Economical weighing equipment suitable for use in the electronic weighing of livestock and industrial loads and in many other applications is known, in the form of individual weighbeams consisting of a load-receiving member the load forces on which are transferred to a transducer structure, which may take the form of an axially extending bending beam weighbar carrying a strain gauge, or alternatively may comprise a pair of load cells, one load cell being mounted at each end of the load-receiving member. In the case where the transducer used is a bending beam device, such weighbeams may be of the kind described in Australian patent No. 590520.

In many load measurement applications, a pair of such weighbeams are used beneath a load-carrying structure, for example a crate or a cattle crush.

In applications involving dynamic or live loads, and particularly in the weighing of live animals, for example cattle, weighbeams of the type described above have some disadvantages. Where a pair of weighbeams are placed under a cattle crush or in a section of a race, these must be placed transverse to the major direction of movement of the animals on the structure. Such movement tends to roll the weighbeams about their longitudinal axes, and particularly in the case of beams employing loadcells, this can produce undesirable and damaging torque and side loading on transducers, leading to unacceptable weighing results, and equipment damage. Where the equipment uses bending beam transducers of the kind described in the above-mentioned patent this problem is less acute, but still the need exists for a structure which avoids this problem yet still provides a simple, robust and

economical device capable of the desired degree of accuracy.

In this specification the expression "bending beam transducer" means a load measurement device in which load and reaction forces are applied to a beam in equilibrium, these forces being applied to respective force transmission means spaced from one another in the longitudinal direction of the beam, and in which is measured at a selected region of the beam the strain therein which arises from the bending of the beam by those forces and which is proportional to the distances between the said region and the force transmission means. The beam employed in such a transducer will throughout this specification be referred to as a "bending beam weighbar. "

For ease of reference, throughout this specification both a bending beam transducer and a pair of load cells attached to a common load receiving structure the outputs of which are used together in deriving the value of the load on the structure with which they are engaged, will be referred to as an "orientated transducer", and references to the orientation of such a transducer will be to the orientation of the length of the bending beam weighbar or of a line joining the load cell pair.

Also included within the expression "orientated transducer" herein are transducers which comprise a strain measuring region lying between a load application region and a support region, these regions lying substantially on a common axis, and references to the orientation of such a transducer are to the orientation of that common axis.

An example of this last-mentioned type of orientated

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transducer is the well known shearbea loadcell.

The invention broadly resides in weighing apparatus having a longitudinal axis, said apparatus being supported on a pair of orientated transducers as defined herein located substantially adjacent each end of said member, each said transducer being orientated on an axis which intersects said longitudinal axis.

The invention also resides in weighing apparatus comprising a weight-receiving structure for use in the weighing of dynamic loads subjected to impulsive loading predominantly in substantial alignment with a first axis of the structure, said structure being supported ^" by four orientated transducers as defined herein, one such transducer being located in each of the four quadrants defined by said axis and an orthogonal axis passing through the mid-point of the length of the structure along said first axis, each such transducer being supported at a region on each side of an axis normal to said first axis.

The invention will now be described, by way of example only, with reference to several embodiments illustrated in the drawings, in which:

Fig. 1 is a plan view of a weighing unit according to a first embodiment of the invention; Fig. 2 is a side elevation of the unit illustrated in Fig. 1;

Fig. 3 is a sectional elevation taken on the line 3-3 in Fig. 1; Fig. 4 is a bottom plan view of the weighing unit illustrated in Fig. 1; Fig. 5 is a plan view of a second embodiment of the invention; Fig. 6 is a fragmentary side elevation of the unit

illustrated in Fig. 5; Fig. 7 is a plan view of a further embodiment of the invention; Fig. 8 is a cross-section taken on the line 8-8 of Fig. 7;

Fig. 9 is a schematic plan view showing one manner of use of the weighing units embodying the invention; Fig. 10 is a plan view of a further embodiment of the invention;

Fig. 11 is a plan view of a further embodiment of the invention; Fig. 12 is a fragmentary sectional elevation taken on the line 10-10 of Fig. 11; Fig. 13 is a fragmentary sectional elevation taken on the line 11-11 of Fig. 12; and Fig. 14 is a plan view of a further embodiment of the invention.

In the embodiment of the invention shown in Figs. 1-4 a channel section steel beam 20 carries at each end an orthogonally orientated transducer housing 21 formed from similar channel section.

Mounted within each of the housings 21 is a transducer comprising a bending beam bar 23 fitted with a strain gauge unit 24. The bar 23 is, as in the prior art referred to, fixed to the housing 21 and a base member 25 by means of elastomer load transferring members 26. The material and manner of construction of the members 26 are preferably in accordance with the teachings of applicant's Australian patent application No. 33534/89.

The base member 25 in this embodiment comprises a steel plate to which is attached at each end by welding, a lug 27 which extends beyond the plate to

enable the assembly to be fixed, if required, to a floor or other surface.

Studs 28 fixed to the elastomer elements 26 secure these to the housing 21 and the base member 25. In order that the nuts on the external ends of the studs 28 should not stand proud of the surface of the housing 21 and the base member 25, pads 29 are provided between the web of the housing 21 and the upper elastomer elements 26 so that the upper nuts rest within apertures 30 in the web of the housing, while the lower nuts rest in apertures 31 similarly provided in the lugs 27.

The strain gauge units 24 of each bar 23 are interconnected by wiring (not shown) incorporating a balancing circuit to normalize the orientated transducer outputs for a given load.

The use of channel section members in the construction of the unit so far described provides adequate structural strength and rigidity while avoiding the creation of enclosed spaces which encourage the retention of foreign matter, with consequent corrosion. The illustrated configuration also provides ready accessability for service. For example, access to the transducers is gained simply by the removal of the two nuts securing the members 26 to the base member 25, and the removal of the nuts from the upper studs as well enables complete disassembly.

Figs. 5 and 6 illustrate an alternative approach to the construction of a weighing unit having a basic geometry similar to that of the units of Figs . 1 to 4. In this second embodiment a preferably channel-shaped central body portion 40 extends between transverse end pieces 41 formed of steel

angle and thereby having a horizontal flange 42 and a vertical web 43.

A bending beam weighbar 24, in a manner similar to that of the first embodiment, supports the flange 42 by means of elastomer load transfer elements 26.

The weighbars 24 are similarly supported on angle section members 44, comprising a flange 45 and a vertical web 46, which serve with the sections 41 mechanically to protect the transducer assembly. As in the first embodiment, the transducer assembly is secured by studs 28.

Mounting lugs 48 are attached to the flanges 42, forming pads for the elements 26 and allowing the upper stud nuts to be concealed in apertures 47, while mounting lugs 48a are provided on the flanges 45, pads 49 enabling the lower stud nuts to rest in apertures 50 in the flanges 45 and lugs 48a.

In the device illustrated in Figs. 7 and 8 the lateral members 21 are oppositely directed and each houses a shearbeam loadcell 60 which in accordance with the present invention is orientated as illustrated. The members 21 are supported on the loadcell 60 by means of a elastomeric load transfer element 61 and are fixed to the base member 25 by conventional means such as a pair of bolts (not shown) .

Fig. 9 shows schematically a typical application of the invention, where a cattle crush 51 is supported o a pair of devices of the kind described in relation t Figs. 1-4. Such an arrangement will be seen to have an inherent stability along the main axis of animal movement and dynamic loading which is superior to tha

obtained by the prior art devices described. By the use of four short bending beam transducers, moreover, a greater load-carrying capacity and shear strength can be achieved while still retaining the use of inexpensive elastomeric load transfer members, without loss of linearity.

Many variations in the construction of the device may be made without departing from the principles of the present invention. For example, the load carrying member 10 and the housing 11 may be of channel or other section, and the member 10 may be telescopic so as to be adjustable to the dimensions of different loads, or may be constructed in sections for ease of packing and transport.

Fig. 10 illustrates such an arrangement, in which the transducer housings 21 are detachably mounted on the ends of the beam 20, for example by means of stub channels 52 bolted to the ends of the beam 20.

As described earlier, the orientated transducers employed in embodiments of the invention need not be of the bending beam type. They may for example comprise pairs of load cells, for example shear beam load cells, the cells of each pair being located at each end of the respective housing 21. Preferably, the shear beams will be orientated with their longitudinal axis on or parallel to the axis of the housing 21.

Where bending beam transducers are employed, the elastomer elements 26 may be substituted by other means for load transfer and support. For example, pins with elastomeric bushes may be employed, as described in applicant's Australian patent No. 590520. In a particularly simple arrangement,

mini izing cost although being subject to wear, having a shorter life, and providing less accurate weighing, fixed pins may be employed without elastomeric bushes. Figs. 11-13 illustrate such an arrangement, in which the load is applied to the bar 23 by pins 53 engaged with the flanges of the housings 21, and the bar is supported by pins 54 engaged with flanges 55 provided on the base member 25.

Fig. 14 illustrates another embodiment of the present invention, where the approach taken in Fig. 10 is extended. In this case, a cattle crush 56 (or other device) is provided with stubs 57 of steel tube, which may be fixed to the crush by welding. Housings 21 are provided with sockets 58 of steel tube dimensioned for a close sliding fit with the stubs 57, and the stubs and the sockets are provided with holes for the reception of locking pins after the housings have been attached to the crush. In this way, the crush 56 replaces the load-carrying body used in the embodiments described above.