Loading plate counterweight mechanism and multi-component force sensor metering test device

Abstract

The utility model provides a loading plate counterweight mechanism and a multi-component force sensor metering test device. The loading plate counterweight mechanism comprises a main structure frame, a loading plate assembly, a counterweight ring block, a connecting rope and a plurality of pulleys, the main structure frame comprises a bottom plate, a top plate and a plurality of stand columns, the stand columns are installed between the bottom plate and the top plate, the pulleys are installed on the upper surface of the top plate, the connecting rope is wound around the pulleys, and the two ends of the connecting rope are connected with the counterweight ring block and the loading plate assembly respectively; and the weight of the counterweight ring block is consistent with that of the loading plate assembly. According to the utility model, the weight of the loading plate assembly can be balanced through the counterweight ring block, so that the multi-component force sensor can start measurement from a position near an actual zero position, and the measurement accuracy is improved.

Description

Technical Field

[0001] The utility model relates to the technical field of measurement and detection, in particular to a loading plate counterweight mechanism and a multi-component force sensor measurement and testing device. Background Art

[0002] Multi-component force sensors are sensors that can measure forces and torques in multiple directions at the same time, and are widely used in the fields of mechanical testing and quality control in industrial production. For example, six-dimensional force sensors can measure forces and torques in three orthogonal directions in real time.

[0003] For the value traceability of multi-component force sensors, existing metrological testing devices usually use a loading plate to connect to the sensor under test in order to facilitate accurate force application on the sensor under test. However, the gravity of the loading plate makes it impossible to start measurement from near the actual force value zero of the sensor, affecting the measurement accuracy. Utility Model Content

[0004] In order to overcome the above-mentioned deficiencies of the prior art, the purpose of the utility model is to provide a loading plate counterweight mechanism and a multi-component force sensor measurement and testing device.

[0005] In order to achieve the above-mentioned purpose, the technical solution adopted by the utility model to solve its technical problems is: a loading plate counterweight mechanism, including a main structure frame, a loading plate assembly, a counterweight ring block, a connecting rope and a plurality of pulleys, the main structure frame including a bottom plate, a top plate and a plurality of columns, the columns are installed between the bottom plate and the top plate, the pulley is installed on the upper surface of the top plate, the connecting rope is wound around the pulley, and the two ends of the connecting rope are respectively connected to the counterweight ring block and the loading plate assembly, and the weight of the counterweight ring block is consistent with the weight of the loading plate assembly.

[0006] Furthermore, the loading plate assembly includes a horizontal loading plate, a loading vertical plate and a Z-direction loading seat. The central position of the lower surface of the horizontal loading plate is fixedly connected to the upper surface of the multi-component force sensor to be tested. The horizontal loading plate is square. A vertically installed loading vertical plate is provided in the middle of each edge of the upper surface of the horizontal loading plate and in the middle of each edge of the lower surface. A loading point seat is provided at the end of each loading vertical plate. A loading point seat is installed in the center of each side of the horizontal loading plate. Loading point seats are respectively installed at the two ends of the two side surfaces of the horizontal loading plate perpendicular to the X-axis. The Z-direction loading seat is installed at the central position of the upper surface of the horizontal loading plate.

[0007] Furthermore, positioning seats are respectively installed at both ends of the two side surfaces of the horizontal loading plate that are perpendicular to the Y-axis.

[0008] Furthermore, the surface of the horizontal loading plate is in a square shape, and the surface of the counterweight ring block is in a circular ring shape.

[0009] Furthermore, the number of the pulleys is 4, and one end of the connecting rope on each of the 4 pulleys is respectively connected to the 4 corners of the horizontal loading plate.

[0010] Furthermore, the loading vertical plate includes a base plate portion, a vertical panel portion and a rib plate portion, the base plate portion is fitted and connected to the upper surface or lower surface of the horizontal loading plate, the vertical panel portion and the rib plate portion are vertically extended from the surface of the base plate portion, and the rib plate portion is vertically connected to the back side of the vertical panel portion.

[0011] Furthermore, the Z-direction loading seat includes a lower connecting plate, a connecting column and an upper connecting plate, the lower connecting plate is connected to the central position of the upper surface of the horizontal loading plate, the connecting column is connected between the lower connecting plate and the upper connecting plate, a Z-direction loading point seat is provided in the center of the upper surface of the lower connecting plate, and a connecting hole penetrating from top to bottom is provided in the center of the upper connecting plate.

[0012] A multi-component force sensor measurement and testing device comprises the above-mentioned loading plate counterweight mechanism, and the multi-component force sensor to be tested is fixedly connected to the loading plate assembly.

[0013] By adopting the technical solution of the utility model, the weight of the loading plate assembly can be balanced by the counterweight ring block, so as to help the multi-component force sensor to start measurement from the vicinity of the actual zero position, thereby improving the measurement accuracy. BRIEF DESCRIPTION OF THE DRAWINGS

[0014] In order to more clearly illustrate the embodiments of the utility model or the technical solutions in the prior art, the drawings required for use in the embodiments or the description of the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the utility model. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying creative work.

[0015] Figure 1 It is a structural schematic diagram of an implementation manner of the multi-component force sensor measurement and testing device of the utility model.

[0016] Figure 2 is a schematic diagram of the structure of the loading plate assembly.

[0017] Figure 3 is a schematic diagram of the structure of the bottom surface of the loading plate assembly.

[0018] Figure 4 It is a structural schematic diagram of the lateral force source component.

[0019] Figure 5 It is a schematic diagram of the structure of a multi-component force sensor to be tested.

[0020] Figure 6It is a schematic diagram of the structure of the upper and lower connecting plates of the multi-component force sensor to be tested.

[0021] Figure 7 It is a schematic diagram of the structure of the fixture.

[0022] Figure 8 It is a structural diagram of the counterweight mechanism.

[0023] Fig. 9 It is a cross-sectional view of the counterweight mechanism.

[0024] Fig.10 It is a schematic diagram of 17 force sources of the utility model.

[0025] The numbers and letters in the figure represent the names of the corresponding parts:

[0026] 10-main structure frame; 11-bottom plate; 12-top plate; 13-column; 20-sensor fixture assembly; 21-fixture; 211-fixture block; 212-inverted T-shaped long groove; 213-door-shaped groove; 214-upper strip positioning groove; 22-lifting plate; 221-lower strip positioning groove; 23-lifting drive mechanism; 231-reduction motor; 232-transmission chain; 233-screw column; 234-nut; 30-loading plate assembly; 31-horizontal loading plate; 311-material reduction trough; 32-loading vertical plate; 321-base plate; 322-vertical panel; 323-rib plate; 33-Z-direction loading seat; 331-lower connecting plate; 332-connecting column; 333-upper connecting plate; 33 4-Z-direction loading point seat; 335-connecting hole; 34-loading point seat; 35-positioning seat; 36-sensor upper connecting plate; 40-lateral force source assembly; 41-force source lateral mounting bracket; 421 / 422 / 423 / 424 / 425 / 426 / 427 / 428 / 429 / 430 / 431 / 432 / 433 / 434 / 435 / 436-lateral force source; 44-loading plate positioning mechanism; 441-reciprocating drive mechanism; 442-guide column; 443-end plate; 444-positioning shaft; 50-Z-direction force source; 60-counterweight mechanism; 61-counterweight ring block; 62-pulley; 63-connecting rope; 71-sensor lower connecting plate; 72-multi-component force sensor. DETAILED DESCRIPTION

[0027] The following will be combined with the drawings in the embodiments of the utility model to clearly and completely describe the technical solutions in the embodiments of the utility model. Obviously, the described embodiments are only part of the embodiments of the utility model, not all of the embodiments. Based on the embodiments of the utility model, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the utility model.

[0028] like Figure 1 , 8 As shown in Figure 9, a loading plate counterweight mechanism includes a main structure frame 10, a loading plate assembly 30, a counterweight ring block 61, a connecting rope 63 and a plurality of pulleys 62. The main structure frame 10 includes a bottom plate 11, a top plate 12 and a plurality of columns 13. The columns 13 are installed between the bottom plate 11 and the top plate 12. The pulley 62 is installed on the upper surface of the top plate 12. The connecting rope 63 is wound around the pulley 62. The two ends of the connecting rope 63 are respectively connected to the counterweight ring block 61 and the loading plate assembly 30. The weight of the counterweight ring block 61 is consistent with the weight of the loading plate assembly 30.

[0029] like Figure 1-10 As shown, one embodiment of the utility model is: a multi-component force sensor measurement and testing device, comprising:

[0030] The main structure frame 10 includes a bottom plate 11, a top plate 12 and a plurality of columns 13, wherein the columns 13 are installed between the bottom plate 11 and the top plate 12;

[0031] The sensor fixture assembly 20 includes a fixture 21, a lifting plate 22 and a lifting drive mechanism 23. The fixture 21 is used to fix and install the multi-component force sensor 72 to be tested. The fixture 21 is installed on the lifting plate 22. The lifting plate 22 is installed on the column 13 in a liftable manner. The lifting drive mechanism 23 is used to drive the lifting plate 22 to move up and down along the column 13.

[0032] The loading plate assembly 30 includes a horizontal loading plate 31, a loading vertical plate 32 and a Z-direction loading seat 33. The horizontal loading plate 31 is located above the lifting plate 22. The central position of the lower surface of the horizontal loading plate 31 is fixedly connected to the upper surface of the multi-component force sensor 72 to be detected. The horizontal loading plate 31 is square. A vertically installed loading vertical plate 32 is provided in the middle of each side of the upper surface of the horizontal loading plate 31 and in the middle of each side of the lower surface. A loading point seat 34 is provided at the end of each loading vertical plate 32. A loading point seat 34 is installed in the center of each side of the horizontal loading plate 31. The loading point seats 34 are respectively installed at the two ends of the two side surfaces of the horizontal loading plate 31 perpendicular to the X-axis. Positioning seats 35 are respectively installed at the two ends of the two side surfaces of the horizontal loading plate 31 perpendicular to the Y-axis. The Z-direction loading seat 33 is installed at the central position of the upper surface of the horizontal loading plate 31.

[0033] The lateral force source assembly 40 includes a force source lateral mounting frame 41, a lateral force source and a loading plate positioning mechanism 44. The force source lateral mounting frame 41 includes four lateral mounting plates fixedly mounted on the column. The four lateral mounting plates are respectively arranged parallel to and opposite to the four side surfaces of the horizontal loading plate 31. An upper mounting plate extending vertically upward and a lower mounting plate extending vertically downward are arranged in the middle of each lateral mounting plate. A lateral force source 421 / 422 / 423 / 424 / 425 is installed on the force source lateral mounting frame 41 on the positive side of the X-axis, and a lateral force source 429 / 430 is installed on the negative side of the X-axis. / 431 / 432 / 433, a lateral force source 434 / 435 / 436 is installed on the positive side of the Y axis on the force source lateral mounting frame 41, and a lateral force source 426 / 427 / 428 is installed on the negative side of the Y axis, each lateral force source corresponds to and matches a loading point seat on the loading plate assembly, and the force applied by the lateral force source to each loading point seat is thrust; two retractable loading plate positioning mechanisms 44 are respectively installed on the positive side of the Y axis and the negative side of the Y axis on the force source lateral mounting frame 41, and each loading plate positioning mechanism 44 corresponds to and matches a positioning seat 35 on the loading plate assembly;

[0034] A Z-direction force source 50, which is fixedly mounted on the top plate 12, and the Z-direction force source 50 matches the Z-direction loading seat 33;

[0035] The counterweight mechanism 60 includes a counterweight ring block 61 and a plurality of pulleys 62 . The pulleys 62 are mounted on the upper surface of the top plate 12 . The counterweight ring block 61 is connected to the horizontal loading plate 31 via a connecting rope 63 . The weight of the counterweight ring block 61 is consistent with the weight of the loading plate assembly 30 .

[0036] Combination Figure 2 , 4 As shown in 10, lateral force source 430 applies a positive force on the X-axis, lateral force source 423 applies a negative force on the X-axis, lateral force source 427 applies a positive force on the Y-axis, lateral force source 435 applies a negative force on the Y-axis, lateral force source 434 and lateral force source 428 generate a negative moment around the X-axis, lateral force source 436 and lateral force source 426 generate a positive moment around the X-axis, lateral force source 431 and lateral force source 422 generate a positive moment around the Y-axis, lateral force source 429 and lateral force source 424 generate a negative moment around the Y-axis, lateral force source 425 and lateral force source 433 generate a positive moment around the Z-axis, and lateral force source 421 and lateral force source 432 generate a negative moment around the Z-axis. The device of the utility model can realize any combination and synchronous calibration of the components of the multi-component force sensor, and can even load three forces and three torques in space at the same time, and accurately measure the coupling error index between the components, which is also the most important technical index of the multi-component force sensor.

[0037] The beneficial effects of the above technical solution are: the use of an integrated loading plate assembly formed by a horizontal loading plate, a Z-direction loading seat and a plurality of loading vertical plates, the arm structure is stable, and it is convenient to apply 17 force sources to the multi-component force sensor to be tested. For the positive and negative force values ​​in the X, Y, and Z axes, the force values ​​can be directly applied in the corresponding directions; for the positive and negative torques in the X, Y, and Z axes, the force couple torque can be applied in two directions with a certain distance, with a 180° force source, to eliminate the influence of the lateral force on the torque indication. The lateral force source applies thrust, and the lateral force source and the corresponding loading point seat can be automatically connected and disconnected. The lateral force source that does not apply force does not affect the force, thereby improving the detection accuracy. The components of the utility model device are applied independently and do not affect each other, achieving the effect of hardware decoupling, and the accuracy of the device can also be verified by metrological verification. The loading plate positioning mechanism can temporarily position the horizontal loading plate during the installation of the multi-component force sensor to be tested, so that the multi-component force sensor to be tested can be adjusted to a zero force state before testing. The counterweight mechanism can balance the weight of the loading plate assembly through the counterweight ring block, so as to help the multi-component force sensor to start measuring from near the actual zero position, thereby improving the measurement accuracy.

[0038] like Figure 1 As shown, in other embodiments of the present invention, the top plate 12 and the bottom plate 11 are both square, and there are four columns 13 , with one column 13 installed at each of the four corners of the top plate 12 and the bottom plate 11 .

[0039] like Figure 8 As shown, in some other embodiments of the utility model, the lifting drive mechanism 23 includes a reduction motor 231, a transmission chain 232, a screw column 233 and a nut 234. The upper and lower ends of the screw column 233 are rotatably mounted on the top plate 12 and the bottom plate 11 respectively. The nut 234 is fixed on the lifting plate 22. The nut 234 is connected to the external thread of the screw column 233. A sprocket is installed on the output shaft of the reduction motor 231. A sprocket is also installed at the bottom end of the screw column 233. The transmission chain 232 is wound between the sprockets. The beneficial effects of adopting the above technical solution are: it is convenient to adjust the height of the lifting plate, so as to facilitate the installation and adjustment of the sensor to be tested, and to adapt to the detection of sensors of different sizes and models.

[0040] like Figure 7As shown, in some other embodiments of the utility model, the clamp 21 includes a clamp block 211, the upper surface of the clamp block 211 is provided with a center hole, 8 inverted T-shaped long grooves 212 extending radially outward from the periphery of the center hole, the spacing angles between adjacent inverted T-shaped long grooves 212 are the same, and the four side surfaces of the clamp block 211 are respectively provided with laterally concave door-shaped grooves 213, and the bottom surface of the clamp block 211 is provided with an upper strip positioning groove 214 corresponding to the middle position of the four side surfaces and perpendicular to the corresponding side surfaces, and the lifting plate 22 is provided with 4 lower strip positioning grooves 221, the lower strip positioning grooves 214 are arranged opposite to the upper strip positioning grooves 214 in upper and lower directions, and the lower strip positioning grooves 214 extend outward and exceed the edge of the clamp block 211. The beneficial effects of adopting the above technical solution are: the inverted T-shaped long groove can adapt to the installation and locking of sensors of different sizes; the door-shaped groove on the side is convenient for lifting and debugging the fixture block in all directions through a small lifting height adjustment device when the sensor is zero-positioned, so that when the sensor is at zero position, a gasket of corresponding thickness is padded at the bottom of the fixture block; the upper strip positioning groove and the lower strip positioning groove are convenient for XY-axis centering positioning through the positioning key.

[0041] like Figure 3 As shown, in some other embodiments of the present invention, the area within the four peripheral edges of the bottom surface of the horizontal loading plate 31 is provided with a concave material reduction groove 311. The beneficial effect of adopting the above technical solution is: reducing the weight of the horizontal loading plate, and the protruding parts of the four peripheral edges of the bottom surface ensure the structural strength.

[0042] like Figure 3 As shown, in some other embodiments of the present invention, the central position of the material-reducing slot 311 on the bottom surface of the horizontal loading plate 31 is detachably connected with a sensor upper connection plate 36, and the sensor upper connection plate 36 is connected to the upper surface of the multi-component force sensor 72 to be tested via bolts. The beneficial effects of adopting the above technical solution are: improving the versatility of the loading plate assembly, facilitating the docking installation of the tested sensor and the horizontal loading plate, and different types of sensors can be applied by simply replacing the matching sensor upper connection plate.

[0043] like Figure 2 As shown, in some other embodiments of the present invention, the loading vertical plate 32 includes a base plate portion 321, a vertical panel portion 322 and a rib plate portion 323. The base plate portion 321 is connected to the upper surface or the lower surface of the horizontal loading plate 31, the vertical panel portion 322 and the rib plate portion 323 are both vertically extended from the surface of the base plate portion 321, and the rib plate portion 323 is vertically connected to the back of the vertical panel portion 322. The beneficial effect of adopting the above technical solution is: the structural strength of the loading vertical plate is enhanced, and the accuracy of the force arm value is ensured.

[0044] In some other embodiments of the present invention, the bottom surface of the sensor connection plate 36 is in the same plane as the bottom surface of the material reduction slot 311 on the bottom surface of the horizontal loading plate; the guide sleeve axis of the loading point seat installed on the side of the horizontal loading plate 31 and the positioning hole axis of the positioning seat are both in the same plane as the bottom surface of the material reduction slot. The beneficial effect of adopting the above technical solution is: ensuring that the origin of the coordinate system of the loading plate assembly coincides with the origin of the coordinate system of the sensor being tested, thereby improving the detection accuracy.

[0045] like Figure 2 As shown, in some other embodiments of the present invention, the Z-direction loading seat 33 includes a lower connecting plate 331, a connecting column 332 and an upper connecting plate 333. The lower connecting plate 331 is connected to the central position of the upper surface of the horizontal loading plate 31, and the connecting column 332 is connected between the lower connecting plate 331 and the upper connecting plate 333. A Z-direction loading point seat 334 is provided in the center of the upper surface of the lower connecting plate 331, and a connecting hole 335 is provided in the center of the upper connecting plate 333 that penetrates from top to bottom. The Z-direction force source 50 includes a Z-direction linear drive mechanism, a Z-direction standard force sensor, a Z-direction loading pressure head, and a Z-direction loading pull head. When the Z-direction force source applies pressure, the Z-direction standard force sensor is connected between the Z-direction linear drive mechanism and the Z-direction loading pressure head, and the Z-direction loading pressure head matches the Z-direction loading point seat; when the Z-direction force source applies tension, the Z-direction standard force sensor is connected between the Z-direction linear drive mechanism and the Z-direction loading pull head, and the Z-direction loading pull head is connected to the upper connecting plate of the Z-direction loading seat. The specific structural form of the Z-direction linear drive mechanism is not limited and can be selected from the existing technology, such as a linear electric cylinder, etc. The beneficial effect of adopting the above technical solution is: it is convenient to realize the precise force application in the Z direction and the switching of the positive and negative direction force application.

[0046] In some other embodiments of the utility model, the lateral force source includes a linear drive mechanism, a standard force sensor and a loading pressure head, wherein the standard force sensor is connected between the linear drive mechanism and the loading pressure head, and the loading pressure head matches the corresponding loading point seat position. The specific structural form of the linear drive mechanism is not limited and can be selected from the prior art, such as a linear electric cylinder. The loading pressure head cooperates with the guide sleeve on the loading point seat. The beneficial effect of adopting the above technical solution is: it is convenient to realize precise lateral force application.

[0047] like Figure 4As shown, in some other embodiments of the utility model, the loading plate positioning mechanism 44 includes a reciprocating drive mechanism 441, two guide columns 442, an end plate 443 and a positioning shaft 444, the guide column 442 is movably mounted in a guide sleeve of the force source lateral mounting frame 41, the base of the reciprocating drive mechanism 441 is fixedly connected to the force source lateral mounting frame 41, the telescopic rod of the reciprocating drive mechanism 441 is connected in the middle of the end plate 443, the two guide columns 442 are respectively mounted at both ends of the end plate 443, the positioning shaft 444 is mounted on the front side of the end plate 443, and the positioning shaft 444 cooperates with the positioning hole of the positioning seat 35 of the horizontal loading plate for positioning. Before installing the sensor to be tested, the horizontal loading plate is positioned through the loading plate positioning mechanism at 4 points. First, the upper connecting plate of the sensor is installed on the upper surface of the sensor to be tested, and the lower connecting plate of the sensor is installed on the lower surface. The sensor to be tested is placed on the fixture, and the fixture and the sensor to be tested are raised through the lifting drive mechanism. The upper connecting plate of the sensor and the horizontal loading plate are locked and fixed, and the height of the fixture is adjusted by the gasket to make the sensor to be tested indicate the zero position. After that, the loading plate positioning mechanism is released to position the horizontal loading plate, and the sensor is tested for force and torque in all directions.

[0048] The above embodiments are only for illustrating the technical concept and features of the utility model, and their purpose is to enable ordinary technicians in the field to understand the content of the utility model and implement it. They cannot be used to limit the protection scope of the utility model. All equivalent changes or modifications made according to the spirit of the utility model should be included in the protection scope of the utility model.

Claims

1. A loading plate counterweight mechanism, characterized in that: It includes a main structure frame, a loading plate assembly, a counterweight ring block, a connecting rope and multiple pulleys. The main structure frame includes a bottom plate, a top plate and multiple columns. The columns are installed between the bottom plate and the top plate. The pulley is installed on the upper surface of the top plate. The connecting rope is wound around the pulley. The two ends of the connecting rope are respectively connected to the counterweight ring block and the loading plate assembly. The weight of the counterweight ring block is consistent with the weight of the loading plate assembly.

2. The loading plate counterweight mechanism according to claim 1, characterized in that: The loading plate assembly includes a horizontal loading plate, a loading vertical plate and a Z-direction loading seat. The central position of the lower surface of the horizontal loading plate is fixedly connected to the upper surface of the multi-component force sensor to be tested. The horizontal loading plate is square. A vertically installed loading vertical plate is provided in the middle of each edge of the upper surface of the horizontal loading plate and in the middle of each edge of the lower surface. A loading point seat is provided at the end of each loading vertical plate. A loading point seat is installed in the center of each side of the horizontal loading plate. Loading point seats are respectively installed at the two ends of the two side surfaces of the horizontal loading plate perpendicular to the X-axis. The Z-direction loading seat is installed in the central position of the upper surface of the horizontal loading plate.

3. The loading plate counterweight mechanism according to claim 2, characterized in that: Positioning seats are respectively installed at two ends of two side surfaces of the horizontal loading plate that are perpendicular to the Y axis.

4. The loading plate counterweight mechanism according to claim 2, characterized in that: The surface of the horizontal loading plate is in a square shape, and the surface of the counterweight ring block is in a circular shape.

5. The loading plate counterweight mechanism according to claim 4, characterized in that: There are four pulleys, and one end of a connecting rope on each of the four pulleys is connected to four corners of the horizontal loading plate respectively.

6. The loading plate counterweight mechanism according to claim 2, characterized in that: The loading vertical plate includes a base plate portion, a vertical panel portion and a rib plate portion. The base plate portion is fitted and connected to the upper surface or the lower surface of the horizontal loading plate. The vertical panel portion and the rib plate portion are vertically extended from the surface of the base plate portion. The rib plate portion is vertically connected to the back side of the vertical panel portion.

7. The loading plate counterweight mechanism according to claim 2, characterized in that: The Z-direction loading seat includes a lower connecting plate, a connecting column and an upper connecting plate. The lower connecting plate is connected to the central position of the upper surface of the horizontal loading plate. The connecting column is connected between the lower connecting plate and the upper connecting plate. A Z-direction loading point seat is provided in the center of the upper surface of the lower connecting plate. A connecting hole penetrating from top to bottom is provided in the center of the upper connecting plate.

8. A multi-component force sensor measurement and testing device, characterized in that: It comprises a loading plate counterweight mechanism as described in any one of claims 1 to 7, and the detected multi-component force sensor is fixedly connected to the loading plate assembly.

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