An adjustable gap measuring device for automotive drum brakes

Abstract

The present application relates to the technical field of brake detection, and specifically relates to an adjustable automobile drum brake gap measuring device, which comprises a mounting frame, a sliding groove is formed in the front end of the mounting frame, an auxiliary plate is fixedly installed at the rear end of the mounting frame, and a drum brake is arranged at the front end of the mounting frame; the gap measuring device further comprises a concentric control mechanism and a gap measuring assembly; the concentric control mechanism further comprises a rotating assembly, a first positioning assembly and a second positioning assembly; through the design of the concentric control mechanism, under the limitation of guide bars, the first servo motor can drive two groups of movable blocks to move towards or away from each other, so that three groups of guide bars can clamp the brake drum, and through the rotation of a handle, the restoring force of the first return spring is released, so that three groups of top plates can press the brake drum, the brake drum is prevented from being skewed, and the brake drum is driven to rotate by a brake motor, so that different positions of the inner wall of the brake drum can be detected.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of brake detection, and particularly relates to an adjustable automobile drum brake gap measuring device. BACKGROUND

[0002] The automobile drum brake gap refers to the distance between the brake drum and the brake shoe friction lining, and the gap size has a key influence on the automobile braking performance and operating cost. If the gap is too small, the friction plate and the brake drum will excessively rub during braking, which will cause the friction plate to wear out, shorten its service life, and increase the automobile fuel consumption due to the additional friction resistance. If the gap is too large, the brake shoe needs to move a longer distance to effectively contact the brake drum during braking, which will increase the braking distance, affect the braking response speed, and bring inconvenience to the driving operation. Therefore, accurate measurement of the brake gap is of great significance to ensure the safety of automobile braking and reduce the operating cost.

[0003] In the actual measurement of the drum brake gap, three key points, i.e., the two ends and the middle position, are selected on each friction plate for measurement to ensure that the gap data is comprehensively and accurately obtained. In the measurement process, the brake drum needs to be rotated to switch different measurement points, and the brake shoe and the measuring instrument need to be kept in a fixed state to avoid measurement deviation caused by the movement of the components. The existing measuring equipment has poor coordination and is difficult to directly meet the measurement requirements. Various tools need to be used for auxiliary operation, and the gap measurement effect is poor.

[0004] In view of the above technical problems, Chinese patent application No. 201810900791.1 discloses an automobile drum brake gap measuring tool and a measuring method. Although the distance between the brake drum and the brake shoe friction lining can be detected, the brake drum needs to be rotated, and manual operation is prone to hand shaking and other adverse operation accidents, which affects the measurement accuracy.

[0005] Therefore, an adjustable automobile drum brake gap measuring device is provided. SUMMARY

[0006] The present application aims to provide an adjustable automobile drum brake gap measuring device to solve the problem of poor drum brake gap measurement effect in the background art.

[0007] In order to achieve the above object, the present application provides the following technical scheme: A drum brake gap measuring device with adjustable automobile, comprising a mounting frame, a sliding groove is formed in the front end of the mounting frame, an auxiliary plate is fixedly installed at the rear end of the mounting frame, a drum brake is arranged at the front end of the mounting frame, the gap measuring device further comprises a concentric control mechanism and a gap measuring assembly, the concentric control mechanism further comprises a rotating assembly, a first positioning assembly and a second positioning assembly, the rotating assembly is arranged at the front and rear ends of the mounting frame and used to drive the fixed brake drum to rotate, the first positioning assembly is arranged on the rotating assembly and used to fix the brake drum with different shaft diameters, the second positioning assembly is arranged at the front and rear ends of the mounting frame and used to fix the brake bottom plate with different profiles, the gap measuring assembly is arranged above the front end of the mounting frame and used to adjust the position of the laser displacement sensor, so that the laser displacement sensor can select point measurement of the gap between the friction plate and the brake drum.

[0008] Preferably, the drum brake comprises a brake bottom plate arranged at the front end of the mounting frame, a brake shoe is fixedly installed at the front end of the brake bottom plate, a wheel cylinder is arranged on the brake shoe, a friction plate is fixedly installed on the outer layer of the brake shoe, a brake drum is rotatably connected to the front end of the brake shoe, and an observation window is formed in the front end of the brake drum.

[0009] Preferably, the rotating assembly comprises an emergency brake motor fixedly installed on the auxiliary plate, the output shaft of the emergency brake motor penetrates through the auxiliary plate and is fixedly connected with a first belt pulley, the first belt pulley is drivingly connected with a second belt pulley through a belt, the front end of the second belt pulley is fixedly installed with a mounting plate, and the mounting plate is rotatably connected to the auxiliary plate.

[0010] Preferably, the front end of the auxiliary plate is fixedly connected with three groups of guide bars, the three groups of guide bars are uniformly arranged in a circular shape, and the other end of the guide bar penetrates through the mounting frame and is fixedly connected with a limiting plate.

[0011] Preferably, the first positioning assembly comprises a first servo motor fixedly installed on the second belt pulley, the output shaft of the first servo motor penetrates through the second belt pulley and the mounting plate and is fixedly connected with a first bidirectional screw rod, the outer side of the first bidirectional screw rod is drivingly connected with two groups of movable blocks, a guide bar groove is formed in the outer side of the movable block, three groups of connecting rods are hinged to the outer side of the movable block, the other end of the connecting rod is hinged with a clamping plate, and the clamping plate is hinged with two groups of connecting rods.

[0012] Preferably, the clamping plate is provided with a top plate, one end of a top rod is fixedly connected with the top plate, the other end of the top rod penetrates through the clamping plate and is fixedly connected with a pull handle, two groups of clamping strips are symmetrically arranged on the outer side of the clamping plate, a clamping strip opening is formed in the clamping plate for the clamping strip to pass through, a first return spring is arranged between the clamping plate and the top plate, and the first return spring is sleeved on the top rod.

[0013] Preferably, the second positioning assembly comprises a second servo motor fixedly installed at the rear end of the auxiliary plate, the output shaft of the second servo motor penetrates through the auxiliary plate and is fixedly connected with a first bevel gear, the first bevel gear is engaged with a second bevel gear, the second bevel gear is fixedly connected with a second bidirectional screw rod, the outer side of the second bidirectional screw rod is drivingly connected with two groups of movable plates, the front end of the movable plate is fixedly connected with a sliding block, and the front end of the sliding block is fixedly connected with a clamping plate.

[0014] Preferably, the sliding block is slidingly connected in the sliding groove, the sliding block is sleeved on the guide rod, the guide rod is fixedly installed in the sliding groove, the outer side of the guide rod is sleeved with a second return spring, and the second return spring is arranged between the inner wall of the sliding groove and the sliding block.

[0015] Preferably, the gap measuring assembly comprises a sliding rail fixedly installed at the front end of the mounting frame, the sliding rail is slidingly connected with a sliding seat, the front end of the sliding seat is fixedly connected with a static plate, the front end of the static plate is slidingly connected with a dynamic plate, the bottom end of the dynamic plate is fixedly installed with a laser displacement sensor, the upper end of the static plate is fixedly installed with an electric push rod, the other end of the electric push rod is fixedly connected with a backing plate, and the backing plate is fixedly installed at the upper end of the dynamic plate.

[0016] Preferably, the front end of the sliding seat is fixedly installed with a third servo motor, the output shaft of the third servo motor penetrates through the sliding seat and is fixedly connected with a gear, the gear is engaged with a rack, and the rack is fixedly installed on the sliding rail.

[0017] The present application has the following beneficial effects:

[0018] 1. The present application designs a concentric control mechanism, under the limitation of guide bars, the first servo motor can drive two groups of movable blocks to move towards or away from each other, so that three groups of guide bars can clamp the brake drum, and the restoring force of the first return spring is released by rotating the handle, so that the three groups of top plates can press the brake drum, so as to avoid the brake drum from being skewed, and the brake drum is driven to rotate by the brake motor, so as to detect different positions of the inner wall of the brake drum, and the two groups of clamping plates are clamped to the outer side of the brake plate by the second servo motor, so as to fix the friction plate on the brake shoe, and the movement of the clamping plate is assisted by the restoring force of the second return spring, which can assist the second positioning assembly to be fixed, improve the stability of the structure, and avoid the rotation assembly and the first positioning assembly, so as to coordinate the installation structure of the assembly.

[0019] 2. The present application designs a gap measuring assembly matched with a concentric control mechanism, the third servo motor drives the laser displacement sensor to rotate around the center of the brake drum, so as to adjust the measurement angle of the laser displacement sensor, the electric push rod drives the laser displacement sensor to expand or contract, so as to select the point of the observation window, and the distance between the inner wall of the brake drum and the friction plate can be accurately measured. BRIEF DESCRIPTION OF DRAWINGS

[0020] In order to make the technical solutions in the present application or the prior art clearer, the accompanying drawings needed in the embodiments or the prior art description will be briefly introduced. Obviously, the accompanying drawings in the following description only aim at the present application, and based on these drawings, those skilled in the art can obtain other drawings without any creative effort.

[0021] Figure 1 It is a front perspective view of the whole adjustable automobile drum brake gap measuring device according to the embodiment of the present application.

[0022] Figure 2 It is an exploded view of the drum brake of the adjustable automobile drum brake gap measuring device according to the embodiment of the present application.

[0023] Figure 3 It is a rear perspective view of the whole adjustable automobile drum brake gap measuring device according to the embodiment of the present application.

[0024] Figure 4 It is a perspective view of the rotating assembly and the first positioning assembly of the adjustable automobile drum brake gap measuring device according to the embodiment of the present application.

[0025] Figure 5 It is a partial perspective view of the adjustable automobile drum brake gap measuring device according to the embodiment of the present application.

[0026] Figure 6 It is a perspective view of the second positioning assembly of the adjustable automobile drum brake gap measuring device according to the embodiment of the present application.

[0027] Figure 7 It is a perspective view of the gap measuring assembly of the adjustable automobile drum brake gap measuring device according to the embodiment of the present application.

[0028] Figure 8 It is a perspective view of the adjustable automobile drum brake gap measuring device according to the embodiment of the present application. Figure 7 It is an enlarged view of A in the above figure.

[0029] In the figure, the marks are as follows: 1, mounting frame; 11, sliding groove; 12, auxiliary plate;

[0030] 2, drum brake; 21, brake bottom plate; 22, brake shoe; 23, friction plate; 24, wheel cylinder; 25, brake drum; 251, observation window;

[0031] 3, rotating assembly; 31, band brake motor; 32, first belt pulley; 33, second belt pulley; 34, mounting plate; 35, guide strip; 36, limiting plate;

[0032] 4, first positioning assembly; 41, first servo motor; 42, first bidirectional screw rod; 43, movable block; 431, guide slot; 44, connecting rod; 45, clamping plate; 451, top plate; 452, top rod; 453, pull handle; 454, clamping strip; 455, clamping strip opening; 456, first return spring;

[0033] 5, second positioning assembly; 51, second servo motor; 52, first bevel gear; 53, second bevel gear; 54, second bidirectional screw rod; 55, movable plate; 56, sliding block; 57, clamping plate; 58, guide rod; 59, second return spring;

[0034] 6, gap measuring assembly; 61, sliding rail; 62, sliding seat; 63, static plate; 64, dynamic plate; 65, laser displacement sensor; 66, electric push rod; 661, pad plate; 67, third servo motor; 68, gear; 69, rack. DETAILED DESCRIPTION

[0035] In order to make the objectives, technical solutions and advantages of the present application clearer, the present application will be further described in detail below with reference to specific embodiments.

[0036] It should be noted that, unless otherwise defined, technical or scientific terms used in the present application should be understood as their common meanings to those of ordinary skill in the art to which the present application pertains. The terms "first", "second" and similar terms used in the present application do not denote any order, quantity or importance, but are only used to distinguish different components. The terms "comprise", "include" and similar terms mean that the components or objects before the terms encompass the components or objects listed after the terms and their equivalents, and do not exclude other components or objects. The terms "connect" or "connected" and similar terms do not mean physical or mechanical connection, but can include electrical connection, whether direct or indirect. The terms "upper", "lower", "left", "right" and the like only represent relative positional relationships, and when the absolute positions of the described objects change, the relative positional relationships can also change accordingly.

[0037] Please refer to Figures 1 to 8The application provides a technical scheme: an adjustable automobile drum brake gap measuring device, which comprises a mounting frame 1, a sliding groove 11 is formed in the front end of the mounting frame 1, an auxiliary plate 12 is fixedly installed at the rear end of the mounting frame 1, a drum brake 2 is arranged at the front end of the mounting frame 1, the gap measuring device further comprises a concentric control mechanism and a gap measuring assembly 6, the concentric control mechanism further comprises a rotating assembly 3, a first positioning assembly 4 and a second positioning assembly 5, the rotating assembly 3 is arranged at the front and rear ends of the mounting frame 1 and is used for driving the fixed brake drum 25 to rotate, the first positioning assembly 4 is arranged on the rotating assembly 3 and is used for fixing the brake drum 25 with different shaft diameters, the second positioning assembly 5 is arranged at the front and rear ends of the mounting frame 1 and is used for fixing the brake bottom plate 21 with different contours, the gap measuring assembly 6 is arranged above the front end of the mounting frame 1 and is used for adjusting the position of the laser displacement sensor 65, so that the laser displacement sensor 65 can select points to measure the gap between the friction plate 23 and the brake drum 25, the drum brake 2 comprises a brake bottom plate 21 arranged at the front end of the mounting frame 1, a brake shoe 22 is fixedly installed at the front end of the brake bottom plate 21, a wheel cylinder 24 is arranged on the brake shoe 22, a friction plate 23 is fixedly installed on the outer layer of the brake shoe 22, a brake drum 25 is rotatably connected to the front end of the brake shoe 22, and an observation window 251 is formed in the front end of the brake drum 25.

[0038] As an embodiment of the application, as Figure 3 、 Figure 4 and Figure 5As shown, the rotating assembly 3 comprises a brake motor 31 fixedly installed on the auxiliary plate 12, the output shaft of the brake motor 31 penetrates through the auxiliary plate 12 and is fixedly connected with a first belt pulley 32, the first belt pulley 32 is drivingly connected with a second belt pulley 33 through a belt, the front end of the second belt pulley 33 is fixedly installed with a mounting plate 34, the mounting plate 34 is rotatably connected on the auxiliary plate 12, the front end of the auxiliary plate 12 is fixedly connected with three groups of guide bars 35, the three groups of guide bars 35 are uniformly arranged in a circle, the other end of the guide bar 35 penetrates through the mounting frame 1 and is fixedly connected with a limiting plate 36, the first positioning assembly 4 comprises a first servo motor 41 fixedly installed on the second belt pulley 33, the output shaft of the first servo motor 41 penetrates through the second belt pulley 33 and the mounting plate 34 and is fixedly connected with a first bidirectional screw rod 42, the outer side of the first bidirectional screw rod 42 is threadedly drivingly connected with two groups of movable blocks 43, the outer side of the movable block 43 is provided with a guide bar groove 431, the outer side of the movable block 43 is hingedly connected with three groups of connecting rods 44, the other end of the connecting rod 44 is hingedly connected with a clamping plate 45, the clamping plate 45 is hingedly connected with two groups of connecting rods 44, the inner side of the clamping plate 45 is provided with a top plate 451, one end of a top rod 452 is fixedly connected with the top plate 451, the other end of the top rod 452 penetrates through the clamping plate 45 and is fixedly connected with a pull handle 453, the outer side of the clamping plate 45 is provided with two groups of clamping strips 454 which are symmetrical, the clamping plate 45 is provided with clamping strip openings 455 for the clamping strips 454 to pass through, the first reset spring 456 is arranged between the clamping plate 45 and the top plate 451, and the first reset spring 456 is sleeved on the top rod 452.

[0039] By adopting the above technical scheme, when in use, the first servo motor 41 is started, the first servo motor 41 drives the first bidirectional screw rod 42 to rotate, because the guide bar 35 is clamped in the guide bar groove 431, the rotation of the movable block 43 is limited by the guide bar 35, so the first bidirectional screw rod 42 can drive the two groups of movable blocks 43 to move towards each other, then the two groups of movable blocks 43 can drive the three groups of clamping plates 45 to clamp the center hole wall of the brake drum 25 through the connecting rods 44, then the clamping strips 454 on the top rod 452 are aligned with the clamping strip openings 455 provided on the clamping plate 45 by rotating the pull handle 453, then the restoring force of the first reset spring 456 drives the top plate 451 to press the brake drum 25, finally the brake motor 31 is started, the brake motor 31 drives the first belt pulley 32 to rotate, because the first belt pulley 32 is drivingly connected with the second belt pulley 33, the second belt pulley 33 drives the brake drum 25 to rotate through the mounting plate 34 and the guide bar 35, which is beneficial to the first servo motor 41 driving the two groups of movable blocks 43 to move towards or away from each other under the limitation of the guide bar 35, and is beneficial to the three groups of guide bars 35 clamping the brake drum 25, and is beneficial to the three groups of top plates 451 pressing the brake drum 25 by releasing the restoring force of the first reset spring 456 through rotating the pull handle 453, which avoids the brake drum 25 from being skewed, and utilizes the brake motor 31 to drive the brake drum 25 to rotate, which is beneficial to detecting different positions of the inner wall of the brake drum 25.

[0040] As an embodiment of the present application, as shown in Figure 1 、 Figure 3 and Figure 6 The second positioning assembly 5 includes a second servo motor 51 fixedly installed at the rear end of the auxiliary plate 12, the output shaft of the second servo motor 51 penetrates through the auxiliary plate 12 and is fixedly connected with a first bevel gear 52, the first bevel gear 52 is engaged with a second bevel gear 53, the second bevel gear 53 is fixedly connected on a second bidirectional screw rod 54, two groups of movable plates 55 are drivingly connected with the outer side of the second bidirectional screw rod 54, the front end of the movable plate 55 is fixedly connected with a sliding block 56, the front end of the sliding block 56 is fixedly connected with a clamping plate 57, the sliding block 56 is slidingly connected in the sliding groove 11, the sliding block 56 is sleeved on a guide rod 58, the guide rod 58 is fixedly installed in the sliding groove 11, the outer side of the guide rod 58 is sleeved with a second return spring 59, and the second return spring 59 is arranged between the inner wall of the sliding groove 11 and the sliding block 56.

[0041] By adopting the above technical scheme, first, the brake bottom plate 21 provided with the brake shoe 22 is attached to the front end of the mounting frame 1, so as to avoid the friction plate 23 on the brake shoe 22 from being skewed, then the second servo motor 51 is started, the second servo motor 51 drives the first bevel gear 52 to rotate, then because the first bevel gear 52 engages the second bevel gear 53, the second bevel gear 53 is fixedly connected on the movable plate 55, so the second servo motor 51 can drive the two groups of movable plates 55 to move towards each other, and because the restoring force of the second return spring 59 can act on the sliding block 56, the movable plate 55 can stably transmit the acting force to the clamping plate 57 through the sliding block 56, so that the two groups of clamping plates 57 clamp the brake bottom plate 21, which is conducive to clamping the outer side of the brake bottom plate 21 by the two groups of clamping plates 57 driven by the second servo motor 51, so as to stably fix the brake shoe 22 installed inside the brake bottom plate 21 on the mounting frame 1, and the restoring force of the second return spring 59 assists the movement of the clamping plate 57, which not only assists the second positioning assembly 5 to be fixed and improves the stability of the assembly, but also avoids the rotating assembly 3 and the first positioning assembly 4, thereby coordinating the assembly mounting structure.

[0042] As an embodiment of the present application, as shown in Figure 1 、 Figure 7 and Figure 8As shown, the gap measuring assembly 6 comprises a slide rail 61 fixedly installed at the front end of the mounting rack 1, a slide base 62 slidingly connected with the slide rail 61, a static plate 63 fixedly connected with the front end of the slide base 62, a dynamic plate 64 slidingly connected with the front end of the static plate 63, a laser displacement sensor 65 fixedly installed at the bottom end of the dynamic plate 64, an electric push rod 66 fixedly installed at the upper end of the static plate 63, a backing plate 661 fixedly installed at the other end of the electric push rod 66, the backing plate 661 being fixedly installed at the upper end of the dynamic plate 64, a third servo motor 67 fixedly installed at the front end of the slide base 62, an output shaft of the third servo motor 67 penetrating through the slide base 62 and fixedly connected with a gear 68, the gear 68 being engaged with a rack 69, the rack 69 being fixedly installed on the slide rail 61.

[0043] By adopting the technical scheme, first, the third servo motor 67 is started, the third servo motor 67 drives the gear 68 to rotate, because the gear 68 is engaged with the rack 69 and the slide base 62 is slidingly connected with the slide rail 61, so the slide base 62 can drive the laser displacement sensor 65 to rotate around the center of the brake drum 25 through the static plate 63 and the dynamic plate 64, then the electric push rod 66 is started, the electric push rod 66 drives the dynamic plate 64 to slide on the static plate 63 through the backing plate 661, so that the rear end of the laser displacement sensor 65 is aligned with the observation window 251, finally the laser displacement sensor 65 measures the gap distance from the outer side of the friction plate 23 to the inner wall of the brake drum 25 through the observation window 251, which is beneficial to rotating the laser displacement sensor 65 around the center of the brake drum 25 by the third servo motor 67, facilitating the laser displacement sensor 65 to adjust the measuring angle, and expanding or retracting the laser displacement sensor 65 by the electric push rod 66, so that the laser displacement sensor 65 is aligned with the observation window 251 to select points and measure the distance between the brake drum 25 and the friction plate 23.

[0044] Working principle: in use, the first servo motor 41 is started, the first servo motor 41 drives the first bidirectional screw rod 42 to rotate, because the guide strip 35 is clamped in the guide strip groove 431, the rotation of the movable block 43 is limited by the guide strip 35, so the first bidirectional screw rod 42 can drive the two groups of movable blocks 43 to move towards each other, then the two groups of movable blocks 43 can drive the three groups of clamping plates 45 to clamp the central hole wall of the brake drum 25 through the connecting rods 44, then the clamping strip 454 on the top rod 452 is aligned with the clamping strip opening 455 on the clamping plate 45 by rotating the pull handle 453, then the restoring force of the first return spring 456 drives the top plate 451 to press the brake drum 25, finally the brake motor 31 is started, the brake motor 31 drives the first pulley 32 to rotate, because the first pulley 32 is drivingly connected with the second pulley 33, the second pulley 33 drives the brake drum 25 to rotate through the mounting plate 34 and the guide strip 35;

[0045] The brake bottom plate 21 installed with the brake shoe 22 is attached to the front end of the mounting frame 1 to avoid the friction plate 23 on the brake shoe 22 from being skewed, then the second servo motor 51 is started, the second servo motor 51 drives the first bevel gear 52 to rotate, then because the first bevel gear 52 meshes with the second bevel gear 53, the second bevel gear 53 is fixedly connected to the movable plate 55, so the second servo motor 51 can drive the two groups of movable plates 55 to move towards each other, and because the restoring force of the second return spring 59 can act on the sliding block 56, the movable plate 55 can stably transmit the force to the clamping plate 57 through the sliding block 56, so that the two groups of clamping plates 57 clamp the brake bottom plate 21;

[0046] The third servo motor 67 is started, the third servo motor 67 drives the gear 68 to rotate, because the gear 68 meshes with the rack 69, the sliding seat 62 is slidingly connected to the sliding rail 61, so the sliding seat 62 can drive the laser displacement sensor 65 to rotate around the center of the brake drum 25 through the static plate 63 and the movable plate 64, then the electric push rod 66 is started, the electric push rod 66 drives the movable plate 64 to slide on the static plate 63 through the backing plate 661, so that the rear end of the laser displacement sensor 65 is aligned with the observation window 251, finally the laser displacement sensor 65 measures the gap distance from the outer side of the friction plate 23 to the inner wall of the brake drum 25 through the observation window 251.

[0047] The above only describes the preferred embodiments of the present application and is not used to limit the present application, any modification, equivalent replacement and improvement made within the spirit and principle of the present application shall be included in the protection scope of the present application.

[0048] In addition, it should be understood that although the present specification is described in terms of embodiments, not every embodiment contains only one independent technical solution, and the description of the specification is only for the sake of clarity, and those skilled in the art should consider the specification as a whole, and the technical solutions in each embodiment can be combined appropriately to form other embodiments that those skilled in the art can understand.

Claims

1. Adjustable automobile drum brake gap measuring equipment, including mounting bracket (1), the front end of the mounting bracket (1) is provided with a sliding groove (11), the rear end of the mounting bracket (1) is fixedly installed with auxiliary plate (12), the front end of the mounting bracket (1) is provided with drum brake (2), characterized in that: The gap measuring equipment further comprises a concentric control mechanism and a gap measuring assembly (6), the concentric control mechanism further comprises a rotating assembly (3), a first positioning assembly (4) and a second positioning assembly (5), the rotating assembly (3) is arranged at the front and rear ends of the mounting bracket (1), used to drive the fixed brake drum (25) to rotate, the first positioning assembly (4) is arranged on the rotating assembly (3), used to fix different shaft diameter brake drums (25), the second positioning assembly (5) is arranged at the front and rear ends of the mounting bracket (1), used to fix brake bottom plates (21) of different profiles, the gap measuring assembly (6) is arranged above the front end of the mounting bracket (1), used to adjust the position of the laser displacement sensor (65), so that the laser displacement sensor (65) can select point measurement of the gap between the brake drum (25) and the brake drum (25); The rotating assembly (3) comprises an emergency brake motor (31) fixedly installed on the auxiliary plate (12), the output shaft of the emergency brake motor (31) penetrates the auxiliary plate (12) and is fixedly connected with a first pulley (32), the first pulley (32) is connected with a second pulley (33) through a belt drive, the front end of the second pulley (33) is fixedly installed with a mounting plate (34), the mounting plate (34) is rotatably connected to the auxiliary plate (12), the front end of the auxiliary plate (12) is fixedly connected with three groups of guide bars (35), the three groups of guide bars (35) are uniformly arranged in a circular shape, the other end of the guide bar (35) penetrates the mounting bracket (1) and is fixedly connected with a limiting plate (36); The first positioning assembly (4) comprises a first servo motor (41) fixedly installed on the second pulley (33), the output shaft of the first servo motor (41) penetrates the second pulley (33) and the mounting plate (34) and is fixedly connected with a first bidirectional screw rod (42), the outer thread of the first bidirectional screw rod (42) is drivingly connected with two groups of movable blocks (43), the outer side of the movable block (43) is provided with a guide bar groove (431), the outer side of the movable block (43) is hinged with three groups of connecting rods (44), the other end of the connecting rod (44) is hinged with a clamping plate (45), the clamping plate (45) is hinged with two groups of connecting rods (44); The second positioning assembly (5) comprises a second servo motor (51) fixedly installed at the rear end of the auxiliary plate (12), the output shaft of the second servo motor (51) penetrates through the auxiliary plate (12) and is fixedly connected with a first bevel gear (52), the first bevel gear (52) is engaged with a second bevel gear (53), the second bevel gear (53) is fixedly connected on a second bidirectional lead screw (54), the outer side of the second bidirectional lead screw (54) is in threaded transmission connection with two groups of movable plates (55), the front end of the movable plate (55) is fixedly connected with a sliding block (56), and the front end of the sliding block (56) is fixedly connected with a clamping plate (57).

2. An adjustable gap measuring device for automotive drum brakes as claimed in claim 1 wherein, The drum brake (2) comprises a brake bottom plate (21) arranged at the front end of the mounting rack (1), the front end of the brake bottom plate (21) is fixedly installed with a brake shoe (22), the brake shoe (22) is provided with a wheel cylinder (24), the outer layer of the brake shoe (22) is fixedly installed with a friction plate (23), the front end of the brake shoe (22) is rotatably connected with a brake drum (25), and the front end of the brake drum (25) is provided with an observation window (251).

3. An adjustable gap measuring device for automotive drum brakes as claimed in claim 1 wherein, The inside of the clamping plate (45) is provided with a top plate (451), one end of a top rod (452) is fixedly connected with the top plate (451), the other end of the top rod (452) penetrates through the clamping plate (45) and is fixedly connected with a pull handle (453), the outside of the clamping plate (45) is provided with two groups of clamping strips (454) which are symmetrical, the clamping plate (45) is provided with clamping strip openings (455) for the clamping strips (454) to pass through, and the first reset spring (456) is arranged between the clamping plate (45) and the top plate (451).

4. An adjustable gap measuring device for automotive drum brakes as claimed in claim 1 wherein, The sliding block (56) is slidably connected in the sliding groove (11), the sliding block (56) is sleeved on the guide rod (58), the guide rod (58) is fixedly installed in the sliding groove (11), the second reset spring (59) is sleeved on the outside of the guide rod (58), and the second reset spring (59) is arranged between the inner wall of the sliding groove (11) and the sliding block (56).

5. An adjustable gap measuring device for automotive drum brakes as claimed in claim 1 wherein, The gap measuring assembly (6) comprises a sliding rail (61) fixedly installed at the front end of the mounting rack (1), the sliding rail (61) is slidably connected with a sliding seat (62), the front end of the sliding seat (62) is fixedly connected with a static plate (63), the front end of the static plate (63) is slidably connected with a dynamic plate (64), the bottom end of the dynamic plate (64) is fixedly installed with a laser displacement sensor (65), the upper end of the static plate (63) is fixedly installed with an electric push rod (66), the other end of the electric push rod (66) is fixedly connected with a backing plate (661), and the backing plate (661) is fixedly installed on the upper end of the dynamic plate (64).

6. An adjustable gap measuring device for a drum brake of a vehicle as defined in claim 5, wherein The front end of the sliding seat (62) is fixedly installed with a third servo motor (67), the output shaft of the third servo motor (67) penetrates through the sliding seat (62) and is fixedly connected with a gear (68), the gear (68) is engaged with a rack (69), and the rack (69) is fixedly installed on the sliding rail (61).

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