Railways – Track layers
Reexamination Certificate
1999-10-26
2001-11-06
Le, Mark T. (Department: 3617)
Railways
Track layers
C033S287000
Reexamination Certificate
active
06311624
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention The present invention relates to a method of tamping a track with a track tamper running along the track on two undercarriages in an operating direction, which comprises the steps of generating an optical reference line determined by two reference points, each reference point being formed by a sensing element running along the track on a flanged roller, a first one of the sensing elements being positioned ahead of the track tamper in the operating direction and a second one of the sensing elements being positioned between the undercarriages, and measuring the position of the track in relation to the optical reference line. It also relates to a track tamper useful for carrying out this method.
2. Description of the Prior Art
U.S. Pat. No. 3,545,384 discloses a track tamper comprising a machine frame running on two undercarriages along the track in an operating direction. A tamping unit for tamping the track and a track position correcting unit are mounted on the machine frame. To correct the track position, a track position measuring system with a light beam reference line is used. The reference line is defined by a first reference point preceding the track tamper in the operating direction and a second reference point positioned at the track position correcting unit. The reference line is brought into a position extending parallel to the desired track position. A receiver having two light-sensitive cells forms the second reference point, the light-sensitive cells being spaced from each other in a vertical direction by a predetermined distance. Thus, the reference beam causes two different pulses which are used to control the tamping unit and the track position correcting unit.
It is known from Austrian patent No. 314,580 to control track lining tools by a laser beam emitter. In this machine, a laser beam is directed onto a fixed reference point laterally adjacent the track. This enables the track to be lined by moving it laterally until the reference beam registers with a mark on the fixed reference point.
According to European patent No. 401,260, a reference line ahead of a measuring bogie is defined by a reference point determined by known coordinates and a reference point positioned in the center of a receiver formed by a multiplicity of photo cells. In connection with a distance measuring instrument, the deviation of the second reference point from a desired position can be determined.
Finally, Austrian patent No. 328,490 discloses yet another type of track position correcting machine with a reference system preceding and comprising a reference line determined by two reference points.
SUMMARY THE INVENTION
It is the primary object of this invention to optimize a method and machine of the first-described type so that short track sections in particular may be readily brought into a desired position.
The above and other objects are accomplished according to the invention with a method of tamping a track with a track tamper running along the track on two undercarriages in an operating direction, which comprises generating an optical reference line determined by two reference points, each reference point being formed by a sensing element running along the track on a flanged roller, a first one of the sensing elements being positioned ahead of the track tamper in the operating direction and a second one of the sensing elements being positioned between the undercarriages. The position of the track in relation to the optical reference line is measured by recording displacements between the two reference points relative to each other during a first advance of the track tamper along the track to form a first curve indicating an existing track position, computing a second curve indicating a desired track position on the basis of correction values derived from the first curve, and repositioning the track to the desired track position, during a second advance of the track tamper along the track in response to the correction values, and tamping the track.
This method is carried out in accordance with another aspect of the present invention with a track tamper comprising a machine frame running on two undercarriages along the track in an operating direction, a tamping unit mounted on the machine frame, a track position correcting unit mounted on the machine frame, a track position sensing element mounted on the machine frame and running on a flanged roller along the track, a generator of an optical reference line arranged ahead of the machine frame in the operating direction, and a digital camera fixedly connected to the track position sensing element and arranged to receive the optical reference line.
In this manner, the existing track position may be rapidly determined and the track repositioning may be done accurately with a minimum of retrofitting. The track displacements may be advantageously determined with great accuracy while the tamper advances by recording the relative displacement between the two reference points so that the track position after correction corresponds precisely to the computed desired values. It is a particular advantage of this direct control of the second reference point and the track position correcting unit that the track position correction in the track section to be corrected may be carried out without a time-consuming formation of a ramp leading to the adjacent track section which remains unchanged.
REFERENCES:
patent: 3750299 (1973-08-01), Plasser et al.
patent: 4658730 (1987-04-01), Bechmann et al.
patent: 5012413 (1991-04-01), Sroka et al.
patent: 5090329 (1992-02-01), Theurer
patent: 5613442 (1997-03-01), Ahola et al.
Lichtberger Bernhard
Theurer Josef
Collard & Roe P.C.
Franz Plasser Bahn-baumaschinen-Industriegesellschaft m.b.H.
Le Mark T.
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