CA1211481A - Weighing module - Google Patents
Weighing moduleInfo
- Publication number
- CA1211481A CA1211481A CA000484498A CA484498A CA1211481A CA 1211481 A CA1211481 A CA 1211481A CA 000484498 A CA000484498 A CA 000484498A CA 484498 A CA484498 A CA 484498A CA 1211481 A CA1211481 A CA 1211481A
- Authority
- CA
- Canada
- Prior art keywords
- load
- lever
- support
- weighing module
- main
- Prior art date
- Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
- Expired
Links
Classifications
-
- G—PHYSICS
- G01—MEASURING; TESTING
- G01G—WEIGHING
- G01G21/00—Details of weighing apparatus
- G01G21/23—Support or suspension of weighing platforms
- G01G21/235—Support or suspension of weighing platforms using knife-edge bearings
-
- G—PHYSICS
- G01—MEASURING; TESTING
- G01G—WEIGHING
- G01G19/00—Weighing apparatus or methods adapted for special purposes not provided for in the preceding groups
- G01G19/02—Weighing apparatus or methods adapted for special purposes not provided for in the preceding groups for weighing wheeled or rolling bodies, e.g. vehicles
- G01G19/021—Weighing apparatus or methods adapted for special purposes not provided for in the preceding groups for weighing wheeled or rolling bodies, e.g. vehicles having electrical weight-sensitive devices
-
- G—PHYSICS
- G01—MEASURING; TESTING
- G01G—WEIGHING
- G01G21/00—Details of weighing apparatus
- G01G21/14—Beams
- G01G21/16—Beams of composite construction; Connections between different beams
- G01G21/161—Connections between different beams
- G01G21/162—Connections between different beams using knife-edge bearings
-
- G—PHYSICS
- G01—MEASURING; TESTING
- G01G—WEIGHING
- G01G21/00—Details of weighing apparatus
- G01G21/18—Link connections between the beam and the weigh pan
- G01G21/182—Link connections between the beam and the weigh pan using knife-edge bearings
Landscapes
- Physics & Mathematics (AREA)
- General Physics & Mathematics (AREA)
- Devices For Checking Fares Or Tickets At Control Points (AREA)
Abstract
C A N A D A
ROGERS, BERESKIN & PARR
TITLE: WEIGHING MODULE
INVENTOR: MARK S. NIELSEN
ABSTRACT OF THE DISCLOSURE
A weighing module for use in motor truck scales and the like has two first supports for two main levers.
Each main lever is pivotally mounted at one end on a first support. Two chairs apply loads to the main levers through pivots adjacent their one ends. A transfer lever is pivotally mounted at one end on a second support. The other ends of the main levers apply loads to the transfer lever adjacent the second support. The other end of the transfer lever is supported by a load cell. The lever system reduces the load sensed at the load cell, so that a relatively low capacity load cell can be employed. In a whole truck scale, a number of identical weighing modules are included, to support the sections of the deck.
ROGERS, BERESKIN & PARR
TITLE: WEIGHING MODULE
INVENTOR: MARK S. NIELSEN
ABSTRACT OF THE DISCLOSURE
A weighing module for use in motor truck scales and the like has two first supports for two main levers.
Each main lever is pivotally mounted at one end on a first support. Two chairs apply loads to the main levers through pivots adjacent their one ends. A transfer lever is pivotally mounted at one end on a second support. The other ends of the main levers apply loads to the transfer lever adjacent the second support. The other end of the transfer lever is supported by a load cell. The lever system reduces the load sensed at the load cell, so that a relatively low capacity load cell can be employed. In a whole truck scale, a number of identical weighing modules are included, to support the sections of the deck.
Description
:~2~
This invention relates to a weighing module, and is more particulArly concerned with motor truck scales and railroad track scales.
For both trucks, such as tractor-trailer tr~cks, and railroad cars, there is a need to be able to weigh the complete vehicle. By weighing a vehicle both before and after it is unloaded or loaded, one can determine the weight of goods loaded or unloaded onto the vehicle. Also, scales are used to ensure that maximum weight limits are not exceeded.
At the present time, there are two basic types of scales. The first type is a mechanical lever system scale, which is wholly mechanical~ The second type of scale is a Eully electronic scale, employing load cells. For trucks, they are produced in various sizes, for weighing, for example up to 40 tonnes, or up to 120 tonnesu The same principles can be employed for railroad track scales, but the weights involved are greater~
Mechanical truck scales typically have a reinforced ` concrete deck, supported on a Erame work of girders. In turn, these girders are supported on a number of chairs of the scale mechanism. Each chair transfers the load applied to it through a main lever to a transfer lever. A number of transfer levers are provided, which transfer the loads applied to them to an end lever. The end lever is attached to some measuring ~5 device, for example: a bar and sliding poise; a mechanical dial unit; or a single, low capacity load cell. Typically, the dimensions of the various levers are such as to give a ratio between ~he applied load and the load at the end lever, which is in the range 200:1 to ~00:1.
A variation of the mechanical lever design utilizes a torque lever design. ~ssentially, instead of transmitting the applied loads hy bending, the loads are transmitted as tor~ues through various tubes. O-therwise, the principles are generally the same.
Mechanical scales have the advantage of being relatively robust and reliable. However, they have a large number of moving parts. It can be time consuming, and sometimes difficult, to ensure that they are all pro~erly aligned. Further, if a mechanical scale is not properly maintained, friction can arise at the pivots, which can give a false reading. The tolerance on the measured weight should be less than .1~.
A further disadvantage of the mechanical lever design is that it includes a large number of cumbersome and heavy components. Many scales include a small manhole, to enable maintenance personnel to gain excess to the underside of the scale. However, the larger components cannot be manipulated through the manhole, and consequently the deck has to be dismantled, to effect major repairs or replacement. Also, the individual components of the mechanical lever design can be extremely heavy, which also hinders, for example, repair or maintenance of pivots. A combination lever can weigh ~00 lbs., whilst a T-lever of the torque tube design can weigh 1000 lbs.
The fully electronic load cell scale has the advantage of mechanical simplicity. It dispenses with the need for levers --3~
and pivots, and hence the problems associated therewith are not encountered. It includes the concrete deck and supporting framework of the mechanical lever design. The frame work is supported on a number of load cells. Since the load is applied directly to these load cells, and is not reduced, each load cell has to be of a high capacity, typically 50,000-100,00~ lbs.
The number of load cells is provided in accordance with the size of the scale. Thus, a seventy foot long truck scale would typically need 6-8 load cells, although 4 load cells can be used for smaller scales. For the mechanical scale, the load is ultimately applied at a single point~ Accordinglv, the final measuring device is sized, in accordance with the maximum load at the end lever. For the electronic scale, one cannot assume that the load will be evenly distributed between the load cells. Accordingly, each load cell has to be of ~uite a large capacity, so that the total capacity of all the load cells is considerably greater than the rated capacity of the scale. ~!
Electronic load cell scales suffer from a number of disadvantages. Firstly, the load is applied directly to the load cells, which are ~uite sensitive. Shock loadings can damage the load cells. Also, as each load cell is of large capacity, it is difficult to calibrate them. During manufasture, one needs special dead weights etc. to calibrate the cells and to ensure that they are linear throughout the full scale. In use, it can be difficult to detect a ~aulty load cell. To check each load cell, one really needs to be able to provide a varying load up to its maximum rating.
,, ~2'~
In accordance with the present invention, there is provided a weighing module comprising: two first supports;
two, corresponding main levers, each of which is pivotally mounted at one end to a respective first support; two chairs, each of which is pivotally attached to a respective main lever adjacent the respective first support, for applying a load to that main lever~; a second support; a transfer lever pivotally mounted at one end to a second support, with the other ends of the main levers pivotally supported on the transfer lever adjacent the second support; and a third, end support, including a load cell, which supports the other end of the transfer lever, so that the load sensed by the load cell is dependant on the loads applied to the chairs.
The present invention also provides a weigh bridge, which can be for a motor truck or railway car for example, the weigh bridge comprising a foundation, a plurality of weighing modules as just defined mounted on the foundation, a deck supported on the chairs of the weighing modules, and a summing unit connected to the load cells to sum the outputs thereof.
The weighing modules and weigh bridge of the present invention have a number of advantages over known scales or weigh bridges. Mechanical scales require the positioning and alignment - of for example 13 levers and stands. In contrast, each individual weighing apparatus of the present invention can be positioned and aligned individually. It only includes 3 levers, and 4 supports. It is only necessary for the individual apparatuses to be sufficiently aligned, for attachment of the deck. Since there are no long, heavy levers for transferring the load to a single load sensing device, the weigh bridge is easier to install. The heaviest component, the main lever can be lifted by two people. Consequently, one requires no heavy lifting machinery. Thus, the weigh bridge can be manufactured and installed at a lower cost.
Further, a weigh bridge in accordance with the present invention, is e~pected to have lower maintenance costs, in contrast to fully mechanical scales, it has fewer moving parts, resulting in lower maintenance costs during repairs. On the other hand, as compared to fully electronic scales, it does not have high capacity load cells that have to be tested. The individual load cells can be of relatively low capacity.
As the components of the individual apparatuses or assemblies are small, they can be easily handled in a pit in which the scale is located. For maintenance, the deck can be jacked up, and then the mechanical components dismantled. The individual levers can then be taken out through a manhole access, if :cequired. This is not possible within any other scale. This saves the time and cost of a crane required to remove the deck for major repairs.
The weigh bridge or scale is also expected to have a high degree of reliability. Fully mechanical scales are reliable, but expensive to repair when mechanical parts wear and corrode. Electronic scales, whilst ln theory having fewer .. ~ . .
parts to wear, require high capacity load cells which can be difficult to test and costly to replace. The weigh bridge of the present invention incorporates the advantages of both mechanical and electronic scales~ The mechanical lever system provides for great reliability, whilst serving to isolate the load cell from shock loadings, or at least reduce any shock loads. Slnce the load cell can be of low capacity, t~pically
This invention relates to a weighing module, and is more particulArly concerned with motor truck scales and railroad track scales.
For both trucks, such as tractor-trailer tr~cks, and railroad cars, there is a need to be able to weigh the complete vehicle. By weighing a vehicle both before and after it is unloaded or loaded, one can determine the weight of goods loaded or unloaded onto the vehicle. Also, scales are used to ensure that maximum weight limits are not exceeded.
At the present time, there are two basic types of scales. The first type is a mechanical lever system scale, which is wholly mechanical~ The second type of scale is a Eully electronic scale, employing load cells. For trucks, they are produced in various sizes, for weighing, for example up to 40 tonnes, or up to 120 tonnesu The same principles can be employed for railroad track scales, but the weights involved are greater~
Mechanical truck scales typically have a reinforced ` concrete deck, supported on a Erame work of girders. In turn, these girders are supported on a number of chairs of the scale mechanism. Each chair transfers the load applied to it through a main lever to a transfer lever. A number of transfer levers are provided, which transfer the loads applied to them to an end lever. The end lever is attached to some measuring ~5 device, for example: a bar and sliding poise; a mechanical dial unit; or a single, low capacity load cell. Typically, the dimensions of the various levers are such as to give a ratio between ~he applied load and the load at the end lever, which is in the range 200:1 to ~00:1.
A variation of the mechanical lever design utilizes a torque lever design. ~ssentially, instead of transmitting the applied loads hy bending, the loads are transmitted as tor~ues through various tubes. O-therwise, the principles are generally the same.
Mechanical scales have the advantage of being relatively robust and reliable. However, they have a large number of moving parts. It can be time consuming, and sometimes difficult, to ensure that they are all pro~erly aligned. Further, if a mechanical scale is not properly maintained, friction can arise at the pivots, which can give a false reading. The tolerance on the measured weight should be less than .1~.
A further disadvantage of the mechanical lever design is that it includes a large number of cumbersome and heavy components. Many scales include a small manhole, to enable maintenance personnel to gain excess to the underside of the scale. However, the larger components cannot be manipulated through the manhole, and consequently the deck has to be dismantled, to effect major repairs or replacement. Also, the individual components of the mechanical lever design can be extremely heavy, which also hinders, for example, repair or maintenance of pivots. A combination lever can weigh ~00 lbs., whilst a T-lever of the torque tube design can weigh 1000 lbs.
The fully electronic load cell scale has the advantage of mechanical simplicity. It dispenses with the need for levers --3~
and pivots, and hence the problems associated therewith are not encountered. It includes the concrete deck and supporting framework of the mechanical lever design. The frame work is supported on a number of load cells. Since the load is applied directly to these load cells, and is not reduced, each load cell has to be of a high capacity, typically 50,000-100,00~ lbs.
The number of load cells is provided in accordance with the size of the scale. Thus, a seventy foot long truck scale would typically need 6-8 load cells, although 4 load cells can be used for smaller scales. For the mechanical scale, the load is ultimately applied at a single point~ Accordinglv, the final measuring device is sized, in accordance with the maximum load at the end lever. For the electronic scale, one cannot assume that the load will be evenly distributed between the load cells. Accordingly, each load cell has to be of ~uite a large capacity, so that the total capacity of all the load cells is considerably greater than the rated capacity of the scale. ~!
Electronic load cell scales suffer from a number of disadvantages. Firstly, the load is applied directly to the load cells, which are ~uite sensitive. Shock loadings can damage the load cells. Also, as each load cell is of large capacity, it is difficult to calibrate them. During manufasture, one needs special dead weights etc. to calibrate the cells and to ensure that they are linear throughout the full scale. In use, it can be difficult to detect a ~aulty load cell. To check each load cell, one really needs to be able to provide a varying load up to its maximum rating.
,, ~2'~
In accordance with the present invention, there is provided a weighing module comprising: two first supports;
two, corresponding main levers, each of which is pivotally mounted at one end to a respective first support; two chairs, each of which is pivotally attached to a respective main lever adjacent the respective first support, for applying a load to that main lever~; a second support; a transfer lever pivotally mounted at one end to a second support, with the other ends of the main levers pivotally supported on the transfer lever adjacent the second support; and a third, end support, including a load cell, which supports the other end of the transfer lever, so that the load sensed by the load cell is dependant on the loads applied to the chairs.
The present invention also provides a weigh bridge, which can be for a motor truck or railway car for example, the weigh bridge comprising a foundation, a plurality of weighing modules as just defined mounted on the foundation, a deck supported on the chairs of the weighing modules, and a summing unit connected to the load cells to sum the outputs thereof.
The weighing modules and weigh bridge of the present invention have a number of advantages over known scales or weigh bridges. Mechanical scales require the positioning and alignment - of for example 13 levers and stands. In contrast, each individual weighing apparatus of the present invention can be positioned and aligned individually. It only includes 3 levers, and 4 supports. It is only necessary for the individual apparatuses to be sufficiently aligned, for attachment of the deck. Since there are no long, heavy levers for transferring the load to a single load sensing device, the weigh bridge is easier to install. The heaviest component, the main lever can be lifted by two people. Consequently, one requires no heavy lifting machinery. Thus, the weigh bridge can be manufactured and installed at a lower cost.
Further, a weigh bridge in accordance with the present invention, is e~pected to have lower maintenance costs, in contrast to fully mechanical scales, it has fewer moving parts, resulting in lower maintenance costs during repairs. On the other hand, as compared to fully electronic scales, it does not have high capacity load cells that have to be tested. The individual load cells can be of relatively low capacity.
As the components of the individual apparatuses or assemblies are small, they can be easily handled in a pit in which the scale is located. For maintenance, the deck can be jacked up, and then the mechanical components dismantled. The individual levers can then be taken out through a manhole access, if :cequired. This is not possible within any other scale. This saves the time and cost of a crane required to remove the deck for major repairs.
The weigh bridge or scale is also expected to have a high degree of reliability. Fully mechanical scales are reliable, but expensive to repair when mechanical parts wear and corrode. Electronic scales, whilst ln theory having fewer .. ~ . .
parts to wear, require high capacity load cells which can be difficult to test and costly to replace. The weigh bridge of the present invention incorporates the advantages of both mechanical and electronic scales~ The mechanical lever system provides for great reliability, whilst serving to isolate the load cell from shock loadings, or at least reduce any shock loads. Slnce the load cell can be of low capacity, t~pically
2,000 lbs., it is relatively easy to test and check in service.
For a better understanding of the present invention, and to show more clearly how it may be carried into effect, reference will now be made by way of example, to the accom-panying drawings, which show an embodiment of the present invention, and in which:
Figure 1 shows a side view, and partial section, of a truck scale in accordance with the present invention;
. ~.
Figure 2 shows a plan view of the truck scale of Figure l;~and, Figure 3 shows a perspective view of a weighing module viewing part of a -truck scale of Figures 1 and 2.
As mentioned above, the present invention can be applied to motor truck scales, railroad car scales, or other purposes. However, for clarity, the following description is directed solely to a txuck scale. A scale or weigh bridge for railroad cars would be similarly constructed, but of heavier construction.
With reference to Figures 1 and 2, the whole weigh bridge or truck scale is generally denoted by the reference 1.
In known manner, it is located in a pit 2 dug in the ground, so as to be flush with the top of the ground. The pit 2 is lined with concrete walls 3 and a bottom 4.
Within the pit 2, there are three separate weighing modules, each designated by the reference 6. For each weighing module 6, concrete support blocks are formed on the bottom 4.
As indicated for the middle module 6 in Figure 2, there are two first support blocks 8, adjacent the side walls, a second support block 10, and an end sup~ort block 12 The support blocks are dimensioned, in accordance with the loads applied to them. Thus, the bulk of the load applied to each weighing apparatus 6 is transmitted through the first support blocks 8, and they are therefore the largest.
The two weighing apparatus 6 a-~ either end are Provided with similar support blocks.
As explained in greater detail below, each module 6 includes two chairs 14, 16. A framework 18, o~ girders is supported on these chairs 14, 16. On top of the framework 18, there is a deck 20, which can be wood, steel or reinforced concrete. The framework 18 and deck 20 can either be formed as a single unit, or, as indicated schematically at 22 they can be divided into two halves. In this latter case, the central weighing apparatus 6 would support the ends of the two halves. Also, as shown, there should be~sufficient ¢learance around the framework 18 and deck 20, to enable any loads applied to it to be transmitted, without interference, to the weighing module 6. In use, in known manner, a truck is simply driven onto the deck 20. The details of the deck 20 and the framework 18 can be conventional, and will not be described in greater detail here.
A description will now be given of one of the weighing modules 6, with reference -to Figure 3. It is to be appreciated that the three lever modules 6 are identical.
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--8~
Each weighing module 6 includes two main lever assemblies, denoted by the references 24, 26, for the two chairs 14, 16 respectively. Slnce ~hese two main lever assemblies 24, 26 are identical, only the main lever assembly 24 is described in detail.
The main lever assembly 24 includes a respective first support 30, including holes 32 for holting it to its first support block 8. The first support 30 includes two channel sections extending upwardly, and supporting a bearing 34 for a first pivot.
A main lever 36 is formed from two channel section members 38, which are at an angle, as viewed in plan. At one end, a rectangular section member 40 extends between and is welded to the two channel-section members 38. A knife edge 42 is mounted at the bottom of the member 40, and forms a first pivot with the bearing 34.
Another réctangular-section member 44 extends between the two channel-section members 38. It also carries a corresponding knife edge 46. The chair 14 is mounted on this knife edge or pivot 46 hy a parallel link suspension system 48.
The chair 14 includes a top plate 50 including holes 52 for bolting it to the framework 18. Extending down from the top plate 50, there are two side plates 54. The parallel link suspension 48 includes two plates 56, which include elongate slots. A first rod 58 extends between the plates 56 at the bottom of the slots, whilst a second rod 60 is located at the top of these slots. The plates 56 are rotatably mounted relative to the chair 14. The plates 56 are also rotatable ~2~
g relative to a support member 62. The second rod 60 is welded to the bearing support member 62, including a bearing 64. The bearing 64 and knife edge or pivot 46 form a chair or load . .
pivot. It will thus be seen that the parallel link suspension 48 serves to transfer any load from the chair 14 to the main lever at 46, adjacent its first support.
At the other end of the main lever 36, the channel-section members 38 are cut back, as indicated at 66. A
tapered block 68 is welded between the members 38, and a knife edge 70 is provided on its bottom surface, for supporting the other end of the main lever assembly 24.
A second support is provided at 720 It is generally similar to the first support 30 described above. It includes a bearing 74. A transfer lever 76 comprises two channel-section members 78, like the main lever channel beams 38. At one end, the transfer lever 76 includes a cross bar 80 of circular section. On its bottom, the cross bar 80 is provided with a knife edge 82, which, together with the bearing 74 forms a fulcrum pivot to support one end of the transfer lever 76.
Each main lever 36 is supported on the transfer lever 76 by a respective connection assembly 84.
Each connection assembly 84 includes a bottom plate 86 and a top plate 88, the two plates 86, 88 are joined by means of threaded shafts and nuts 90. The bottom plate 86 includes a longitudinally extending bearing 92, whilst the top plate 88 includes a transverse bearing 94. The bearing 92 and knife edge 70 form a pivot for the other end of the main lever 36. The transfer lever 76 also includes another cross bar 96 including a respective knife edge 98. The knife edge 98 is common to the two bearings 94. Thus, the loads at the ends of the two main assemblies 24, ?6 are transferred via the two connection assemblies 84 to the trans~er lever 76, adjacent the second support 72.
At the other end of the transfer lever 76, there is an end support 100. The end support 100 includes a base plate 102 with holes 104 for boltin~ it to its support block 12. The end support 100 has sidewalls 106 and a top plate 10 108. A load cell 110 is suspended from the top plate 108.
From the lower end of the load cell 110, there is an end connection assembly 112, comparible to the connection assemblies 84.
The end connection assembly 112 includes two horizontal 15 members 114, 116. ~he cross member 116 includes a bearing 118. A knife edge 120 is secured to the end of the transfer lever 76 and bears on the bearing 118. Threaded shafts and nuts 122 connect the two cross-members 114, 116 together.
The cross-member 114 is suitabl~ suspended from the load 20 cell 110.
It will thus be seen that the arrangement of the chairs 14, 16 the main levers 24, 26 and the transfer lever 76 are such as to reduce the load received at the load cell 110.
Typically, the main levers 24, 26 will reduce the load received 25 on the chairs 14, 16 in the ratio 7:1. The location of the pivots on the transfer lever 76 is typically such as to reduce the load at the load cell 110 by a further factor of 10:1.
Thus, the load received at the load cell 110 is 1/70th of the load applied to the chairs 14, 16. This enab~es a relatively low capacity load cell to be used. For example, the load cell can have a capacity of 2,000 lbs. In which case, a single weighing module 6 could receive a load of 140,000 lbs.
Whilst the embodiment described above includes 3 weighing modules or sections, i-t is to be appreciated that the number of individual weighing modules or sections can be varied depending upon -the size of scale or weigh bridge required. Thus, for a long scale, one could have five or more weighing modules. The framework 18 and deck 20 of the scale could either be provided as a;single unit, or cut into separate sections, with each section supported on the four chairs of two adjacent weighing apparatus.
For the truck scale of the Figures 1 and 2, the output of the load cells of the three weighing modules 6 are connected to an electrical, summing unit. This would conveniently be located in a cabin for the operator. The summing unit would sum the outputs of the load cells, and the summed output would be converted to give the weight measured. This measured weight could then be displayed in known manner.
For a better understanding of the present invention, and to show more clearly how it may be carried into effect, reference will now be made by way of example, to the accom-panying drawings, which show an embodiment of the present invention, and in which:
Figure 1 shows a side view, and partial section, of a truck scale in accordance with the present invention;
. ~.
Figure 2 shows a plan view of the truck scale of Figure l;~and, Figure 3 shows a perspective view of a weighing module viewing part of a -truck scale of Figures 1 and 2.
As mentioned above, the present invention can be applied to motor truck scales, railroad car scales, or other purposes. However, for clarity, the following description is directed solely to a txuck scale. A scale or weigh bridge for railroad cars would be similarly constructed, but of heavier construction.
With reference to Figures 1 and 2, the whole weigh bridge or truck scale is generally denoted by the reference 1.
In known manner, it is located in a pit 2 dug in the ground, so as to be flush with the top of the ground. The pit 2 is lined with concrete walls 3 and a bottom 4.
Within the pit 2, there are three separate weighing modules, each designated by the reference 6. For each weighing module 6, concrete support blocks are formed on the bottom 4.
As indicated for the middle module 6 in Figure 2, there are two first support blocks 8, adjacent the side walls, a second support block 10, and an end sup~ort block 12 The support blocks are dimensioned, in accordance with the loads applied to them. Thus, the bulk of the load applied to each weighing apparatus 6 is transmitted through the first support blocks 8, and they are therefore the largest.
The two weighing apparatus 6 a-~ either end are Provided with similar support blocks.
As explained in greater detail below, each module 6 includes two chairs 14, 16. A framework 18, o~ girders is supported on these chairs 14, 16. On top of the framework 18, there is a deck 20, which can be wood, steel or reinforced concrete. The framework 18 and deck 20 can either be formed as a single unit, or, as indicated schematically at 22 they can be divided into two halves. In this latter case, the central weighing apparatus 6 would support the ends of the two halves. Also, as shown, there should be~sufficient ¢learance around the framework 18 and deck 20, to enable any loads applied to it to be transmitted, without interference, to the weighing module 6. In use, in known manner, a truck is simply driven onto the deck 20. The details of the deck 20 and the framework 18 can be conventional, and will not be described in greater detail here.
A description will now be given of one of the weighing modules 6, with reference -to Figure 3. It is to be appreciated that the three lever modules 6 are identical.
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--8~
Each weighing module 6 includes two main lever assemblies, denoted by the references 24, 26, for the two chairs 14, 16 respectively. Slnce ~hese two main lever assemblies 24, 26 are identical, only the main lever assembly 24 is described in detail.
The main lever assembly 24 includes a respective first support 30, including holes 32 for holting it to its first support block 8. The first support 30 includes two channel sections extending upwardly, and supporting a bearing 34 for a first pivot.
A main lever 36 is formed from two channel section members 38, which are at an angle, as viewed in plan. At one end, a rectangular section member 40 extends between and is welded to the two channel-section members 38. A knife edge 42 is mounted at the bottom of the member 40, and forms a first pivot with the bearing 34.
Another réctangular-section member 44 extends between the two channel-section members 38. It also carries a corresponding knife edge 46. The chair 14 is mounted on this knife edge or pivot 46 hy a parallel link suspension system 48.
The chair 14 includes a top plate 50 including holes 52 for bolting it to the framework 18. Extending down from the top plate 50, there are two side plates 54. The parallel link suspension 48 includes two plates 56, which include elongate slots. A first rod 58 extends between the plates 56 at the bottom of the slots, whilst a second rod 60 is located at the top of these slots. The plates 56 are rotatably mounted relative to the chair 14. The plates 56 are also rotatable ~2~
g relative to a support member 62. The second rod 60 is welded to the bearing support member 62, including a bearing 64. The bearing 64 and knife edge or pivot 46 form a chair or load . .
pivot. It will thus be seen that the parallel link suspension 48 serves to transfer any load from the chair 14 to the main lever at 46, adjacent its first support.
At the other end of the main lever 36, the channel-section members 38 are cut back, as indicated at 66. A
tapered block 68 is welded between the members 38, and a knife edge 70 is provided on its bottom surface, for supporting the other end of the main lever assembly 24.
A second support is provided at 720 It is generally similar to the first support 30 described above. It includes a bearing 74. A transfer lever 76 comprises two channel-section members 78, like the main lever channel beams 38. At one end, the transfer lever 76 includes a cross bar 80 of circular section. On its bottom, the cross bar 80 is provided with a knife edge 82, which, together with the bearing 74 forms a fulcrum pivot to support one end of the transfer lever 76.
Each main lever 36 is supported on the transfer lever 76 by a respective connection assembly 84.
Each connection assembly 84 includes a bottom plate 86 and a top plate 88, the two plates 86, 88 are joined by means of threaded shafts and nuts 90. The bottom plate 86 includes a longitudinally extending bearing 92, whilst the top plate 88 includes a transverse bearing 94. The bearing 92 and knife edge 70 form a pivot for the other end of the main lever 36. The transfer lever 76 also includes another cross bar 96 including a respective knife edge 98. The knife edge 98 is common to the two bearings 94. Thus, the loads at the ends of the two main assemblies 24, ?6 are transferred via the two connection assemblies 84 to the trans~er lever 76, adjacent the second support 72.
At the other end of the transfer lever 76, there is an end support 100. The end support 100 includes a base plate 102 with holes 104 for boltin~ it to its support block 12. The end support 100 has sidewalls 106 and a top plate 10 108. A load cell 110 is suspended from the top plate 108.
From the lower end of the load cell 110, there is an end connection assembly 112, comparible to the connection assemblies 84.
The end connection assembly 112 includes two horizontal 15 members 114, 116. ~he cross member 116 includes a bearing 118. A knife edge 120 is secured to the end of the transfer lever 76 and bears on the bearing 118. Threaded shafts and nuts 122 connect the two cross-members 114, 116 together.
The cross-member 114 is suitabl~ suspended from the load 20 cell 110.
It will thus be seen that the arrangement of the chairs 14, 16 the main levers 24, 26 and the transfer lever 76 are such as to reduce the load received at the load cell 110.
Typically, the main levers 24, 26 will reduce the load received 25 on the chairs 14, 16 in the ratio 7:1. The location of the pivots on the transfer lever 76 is typically such as to reduce the load at the load cell 110 by a further factor of 10:1.
Thus, the load received at the load cell 110 is 1/70th of the load applied to the chairs 14, 16. This enab~es a relatively low capacity load cell to be used. For example, the load cell can have a capacity of 2,000 lbs. In which case, a single weighing module 6 could receive a load of 140,000 lbs.
Whilst the embodiment described above includes 3 weighing modules or sections, i-t is to be appreciated that the number of individual weighing modules or sections can be varied depending upon -the size of scale or weigh bridge required. Thus, for a long scale, one could have five or more weighing modules. The framework 18 and deck 20 of the scale could either be provided as a;single unit, or cut into separate sections, with each section supported on the four chairs of two adjacent weighing apparatus.
For the truck scale of the Figures 1 and 2, the output of the load cells of the three weighing modules 6 are connected to an electrical, summing unit. This would conveniently be located in a cabin for the operator. The summing unit would sum the outputs of the load cells, and the summed output would be converted to give the weight measured. This measured weight could then be displayed in known manner.
Claims (15)
PROPERTY OR PRIVILEGE IS CLAIMED ARE DEFINED AS FOLLOWS:
1. A weighing module comprising: two first supports; two corresponding main levers, each of which is pivotally mounted at one end to a respective first support; two chairs each of which is pivotally attached to a respective main lever adjacent the respective first support, for applying a load to that main lever; a second support;
a transfer lever pivotally mounted at on end to the second support, with the other ends of the main levers pivotally supported on the transfer lever adjacent the second support;
and a third, end support, including a load cell, which supports the other end of the transfer lever, so that the load sensed by the load cell is dependant on the loads applied to the chairs.
a transfer lever pivotally mounted at on end to the second support, with the other ends of the main levers pivotally supported on the transfer lever adjacent the second support;
and a third, end support, including a load cell, which supports the other end of the transfer lever, so that the load sensed by the load cell is dependant on the loads applied to the chairs.
2. A weighing module as claimed in claim 1, wherein each of the main and transfer levers comprises two channel-section members.
3. A weighing module as claimed in claim 1, wherein each pivot is formed by a knife edge and corresponding bearing.
4. A weighing module as claimed in claim 3, wherein the knife edge of each pivot is carried by a respective lever.
5. A weighing module as claimed in claim 4, wherein the main levers are disposed symmetrically on either side of the transfer lever, and the other ends of the main levers are supported from the transfer lever by similar connection assemblies, which connection assemblies are suspended from a common knife edge of the transfer lever.
6. A weighing module as claimed in claim 1, wherein the ratio of a load applied to a chair to the load applied by the other end of the respective main lever to the transfer lever is 7:1.
7. A weighing module as claimed in claim 1 or 6, wherein the ratio of the load applied to the transfer lever by the main levers to the load sensed by the load cell is in the ration 10:1.
8. A weighing module as claimed in claim 1, wherein the load cell is rated to measure a load in the range of 1000-3000 lbs.
9. A weighing module as claimed in claim 8, wherein the load cell is rated to measure a load of around 2000 lbs.
10. A weigh bridge comprising a foundation, a plurality of weighing modules as claimed in claim 1, a deck supported on the chairs of the weighing modules, and a summing unit connected to the load cells of the weighing modules, to sum the outputs thereof.
11. A weigh bridge as claimed in claim 10, wherein the weighing modules are all identical.
12. A weigh bridge as claimed in claim 10, wherein the deck comprises a one-piece deck.
13. A weigh bridge as claimed in claim 10, wherein the deck comprises a plurality of individual deck sections, each of which is supported at either end on the chairs of one weighing module.
14. A weigh bridge as claimed in claim 10 or 11, which includes a display device connected to an output of the summing unit, for displaying the weight measured by the weigh bridge.
15. A weigh bridge as claimed in claim 10 or 11, which includes a printer unit, for printing details of a measured weight, which printing unit is connected to an output of the summing unit, to receive the measured weight.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CA000484498A CA1211481A (en) | 1985-06-19 | 1985-06-19 | Weighing module |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CA000484498A CA1211481A (en) | 1985-06-19 | 1985-06-19 | Weighing module |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| CA1211481A true CA1211481A (en) | 1986-09-16 |
Family
ID=4130759
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CA000484498A Expired CA1211481A (en) | 1985-06-19 | 1985-06-19 | Weighing module |
Country Status (1)
| Country | Link |
|---|---|
| CA (1) | CA1211481A (en) |
Cited By (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| FR2625315A1 (en) * | 1987-12-24 | 1989-06-30 | Largenton Jean Luc | VEHICLE WEIGHING DEVICE |
-
1985
- 1985-06-19 CA CA000484498A patent/CA1211481A/en not_active Expired
Cited By (2)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| FR2625315A1 (en) * | 1987-12-24 | 1989-06-30 | Largenton Jean Luc | VEHICLE WEIGHING DEVICE |
| EP0323293A1 (en) * | 1987-12-24 | 1989-07-05 | S.A. Pic | Apparatus for weighing vehicles |
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| MKEX | Expiry |