A gear and rack loading test bench and a loading test method thereof

Abstract

The application discloses a kind of rack and pinion loading test bench and loading test method thereof.The rack and pinion loading test bench of the application includes foundation pit and test bench, and upper and lower test benches are arranged at intervals in the test bench.The upper test bench is connected with the piston rod of damping oil cylinder fixed on the top beam of test bench, and the lower test bench is connected with the piston rod of working oil cylinder fixed on the bottom of foundation pit.The test rack is fixed on the two side columns of test bench respectively.The test gear engaged with test rack is placed between the upper and lower test benches, and is integrated with the upper and lower test benches through connecting assembly.Under the drive of working oil cylinder, the test gear and the upper and lower test benches are lifted along the test rack together.The horizontal test bench is changed into vertical structure in the application, which not only has compact structure and is easy to operate, but also can test two sets of rack and pinion simultaneously, with high test efficiency.The complex and variable operating conditions of rack and pinion transmission system can be simulated in all directions and to the maximum extent during the test process, and the comprehensive performance of rack and pinion is fully verified.

Description

Technical Field

[0001] This invention relates to gear and rack testing, and more particularly to a gear and rack loading test bench, and also to a method for performing loading tests on gears and racks using the test bench. Background Technology

[0002] Rack and pinion lifting systems are widely used in the field of self-elevating platforms. Some domestic ship lifts employ large-module rack and pinion transmission mechanisms for their drive systems. Furthermore, large offshore platform lifting systems also utilize rack and pinion transmission devices. During operation, the rack is fixed, and the meshing of the gears and rack drives the ship's hull (platform) to move up and down.

[0003] In rack and pinion lifting systems, the load-bearing capacity, dynamic characteristics, and lubrication characteristics of the gears and racks are key factors for the safe and stable operation of the system. Existing rack and pinion test benches are primarily horizontally arranged, with either mechanical or electrical power closed configurations. These benches are structurally complex, difficult to test, require significant equipment investment, occupy a large area, and consume a lot of energy. Horizontal arrangements cannot adequately simulate the varied operating conditions of vertical transmissions, and are particularly inadequate for simulating the impact of lubrication media and methods on the scuffing performance of the gears and racks, making it impossible to accurately evaluate the lubrication system and verify actual operational effectiveness. Summary of the Invention

[0004] The purpose of this invention is to address the shortcomings of existing horizontally arranged test benches for load testing by providing a vertically structured gear and rack load test bench. This invention also provides a method for performing load tests on gears and racks using this test bench.

[0005] To achieve the above objectives, the present invention can adopt the following technical solutions:

[0006] The gear and rack loading test bench of the present invention includes a foundation pit and a test bench frame erected above the foundation pit. An upper frame and a lower frame are spaced apart within the test bench frame. The upper frame is connected to a damping cylinder piston rod fixed on the top beam of the test bench frame, and the lower frame is connected to a working cylinder piston rod fixed at the bottom of the foundation pit. The test rack is fixed on the two side columns of the test bench frame. The test gear meshing with the test rack is placed between the upper frame and the lower frame and is connected to the upper frame and the lower frame as a whole through a connecting assembly. Under the drive of the working cylinder, the test gear, the upper frame, and the lower frame move up and down together along the test rack.

[0007] This invention transforms the traditional horizontal gear and rack loading test bench into a vertical structure, which is not only compact and easy to operate, but also allows for the simultaneous testing of two sets of gears and racks, resulting in high testing efficiency. During the test, it can comprehensively and to the maximum extent simulate the complex and varied operating conditions of the gear and rack transmission system, fully verify the comprehensive performance of the gears and racks, simulate the influence of lubrication media and lubrication methods on the adhesion performance of the gears and racks, accurately evaluate the lubrication system, and verify the actual operating effect.

[0008] Specifically:

[0009] To increase the operational flexibility of the test bench, the connection assembly used in this invention includes an upper frame bearing seat fixed to the lower part of the upper frame and a lower frame bearing seat fixed to the upper part of the lower frame. The two ends of the gear shaft of the test gear are placed in the upper frame bearing and the lower frame bearing in the upper frame bearing seat and the lower frame bearing seat, and are fixed by bearing covers. A sealed cap is provided on the outer end face of the bearing cover, and a transparent cap is provided on the inner end face of the bearing cover.

[0010] Grease cups are installed on each bearing cover, allowing grease to be injected periodically during testing to ensure the service life of the bearings.

[0011] The width of the upper frame is greater than that of the lower frame. The upper frame bearing is located outside the lower frame bearing, and a positioning sleeve is provided between the upper frame bearing and the lower frame bearing. The fixing bolt holes on the two adjacent transparent covers are staggered, which makes the structure more compact.

[0012] The test bench, upper bench, and lower bench are all frame structures welded from square steel.

[0013] The working cylinder is a reciprocating servo electric cylinder, and the damping cylinder is a linear servo electric cylinder; and the working performance of the working cylinder and the damping cylinder can be interchanged.

[0014] The gear and rack loading test bench of the present invention further includes a lubrication oil circuit, which includes a lubrication bracket fixed on the test bench frame. Lubrication oil nozzles are respectively arranged on the meshing side and the meshing-out side near the test gear. The lubrication oil nozzles are hinged to the lubrication bracket, and their oil inlets are connected to the lubrication pump station through hoses.

[0015] The lubricating oil nozzles of this application can be arranged in multiple ways according to actual conditions and fixed on the lubrication bracket by hinge. Their spray angle can be adjusted. At the same time, each nozzle can also slide along the lubrication bracket to increase or decrease the number of nozzles and adjust the distance between adjacent nozzles.

[0016] The gear and rack loading test bench of the present invention further includes a control system, which comprises a PLC main controller, a damping cylinder unit, and a working cylinder unit. Both the damping cylinder unit and the working cylinder unit are electrically connected to an external power supply.

[0017] The damping cylinder unit includes a first operating processor, a first driving circuit, and a damping cylinder. The signal output terminal of the first operating processor is electrically connected to the signal input terminal of the first driving circuit, and the signal output terminal of the first driving circuit is electrically connected to the signal input terminal of the damping cylinder.

[0018] The working cylinder unit includes a second operating processor, a second drive circuit, and a working cylinder. The signal output terminal of the second operating processor is electrically connected to the signal input terminal of the second drive circuit, and the signal output terminal of the second drive circuit is electrically connected to the signal input terminal of the working cylinder.

[0019] The PLC main controller is communicatively connected to the first and second running processors for position feedback; it is also communicatively connected to the first and second drive circuits for speed feedback; and it is communicatively connected to the monitoring computer and the monitoring sensor. The signal output terminal of the monitoring sensor is electrically connected to the signal input terminal of the monitoring computer for collecting detection data and displaying it on the monitoring computer.

[0020] In this application, the working cylinder and damping cylinder are connected to a PLC control system, realizing closed-loop servo control with a control accuracy of 0.01mm. Precise thrust control is achieved by adding a pressure monitoring sensor, realizing high-precision motion control with an accuracy of 1%. During testing, the acceleration and loading control process of the working cylinder can be pre-set on the computer-PLC control system according to the magnitude of the force required to be applied to the gear and rack, thus fulfilling the loading requirements. The damping cylinder control process is also set to control the meshing surface of the gear and rack and the magnitude and direction of the force, improving the accuracy of the test results.

[0021] The gear and rack loading test method of the present invention uses a gear and rack loading test bench designed as described above; the specific test steps include:

[0022] S1: Parameter Linkage Debugging

[0023] After the test bench is installed, the monitoring computer sets the test operation mode and sends instructions to the PLC control system. The working cylinder pushes the upper frame, lower frame and test gear together to accelerate, uniformly speed up and down along the test rack; at the same time, the damping cylinder is controlled to apply force to ensure the meshing state of the test gear and test rack.

[0024] S2: Fatigue life test

[0025] The required load value and number of meshing cycles for the test are calculated based on actual operating conditions and service life. Test specifications are formulated with reference to GB / T14230 "Test Method for Bending Fatigue Strength of Gears" and GB / T14229 "Test Method for Contact Fatigue Strength of Gears", using the pitting area R of a single tooth as the benchmark. s =4% is used as the criterion for contact fatigue failure, and the appearance of visible fatigue cracks or tooth breakage at the tooth root is used as the criterion for bending fatigue failure. The test is carried out under reciprocating load until the test gear rack shows fatigue failure or the number of cycles reaches the specified value, and the test ends. During the test, strain gauges are placed at the tooth root of the gear under stable load, and sensors for torque, speed, temperature, vibration, etc. are placed at predetermined monitoring points of the electrical control system or mechanical equipment. The operating status of the drive components and transmission device during the test is monitored by the monitoring sensor circuit to collect data or ensure the safe operation of the test equipment.

[0026] S3: Optimization Test of Lubrication Method and Lubrication Medium

[0027] Static single-tooth spraying effect test: During the test, the rack and spraying device were kept stationary. By comparing the spraying effect of the tooth surface lubricating medium under different numbers, structures and installation positions of nozzles, the lubricating medium and nozzle arrangement were optimized.

[0028] Dynamic single-tooth spraying effect test: The tooth surface spraying effect test was carried out under the condition of relative motion between the rack and the spraying device according to the optimized nozzle arrangement. The distribution of tooth surface lubricating medium under different oil spraying volume and different oil spraying operation time / frequency was compared. The minimum lubricating medium requirement required to meet the good lubrication state of the tooth surface was used as the indicator to optimize the working parameters of the lubrication system.

[0029] Full-dynamic gear and rack lubrication effect test: The lubrication effect is tested during actual operation. The evaluation indicators are gear and rack transmission efficiency, risk of scuffing damage and oil consumption. The actual operation effect of the optimized lubrication scheme is compared and verified to form a gear and rack lubrication system scheme.

[0030] The gear and rack loading test bench provided by this invention has a simple structure and comprehensive test items, enabling full-cycle fatigue life testing, dynamic characteristic testing, lubrication medium optimization testing, and lubrication method anti-galling performance testing, with high testing efficiency. It uses a servo electric cylinder as the loading drive to propel the gears up and down. Compared with traditional motors and gearboxes, this allows for precise speed control, precise revolution control, precise torque control, and precise position control, and is easily connected to a PLC control system for high-precision motion control. The damping cylinder also uses a servo electric cylinder, which can precisely control the direction and magnitude of force on the gears and racks during testing. The entire test bench of this invention adopts a vertical layout, allowing simultaneous testing of both sets of gears and racks. It has a small footprint, compact structure, is easy to operate, has low maintenance costs, and is energy-efficient and cost-effective. Attached Figure Description

[0031] Figure 1 This is a schematic diagram of the structure of the present invention.

[0032] Figure 2 yes Figure 1 Top view of the structure.

[0033] Figure 3 yes Figure 1 Enlarged cross-sectional view along the AA direction.

[0034] Figure 4 , Figure 5 yes Figure 1 A schematic diagram of the upper and middle platform.

[0035] Figure 6 , Figure 7 yes Figure 1 Schematic diagram of the lower platform.

[0036] Figure 8 , Figure 9 yes Figure 1 A schematic diagram of the structure of the test bench.

[0037] Figure 10 , Figure 11 This is a diagram of the lubrication circuit structure of the present invention.

[0038] Figure 12 This is a block diagram of the control system of the present invention. Detailed Implementation

[0039] The structure of the gear and rack loading test bench of the present invention will be described in more detail below with reference to the accompanying drawings, so as to facilitate the understanding of those skilled in the art.

[0040] Those skilled in the art should understand that this embodiment is merely used to explain the technical principles of this application and is not intended to limit the scope of protection of this application.

[0041] Furthermore, in the description of this application, unless otherwise expressly specified and limited, the terms "installation," "connection," and "linkage" should be interpreted broadly, and can refer to fixed connections, detachable connections, or integral structures; they can refer to mechanical connections or electrical connections; they can refer to direct connections or indirect connections through an intermediate medium; they can also refer to the internal communication of two components or the interaction between two components. Those skilled in the art can understand the specific meaning of the above terms in this application according to the specific circumstances.

[0042] like Figure 1-2 As shown, the gear and rack loading test bench provided by the present invention includes a pit 1 (the depth of the pit is determined according to the length of the rack and the length of the hydraulic cylinder) and a test bench 2 erected above the pit 1. An upper bench 3 and a lower bench 4 are spaced apart within the test bench 2. The upper bench 4 is connected to the piston rod of a damping hydraulic cylinder 5 fixed to the top beam of the test bench 2 via a connecting plate welded to it. Similarly, the lower bench 4 is also connected to the piston rod of a working hydraulic cylinder 6 fixed to the bottom of the pit 1 via a connecting plate welded to it. To ensure that its strength meets the loading test requirements, the test bench 2, upper bench 3, and lower bench 4 of the present invention are all frame structures welded from square steel. Figure 8 , Figure 9 As shown, the damping cylinder 5 is fixed to the top beam of the test bench 2 by clamp 501 and clamp fixing bracket 502. Multiple rack fixing blocks 201 are fixed on the two side columns of the test bench 2. The test rack CT is fixed to the rack fixing blocks 201 by bolts. Since two sets of gear racks can be loaded at the same time, the test cost is reduced. The test gear CL, which meshes with the test rack CT, is placed between the upper bench 3 and the lower bench 4 and is connected to the upper bench 3 and the lower bench 4 by a connecting assembly. Under the drive of the working cylinder 6, the test gear CL and the upper bench 3 and the lower bench 4 move up and down together along the test rack CT.

[0043] To increase the operational flexibility of the test bench, the present invention employs the following connection components:

[0044] like Figure 3As shown, the test gear CL includes an upper frame bearing seat 301 (with an upper frame bearing 302 installed inside) fixed to the lower part of the upper frame 3 and a lower frame bearing seat 401 (with a lower frame bearing 402 installed inside) fixed to the upper part of the lower frame 4. The two ends of the gear shaft 7 are placed inside the upper frame bearing 302 and the lower frame bearing 402 and fixed by bearing covers. In this application, the width of the upper frame 3 is designed to be greater than the width of the lower frame 4, so that the upper frame bearing 302 is installed on the outside of the lower frame bearing 402. A positioning sleeve 8 is provided between the upper frame bearing 302 and the lower frame bearing 402. A sealed cap 9 is provided on the bearing cover end face located on the outer side, and a through cap is provided on the bearing cover end face located on the inner side. The through cap is conventionally equipped with an oil leak-proof seal. A sealing gasket is also provided between the sealed cap 9 and the through cap and the bearing seat and bearing cover mating end face.

[0045] It is important to note that the bolt holes on adjacent covers should be staggered, meaning the fixing bolts should be installed in an offset manner. Figure 4 , Figure 5 , Figure 6 , Figure 7 The through-cover bolt holes 303 on the outer side of the upper frame 3 and the through-cover bolt holes 403 on the inner side of the lower frame 4 are staggered (α1 and α2 differ by 22.5°), which makes the structure more compact.

[0046] Each bearing cap is equipped with a grease cup 10 to facilitate the injection of different lubricating media during the test and to conduct a lubricating media optimization test.

[0047] The working cylinder 6 (driving cylinder) of the present invention can be a folding servo electric cylinder, and the damping cylinder 5 can be a linear servo electric cylinder; and the working performance of the working cylinder 6 and the damping cylinder 5 can be interchanged.

[0048] The gear and rack loading test bench of the present invention also includes a lubrication oil circuit, such as... Figure 10 , Figure 11 As shown, the lubrication circuit includes a lubrication bracket 11 fixed on the test bench, and lubrication nozzles 12 are arranged on the meshing side and the meshing side near the test gear, respectively. The lubrication nozzles 12 are hinged to the lubrication bracket 11, and their oil inlets are connected to the lubrication pump station 14 through a hose 13.

[0049] The lubricating oil nozzles 12 of this application can be arranged in multiple ways according to actual conditions and fixed on the lubrication bracket 11 by hinges. The spray angle can be adjusted. At the same time, each nozzle can also slide along the lubrication bracket to adjust its position, thereby increasing or decreasing the number of nozzles and adjusting the distance between adjacent nozzles. When lubricating oil (grease) ages and deteriorates after long-term use, it will damage the meshing tooth surface. By spraying lubricating oil directly onto the meshing tooth surface from the lubricating oil nozzles 12 through the lubrication oil passage, the tooth surface can be effectively protected.

[0050] To ensure the accuracy of the test structure, the gear and rack loading test bench of this invention is also designed with a control system, such as... Figure 12 As shown:

[0051] The control system of this invention includes a PLC main controller, a damping cylinder unit, and a working cylinder unit. Both the damping cylinder unit and the working cylinder unit are electrically connected to an external power supply.

[0052] The damping cylinder unit includes a first operating processor, a first driving circuit, and a damping cylinder. The signal output terminal of the first operating processor is electrically connected to the signal input terminal of the first driving circuit, and the signal output terminal of the first driving circuit is electrically connected to the signal input terminal of the damping cylinder.

[0053] The working cylinder unit includes a second operating processor, a second drive circuit, and a working cylinder. The signal output terminal of the second operating processor is electrically connected to the signal input terminal of the second drive circuit, and the signal output terminal of the second drive circuit is electrically connected to the signal input terminal of the working cylinder.

[0054] The PLC main controller is communicatively connected to the first and second running processors for position feedback; it is also communicatively connected to the first and second drive circuits for speed feedback; simultaneously, the PLC main controller is communicatively connected to the monitoring computer and monitoring sensors (including torque, speed, temperature, vibration, etc.). The signal output terminals of the monitoring sensors are electrically connected to the signal input terminals of the monitoring computer to collect detection data and display it on the monitoring computer.

[0055] The gear and rack loading test bench designed using this invention includes the following specific test steps:

[0056] S1: Parameter Linkage Debugging

[0057] After the entire test bench is installed, the system undergoes parameter linkage debugging to ensure the accuracy of the test results. The specific control method is as follows: the monitoring computer sets the test operation mode and sends the command to the PLC control system. The working cylinder pushes the upper frame 3, lower frame 4, and test gear CL together to accelerate, maintain constant speed, and decelerate as they move up and down along the test rack CT. At the same time, the damping cylinder 5 is controlled to apply force to ensure the meshing state of the test gear and rack.

[0058] The entire test process is a cycle of acceleration-uniform speed-deceleration-reversal. The piston rod of the working cylinder rises (retracts), driving the upper platform 3, lower platform 4, and test gear CL to accelerate upward (downward) to reach the predetermined running speed. Loading is applied simultaneously with acceleration to ensure that the speed and load of the platform gear system reach the predetermined test values ​​when it reaches the test teeth. The thrust value is kept constant, and the system rises (downward) at a uniform speed and constant load within the test tooth range, collecting monitoring data at this time. After the uniform speed operation ends, the computer test process sends instructions to the PLC control system, which simultaneously decelerates and reduces the load until it stops, and then reverses direction.

[0059] After reversing, the working cylinder can continue to be used as a power cylinder, or it can be interchanged with the damping cylinder.

[0060] Remove the number of teeth at both ends for acceleration and deceleration, and use the number of teeth in the middle for constant speed and constant load operation as the test teeth.

[0061] S2: Fatigue life test

[0062] The required load value and number of meshing cycles for the test are calculated based on actual operating conditions and service life. Test specifications are formulated with reference to GB / T14230 "Test Method for Bending Fatigue Strength of Gears" and GB / T14229 "Test Method for Contact Fatigue Strength of Gears", using the pitting area R of a single tooth as the benchmark. s =4% is used as the criterion for contact fatigue failure, and the appearance of visible fatigue cracks or tooth breakage at the tooth root is used as the criterion for bending fatigue failure. The test is carried out under reciprocating load until the test gear rack shows fatigue failure or the number of cycles reaches the specified value, and the test ends. During the test, strain gauges are placed at the tooth root of the gear under stable load, and sensors for torque, speed, temperature, vibration, etc. are placed at predetermined monitoring points of the electrical control system or mechanical equipment. The operating status of the drive components and transmission device during the test is monitored by the monitoring sensor circuit to collect data or ensure the safe operation of the test equipment.

[0063] S3: Optimization Test of Lubrication Method and Lubrication Medium

[0064] Static single-tooth spraying effect test: During the test, the rack and spraying device were kept stationary. By comparing the spraying effect of the tooth surface lubricating medium under different numbers, structures and installation positions of nozzles, the lubricating medium and nozzle arrangement were optimized.

[0065] Dynamic single-tooth spraying effect test: The tooth surface spraying effect test was carried out under the condition of relative motion between the rack and the spraying device according to the optimized nozzle arrangement. The distribution of tooth surface lubricating medium under different oil spraying volume and different oil spraying operation time / frequency was compared. The minimum lubricating medium requirement required to meet the good lubrication state of the tooth surface was used as the indicator to optimize the working parameters of the lubrication system.

[0066] Full-dynamic gear and rack lubrication effect test: The lubrication effect is tested during actual operation. The evaluation indicators are gear and rack transmission efficiency, risk of scuffing damage and oil consumption. The actual operation effect of the optimized lubrication scheme is compared and verified to form a gear and rack lubrication system scheme.

[0067] Taking a ship lift as an example, a comparison of the stress conditions of the vertically arranged gear and rack loading test bench of this invention with those of the traditional horizontally arranged gear and rack test bench shows that:

[0068] During the ascent and descent of the ship lift, the rack tooth surface experiences 24 different force conditions. The specific tooth surface subjected to these forces and their magnitude are related to various factors such as the depth of the water during the misloading, vibration, wind speed, friction, and acceleration. This invention's test bench controls the force-bearing tooth surface and its magnitude by adjusting the thrust of the working and damping cylinders, realistically simulating various complex stress conditions. In contrast, horizontal test benches apply constant loads to fixed tooth surfaces, making it impossible to simulate complex stress conditions and thus obtain accurate test results. Therefore, the vertical test bench of this invention has unparalleled advantages over horizontal test benches.

Claims

1. A rack and pinion loading test method, characterized by The gear and rack loading test bench comprises a foundation pit and a test bench frame erected above the foundation pit, an upper frame and a lower frame are arranged in the test bench frame, the upper frame is connected with a damping oil cylinder piston rod fixed on the top beam of the test bench frame, the lower frame is connected with a working oil cylinder piston rod fixed on the bottom of the foundation pit, and test racks are respectively fixed on the two side columns of the test bench frame; a test gear meshing with the test racks is arranged between the upper frame and the lower frame and is integrated with the upper frame and the lower frame through a connecting assembly, and under the driving of the working oil cylinder, the test gear, the upper frame and the lower frame ascend and descend along the test racks; The specific test steps include: S1: parameter linkage debugging After the test bench is installed, the monitoring computer sets the test running mode, the command is sent to the PLC control system, the working oil cylinder pushes the upper frame, the lower frame and the test gear to ascend and descend along the test rack at acceleration, constant speed and deceleration; at the same time, the damping oil cylinder is controlled to apply force to ensure the meshing state of the test gear and the test rack; S2: fatigue life test According to the actual use condition and service life, the required loading value and meshing cycle number are calculated, the single-tooth pitting area Rs =4% is taken as the criterion of contact fatigue failure, the visible fatigue cracks on the gear tooth root or the broken tooth on the gear tooth root is taken as the criterion of bending fatigue failure, the up-and-down reciprocating load operation is carried out, until the test gear and rack appear fatigue failure or the cycle number reaches the specified value, the test is ended; during the test, strain gauges are arranged at the stable load running gear tooth root, torque, speed, temperature and vibration sensors are arranged at the predetermined monitoring points of the electric control system or mechanical equipment, the running state of the driving element and the transmission device during the test is monitored through the monitoring sensor circuit, the data is collected or the safe operation of the test equipment is ensured; S3: lubrication mode and lubricating medium optimization test Static single-tooth spraying effect test: the rack and the spraying device are kept static, the lubricating medium spraying effect of the tooth surface under different nozzle numbers, structures and installation positions is compared, and the lubricating medium and nozzle arrangement mode are optimized; Dynamic single-tooth spraying effect test: the tooth surface spraying effect test under the relative motion condition of the rack and the spraying device is carried out according to the optimized nozzle arrangement mode, the tooth surface lubricating medium distribution amount under different oil injection amounts and different oil injection operation time / frequency is compared, the minimum lubricating medium demand amount required for the tooth surface to meet the good lubrication state is taken as the index, and the lubricating system working parameters are optimized; Full-dynamic gear and rack lubrication effect test: the lubrication effect test during actual operation is carried out, the gear and rack transmission efficiency, the risk of gluing damage and the oil consumption are taken as the evaluation indexes, the actual operation effect of the optimized lubrication scheme is verified and compared, and the gear and rack lubrication system scheme is formed.

2. The gear rack load test method according to claim 1, characterized by: The connecting assembly comprises an upper rack bearing seat fixed on the lower part of the upper rack and a lower rack bearing seat fixed on the upper part of the lower rack, the gear shaft of the test gear is arranged in the upper rack bearing and the lower rack bearing at both ends of the upper rack bearing seat and the lower rack bearing seat, and is fixed through bearing covers, the outer side of the bearing cover is provided with a cover, and the inner side of the bearing cover is provided with a transparent cover.

3. The gear rack load test method according to claim 2, characterized by: An oil injection cup is arranged on each bearing cover.

4. The gear rack load test method according to claim 2, characterized by: The width of the upper rack is greater than that of the lower rack, the upper rack bearing is arranged outside the lower rack bearing, a positioning sleeve is arranged between the upper rack bearing and the lower rack bearing, and the fixing bolt holes on the adjacent two transparent covers are arranged in a staggered manner.

5. The gear rack load test method according to claim 2, characterized by: The test rack, the upper rack and the lower rack are all frame structures welded by square steels.

6. The gear rack load test method according to claim 1, characterized by: The working oil cylinder is a return type servo electric cylinder, and the damping oil cylinder is a linear type servo electric cylinder.

7. The gear rack load test method according to claim 1, characterized by: The lubricating oil path comprises a lubricating support fixed on the test rack, lubricating oil nozzles arranged on the meshing in side and the meshing out side of the test gear, and the lubricating oil nozzles are hinged to the lubricating support, and the oil inlet of the lubricating oil nozzle is connected with a lubricating pump station through a hose.

8. The gear rack load test method of claim 1, wherein: The control system comprises a PLC main controller, a damping oil cylinder unit and a working oil cylinder unit, the damping oil cylinder unit and the working oil cylinder unit are electrically connected with an external power supply, the damping oil cylinder unit comprises a first running processor, a first driving circuit and a damping oil cylinder, the signal output end of the first running processor is electrically connected with the signal input end of the first driving circuit, and the signal output end of the first driving circuit is electrically connected with the signal input end of the damping oil cylinder; the working oil cylinder unit comprises a second running processor, a second driving circuit and a working oil cylinder, the signal output end of the second running processor is electrically connected with the signal input end of the second driving circuit, and the signal output end of the second driving circuit is electrically connected with the signal input end of the working oil cylinder; the PLC main controller is in communication connection with the first running processor and the second running processor, and is used for position feedback; the PLC main controller is in communication connection with the first driving circuit and the second driving circuit, and is used for speed feedback; meanwhile, the PLC main controller is in communication connection with a monitoring computer and a monitoring sensor, the signal output end of the monitoring sensor is electrically connected with the signal input end of the monitoring computer, and is used for collecting detection data and displaying the detection data in the monitoring computer.

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