WO2004027355A1

WO2004027355A1 - Rail load measuring apparatus

Info

Publication number: WO2004027355A1
Application number: PCT/GB2003/004140
Authority: WO
Inventors: Duncan Alexander Maclennan; Bryan Arthur Phillips
Original assignee: Avery Berkel Limited
Priority date: 2002-09-20
Filing date: 2003-09-19
Publication date: 2004-04-01
Also published as: GB0221865D0; AU2003271856A1

Abstract

A load measuring apparatus for measuring the load on a rail when a railway vehicle passes over the rail is disclosed which comprises a transducer (11) mounted on a rail (12) to measure the sheer stresses induced in that rail by the railway vehicle passing along the rail (12) over the transducers (11). A apparatus comprises a body (17) having bores (18) therein which fasteners can pass to secure the transducers (11) to a rail web.

Description

RAH, LOAD MEASURING APPARATUS

This invention relates to rail load measuring apparatus for measuring the

load on a rail from a railway vehicle wheel and hence the weight of the railway

vehicle..

Traditionally, the load on a rail caused by a railway vehicle has been

measured using a dynamic rail weighbridge which consists of a steel frame

mounted on four load cells which were provided in a civil foundation. The

steel frame carried rails over which the railway vehicle passed and the load

from the wheels of the railway vehicle were transferred from these rails through

the framework and into the load cells which were connected via an electrical

output to a load display.

The present Applicants developed an improved apparatus for measuring

load and this system has become known as the "weighline" system. In this

apparatus, the shear stresses in the rail caused by the wheels of the rail was

vehicle are measured by strain gauges which are attached to the rail. This

system is described in more detail in European Patent No. 0324218.

The "weighline" system has a number of advantages over the existing

arrangements for measuring load in that expensive civil foundations are not

required for the system to operate correctly. Furthermore, the strain gauges of

the "weighline" system can be mounted on the rail without necessarily having

to remove the rail from the track and thereby taking that track out of service. Still further, the use of strain gauges to measure stresses in this way can allow

measuring of the load of railway vehicles which are travelling along the rail at

up to normal line speed. This is much greater than existing dynamic rail

weighbridges which can typically only measure the load of railway vehicles

travelling at up to 20 km/h. Furthermore the use of strain gauges in the

"weighline" system enables the system to withstand the dynamic impacts of

railway vehicles passing over them at such speeds whereas the traditional prior

art arrangements would not.

However, the present Applicants have realised that a problem exists in

the use of the "weighline" system insofar as, in order to ensure accuracy,

precision and durability of the apparatus, the system must be installed on to a

rail under controlled conditions. This means that the rails which are required to

be transformed into load measuring apparatus must be taken from the track,

wherever in the world that track is situated, and delivered to the premises of the

Applicant.

It is an object of present invention to provide a load measuring apparatus

in which the system can be retrofit to a rail without the need for a rail to be

taken from the track.

Thus and in accordance with the present invention there is provided a

load measuring apparatus comprising at least one transducer having at least one

foot provided on one surface thereof, said transducer being adapted to be secured to a rail such that said foot is in contact with the rail, the transducer

including a load transfer plate upon which a strain gauge is secured, said strain

gauge measuring the shear stresses induced in said rail when a railway vehicle

wheel passes over a rail to which the transducer is connected, said shear

stresses being transmitted to said strain gauge via said foot and said load

transfer plate.

With this arrangement, a load measuring apparatus can be connected

directly to a rail on site without the need to secure the rail from the track.

The strain gauge is connected to suitable processing circuitry in order to

process the signals generated in the strain gauge and convert these to a signal

which is capable of display on a load display apparatus. The load display

apparatus can be remote from the measuring apparatus or may be adjacent

thereto. The connection between the measuring apparatus and the load display

apparatus may be wireless or hard wired.

The strain gauge can be of any suitable type for example metal, semi¬

conductor vapour deposited thin film or fibre optic.

Preferably said load measuring apparatus is utilised which comprises at

least four said transducers provided at spaced positions, on opposed sides of the

rail. In these circumstances, the strain gauge of each load transducer may be

electrically connected to one or more processing circuits which generate a

signal capable of display on a load display apparatus. Preferably the transducer has a plurality of bores therein by which the

transducer can be secured to the rail using one or more fasteners such as bolts.

This means that all that is required to fit the load measuring apparatus is to

provide corresponding apertures in the rail through which the bolts or other

fasteners can pass.

The invention will now be described further by way of example only and

with reference to the accompanying drawings, in which:

FIGURE 1 shows one embodiment of apparatus in accordance with the

present invention mounted on a rail web;

FIGURE 2 A to C shows respectively side sectional view, top and front

view of attendance of the load measuring system of figure 1; and

FIGURE 3 shows an alternative embodiment of a load measuring system

in accordance with the present invention.

Referring now to the figures there is shown in Figure 1, an embodiment

of load measuring system 10 according to the present invention.

The load measuring system 10 comprises transducers 11 mounted on a

rail 12 to measure the shear stresses induced in that rail by a railway vehicle(s)

passing along the rail 12 over the transducers 11. Whilst in the figure, only two

transducers 11 are shown, in practice preferably four transducers 11 are utilised at least two mounted on a rail in spaced positions on one side and at least two

mounted in corresponding spaced positions on the other side of the rail web.

The transducers 11 are electrically connected by connectors 16 to

processing circuitry (not shown) to process the signal obtained by each

. transducer and to convert it into a signal that can be supplied to a load display

^• indicator (not shown) on which the measured load can be displayed.

A transducer 11 is shown more clearly in Figures 2 A to 2C. Each

transducer 11 comprises a body 17 having bores 18 therein through which

fasteners (not shown) can pass to secure the transducer 11 to a rail web. The

body 17 also comprises an cavity 19 which is filled with, a potting compound,

the bottom surface 21 of which is of such thickness so as to constitute an

efficient load transfer plate. The body 17 further includes four feet 23 which

project from a bottom surface 21 of the transducer 11, on the opposite side to

the cavity 19. Whilst four feet 22 are shown in the figure, it can be appreciated

that as many feet 22 as are required can be used, as desired or as appropriate

given the shape or configuration of the body 17. In the cavity 19, on the bottom

surface 21 thereof is mounted at least one strain gauge 23 for measuring the

shear strain in the rail 12 in a manner to be described hereinafter.

In practice, the body 17 may be formed from a metallic material but of

course it will be appreciated that any suitable material can be utilised as

appropriate or as desired. The body 17 further includes in at least one wall thereof, a bore which

may be screw threaded or plain to receive an electrical connector 24 from the

strain gauge to the processing circuitry

In use, as shown in Figure 1, each transducer 11 is fitted to an existing

railway track without the need for removal of track as follows:

For each transducer 11, a pair of holes, the same distance apart as the

bores 18 in the body 17 are drilled in the web of the rail. Each transducer 11 is

attached to the web by passing fasteners, for example, bolts through the bores

18 in the body 17 and through the holes in the rail web. The body 17 is then

secured in position using the fastener with the projecting feet 22 in contact with

the surface of the rail web. In practice, it is preferred that four such transducers

11 are secured to the rail web, a pair on one side of the web at spaced positions

and a corresponding pair on the opposite side of the web in corresponding

spaced positions.

It is important, for accurate operation of the system, for the transducers

to be mounted between sleepers 26 supporting the rail.

Each transducer 11 is electrically connected to processing circuitry

which converts the signals generated by the gauges into signals which are

indicative of the measured load and the signals are then passed to a load

display, such as a computer or microprocessor based system, for display of

measured values. Once attached to the rail and connected to the processing circuitry and

display, when a railway vehicle wheel passes over the rail to which the

transducers have been fitted, the shear stresses induced in the rail by the railway

vehicle(s) wheel is transmitted via the feet 22 to the load transfer plates 21

member and to the strain gauge 23 which measures the load.

Each transducer 11 may include processing circuitry provided integrally

therewith and the transducer 11 may in these circumstances be potted in resin

for protection of the circuitry. Alternatively, the processing circuitry may be

provided separately from the transducer and may be connected thereto by

suitable connections or by wireless link.

Considerable benefits stem from the system of the invention. Firstly due

to the nature of the fixing of the transducer to the rail, the rninimum amount of

damage is caused to the rail. Furthermore, the system can be fit to a rail easily

and simply as a retrofit. Also, the transducer of the present invention can

measure loads of railway vehicles travelling along the rail to which the

transducers are fitted at approximately at normal lines speeds. Still further,

because the transducer is never in contact with any part of the railway vehicle,

particularly its wheels, there is no damage caused to those wheels by the load

measuring system. It important to avoid damage to the wheels of the railway

vehicle since clearly if the wheels become damaged then there are serious

safety implications. Further no disturbance is caused to the track or civil foundations during installation of the apparatus. Also transducers can be

installed even when rails are continuously welded thereby avoiding dynamic

disturbance during weighing.

It is of course to be understood that the invention is not intended to be

restricted to details of the above embodiment which is described by way of

example only.

Thus, for example, as shown in Figure 3, each transducer 11 may be

secured to the rail 12 without the need to drill holes therein to receive fasteners.

In this embodiment, a generally u-shaped cradle 28 is provided, a base 29 of

which extends under the rail and side arms 31 of which extend generally

parallel to a vertical axis of the rail. Apertures 33 are provided in each side arm

31 of the cradle 28 through which fasteners 33 can pass into engagement with

the transducer 11, whereby each transducer 11 can be held in place by the

fastener 33 bearing on the external surface of the transducer 11 or by engaging

a suitable formation such as a screw- threaded bore on the transducer 11.

Alternatively,- a clamping device 32 can be provided which is mounted

on the fastener such that when the fastener 33 is fastened, the clamping member

32 bears against the transducer to secure the device in position.

Claims

1. A load measuring apparatus comprising at least one transducer having at

at least one foot provided on one surface thereof, said transducer being

adapted to be secured to a rail such that the foot is in contact with the

rail, the transducer including a load transfer plate upon which a strain

gauge is secured, said strain gauge measuring the shear stresses induced

in said rail when a railway vehicle wheel passes over a rail to which the

transducer is connected, said shear stresses being transmitted to said

strain gauge via said foot and said load transfer plate.

2. A load measuring apparatus according to claim 1 wherein the strain

gauge is connected to suitable processing circuitry to process the signals

received in the strain gauge and convert these to a signal which is

capable of display on a load display apparatus.

3. A load measuring apparatus according to claim 2 wherein the load

display apparatus is remote from the measuring apparatus.

4. A load measuring apparatus according to claim 3 wherein the load

display apparatus is adjacent to the measuring apparatus.

5. A load measuring apparatus according to claim 3 or claim 4 wherein a

connection between the measuring apparatus and the load display

apparatus is hard wired.

6. A load measuring apparatus according to anyone of claims 1 to 5

wherein the apparatus comprising at least four said transducers provided

at spaced positions, on opposed sides of the rail.

7. A load measuring apparatus according to claim 6 wherein the strain

gauge of each load transducer is electrically connected to one or more

processing circuits which generates the signal capable of the load display

apparatus.

8. A load measuring apparatus in which the transducer has a plurality of

bores therein by which the transducer can be secured to the rail using

one or more fasteners such as bolts.