GB2245363A

GB2245363A - Hydraulic track profile measuring system for railways

Info

Publication number: GB2245363A
Application number: GB9011882A
Authority: GB
Inventors: William Mcmorran
Original assignee: TDM Tape Services Ltd
Current assignee: TDM Tape Services Ltd
Priority date: 1990-05-26
Filing date: 1990-05-26
Publication date: 1992-01-02
Anticipated expiration: 2010-05-26
Also published as: GB2245363B; GB9011882D0

Abstract

The apparatus comprises a plurality, preferably four, of sensitive pressure transducers 28-34 which are attached to known points on a rail vehicle and connected to a reference point 50 by hydraulic fluid containing pipes 46. The transducers sense the relative pressure changes as the vehicle moves along the rails due to changes in relative height of the part of the vehicle to which each transducer is attached relative to the other transducers and the transducer outputs are determined at regular intervals of distance determined from tacho 62 and recorded. Track profile is calculable from the series of pressure readings. <IMAGE>

Description

HYDRAULIC TRACK PROFILE MEASURING SYSTEM FOR RAILWAYS The present invention relates to hydraulic track profile measuring system for railways and more particularly to an apparatus suitable for attachment to a rail vehicle and adjustable to be adapted to the vehicle.

Most railway track measuring systems are very sophisticated and require a purpose built vehicle. Measurements are taken of the track profile at the exact physical spacing corresponding to the measurement base, ie. if the track twist over 3 meters is required then the measurements are made at a 3 meter spacing.

These purpose built vehicles do not relate directly to the range of rolling stock which all have different wheel bases and axle loads.

The hydraulic profile measuring system of the present invention can almost be treated as a portable measuring kit which can be fitted to any vehicle. Hence the track profiles can be measured 'as seen' by a particular vehicle or axle load condition.

a hydraulic track profile measuring systems for railways including a plurality of sensitive pressure transducers, each sensitive pressure transducer being attached to a known point on a rail vehicle, hydraulic pipe means joining each pressure sensor to a predetermined reference point and means for recording the pressures measured by each sensitive pressure transducer at predetermined intervals as the vehicle moves along the rails.

Preferably four sensitive pressure transducers are provided, each sensitive pressure transducer being mounted in use on respective ends of forward and rear axles of a four wheel bogie of a rail vehicle.

Preferably the predetermined reference point is situated between the forward and rear axles.

Preferably the system comprises an electronic interface unit the electronic interface unit being connected to receive as inputs output signals generated by the sensitive pressure transducer and in which the output of the electronic interface unit is connected to a recording apparatus.

Preferably one or both of the forward or rear axles is provided with movement measurement means to provide a signal representative of the movement of the vehicle, the output of the movement measurement means being connected to the recording apparatus via the electronic interface unit.

Preferably the hydraulic pipe means comprises pipe work means for coupling together all four sensitive pressure transducers to a main system reference and calibration point, the pipe work means being vented to atmosphere at a convenient point.

Preferably the system comprises means for detachably attaching each transducer to a respective axle.

The present invention also provides a method for measuring the track profile of a railway track including the steps of: (a) mounting a plurality of sensitive pressure transducers at predetermined positions on a rail vehicle, each sensitive pressure transducer having an electrical output terminal, (b) connecting together all of the plurality of sensitive pressure transducers by hydraulic pipe means, (c) filling the hydraulic pipe means with a hydraulic fluid, (d) venting the hydraulic pipe means, (e) connecting the electrical output terminals of all sensitive pressure transducers to an electronic interface unit, (f) connecting the interface unit to a memory and recording means, (g) measuring the distance between the rail centres, (h) measuring the distances between each sensitive pressure transducer and all other sensitive pressure transducers, (i) reading individual signals from every one of the plurality of sensitive pressure transducers at predetermined positions relative to the movement of rail vehicle, (j) storing the signals in the memory and recording means.

Preferably four sensitive pressure transducers are provided, each sensitive pressure transducer being mounted on a respective end of a forward and rear axle of a four wheel bogie.

Preferably the predetermined positions are sub-divisions of the distance between the forward and rear axle centres.

Embodiments of the present invention will now be described, by way of example with reference to the accompanying drawing, which shows diagrammatically the hydraulic track profile measuring system according to the present invention.

With reference now to the drawing, a rail vehicle 10 is shown diagrammatically by four wheels 12, 14, 16, 18 the vehicle comprising a body (not shown) mounted on a four wheel two axle bogie. In known manner the vehicle may comprise front and rear bogies or many other arrangements but since the design of the rail vehicle is not part of the inventive concept this will not be described further. The system can be modified and expanded to take measurements at more axles if required.

The rail vehicle 10 runs on rails 20, 22 as indicated by the dotted lines, axle 24 being, for reference purposes the forward or leading axles and axle 26 the rear or trailing axle.

The hydraulic track profile measuring system comprises a number of sensitive pressure transducers 28, 30, 32, 34 mounted at selected measuring points which are usually the axle boxes 36, 38, 40, 42. All the pressure transducers are coupled together by pipework 44, 46, 48 filled with hydraulic fluid.

The pipework is vented at one convenient point 50 to atmosphere.

All the pressure transducers are accurately matched and the electrical outputs from all of them are coupled via an electronic interface unit 52 and signal conditioning unit 54 to a computer 56. A chart recorder 58 and data store 60 are attached to the computer 56. When the vehicle is stationary the differences in pressure at the four measuring points is proportional to the difference in height at these points. The trailing left wheel 16 is treated as the reference point therefore the height of the track under the other three wheels (12, 14, 18) (assuming a four wheel system) relative to the height of the track under the reference wheel 16 is known. As the vehicle moves forward over a distance recorded by a tachometer 62, instantaneous readings at the four wheels are taken every 1/100th of the distance between the axles (wheel base). All these results are stored in memory.Once the vehicle has moved forward exactly one wheel base (100 readings) the height of the track under all the wheels, relative to the reference wheel, can be calculated as before. With the reference wheel 16 now positioned exactly where the leading wheel 12 stood at the start, the height of this point relative to the starting reference point is known therefore the true height of the track under all the wheels can also be calculated.

This process is repeated for every measurement taken and the actual height of the track calculated and stored in store 60.

The true track height is then known at intervals of 1/100th of the wheel base. This finite increment in distance can of course be changed to meet required measurement accuracies. To produce the track profile data over any given length, the data is simply extracted from the memory for the locations of given distance apart and the desired parameters are calculated.

The following data is required by the computer for each installation: 1. The distance between all the pressure transducers 28, 30, 32, 34.

2. The distance between the centre of the rails (running centre) D1.

3. The wheel base.

4. The longitudinal measurement base required.

The system is designed as a low cost, low to medium speed recording system. To increase the accuracy of the basic system several compensation circuits may be included, the most important being compensation for longitudinal and lateral acceleration. As the system is developed it is envisaged that many more compensation circuits or algorithms will be added.

The following track parameters can be measured with this system over various selected base lengths: Variations in top left rail Variations in top right rail True cross level Variation in cross level True twist Variation in twist True cant Variation in cant True gradient Variations in gradient In addition to these, it will also be possible to produce the following measurements by using these algorithms by obtaining the relevant signals from additional measuring transducers.

True gauge Variations in gauge True versine Variations in versine The advantages of the present invention are as follows: 1. There is no movement of the hydraulic fluid. It is a closed system which is fully compensated against changes in temperature and atmospheric pressure.

2. The principle of being able to use any vehicle wheel base to calculate the true track height from which all profiles can be calculated. All track profile data produced is independent of the measurement distance enabling profiles to be produced over an infinite measurement base. By using a more powerful data processing computer it is possible to calculate profiles over several measurements simultaneously.

3. The measurement system can be fitted to almost any standard vehicle.

Claims

1. A hydraulic track profile measuring systems for railways including a plurality of sensitive pressure transducers, each pressure transducer being attached to a known point on a rail vehicle, hydraulic pipe means joining each sensitive pressure sensor to a predetermined reference point and means for recording the pressures measured by each sensitive pressure transducer at predetermined intervals as the vehicle moves along the rails.

2. A hydraulic track profile measuring system as claimed in Claim 1 including four sensitive pressure transducers, each sensitive pressure transducer being mounted in use on respective ends of forward and rear axles of a four wheel bogie of a rail vehicle.

3. A hydraulic track profile measuring systems as claimed in Claim 1 or Claim 2 in which the predetermined reference point is situated between the forward and rear axles.

4. A hydraulic track profile measuring system as claimed in Claim 1, Claim 2, or Claim 3 in which the system comprises an electronic interface unit the electronic interface unit being connected to receive as inputs output signals generated by the sensitive pressure transducer and in which the output of the electronic interface unit is connected to a recording apparatus.

5. A hydraulic track profile measuring system as claimed in any one of Claims 2 and Claims 3 and 4 when dependant on Claim 2 in which one or both of the forward or rear axles is provided with movement measurement means to provide a signal representative of the movement of the vehicle along the rail, the output of the movement measurement means being connected to the recording apparatus via the electronic interface unit.

6. A hydraulic track profile measuring system as claimed in any one of Claims 2 to 5 in which the hydraulic pipe means comprises pipe work means for coupling together all four sensitive pressure transducers to a main system reference and calibration point, the pipe work means being vented to atmosphere at a convenient point.

7. A hydraulic track profile measuring system as claimed in any one of the preceding claims in which the system comprises means for detachably attaching each transducer to a respective axle.

8. A method of measuring the track profile of a railway track including the steps of: (a) mounting a plurality of sensitive pressure transducers at predetermined positions on a rail vehicle, each sensitive pressure transducer having an electrical output terminal, (b) connecting together all of the plurality of sensitive pressure transducers by hydraulic pipe means, (c) filling the hydraulic pipe means with a hydraulic fluid, (d) venting the hydraulic pipe means, (e) connecting the electrical output terminals of all sensitive pressure transducers to an electronic interface unit, (f) connecting the interface unit to a memory and recording means, (g) measuring the distance between the rail centres, (h) measuring the distances between each sensitive pressure transducer and all other sensitive pressure transducers, (i) reading individual signals from every one of the plurality of sensitive pressure transducers at predetermined positions relative to the movement of rail vehicle, (j) storing the signals in the memory and recording means (k) calculating the track profile using a combination of the measurements of the distances between the rail sensors, the distances between the sensitive pressure transducers and the individual signals obtained from the plurality of sensitive pressure transducers.

9. A method of measuring the track profile of a railway track as claimed in Claim 8 in which four sensitive pressure transducers are provided, each sensitive pressure transducer being mounted on a respective end of a forward and rear axle of a four wheel bogie.

10. A method of measuring the track profile of a railway track as claimed in Claim 9 in which predetermined positions are subdivisions of the distance between the forward and rear axle centres.

11. A hydraulic track profile measuring system substantially as described with reference to the accompanying drawing.

12. A method of measuring the track profile of a railway track substantially as described with reference to the accompanying drawing.