Railways – Track layers – Track raising car
Patent
1994-11-15
1997-02-04
Le, Mark T.
Railways
Track layers
Track raising car
104 2, E01B 3300
Patent
active
055987826
DESCRIPTION:
BRIEF SUMMARY
This invention relates to methods of railway track maintenance utilizing a track maintenance machine which runs on the track. The invention is applicable to both the correction of horizontal track geometry (i.e. alignment) and vertical track geometry (i.e. level). Track lining systems are described for example in GB-A-21112050 and FR-A-2300171.
The present invention is based upon the known two-pass track maintenance method in which a survey of a stretch of track to be maintained is first made and from the data obtained an improved horizontal or vertical track geometry (i.e a design profile) is determined and the necessary adjustments to be made to the track to achieve the design profile calculated. The predetermined adjustments are then made by the track maintenance machine as it runs along the track.
One such commonly used method for track alignment involves the use of a lining machine fitted with a measuring system for measuring the local curvature of the track. The survey comprises a preliminary measuring run by the machine during which the pattern of curvature is recorded throughout the stretch of track to be maintained An improved pattern of track curvature, i.e. the design profile, is determined either by graphical or computational means. This then provides the basis for determining the correction values necessary to achieve she design profile. These correction values are then used to control the sluing of the track as the machine passes along the stretch of track during a subsequent maintenance run. Such a method is described in GB 2036379B.
The accuracy of track lining by this method is significantly compromised however by errors in the sluing of the track. These errors arise from a number of sources, such as the natural lateral stiffness of the track structure which causes track "springback" immediately after lining, and tolerances n the lining control system. On most machines the track is tamped after lining has taken place and this often causes the track to slide sideways, especially where heavily canted.
In the case of track level adjustment by tamping a similar method to that described above may be applied to the correction of vertical track misalignments. Again the survey comprises a preliminary measuring run by a track level correcting machine during which track level measurements are recorded throughout the stretch of track to be maintained in order to determine the existing track profile from which an improved vertical track profile, i.e. the design profile,can be determined. This then provides the basis for determining the correction values necessary to achieve the design profile. These correction values are then used to control the lifting of the track as the machine passes along the stretch of track during a subsequent maintenance run. The accuracy of track lifting can be somewhat unpredictable for various reasons and errors can be introduced into the vertical track geometry.
It is the object of this invention to provide an improved method of railway track maintenance by countering the aforesaid problems in achieving the design profile.
According to the present invention a method of adjusting the geometry of a stretch of railway track using a track maintenance machine which runs on the track and which has a) track correcting tools, b) at least one measuring reference system guided by feelers on the track and comprising at least one straight reference line extending from a front position located forwardly of the track maintenance machine on uncorrected track to a rear position located rearwardly of the machine on corrected track and c) a sensor arrangement comprising a first sensor means located in the vicinity of the track correcting tools and a second sensor means located rearwardly of the rearmost load bearing wheels of the track maintenance machine for measuring the respective offsets of the track from said line at these locations, the method comprising performing a preliminary measuring run to acquire a series of track measurements at spaced points along the track by said first sens
REFERENCES:
patent: 3486461 (1969-12-01), Plasser et al.
patent: 3552319 (1971-01-01), Flasser
patent: 4031625 (1977-06-01), Theurer
patent: 4176456 (1979-12-01), Beckmann
patent: 4497255 (1985-02-01), Theurer
patent: 5012413 (1991-04-01), Sroka et al.
Marriott David C.
Wiseman Paul W.
British Railways Board
Le Mark T.
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