Collision test apparatus

Abstract

To provide a collision test apparatus that can reduce the size of a conventional drop-weight type collision test apparatus and perform a collision test even if an installation area is narrow.SOLUTION: A collision test apparatus according to the present invention that makes a collision carriage collide with a rigid wall and a test body fixed to the rigid wall using the energy of gravity fall, comprises: a rail structure which includes a first rail and a second rail on a horizontal part on the rigid wall side, a curved part continuous with the horizontal part, and a vertical part continuous with the curved part; a collision carriage which travels along the first rail; and a traction carriage which travels along the first rail, and has an electromagnet that controls connection between moving-up / down means that moves up / down the rail structure using the second rail and the collision carriage. When the collision carriage towed by being connected to the traction carriage reaches a prescribed height of the rail structure, connection of the electromagnet is released, only the collision carriage is made to travel along the first rail and collide with the test body.SELECTED DRAWING: Figure 1

Description

[Technical field]

[0001] The present invention relates to a crash test apparatus for evaluating dynamic strength such as the crash performance of a structure, and more particularly to a crash test apparatus in which a crash cart crashes into a test body fixed to a rigid wall. [Background technology]

[0002] Evaluating the crashworthiness of vehicles is extremely important, and includes frontal crash tests, side crash tests, pole crash tests, etc., and automobile manufacturers use crash test equipment to evaluate and design vehicles that ensure the safety of passengers. At the same time, parts and component manufacturers that supply parts and materials to automobile manufacturers also need to conduct crash performance evaluation tests that involve dynamic deformation, and the results of evaluations using crash test equipment are used to improve the prediction accuracy of crash tests using CAE (Computer Aided Engineering) and to design new parts and materials with superior crashworthiness.

[0003] Conventionally, frontal collision tests and pole collision tests have been performed using a collision test method in which a vehicle is towed against a fixed rigid wall or pole and the front or side of the vehicle is collided with the wall or pole, while side collision tests have been performed using a collision test method in which a collision cart or the like is towed against a stationary vehicle or a fixed part or component.

[0004] However, a sufficient distance is required to tow the vehicle or the collision cart on a flat surface with a towing rope to reach the specified test speed, and it is necessary to provide a collision test device that is designed so that the towing rope is detached from the vehicle or the collision cart just before the collision. Therefore, the installation area of ​​the collision test device is inevitably large, which causes problems such as high installation costs.

[0005] As one method for towing a vehicle or a collision cart on a flat surface with a towing rope, a drop weight type collision test device is known in which the other end of the towing rope of the vehicle or the collision cart is connected to a drop weight, which drops to tow the vehicle or the collision cart. Although the configuration of this collision test device is simple, it has the drawback of being large in size because the towing speed cannot be increased unless the drop height of the drop weight is increased and the weight of the drop weight is made large relative to the frictional resistance of the vehicle or the collision cart.

[0006] The crash test device in Patent Document 1 uses a movable pulley for the falling weight, which reduces the height at which the falling weight of the crash test device falls, but the weight of the falling weight is large, so a buffer device is required to cushion the impact of the falling weight, which creates a new problem of the device itself becoming larger. In addition, the falling weight is stopped by the buffer device midway, so it cannot be said that the energy of gravity is fully utilized. [Prior art documents] [Patent documents]

[0007] [Patent Document 1] JP 2016-114384 A Summary of the Invention [Problem to be solved by the invention]

[0008] The object of the present invention is to provide a collision test device that can perform collision tests even in a small installation area by efficiently converting the gravitational energy of a conventional drop weight type collision test device into kinetic energy of a collision cart, thereby reducing the size of the collision test device and eliminating the need for a tow rope. [Means for solving the problem]

[0009] The collision test apparatus of the present invention is a collision test apparatus that uses the energy of gravitational fall to collide a collision trolley with a rigid wall and a test body fixed to the rigid wall, and is characterized in that it comprises a rail structure having a horizontal section on the rigid wall side, a curved section continuing from the horizontal section, and a vertical section continuing from the curved section, a first rail and a second rail, a collision trolley that runs along the first rail, and a towing trolley that runs along the first rail and is equipped with a lifting means that uses the second rail to raise and lower the rail structure and an electromagnet that controls the connection with the collision trolley, and when the collision trolley, which is connected to and towed by the towing trolley, reaches a predetermined height of the rail structure, the electromagnet is released from connection, and the collision trolley runs alone along the first rail, causing the collision trolley to collide with the test body.

[0010] The rail structure has a horizontal section on the rigid wall side, a curved section continuing from the horizontal section, and a vertical section continuing from the curved section, and includes a first rail for running and a second rail for lifting and descending.The collision cart converts the energy of gravitational fall into kinetic energy from a specified height and runs on the first rail, colliding with the test specimen fixed to the rigid wall at the horizontal section.This means that there is little waste in energy conversion, the overall length of the equipment is shortened, and the collision test equipment can be made more compact.

[0011] In addition, the collision cart is coupled to the towing cart by an electromagnet and towed to a predetermined height on the rail structure by a towing cart equipped with a lifting means that travels along the first rail and rises and falls using the second rail. When the collision cart reaches the predetermined height, the electromagnet of the towing cart is released and the collision cart travels alone along the first rail and collides with the test object. This has the advantage that no towing rope is required for the collision test device, making it possible to miniaturize the test device and enabling collision tests to be performed even in a small installation area.

[0012] Furthermore, in the collision test apparatus of the present invention, the lifting means that uses the second rail to move up and down is characterized in that the second rail has a rack, and the towing cart has a pin gear driven by a motor, and the towing cart moves up and down the second rail by meshing with the rack and the pin gear.

[0013] As a means for raising and lowering the rail structure of the towing cart, the second rail has a rack, and the towing cart has a pin gear driven by a motor, and the towing cart is raised and lowered by the meshing of the rack and the pin gear.This eliminates the need for a towing rope as a lifting means, and makes it possible to miniaturize the collision test equipment.

[0014] In addition, in the collision test device of the present invention, the electromagnet is supported by a rotation support mechanism so as to cancel the relative angle of the connection between the towing cart and the collision cart that occurs at the curved portion of the first rail.

[0015] The electromagnet of the towing cart is supported by a rotating support mechanism and is linearly connected to the rear of the collision cart so as to cancel out the relative angle of the connection between the towing cart and the collision cart that occurs at the curved part of the first rail, thereby enabling it to maintain a strong adhesive force.

[0016] In addition, in the collision test device of the present invention, the first rail is characterized in that the cross section formed by the rail head and rail side portions is approximately rectangular, and the first rail is composed of two rails with the rail heads oriented horizontally opposite each other and on the inside.

[0017] The first rail has a roughly rectangular cross section formed by the rail head and rail side sections. It is made up of two rails with the rail heads facing sideways toward the inside. This allows the collision trolley to run and collide with reduced swaying by restraining the rail sides with the rail side restraining wheels and restraining the gap between the rail heads with the rail gap restraining wheels.

[0018] Furthermore, in the collision test device of the present invention, the collision cart is characterized in having at least two pairs of rail side restraining wheels that restrain the rail sides of the first rail in the thickness direction, and rail spacing restraining wheels that restrain the spacing between the rail heads of the first rail, arranged in the longitudinal direction.

[0019] The collision cart is required to collide with the test specimen at high speed and with high positional accuracy. In order to reduce swaying and lateral displacement of the collision cart during collision, it is necessary to have at least two pairs of rail side restraining wheels that restrain the rail sides of the first rail in the thickness direction, and rail spacing restraining wheels that restrain the spacing between the rail heads of the first rail, in the longitudinal direction. Effect of the Invention

[0020] In the collision test device of the present invention, the collision cart converts the energy of gravity fall into kinetic energy and travels from a predetermined height of a rail structure having a horizontal section on the rigid wall side, a curved section continuing from the horizontal section, and a vertical section continuing from the curved section, and a first rail and a second rail, and collides with a test object fixed to the rigid wall at the horizontal section. This reduces the waste of energy conversion, shortens the overall length of the device, and allows the collision test device to be made compact. In addition, the collision cart is connected to an electromagnet by a towing cart equipped with a lifting means and is towed to a predetermined height of the rail structure. When the collision cart reaches the predetermined height, the electromagnet of the towing cart is released, and only the collision cart travels along the first rail and collides with the test object. Therefore, the collision test device does not require a towing rope, making it possible to make the test device compact, and a collision test can be performed even if the installation area of ​​the test device is small. [Brief description of the drawings]

[0021] [Figure 1] 1 is a schematic front view of a collision test device according to an embodiment. FIG. [Diagram 2] FIG. 2 is an enlarged view of a cross section taken along line AA in FIG. [Diagram 3] 1A is a plan view, FIG. 1B is a front view, FIG. 1C is a cross-sectional view taken along line BB in FIG. 1B, and FIG. 1D is a cross-sectional view taken along line CC in FIG. [Figure 4] 1A is a plan view, FIG. 1B is a front view, FIG. 1C is a cross-sectional view taken along line DD in FIG. 1B, and FIG. 1D is a cross-sectional view taken along line EE in FIG. 1B. [Diagram 5] FIG. 4 is a flow chart showing a test operation of the collision test device. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0022] Hereinafter, preferred embodiments of the present invention will be described with reference to the drawings. EXAMPLES

[0023] 1 is a schematic front view of a collision test apparatus according to an embodiment of the present invention. The collision test apparatus 1 comprises a rail structure 2, a rigid wall 4, a collision cart 6, and a towing cart 8.

[0024] The rigid wall 4 is provided at the end of the horizontal part of the rail structure 2, and absorbs the impact of a collision by the collision cart 6 of the test specimen T fixed to the rigid wall 4. In the present invention, the test specimen T fixed to the rigid wall 4 means that at least a part of the test specimen T is in contact with the rigid wall 4 before testing. In addition, when a posture maintaining device is used to maintain the posture of the test specimen T, it means that the posture maintaining device is in contact with the rigid wall 4.

[0025] The rail structure 2 is composed of a horizontal section on the side of the rigid wall 4, a curved section continuing from the horizontal section, and a vertical section continuing from the curved section, and is provided with a first rail 22 for traveling and a second rail 25 for ascending and descending. The length of the horizontal section may be approximately the same as the sum of the length of the maximum test object T, the length of the collision cart 6, and the length of the towing cart 8, and the curved section is a 1 / 4 arc of radius R in the first rail 22 of this embodiment, and is smoothly connected to the horizontal section and the vertical section. The speed of the collision cart 6 is determined by the height of the curved section and the length of the vertical section formed vertically and continuing vertically. For example, if the length of the vertical section is equal to the radius R of the arc, it is equivalent to a fall from a height of 2R. If R=5m, and friction and the like are ignored, the collision cart 6 will collide with the test object T at 14m / s (50.4km / h). Although a 1 / 4 curved shape such as an ellipse can be assumed for the curved portion, a 1 / 4 circle shape is preferable since it has a constant radius of curvature and the design and construction of the rail structure 2 is easy.

[0026] Figure 2 is an enlarged view of the cross section taken along line AA in Figure 1. The first rail 22 has a substantially rectangular cross section formed by the rail head portion 24 and rail side portion 23, and is made up of two rails with the rail head portions 24 facing inward and sideways. A second rail 25 having a rack 26 is laid below the first rail 22. The first rail 22 and the second rail 25 are supported by a steel frame.

[0027] Fig. 3(a) is a plan view of the collision cart, and Fig. 3(b) is a front view of the collision cart. Note that Fig. 3(b) omits the bottom of the first rail 22. The collision cart 6 is composed of three parts: a front part 60a, a middle part 60b, and a rear part 60c.

[0028] In this embodiment, a pole-shaped collision member 61 is attached to the front part 60a, but this part can be replaced with an aluminum honeycomb shock absorbing member or the like depending on the collision test. Also, reinforcing materials 66 such as H-shaped steel and I-shaped steel are used in the traveling direction to prevent deformation due to the impact of a collision.

[0029] The middle section 60b is connected to the front section 60a and the rear section 60c at the front and rear with bolts or the like. In order to absorb the impact of a collision of the front section 60a, reinforcing members 66 such as H-shaped steel and I-shaped steel are used in the middle section 60b in the traveling direction. Also, in order to reduce the shaking and lateral displacement of the collision cart 6 during a collision, rail gap restraining wheels 64a, 64b that restrain the gap between the rail heads 24 of the first rails 22 are provided.

[0030] The rear part 60c is provided with a pair of rail side restraining wheels 62a, 62b at the front and rear that restrain the rail side parts 23 of the first rail 22 from the thickness direction. This allows the car to travel along the rail side parts 23 of the first rail 22, preventing vertical shaking. In addition, in front of the rear rail side restraining wheels 62a, 62b, rail interval restraining wheels 64a, 64b that restrain the interval of the rail head part 24 of the first rail 22 are provided. This prevents lateral shaking of the rear part 60c, and in combination with the rail interval restraining wheels 64a, 64b at the middle part 60b, the collision cart 6 is provided with at least two pairs of rail side restraining wheels 62a, 62b that restrain the rail side parts 23 of the first rail 22 from the thickness direction and rail interval restraining wheels 64a, 64b that restrain the interval between the rail head part 24 of the first rail in the length direction, thereby reducing shaking and lateral displacement of the collision cart 6 during travel and collision.

[0031] The rear section 60c is provided with an attraction member 67 made of ferromagnetic iron that is attracted to the electromagnet 81 of the towing cart 8. Furthermore, a weight can be loaded and fixed to adjust the weight of the collision cart 6 in order to change the amount of energy of the collision of the collision cart 6. The rear section 60c also uses a reinforcing material 66, like the front section 60a and the middle section 60b, to prevent deformation due to the impact at the time of collision.

[0032] Fig. 3(c) is a cross-sectional view taken along line BB in Fig. 3(b), and is a cross-sectional view from the rear part 60c of the middle part 60b of the collision cart 6. Rail side restraining wheels 62a, 62b that restrain the cross section of the reinforcing member 66 of the middle part 60b and the rail side part 23 of the first rail 22 of the rear part 60c from the thickness direction are attached to the axle 63 of the rail side restraining wheels. In this embodiment, two wheels are attached to one axle, but it is also possible to attach one wheel to one axle so that the wheel rotates independently.

[0033] Fig. 3(d) is a cross-sectional view taken along line CC in Fig. 3(b), which is a cross-sectional view from the middle part 60b of the front part 60a of the collision cart 6. Rail gap restraining wheels 64a, 64b that restrain the gap between the cross section of the reinforcing member 66 of the front part 60a and the rail head part 24 of the first rail 22 in the middle part 60b are attached to the axles 65 of the rail gap restraining wheels, respectively.

[0034] Fig. 4(a) is a plan view of the towing bogie, Fig. 4(b) is a front view of the towing bogie, Fig. 4(c) is a cross-sectional view taken along line DD in Fig. 4(b), and Fig. 4(d) is a cross-sectional view taken along line EE in Fig. 4(b). Note that the bottom of the first rail 22 is omitted in Fig. 4(b). The towing bogie 8 is mainly composed of a drive part driven by a motor 80 and an attraction part driven by an electromagnet 81.

[0035] The towing bogie 8 is provided with a pair of rail side restraining wheels 82a, 82b on the front and rear that restrain the rail side 23 of the first rail 22 from the thickness direction. Unlike the collision bogie 6, the towing bogie 8 does not need to travel at high speed, so it does not particularly need dedicated wheels that restrain the rail gap. Instead, as shown in Fig. 4(c), wheels with flanges are used for the rail side restraining wheels 82a, 82b so that lateral deviation can also be prevented, and are attached to the axles 83 of the rail side restraining wheels.

[0036] The driving force of the motor 80 is transmitted from the motor side sprocket 91 to the gear side sprocket 92 by the chain belt 90. As shown in FIG. 4(d), the gear side sprocket 92 rotates the gear shaft 94, which rotates the pin gear 93 fixed to the gear shaft 94. The pin gear 93 meshes with the rack 26 of the second rail 25 to provide the propulsion force for raising and lowering the rail structure 2. The towing cart 8 then travels forward and backward on the first rail 22 using the rail side restraining wheels 82a and 82b. The motor 80 may be a motor alone or may include a reducer. In addition, the driving force of the motor is used to rotate the pin gear using a sprocket and a chain belt, but the present invention is not limited to this embodiment, and it is also possible to rotate the pin gear using a gear from the motor.

[0037] The towing bogie 8 is equipped with an electromagnet 81 for connecting and towing the collision bogie 6. If the electromagnet 81 of the towing bogie 8 is fixedly supported, there is no problem in towing the collision bogie 6 on the horizontal and vertical parts of the first rail 22. However, on the curved parts of the first rail 22, an angle is generated at the connection part between the towing bogie 8 and the collision bogie 6, and there is a risk that the connection of the electromagnet 81 will be cut off. Therefore, the electromagnet 81 needs a rotation support mechanism that cancels the relative angle of the connection between the towing bogie 8 and the collision bogie 6.

[0038] The rotation support mechanism in this embodiment is as follows. The electromagnet holder 85 has two arms attached to a member shaped to enclose the lower half of the circumferential direction and the lower half of the back surface of the electromagnet 81, whose attraction portion is circular, and the arms are rotatably screwed to the electromagnet support portion 84. The back of the electromagnet 81 is rotatably connected by a link chain 86, which is also rotatably screwed to the electromagnet support portion 84. Therefore, the arms of the electromagnet holder 85 rotate around the screw fastening of the electromagnet support portion 84, and the electromagnet 81 rotates at the connection portion of the link chain 86 behind the electromagnet 81, so that the connection between the attraction surface of the electromagnet 81 and the collision cart 6 becomes linear, and it is possible to prevent the connection from being cut off. Furthermore, an elastic body of a spring 87 is interposed between the arm of the electromagnet holder 85 and the cart surface of the towing cart 8, so that in the horizontal section, the spring 87 is compressed by the load of the electromagnet 81 to keep the electromagnet holder 85 horizontal, and in the curved section, the pressure from the electromagnet 81 to the spring 87 decreases, so that the spring 87 expands and rotates the electromagnet holder 85 slightly, thereby acting to reduce the angle of connection.

[0039] Next, a flow showing the test operation in the collision test device will be described with reference to Fig. 5. Before the start of the test, the test body T, the collision cart 6, and the towing cart 8 are stopped on the horizontal part of the rail structure 2 as shown in Fig. 1, and the test body T is fixed to the rigid wall 4 (step S10).

[0040] The towing cart 8 is brought close to the attraction member 67 at the rear of the collision cart 6, the electromagnet 81 of the towing cart 8 is turned on (electromagnet ON), and the electromagnet 81 of the towing cart 8 and the attraction member 67 of the collision cart 6 are attracted to each other, thereby connecting the towing cart 8 and the collision cart 6 (step S20).

[0041] The motor 80 of the towing cart 8 is turned on, and the pin gear 93 of the towing cart 8 starts to rotate in the ascending mode, meshing with the rack 26 of the second rail 25 and proceeding to the curved part of the rail structure 2. At this time, the wheels of the collision cart 6 connected to the wheels of the towing cart 8 run on the first rail 22. When the towing cart 8 and the collision cart 6 reach the curved part of the rail structure 2, an angle is generated between them, but since the electromagnet 81 of the towing cart 8 is supported by the rotation support mechanism so as to cancel the relative angle, the connection between the attraction surface of the electromagnet 81 and the attraction member 67 of the collision cart 6 is linear without bending, and there is no risk of the connection being cut off, and the towing cart 8 and the collision cart 6 rise up the curved part of the rail structure 2 and proceed to the vertical part (step 30).

[0042] When the towing cart 8 and the collision cart 6 proceed to the vertical section and the collision cart 6 reaches a predetermined height on the rail structure 2, the power to the motor 80 of the towing cart 8 is turned off and the collision cart 6 stops at that position (step 40). The predetermined height on the rail structure 2 is the height at which the speed and kinetic energy (collision energy) of the collision cart 6 immediately before colliding with the test body T become the desired values. If friction can be ignored, the speed of the collision cart 6 is determined only by the height, but since there is actually deceleration due to friction, it is sufficient to conduct tests in advance and create a calibration curve of the relationship between height and speed. In addition, since the kinetic energy is calculated from the speed and weight, the predetermined height at which the desired collision speed and kinetic energy are obtained can be determined by adjusting the weight.

[0043] The power to the electromagnet 81 of the towing cart 8 is turned off (electromagnet OFF), the connection with the collision cart 6 is released, and the collision cart 6 travels on the first rail 22 from a predetermined height of the rail structure 2 using the energy of gravity, and collides with the test object T fixed to the rigid wall 4, and the collision test ends (step 50). Although not shown, lighting devices and high-speed cameras, etc. are installed around the test object T to record the deformation behavior of the test object T before and after the collision.

[0044] After the collision test is completed, the deformed test specimen T is removed from the horizontal section of the rail structure 2, the motor 80 of the towing cart 8 parked on the vertical section of the rail structure 2 is powered on, and the pin gear 93 of the towing cart 8 begins to rotate in reverse in descent mode, engaging with the rack 26 of the second rail 25 and descending the rail structure 2 until it reaches the horizontal section, at which point the power to the motor 80 is turned off and the cart returns to its position before the test (step 60).

[0045] The test specimen T for the collision test in the present invention may be the main body of an automobile, a strength member of an automobile, a battery case of an electric automobile, etc., and the test method may be a frontal collision, a side collision, a rear collision, a pole collision, etc., of the collision cart 6 with the test specimen T.

[0046] Crash test evaluations include measuring the amount of deformation of the deformed test specimen T, the amount of absorbed energy, and analyzing the deformation behavior due to the collision using a high-speed camera. In addition, if sensors such as strain gauges and accelerometers are attached to each part of the test specimen T before the test, it is possible to obtain data on the time progression of the deformation amount during the collision. Evaluating the validity of such crash test evaluation results and predictions calculated by CAE, etc., can be used to improve the prediction accuracy of CAE crash tests, and can be used to design new car bodies and components with superior crashworthiness using CAE.

[0047] Although the crash test apparatus of the present invention has been described above based on the embodiments, the present invention is not limited to the structure and operation described in the above embodiments, and the structure and operation can be appropriately changed without departing from the spirit of the present invention. Moreover, the present invention can be applied not only to safety evaluation tests of vehicles, but also to dynamic strength evaluation tests of structures. [Explanation of symbols]

[0048] 1. Crash test equipment 2 Rail structure 4 Rigid Wall 6 Collision trolley 8 Traction trolley 22 The First Rail 23 Rail side 24 Rail head 25 The Second Rail 26 Rack 60a Front 60b middle part 60c rear 61 Collision components 62a, 62b Rail side restraint wheels 63 Rail side restraint wheel axle 64a, 64b Rail spacing restraint wheels 65 Rail spacing restraint wheel axle 66 Reinforcement 67 Adsorption material 80 Motor 81 Electromagnet 82a, 82b Rail side restraint wheels 83 Rail side restraint wheel axle 84 Electromagnet support part 85 Electromagnet Holder 86 Link Chain 87 Spring 90 Chain Belt 91 Motor side sprocket 92 Gear side sprocket 93 Pin Gear 94 Gear shaft T test specimen

Claims

1. A collision test apparatus in which a collision cart is collided with a rigid wall and a test object fixed to the rigid wall by using gravity drop energy, a rail structure including a horizontal portion on the rigid wall side, a curved portion continuous with the horizontal portion, and a vertical portion continuous with the curved portion, the rail structure including a first rail and a second rail; The collision cart that travels along a first rail; a towing cart that travels along a first rail and is equipped with a lifting means that uses a second rail to lift the rail structure and an electromagnet that controls connection with the collision cart; When the collision cart, which is connected to and towed by the towing cart, reaches a predetermined height of the rail structure, the electromagnet is released and the collision cart is allowed to run alone along a first rail, causing the collision cart to collide with the test body.

2. 2. A collision test device as described in claim 1, characterized in that the lifting means for lifting and lowering the rail structure using a second rail has a rack on the second rail, and the towing cart has a pin gear driven by a motor, and the towing cart lifts and lowers the rail structure by meshing with the rack and the pin gear.

3. 2. A collision test apparatus according to claim 1, wherein the electromagnet is supported by a rotation support mechanism so as to cancel a relative angle of connection between the towing cart and the collision cart that occurs at a curved portion of the first rail.

4. 3. A collision test apparatus according to claim 2, wherein the electromagnet is supported by a rotation support mechanism so as to cancel a relative angle of connection between the towing cart and the collision cart generated at a curved portion of the first rail.

5. 5. A collision test device according to claim 1, wherein the first rail has a cross section formed by the rail head and rail side portions that is approximately rectangular, and the first rail is composed of two rails with the rail heads facing horizontally and inwardly.

6. 6. The collision test device according to claim 5, wherein the collision cart includes at least two pairs of rail side restraining wheels that restrain the rail sides of the first rail in a thickness direction and rail gap restraining wheels that restrain the gap between the rail heads of the first rail, arranged in a longitudinal direction.

Images