Method and device for testing dynamic friction coefficient of heavy-duty truck bogie brake shoe

Abstract

The invention discloses a method for testing the dynamic friction coefficient of a heavy-duty truck bogie brake shoe in the field of railway vehicles. The method specifically comprises the following steps: S1, constructing a rotating torque balance equation; s2, calculating the longitudinal suspension force of the adapter; s3, calculating the pressure of the brake shoe; s4, a calculation formula of longitudinal wheel-rail force and tangential friction force generated when the brake shoe is attached to the wheel is constructed; s5, substituting the previous calculation results into the rotation torque balance equation in the step S1, and respectively calculating to obtain dynamic friction coefficients of the left brake shoe and the right brake shoe; the invention further discloses a heavy-duty truck bogie brake shoe dynamic friction coefficient testing device. The method has the advantages that four types of loads borne by the heavy-load train in the braking process are calculated, the left wheel and the right wheel are calculated respectively, the dynamic friction coefficients of the brake shoes on the two sides in the braking process can be more accurately obtained, the dynamic change rule of the friction coefficients of the brake shoes in the real running environment of the heavy-load train is mastered, and the braking accuracy is improved. The method has guiding significance for improving the running safety of the heavy-load train.

Description

Technical Field

[0001] The present invention relates to the field of rail vehicles, and in particular to a method and device for testing the dynamic friction coefficient of brake shoes of a heavy-duty freight car bogie. Background Art

[0002] The huge transport scale of heavy-load trains results in a huge inertial force during the operation of the trains, so the braking force is crucial for the safe operation of heavy-load trains. The braking of heavy-load trains is achieved through the friction generated by the brake shoes against the wheels, and the brake shoe friction coefficient is a key factor in evaluating the braking performance of heavy-load trains. The brake shoe friction coefficient is not a constant value, and its magnitude will change with changes in brake pressure, wheel speed, and brake shoe temperature. At present, people can only test the value of the brake shoe friction coefficient under specific conditions through artificially set simulation test conditions in the laboratory. However, due to the complexity of the actual operating environment of heavy-load trains, the test data obtained through laboratory simulation tests cannot fully reflect the actual dynamic change law of the brake shoe friction coefficient during the braking process of heavy-load trains. This seriously limits the improvement of the braking performance of heavy-load trains, and also increases the uncertainty of the safety assessment of heavy-load train operations.

[0003] Therefore, we propose a method and device for testing the dynamic friction coefficient of brake shoes of heavy-duty freight car bogies. Summary of the Invention

[0004] In view of the above-mentioned deficiencies in the prior art, the present invention provides a method and device for testing the dynamic friction coefficient of brake shoes of heavy-duty truck bogies.

[0005] In order to achieve the above-mentioned object of the invention, the technical solution adopted by the present invention is: A method for testing the dynamic friction coefficient of brake shoes of a heavy-duty truck bogie comprises the following steps: S1. Based on the four types of loads applied to the vehicle during braking, construct the torque equilibrium equations for the four types of loads about the left wheel and track contact points and the right wheel and track contact points about the vertical coordinate axis; S2. Collect the full-bridge strain signals of the left and right load saddles and calculate the longitudinal suspension forces of the left and right load saddles under the four load types. S3. Collect full-bridge strain signals at the left and right ends of the brake beam and calculate the left brake shoe pressure generated when the left brake shoe abuts the left wheel and the right brake shoe pressure generated when the right brake shoe abuts the right wheel, respectively, for each of the four load types. S4. Based on the left and right brake shoe pressures, formulas are constructed for calculating the longitudinal wheel-rail force acting on the left wheel and the longitudinal wheel-rail force acting on the right wheel, respectively, in the four load categories. Formulas are also constructed for calculating the tangential friction force generated when the left brake shoe abuts the wheel and the tangential friction force generated when the right brake shoe abuts the wheel, respectively, in the four load categories. S5. Substitute the calculation results in steps S2, S3, and S4 into the torque balance equation in step S1 to calculate the dynamic friction coefficients of the left brake shoe and the right brake shoe respectively.

[0006] By first establishing a torque balance equation for the contact point between the vehicle and the track on each side around the vertical coordinate axis based on the four types of loads the vehicle is subjected to during braking, and then calculating the four types of loads the vehicle is subjected to during braking, and calculating the left wheel side and the right wheel side of each type of load separately, and finally substituting the calculation results of the four types of loads into the torque balance equation, the dynamic friction coefficients of the left brake shoe and the right brake shoe are calculated respectively. This can accurately grasp the dynamic change law of the brake shoe friction coefficient of heavy-load trains in real operating environments, and can improve the operating safety of heavy-load trains according to this method.

[0007] Further defined, step S1 is specifically as follows: During the vehicle braking process, four types of loads acting on the left and right wheels are collected. These loads include: the longitudinal suspension force of the left and right load-bearing saddles caused by the inertia of the vehicle moving forward; the longitudinal wheel-rail force of the left and right wheels caused by the rails moving forward; the left and right brake shoe pressures generated when the left and right brake shoes abut the wheels; and the tangential friction force generated when the left and right brake shoes abut the wheels. Based on these four loads, the torque balance equations for the contact points of the left and right wheels around the vertical coordinate axis are constructed: ; ; in, is the longitudinal wheel-rail force exerted by the rail on the left wheel, is the longitudinal wheel-rail force exerted by the rail on the right wheel, is the tangential friction force generated when the left brake shoe is against the wheel, is the tangential friction force generated when the right brake shoe is against the wheel, is the angle between the brake shoe pressure and the horizontal line, is the horizontal distance between the left wheel-rail contact point and the right wheel-rail contact point, It is the horizontal distance between the load saddle and the wheel-rail contact point on the same side.

[0008] Further defined, step S2 is specifically as follows: Strain gauges are arranged on the left and right load saddles respectively so that a Huisden strain gauge full bridge test circuit is formed on each of the load saddles on both sides; Collect the output signal of the left saddle Huisten strain gauge full bridge test circuit , Output signal of the strain gauge full bridge test circuit on the right side of the saddle , based on the output signal and output signal Calculate the longitudinal suspension force on the left load saddle And the longitudinal suspension force on the right load saddle ; ; ; in, is the proportionality coefficient between the output signal of the Huisten strain gauge full-bridge test circuit of the left saddle and the longitudinal load of the left saddle, It is the proportionality coefficient between the output signal of the Huisten strain gauge full-bridge test circuit of the right load saddle and the longitudinal load of the right load saddle.

[0009] Further defined, step S3 is specifically as follows: Strain gauges are arranged at the left and right ends of the brake beam, respectively, so that a Huisden strain gauge full-bridge test circuit is formed at each end of the brake beam; Collect the output signal of the Huisden strain gauge full-bridge test circuit at the left end of the brake beam The output signal of the Huisden strain gauge full bridge test circuit at the right end of the brake beam , based on the output signal and output signal Calculate the left brake shoe pressure generated when the left brake shoe is against the left wheel And the right brake shoe pressure generated when the right brake shoe is against the right wheel ; ; ; in, is the proportional coefficient between the output signal of the Huisden strain gauge full-bridge test circuit at the left end of the brake beam and the left brake shoe pressure, It is the proportional coefficient between the output signal of the Huisden strain gauge full-bridge test circuit at the right end of the brake beam and the right brake shoe pressure.

[0010] Further defined, step S4 is specifically as follows: Based on left brake shoe pressure and right brake shoe pressure Construct the tangential friction force generated when the left brake shoe is against the wheel , the tangential friction force generated when the right brake shoe touches the wheel The calculation formula is: ; ; in, is the dynamic friction coefficient of the left brake shoe, is the dynamic friction coefficient of the right brake shoe; Under normal braking conditions, i.e. when the wheels are not locked, the longitudinal wheel-rail force acting on the left wheel is The tangential friction force generated when the left brake shoe touches the wheel The value of the rail acting on the right wheel is the same. Tangential friction generated when the right brake shoe touches the wheel The value is the same, that is: ; .

[0011] Further defined, step S5 is specifically as follows: Substitute the calculation formulas in steps S2, S3, and S4 into the torque balance equation in step S1 to construct the left brake shoe dynamic shoe friction coefficient. , dynamic friction coefficient of right brake shoe The calculation formula is: ; .

[0012] A device for testing the dynamic friction coefficient of brake shoes of a heavy-duty truck bogie is used in the above-mentioned method for testing the dynamic friction coefficient of brake shoes of a heavy-duty truck bogie. The device comprises an axle, wheels, load-bearing saddles, brake shoes, a brake beam and a strain gauge. The wheels comprise a left wheel and a right wheel, the load-bearing saddles comprise a left load-bearing saddle and a right load-bearing saddle, the brake shoes comprise a left brake shoe and a right brake shoe, the left wheel and the right wheel are rotatably connected to the two ends of the axle, and the two end ends of the axle pass through the left wheel and the right wheel, the left load-bearing saddle and the right load-bearing saddle are respectively fixed on the circumferential surface of the end ends on both sides of the axle, the left brake shoe and the right brake shoe are fixed on the two ends of the brake beam, the brake shoes cooperate with the wheel surface of the wheel on the same side to achieve braking of the wheel, and strain gauges are arranged at load-sensitive positions of the left load-bearing saddle, the right load-bearing saddle, the left end of the brake beam and the right end of the brake beam. Four strain gauges are provided at each location to form a Huisden strain full-bridge test circuit.

[0013] The beneficial effects of the present invention are as follows: by calculating the four types of loads that a heavy-loaded train is subjected to during braking, and calculating the left and right wheels separately, the dynamic friction coefficient of the brake shoes on both sides during braking can be obtained more accurately, and the dynamic change law of the brake shoe friction coefficient in a real environment can be mastered, which has guiding significance for improving the operation safety of heavy-loaded trains. BRIEF DESCRIPTION OF THE DRAWINGS

[0014] Figure 1 This is a schematic diagram of the three-dimensional structure of a heavy-duty freight car bogie brake shoe dynamic friction coefficient test device; Figure 2The diagram of the strain gauge installation for the left load saddle is from an upward perspective; Figure 3 Schematic diagram of the Wheatstone strain gauge full-bridge test circuit for testing the longitudinal suspension force of the left-side load saddle; Figure 4 The diagram of the strain gauge installation on the right load saddle from an upward perspective; Figure 5 Schematic diagram of the Wheatstone strain gauge full-bridge test circuit for testing the longitudinal suspension force of the right-side load saddle; Figure 6 This is a schematic diagram of the strain gauge installation at the left end of the brake beam; Figure 7 Schematic diagram of the Wheatstone strain gauge full-bridge test circuit for left brake shoe pressure testing; Figure 8 This is a schematic diagram of the strain gauge installation at the right end of the brake beam; Figure 9 This is a schematic diagram of the Wheatstone strain gauge full-bridge test circuit used for the right brake shoe pressure test; Figure 10 Schematic diagram of the force status of the wheels when the train brakes.

[0015] The symbols of the components are as follows: Axle 1 , wheel 2 , left wheel 21 , right wheel 22 , load saddle 3 , left load saddle 31 , right load saddle 32 , brake shoe 4 , left brake shoe 41 , right brake shoe 42 , brake beam 5 , strain gauge 6 . DETAILED DESCRIPTION

[0016] The specific embodiments of the present invention are described below to facilitate understanding of the present invention by those skilled in the art. However, it should be clear that the present invention is not limited to the scope of the specific embodiments. For those skilled in the art, as long as various changes are within the spirit and scope of the present invention as defined and determined by the appended claims, these changes are obvious, and all inventions and creations utilizing the concepts of the present invention are protected.

[0017] Example: like Figures 1-10 As shown, a method for testing the dynamic friction coefficient of brake shoes of heavy-duty truck bogies includes the following steps: S1. During vehicle braking, the left and right wheels 21 and 22 are subject to four types of loads. These include: the longitudinal suspension forces acting on the left and right load-bearing saddles 31 and 32, respectively, from the inertial force of the vehicle's forward motion; the longitudinal wheel-rail forces acting on the left and right wheels 21 and 22, respectively, from the rails below when the wheels 2 advance; the pressures on the left and right brake shoes 41 and 42, respectively, generated when the left and right brake shoes 41 and 42 abut against the wheels 2; and the tangential friction forces generated when the left and right brake shoes 41 and 42 abut against the wheels 2. Based on these four types of loads, the torque balance equations for the contact points of the left and right wheels 21 and 22 about the vertical coordinate axis are constructed: ; ; in, is the longitudinal wheel-rail force acting on the left wheel 21 by the rail, is the longitudinal wheel-rail force exerted by the rail on the right wheel 22, is the tangential friction force generated when the left brake shoe 41 abuts against the wheel 2, is the tangential friction force generated when the right brake shoe 42 abuts against the wheel 2, is the angle between the pressure of brake shoe 4 and the horizontal line, is the horizontal distance between the left wheel-rail contact point and the right wheel-rail contact point, is the horizontal distance between the load saddle 3 and the wheel-rail contact point on the same side, where the wheel-rail contact point is the contact point between the wheel 2 and the rail on the same side; S2. The strain gauges 6 are arranged on the left and right load-bearing saddles 31 and 32, respectively, so that a strain gauge full-bridge test circuit is formed on each side of the load-bearing saddle 3; Collect the output signal of the Huisden strain gauge full bridge test circuit of the left saddle 31 , the output signal of the Huisden strain gauge full bridge test circuit of the right saddle 32 , based on the output signal and output signal Calculate the longitudinal suspension force on the left saddle 31 And the longitudinal suspension force on the right saddle 32 ; ; ; in, is the proportionality coefficient between the output signal of the Huisten strain gauge full-bridge test circuit of the left load-bearing saddle 31 and the longitudinal load of the left load-bearing saddle 31, is the proportionality coefficient between the output signal of the Huisden strain gauge full bridge test circuit of the right load-bearing saddle 32 and the longitudinal load of the right load-bearing saddle 32. and the proportionality factor All of them are obtained through early calibration tests; S3. Strain gauges 6 are arranged at the left and right ends of the brake beam 5 so that each end of the brake beam 5 forms a Huisden strain full-bridge test circuit; Collect the output signal of the Huisden strain gauge full bridge test circuit at the left end of the brake beam 5 and the output signal of the Huisden strain gauge full bridge test circuit at the right end of the brake beam 5 , based on the output signal and output signal Calculate the pressure of the left brake shoe 41 when the left brake shoe 41 is against the left wheel 21 and the pressure of the right brake shoe 42 generated when the right brake shoe 42 abuts against the right wheel 22 ; ; ; in, is the proportionality coefficient between the output signal of the Huisden strain gauge full-bridge test circuit at the left end of the brake beam 5 and the pressure of the left brake shoe 41, is the proportionality coefficient between the output signal of the Huisden strain gauge full bridge test circuit at the right end of the brake beam 5 and the pressure of the right brake shoe 42. and the proportionality factor All of them are obtained through early calibration tests; S4. Based on the pressure of left brake shoe 41 and right brake shoe 42 pressure The tangential friction force generated when the left brake shoe 41 abuts against the wheel 2 is respectively constructed , the tangential friction force generated when the right brake shoe 42 abuts against the wheel 2 The calculation formula is: ; ; in, is the dynamic friction coefficient of the left brake shoe 41, is the dynamic friction coefficient of the right brake shoe 42; Under normal braking conditions of wheel 2, i.e., wheel 2 is not locked, the longitudinal wheel-rail force acting on the left wheel 21 is The tangential friction force generated when the left brake shoe 41 abuts against the wheel 2 The value of the rail acting on the right wheel 22 is the same. The tangential friction force generated when the right brake shoe 42 abuts against the wheel 2 The value is the same, that is: ; .

[0018] S5. Substitute the calculation formulas in steps S2, S3, and S4 into the torque balance equation in step S1 to construct the dynamic friction coefficient of the left brake shoe 41. , dynamic friction coefficient of right brake shoe 42 The calculation formula is: ; .

[0019] By first establishing a torque balance equation for the contact point between the vehicle and the track on each side around the vertical coordinate axis based on the four types of loads the vehicle is subjected to during braking, and then calculating the four types of loads the vehicle is subjected to during braking, and calculating the left wheel 21 side and the right wheel 22 side of each type of load respectively, and finally substituting the calculation results of the four types of loads into the torque balance equation, the dynamic friction coefficients of the left brake shoe 41 and the right brake shoe 42 are calculated respectively. This can accurately grasp the dynamic change law of the friction coefficient of the brake shoe 4 of a heavy-load train under a real operating environment, and can improve the operating safety of heavy-load trains according to this method.

[0020] A heavy-duty truck bogie brake shoe dynamic friction coefficient testing device, applied to the above-mentioned heavy-duty truck bogie brake shoe dynamic friction coefficient testing method, includes an axle 1, wheels 2, load saddles 3, brake shoes 4, brake beams 5 and strain gauges 6; the wheels 2 include a left wheel 21 and a right wheel 22, the load saddles 3 include a left load saddle 31 and a right load saddle 32, the brake shoes 4 include a left brake shoe 41 and a right brake shoe 42, the left wheel 21 and the right wheel 22 are rotatably connected to the two ends of the axle 1, and the two end ends of the axle 1 pass through the left wheel 21 and the right wheel 22 The left load-bearing saddle 31 and the right load-bearing saddle 32 are respectively fixed on the circumferential surface of the ends on both sides of the axle 1, and the left brake shoe 41 and the right brake shoe 42 are fixed on the two ends of the brake beam 5. The brake shoe 4 cooperates with the wheel surface of the wheel 2 on the same side to achieve braking of the wheel 2. The strain gauge 6 is set at the load-sensitive positions of the left load-bearing saddle 31, the right load-bearing saddle 32, the left end of the brake beam 5, and the right end of the brake beam 5. Each strain gauge 6 is equipped with four to form a Huisden strain full-bridge test circuit. The load-sensitive position is the position on the component that is most obviously subjected to load strain.

Claims

1. A method for testing the dynamic friction coefficient of brake shoes of heavy-duty truck bogies, characterized in that: The specific steps include: S1. Based on the four types of loads applied to the vehicle during braking, the torque balance equations of the four types of loads about the contact point between the left wheel (21) and the track and the contact point between the right wheel (22) and the track around the vertical coordinate axis are constructed; S2. Collect the strain full-bridge signals of the left load saddle (31) and the right load saddle (32), and calculate the longitudinal suspension forces of the left load saddle (31) and the right load saddle (32) in the four types of loads respectively; S3. collecting strain full-bridge signals at the left end of the brake beam (5) and the right end of the brake beam (5), and calculating the pressure of the left brake shoe (41) generated when the left brake shoe (41) is in contact with the left wheel (21), and the pressure of the right brake shoe (42) generated when the right brake shoe (42) is in contact with the right wheel (22) in the four types of loads; S4. Then, according to the pressure of the left brake shoe (41) and the pressure of the right brake shoe (42), respectively, a calculation formula for the longitudinal wheel-rail force of the rail acting on the left wheel (21) and the longitudinal wheel-rail force of the rail acting on the right wheel (22) in the four types of loads is constructed, and a calculation formula for the tangential friction force generated when the left brake shoe (41) is abutted against the wheel (2) and the tangential friction force generated when the right brake shoe (42) is abutted against the wheel (2) in the four types of loads is constructed; S5. Substitute the calculation results in steps S2, S3, and S4 into the torque balance equation in step S1 to calculate the dynamic friction coefficients of the left brake shoe (41) and the right brake shoe (42).

2. The method for testing the dynamic friction coefficient of brake shoes of heavy-duty truck bogies according to claim 1, characterized in that: The step S1 is specifically as follows: During the vehicle braking process, the left wheel (21) and the right wheel (22) are subjected to four types of loads, specifically including: the longitudinal suspension force of the left load-bearing saddle (31) and the longitudinal suspension force of the right load-bearing saddle (32) respectively acted on by the inertial force of the upper vehicle moving forward, the longitudinal wheel-rail force of the lower rail acting on the left wheel (21) and the right wheel (22) respectively when the wheel (2) moves forward, the pressure of the left brake shoe (41) and the pressure of the right brake shoe (42) generated when the left brake shoe (41) and the right brake shoe (42) are abutted against the wheel (2), and the tangential friction force generated when the left brake shoe (41) and the right brake shoe (42) are abutted against the wheel (2); Based on the four types of loads, the torque balance equations of the left wheel (21) and the track contact point around the vertical coordinate axis and the torque balance equations of the right wheel (22) and the track contact point around the vertical coordinate axis are constructed: ； ； in, is the longitudinal wheel-rail force exerted by the rail on the left wheel (21), is the longitudinal wheel-rail force exerted by the rail on the right wheel (22), is the brake shoe pressure generated when the left brake shoe (41) abuts against the wheel (2), is the brake shoe pressure generated when the right brake shoe (42) abuts against the wheel (2), is the tangential friction force generated when the left brake shoe (41) abuts against the wheel (2), is the tangential friction force generated when the right brake shoe (42) abuts against the wheel (2), is the angle between the pressure of the brake shoe (4) and the horizontal line, is the horizontal distance between the left wheel-rail contact point and the right wheel-rail contact point, It is the horizontal distance between the bearing saddle (3) and the wheel-rail contact point on the same side.

3. The method for testing the dynamic friction coefficient of brake shoes of heavy-duty truck bogies according to claim 2, characterized in that: The step S2 is specifically as follows: Strain gauges (6) are arranged on the left load-bearing saddle (31) and the right load-bearing saddle (32), respectively, so that a Huisden strain full-bridge test circuit is formed on each of the load-bearing saddles (3); Collect the output signal of the left load saddle (31) Huisden strain full bridge test circuit , output signal of the right load saddle (32) Huisden strain full bridge test circuit , based on the output signal and output signal Calculate the longitudinal suspension force on the left saddle (31) And the longitudinal suspension force on the right load saddle (32) ; ； ； in, is the proportionality coefficient between the output signal of the Huisden strain gauge full bridge test circuit of the left load saddle (31) and the longitudinal load of the left load saddle (31), It is the proportionality coefficient between the output signal of the Huisden strain full bridge test circuit of the right load-bearing saddle (32) and the longitudinal load of the right load-bearing saddle (32).

4. The method for testing the dynamic friction coefficient of brake shoes of heavy-duty truck bogies according to claim 3, characterized in that: The step S3 is specifically as follows: Strain gauges (6) are respectively arranged at the left end and the right end of the brake beam (5), so that a Huisden strain full-bridge test circuit is formed at each end of the brake beam (5); Collect the output signal of the Huisden strain gauge full bridge test circuit at the left end of the brake beam (5) and the output signal of the Huisden strain gauge full bridge test circuit at the right end of the brake beam (5) , based on the output signal and output signal Calculate the pressure of the left brake shoe (41) when the left brake shoe (41) is against the left wheel (21) and the pressure of the right brake shoe (42) generated when the right brake shoe (42) abuts against the right wheel (22) ; ； ； in, is the proportionality coefficient between the output signal of the Huisden strain gauge full bridge test circuit at the left end of the brake beam (5) and the pressure of the left brake shoe (41), It is the proportionality coefficient between the output signal of the Huisden strain full bridge test circuit at the right end of the brake beam (5) and the pressure of the right brake shoe (42).

5. The method for testing the dynamic friction coefficient of brake shoes of heavy-duty truck bogies according to claim 4, characterized in that: The step S4 is specifically as follows: Based on the pressure of the left brake shoe (41) and right brake shoe (42) pressure The tangential friction force generated when the left brake shoe (41) is pressed against the wheel (2) is respectively constructed The calculation formula of the tangential friction force generated when the right brake shoe (42) is pressed against the wheel (2) is: Calculation formula: ； ； in, is the dynamic friction coefficient of the left brake shoe (41), is the dynamic friction coefficient of the right brake shoe (42); Under normal braking conditions of the wheel (2), that is, the wheel (2) is not locked, the longitudinal wheel-rail force acting on the left wheel (21) is The tangential friction force generated when the left brake shoe (41) abuts against the wheel (2) The longitudinal wheel-rail force acting on the right wheel (21) is the same as The tangential friction force generated when the right brake shoe (42) is pressed against the wheel (2) The value is the same, that is: ； 。 6. The method for testing the dynamic friction coefficient of brake shoes of heavy-duty truck bogies according to claim 5, characterized in that: The step S5 is specifically as follows: Substitute the calculation formulas in steps S2, S3 and S4 into the torque balance equation in step S1 to construct the dynamic friction coefficient of the left brake shoe (41) , dynamic friction coefficient of right brake shoe (42) The calculation formula is: ； 。 7. A device for testing the dynamic friction coefficient of brake shoes for heavy-duty truck bogies, used in the method for testing the dynamic friction coefficient of brake shoes for heavy-duty truck bogies according to claim 5, characterized in that: The invention comprises an axle (1), a wheel (2), a bearing saddle (3), a brake shoe (4), a brake beam (5) and a strain gauge (6); the wheel (2) comprises a left wheel (21) and a right wheel (22); the bearing saddle (3) comprises a left bearing saddle (31) and a right bearing saddle (32); the brake shoe (4) comprises a left brake shoe (41) and a right brake shoe (42); the left wheel (21) and the right wheel (22) are rotatably connected to the two ends of the axle (1); and the two end ends of the axle (1) pass through the left wheel (21) and the right wheel (22); the left bearing saddle (31) and the right bearing saddle (32) are respectively fixed on the circumference of the ends on both sides of the axle (1), the left brake shoe (41) and the right brake shoe (42) are fixed on the two ends of the brake beam (5), the brake shoe (4) cooperates with the wheel surface of the wheel (2) on the same side to achieve braking of the wheel (2), and the strain gauge (6) is provided at the load-sensitive positions of the left bearing saddle (31), the right bearing saddle (32), the left end of the brake beam (5), and the right end of the brake beam (5), and each of the strain gauges (6) is provided with four to form a Huisden strain full-bridge test circuit.

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