from the loading applied towards the other end in order to cause different vertical deformations of the ballast towards the two sleeper ends.
7. A method as claimed in claim 4 wherein a different number of loadings are applied towards the two sleeper ends to cause different vertical deformations of the ballast towards the two sleeper ends.
8. A method as claimed in claim 1, wherein prior to the application of the loading a sleeper end is raised above its desired level and a packing of ballast placed beneath it.
9. A method of raising the level of a sleeper to a desired level comprising lifting at least one sleeper end to a height above the desired level and packing ballast beneath it, and then applying loadings by a method comprising applying a loading to the ballast beneath the sleeper towards at least one end of the sleeper of an intensity greater than the intensity of normal traffic loading, the loading being applied a number of times sufficient to deform the ballast vertically to cause the sleeper end to be lowered to the desired level, the amount by which the sleeper end is lifted above the desired level prior to the application of the loading being such that the rate of vertical deformation of the ballast bed beneath the sleeper towards said end under renewed traffic loading is acceptably low.
10. A method as claimed in claim 9, wherein the loading is applied to the sleeper.
11. A method claimed in claim 9, wherein the loading is applied to the rail head at a position above the sleeper.
12. A method as claimed is applied towards both ends of the sleeper to cause the whole sleeper to be supported at a desired lower level.
the ballast towards the two sleeper ends.
=l l l in claim 9, wherein loading P0-1050 -:UNITED STATES PATENT OFFICE CERTIFICATE OF CORRECTION Patent No. 3, 796, 160 Dated March 12, 1974 JOHNM. WATERS,- MICHAEL J. SHENTON and DONALD L. HEATH It is certified that error appears in the above-identified patent and that said Letters Patent are hereby corrected as shown below:
Foreign Application Priority Data December 1,1970 Great Britain. M.-. 57038/70 Signed and sealed this 29th day of October 1974.
McCOY M. GIBSON JR. C. MARSHALL DANN Attesting Officer Commissioner of Patents