CN102538936B - Calibration device of large weighing apparatus - Google Patents

Abstract

The invention provides a verification device for a large-scale weighing instrument, which includes a verification unit at least in accordance with the number of load cells of the measured weighing device and a foundation for supporting each verification unit, and a foundation for accommodating the measured weighing device pit, and foundation embedded boards are respectively set on the foundations on both sides of the foundation pit; each verification unit includes a base, a force sensor, a booster lever, a lever support, a booster cylinder, and a pair The ball head pressure pad placed on the force sensor, the pressure plate is placed on the weighing platform of the measured instrument, one end of the lever support is fixedly connected with the foundation embedded plate, and the other end of the lever support is pivotally connected to the afterburner As for the lever, one end of the booster lever is located above the ball head pressure pad and is in contact with the ball head pressure pad, and the other end of the booster lever is connected with the piston of the booster cylinder through a support rod. The invention has the advantages of not only greatly improving the work efficiency and safety of verifying large weighing instruments, saving costs, but also having a simple structure.

Description

A verification device for a large weighing instrument

【Technical field】

The invention relates to a device in the technical field of metrology verification, in particular to a verification device for a large weighing instrument.

【Background technique】

Fixed electronic scales are currently the most mature weighing and measuring instruments in the world. They are measuring instruments with a large quantity and a wide range. The process control of trade settlement and weighing process in the production process is an ideal measurement equipment for enterprises to improve the modernization level of weighing measurement. The working principle of the fixed electronic scale is to place the object to be weighed or the truck on the scale platform. Under the action of gravity, the scale platform transmits the gravity to the swing support (steel ball, pressure head, etc.), so that the elastic body of the load cell produces Deformation, the strain gauge bridge attached to the elastic body loses balance, outputs an electrical signal proportional to the weight value, the signal is amplified by a linear amplifier, and then converted into a digital signal by A/D, and then the microprocessor of the instrument After the signal is processed, the weight number is displayed directly.

Fixed electronic weighing instruments must be calibrated before they are actually put into use to determine their accuracy level. In addition, after a period of use or replacement of components, large scales must be calibrated again to confirm their accuracy level so that they can be adjusted accordingly. meet the accuracy requirements. There are mainly three types of standard devices for the verification of fixed electronic weighing instruments. The national standard for fixed electronic weighing instruments with the standard number GB7723-2008 (this standard adopts the international recommendation OIML R76 "Non-automatic Weighing Instruments" (2006E)) clearly states that The following three kinds of verification standards are allowed: one is weight, specifically refers to standard weight or standard mass; It is a standard weight for verification, specifically referring to some standard weights and other arbitrary fixed loads instead of standard weights.

However, in the JJG539-1997 "Digital Indicating Scale" verification regulations, it is stipulated that the standard used for the verification of weighing instruments is: 1. It is a standard weight, 2. It is a standard weight and "a substitute for a standard weight". Therefore, the standard instruments used in the verification of fixed electronic weighing instruments in our country are standard weights or standard weights and their substitutes, and no auxiliary verification device is used as a standard to verify fixed weighing instruments. In the R76 "Non-automatic Weighing Instrument" international proposal and the national standard GB7723-2008 for stationary electronic weighing instruments, only the following provisions are made on the auxiliary verification device: if the weighing instrument is equipped with an auxiliary verification device, or when a separate auxiliary device is used for verification, the maximum The allowable error should be 1/3 of the maximum allowable error of the tested load. What kind of "auxiliary verification device" is, it is not mentioned in the international proposal and GB7723-2008 standard, only the maximum allowable error of "auxiliary verification device" is stipulated. So far, there are few literatures in the country or in the world about the use of "independent auxiliary verification device" for on-site verification of large-tonnage fixed electronic weighing instruments.

The Chinese patent No. on February 17th, 1988 on the date of publication is CN86105843, and its patent name is the invention patent of "Verification Device for Truck Scale and Rail Scale" which discloses a non-weight type verification device, but the quasi- It is impossible for the accuracy of the pressure gauge to meet the accuracy requirements of this type of weighing instrument verification. The Chinese patent number of January 22, 2003 on the date of announcement is CN02230837.7, and its new patent titled "Large Weighing Apparatus Calibration Apparatus" also discloses a non-weight type weighing apparatus verification apparatus. It consists of sensor, display instrument, pressure device and pressure support. The pressure support is integrated with the base of the scale to be verified. The pressure device is fixed on the pressure support. The measurement accuracy of the verification load cell and display instrument is greater than that The measurement accuracy of the weighing instrument is verified by placing the load cell on the scale body of the scale that needs to be verified, the verification load cell and the pressure device are connected through a sphere, and the output of the verification load cell is connected to the display instrument. The pressure of the pressure device is applied to the load cell, which is displayed by the display instrument, and the pressure is simultaneously applied to the scale body of the weighing instrument to be verified, and displayed by the instrument of the weighing instrument, and the measurement of the verified weighing instrument can be determined by comparing their displayed values error, but the verification device can only verify the load cells used in the weighing instrument one by one, and the verification device is actually a superimposed force standard machine. However, the pressure device and the pressure support in this device are manually loaded, which cannot meet the load fluctuation (force source stability) in the "JJG734-2001 Force Standard Machine Verification Regulation" and "JJG144-2007 Standard Force Meter Verification Regulation" , Force value stable maintenance time requirements. The verification range only uses the load value of each weighing sensor in the weighing instrument, not the full scale of the weighing instrument, because the measurement accuracy of the weighing instrument is not only related to the accuracy of each weighing sensor, but also related to the stiffness of the weighing platform, the scale It is related to the foundation of the platform, the accuracy of the instrument, and the junction box. That is to say, the weighing sensor used in the weighing instrument is qualified, but the measurement performance of the weighing instrument is not necessarily qualified. Therefore, it is not a comprehensive verification of the measurement performance of the weighing instrument. During the verification process, the deflection of the weighing platform, the foundation of the weighing platform, the accuracy of the instrument, and the influence of the junction box on the accuracy of the weighing instrument must be considered, because only at the load cell Therefore, the verification process cannot simulate the actual weighing state, so the verification device only performs an approximate analog comparison of the weighing sensor used in the weighing instrument, and the most important thing is that it cannot directly perform the verification on the weighing instrument.

At present, the verification methods for fixed electronic scales in the country are as follows: Take the verification of 100 tons of fixed electronic truck scales as an example, according to the national standard of GB7723-2008 fixed electronic scales or the requirements of the verification regulations of JJG539-1997 "Digital Indicator Scale", the standard Weights and "substitutes for standard weights" for verification. Among them, as shown in Figure 1, what needs to be explained is a fixed electronic truck scale 2' with a specification of 100 tons, three sections with a total length of 18 meters, e=50kg, m=2000, including a scale display instrument 21', including three scales The platform, numbered 211', 212', 213', adopts eight load cells, numbered 231'-238', and includes eight load cell support points above each load cell, numbered respectively 241'-248', a corresponding eccentric load test area is divided around each load cell support point, as shown in the dotted line box in Figure 1, numbered 251'-258' respectively, when verifying, the standard weight or The substitute 3' of the standard weight is placed in each of the above-mentioned partial load test areas to carry out the partial load test one by one. The specific metrological performance verification process is as follows:

1. Preloading: Preload the load once to 100t, or use a load vehicle of not less than 50t to go back and forth through the carrier for no less than 3 times;

2. The accuracy of zero setting and tare removal device;

3. Zero setting before loading;

4. Weighing performance:

4.1 When using standard weights and substitutes for verification, perform repeatability tests on scales to confirm the amount of standard weights: first check the repeatability of the 50t weighing point, and apply 50t standard weights on the carrier for 3 times, if the repeatability error Not greater than 0.3e, the standard weight 3' can be reduced to 35% of the maximum capacity; if the repeatability error is not greater than 0.2e, the standard weight 3' can be reduced to 20% of the maximum capacity;

4.2 Weighing test: add weights or substitutes from 3' to 100t in ascending order from zero, unload the weights to zero in the same way, at least 1t, 25t, 50t, 75t, 100t should be selected for the test check point;

4.3 Tare weighing test: At least 2 different tare weights should be tested for tare weighing, according to 4.2, the test points are: 1t, 50t, the scale with the maximum allowable error change, the possible maximum net weight value, and 80t five check point;

4.4 Eccentric load test: use 14t standard weight 3' to test in 8 eccentric load test areas 251'-258' in turn until the indication error of 251'-258' in 8 eccentric load test areas is satisfied No more than 50kg;

4.5 Identification test: test at 1t, 50t, 100t weighing points, simultaneously during the verification process;

4.6 Repeatability test: Carry out two groups of tests at 50t weighing capacity and near maximum weighing capacity (90t), and repeat at least 3 times for each group.

In the above verification process, the tonnage of weights or substitutes to be transported: 1. 100t needs to be transported in the above preloading process; 2. When using standard weights and substitutes in the above 4.1 for verification, it is necessary to confirm the standard weight. 150t is required for the repeatability test of the scale; 3. 100t is required for the weighing test in 4.2 above; 160t is required for the tare weighing test in 4.3 above; 112t is required for the partial load test in 4.4 above; 6. The repeatability test in 4.6 above needs to carry 270t.

Therefore, the verification method of using standard weights or standard weights and substitutes to verify fixed electronic weighing instruments has the following disadvantages:

1. The verification workload is huge and the efficiency is extremely low. A qualified 100t fixed electronic truck scale needs to move a total of 932t of weights and substitutes. If it is unqualified, it should be adjusted. Substitutes amount to thousands of tons or more;

2. The safety of carrying a large amount of weights or substitutes is extremely poor. Due to the limited loading table area of the electronic truck scale (such as 100 tons, the table area is only 54 square meters), it is very difficult to stack 100 tons of weights or substitutes on the limited area. very dangerous;

3. Substitutes are hard to find. Not every user of large electronic truck scales can provide suitable substitutes. For example, it is difficult to find suitable substitutes for fair scales installed beside roads, railways, ports, poisonous liquids, gas chemical enterprises, textile factories, coal mines, etc. It is also difficult for users to provide suitable substitutes;

4. Standard weights are difficult to transport. For the verification of a 100-ton truck scale, at least 50 tons of standard weight must be transported; for the verification of a 150-ton truck scale, at least 75 tons of standard weight must be transported. At present, only about 15 tons of weights can be transported in China at one time, especially in mountainous areas, where there are dangerous bridges, roads, and terrains, and installation in ravines (such as mines) will limit the weights once. transport volume;

5. The cost is extremely high. Transporting and handling so many standard weights or substitutes requires many weighing trucks and cranes, and the verification takes several days (it usually takes 7 working days to inspect a 100-ton truck scale) and the cooperation of multiple people to complete the verification work .

To sum up, most of the county-level, city-level and provincial-level measurement and verification units do not have enough standard weights for the verification of large scales (such as 150 tons of electronic truck scales); even if there are enough standard weights, the weight The safety of loading and unloading, transporting weights, and transportation costs cannot be guaranteed under the existing technical conditions; secondly, even if the weights are transported to the site, if the verification is carried out according to the verification regulations of JJG539-1997 "Digital Indicating Scale", its The verification workload is huge, and the verification takes too long, so it cannot be guaranteed to be carried out according to the verification regulations. It can be seen that when verifying large-scale fixed electronic weighing instruments, the verification method of standard weights or standard weights and substitutes needs to be improved.

【Content of invention】

The technical problem to be solved by the present invention is to provide a verification device for large scales with a simple structure, which can greatly improve the work efficiency and safety of the verification of large scales and save costs.

The present invention solves the above-mentioned technical problems through the following technical solutions: a verification device for a large-scale weighing instrument, comprising at least the same number of verification units as the load cells of the weigher under test and a base for supporting each verification unit, the base There is a foundation pit for accommodating the weighing apparatus under test, and foundation embedded boards are respectively arranged on the foundations on both sides of the foundation pit; each verification unit includes a base fixed on the foundation embedded board, a A force sensor arranged on a pressure bearing plate, a booster lever, a lever support, a booster oil cylinder set on the base, and a pair of ball head pressure pads placed on the force sensor, the described The pressure bearing plate is placed on the weighing platform of the weighing instrument under test, one end of the lever support is fixedly connected to the foundation embedded plate, and the other end of the lever support is pivotally connected to the booster lever, and one end of the booster lever Located above and in contact with the ball head pressure pad, the other end of the booster lever is connected with the piston of the booster cylinder through a support rod.

Further, the other end of the lever support is pivotally connected to the middle part of the booster lever.

The beneficial effect of the verification device of a large-scale weighing apparatus of the present invention is that: adopting the verification device to verify a large-scale weighing apparatus can solve the problem of using standard weights or standard weights and substitutes or other non-weight type weighing apparatus verification devices in the prior art. When verifying fixed electronic scales, there are various problems such as huge verification workload, time-consuming and labor-consuming verification, cumbersome verification process, and insufficient accuracy, which can greatly improve the work efficiency and safety of the verification, and save costs. In addition, the The verification device has the characteristics of simple structure.

【Description of drawings】

The present invention will be further described below with reference to the accompanying drawings and embodiments.

Fig. 1 is a schematic diagram of a weighing instrument using standard weights or standard weights and substitutes in the prior art.

Fig. 2 is a front view of a verification device of a large scale weighing apparatus according to the present invention when it is applied.

Fig. 3 is a top view (with the foundation removed) of a large-scale weighing instrument verification device of the present invention in application.

Fig. 4 is a schematic diagram of the testing unit in the present invention.

Fig. 5 is a schematic diagram of the three-dimensional structure of the force sensor (without the shell) in the present invention.

Fig. 6 is a cooperation diagram of the thrust joint bearing of the force sensor in the present invention, the upper pressure bearing plate and the pressure equalizing plate.

Fig. 7 is a working principle diagram of the force sensor in the present invention.

【Detailed ways】

Please refer to Fig. 2 and Fig. 4 in combination, a verification device 100 for a large-scale weighing instrument according to the present invention, including a verification unit 101 at least consistent with the number of load cells 201 of the weighing device 200 under test and a foundation 102 for supporting each verification unit , the foundation 102 is provided with a foundation pit 1021 for accommodating the measuring instrument 200, and the foundation 102 on both sides of the foundation pit 1021 is respectively provided with foundation embedded boards 1022; each verification unit 101 includes a fixed A base 1011 on the foundation embedded plate 1022, a force sensor 1013 on a pressure bearing plate 1012, an afterburner bar 1014, a lever support 1015, and an afterburner cylinder on the base 1011 1016, and a ball head pressure bearing pad 1017, the pressure bearing plate 1012 is placed on the weighing platform 202 of the weighing instrument 200 under test, and one end 10151 of the lever support 1015 is fixedly connected with the foundation embedded plate 1022, and the lever The other end 10152 of the support 1015 is pivotally connected to the booster lever 1014. One end 10141 of the booster lever 1014 is located above the ball head pressure pad 1017 and is in contact with the ball head pressure pad 1017. The other end 10141 of the booster lever 1014 One end 10142 is connected to the piston 10161 of the booster cylinder 1016 through a support rod 1018; the ball head pressure pad 1017 is centered on the force sensor 1013, specifically, the longitudinal axis of the ball head pressure pad 1017 is aligned with the force sensor 1013 The longitudinal axis of the force sensor 1013 should meet the requirements of the range of coaxiality, so that the force axis of the force sensor 1013 is basically consistent with the axis of the force sensor 1013 itself, thereby ensuring the accuracy of the measurement of the force sensor 1013; in addition, in this embodiment, the verification unit The number of 101 is consistent with the number of load cells 201 of the weighing apparatus 200 under test.

In order to conveniently and quickly obtain the magnitude of the force generated by the booster cylinder 1016 through the booster lever 1014 on the ball head pressure pad 1017, the other end 10152 of the lever support 1015 is pivotally connected to the middle of the booster lever 1014 , at this time, after the oil circuit is connected, the booster cylinder 1016 promotes the upward movement of the piston 10161, and the piston 10161 makes the other end 10142 of the booster lever 1014 receive an upward force F ₁ through the support rod 1018. According to the principle of leverage, the booster One end 10141 of the lever 1014 will exert a downward force F ₂ on the ball bearing block, and the value of F ₂ is equal to the value of F ₁ .

Please refer to Fig. 2 and Fig. 3 in combination. When the verification device of the present invention is applied, take the verification of the truck scale 200 including 8 load cells 201 as an example to illustrate: the truck scale 200 is placed in the foundation pit 1021, because each weigher A corresponding eccentric load test area (not shown) is divided on the weighing platform 202 above the heavy sensor 201, and each eccentric load test area is correspondingly installed with a verification device 100 of the present invention (as shown in FIG. 3 ), and according to Install as shown in Figure 2, and in the specific installation process, the pressure bearing plate 1012 needs to be placed in the center of the eccentric load test area; then set the control quality value of the afterburner cylinder 1016, and then open the oil pressure of the afterburner cylinder 1016 The booster cylinder 1016 promotes the upward movement of the piston 10161, and the piston 10161 makes the other end 10142 of the booster lever 1014 receive an upward force F ₁ through the support rod 1018. According to the principle of leverage, one end 10141 of the booster lever 1014 will be applied to the ball The downward force F ₂ of the pressure bearing block on the head causes the force sensor 1013 to bear the force and display the corresponding weight value; at the same time, the pressure bearing plate 1012 bears a load equal to the force value of F ₂ , since the pressure bearing plate 1012 is placed on the vehicle On the weighing platform 202 platform of the weighing apparatus 200, the weighing platform 202 platform of the automobile weighing instrument 200 is subjected to a downward force load (equivalent to the weight value of the goods) with the same magnitude as _F2 , and the weight value is displayed through the load cell 201; until When the display value of the force sensor 1013 reaches the mass value set by the booster cylinder 1016, the difference between the weight value displayed by the load cell 201 of the truck scale 200 and the display value of the force sensor 1013 is the measurement error value of the truck scale 200 .

In addition, in order to solve the problem that the existing force sensor is prone to deviation of the detection value caused by the working deformation of the upper pressure bearing plate and the centering error of the measured object, the force sensor 1013 of the present invention adopts the structure shown in Figure 5 .

Please refer to Fig. 5 in detail, the force sensor 1013 includes a display instrument (not shown), a lower pressure bearing plate 1, a sensor group 2 composed of three sensors 21 arranged at 120°, and a sensor group 2 above the sensor group 2. The upper pressure receiving plate 3 , a pressure equalizing plate 4 erected on the sensor group 2 , and three thrust joint bearings 5 respectively arranged above the three sensors 21 and between the pressure equalizing plate 4 and the upper pressure receiving plate 3 . The display instrument (not shown) is connected with the sensor group 2; the sensor group 2 is placed on the lower pressure bearing plate 1, and each sensor 21 is positioned and connected with the lower pressure bearing plate 1 and the pressure equalizing plate 4. Each sensor 21 contains an elastic body 211 and a centering adjustment pressure head 212 that are floatingly connected to each other; the elastic body 211 is inserted in a housing 213, and the upper surface of the elastic body 211 is a first Curved surface 2111; the centering adjustment pressure head 212 is positioned and connected with the pressure equalizing plate 4, that is, each of the sensors 21 is positioned and connected with the pressure equalizing plate 4 through the corresponding centering adjustment pressure head 212, and the centering adjustment pressure head 212 is positioned and connected The bottom surface is provided with a first groove 2121 matching the first curved surface 2111 ; the longitudinal axes of the centering adjustment pressure head 211 and the elastic body 212 coincide.

Please refer to FIG. 5 and FIG. 6 together, each of the thrust joint bearings 5 is fixedly connected with the upper pressure bearing plate 3 , and each of the thrust joint bearings 5 is fixedly connected with the pressure equalizing plate 4 . The longitudinal axis of each thrust joint bearing 5 coincides with the longitudinal axis of the corresponding sensor 21; each thrust joint bearing 5 contains a ball head 51 and a ball seat 52 that are floatingly connected to each other; the ball head 51 passes through A connector 6 is positioned and connected with the upper pressure bearing plate 3, and the bottom surface of the ball head 51 is a second curved surface 511; the ball seat 52 is fixedly connected with the pressure equalizing plate 4, and the upper surface of the ball seat 52 is provided with a The second groove 521 matched with the second curved surface 511 ; the longitudinal axes of the ball head 51 and the ball seat 52 coincide.

Please refer to FIG. 5 and FIG. 7 in conjunction. In order to clearly and conveniently explain the principle of the force sensor 1013 in the present invention, the applicant places three sensors 21 on the same straight line, as shown in FIG. 7, and in FIG. , the applicant relabeled the thrust spherical plain bearing 5 and the middle adjusting pressure head 212 in FIG. N. Thrust joint bearing R, the middle adjustment pressure head 212 will be marked as middle adjustment pressure head M', middle adjustment pressure head N', and middle adjustment pressure head R' from right to left. Among them, thrust joint bearing M, thrust joint bearing N, thrust joint bearing R, centering adjustment pressure head M', centering adjustment pressure head N', centering adjustment pressure head R', upper pressure bearing plate 3 and pressure equalizing plate 4 That constitutes the Robwell Agency. Since each ball head 51 and the corresponding ball seats 52 are in curved surface contact, and each centering adjustment pressure head 212 (see Figure 5) is also in curved surface contact with the corresponding elastic bodies 211, so the thrust joint bearing M and thrust Joint bearing N, thrust spherical joint bearing R, centering adjusting pressure head M', centering adjusting pressure head N', and centering adjusting pressure head R' always form two parallelograms with the same size and shape, respectively parallelogram MM'N 'N and the parallelogram NN'R'R. When the force sensor 1013 bears the load F, the load F is distributed and acts on the top of the three elastic bodies 211. If the load F is unevenly distributed, asymmetrical or the upper pressure bearing plate 3 is deformed, the upper pressure bearing plate 3 will be inclined, and thus With the above-mentioned curved surface contact, no matter how inclined the upper bearing plate 3 is, MM' and RR' are parallel to NN' respectively, so that the working deformation of the upper bearing plate 3 and the centering error of the measured object (not shown) can be effectively reduced Detection errors caused by eccentric loads and inclined loads occur. When the distributed load on the upper bearing plate 3, that is, the component force F ₃ is at a position d away from the elastic body 211, there is a force equal to and in the same direction as F ₃ acting on the thrust joint bearing M and the centering adjustment pressure head M', at this time, there is a torque with a value of F ₃ ·d acting between MM', so that the thrust joint bearing M is pulled to the right at M, and the centering pressure head M' is adjusted at M' Push to the left, but due to the limitation of NN' (that is, the thrust joint bearing N and the centering adjustment pressure head N'), the thrust joint bearing M and the centering adjustment pressure head M' will respectively have the same size and direction Opposite reaction force f ₃ , f ₃ ′, thus forming a reverse torque equal to F ₃ ·d with the value of f ₃ ·s (or f ₃ ′·s) (s is the action of f ₃ and f ₃ ′ The lateral distance between the points), the result F ₃ ·d torque is balanced by f ₃ ·s (or f ₃ ′·s), and finally, only the F _3. Forces of equal size and same direction act, regardless of the eccentric position and eccentric distance. Similarly, this situation occurs on the thrust joint bearing N and the centering adjustment pressure head N', the thrust joint bearing R and the centering adjustment pressure head R' is also exactly the same. Therefore, when a load F, that is, an active force F, is applied to the force sensor 1013, no matter whether it is rotated or the installation state of the force sensor 1013 is changed, the display (not shown) shows that the difference between the two values before and after is very small, so the force sensor 1013 has Good rotation effect, that is, the reproducibility of the detection value is good.

In summary, the verification device 100 for a large weighing instrument of the present invention does not need to use standard weights or standard weights and substitutes to load and unload large weighing instruments. , and can greatly improve the work efficiency and safety of the test, and save costs; in addition, the improvement of the force sensor 1013 in the present invention can effectively improve the accuracy of its detection and indication, and solve the problem of being deformed by the upper pressure plate due to work. The problem of the deviation of the detected indication value caused by the centering error of the measuring sensor.

In addition, although the verification of truck scales is taken as an example in the present invention, the verification device of the present invention is not limited to the verification of truck scales, and can be used for the verification of large fixed electronic scales with various uses and structures.

Claims (2)

1. A verification device for a large-scale weighing instrument, comprising at least a verification unit consistent with the number of load cells of the measured weighing instrument and a foundation for supporting each verification unit, characterized in that: the foundation is provided with a set for accommodating The foundation pit of the weighing instrument to be tested, and the foundation on both sides of the foundation pit are respectively equipped with foundation embedded boards; each verification unit includes a base fixed on the foundation embedded board, a base on a pressure bearing plate The force sensor, a booster lever, a lever support, a booster cylinder on the base, and a pair of ball head pressure pads placed on the force sensor, the pressure plate is placed on the measured On the weighing platform of the weighing instrument, one end of the lever support is fixedly connected to the foundation embedded plate, and the other end of the lever support is pivotally connected to the booster lever, and one end of the booster lever is located above the ball head pressure pad And contact with the ball head pressure pad, the other end of the booster lever is connected with the piston of the booster cylinder through a support rod. 2. A verification device for a large weighing instrument according to claim 1, characterized in that: the other end of the lever support is pivotally connected to the middle part of the booster lever.

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