Driving mechanism of small-sized crown block

Abstract

The utility model discloses a drive mechanism of small crown block, it includes: aerial track, power unit, support and drive wheel group, power unit and drive wheel group all are connected to support, and power unit is used for driving drive wheel group rotation, the bottom of aerial track is equipped with friction face, and drive wheel group includes power wheel, and the wheel face of power wheel is butt joint in friction face, and power wheel is located the below of aerial track. Its through setting up the roller suspension assembly in the track cavity and hang the drive unit in aerial track, and drive roller power unit such as setting up in the outside of aerial track cavity, greatly reduce the cross -sectional dimension of track, reduce track cost, and power unit is located the outside of track also is convenient for later maintenance, further reduce use and operation and maintenance cost. In addition, power unit sets up in the outside of track cavity, also can be convenient different model drive device compatible. And can be through the contact pressure of jack -up subassembly flexible adjustment with track, realizes the climbing of big gradient.

Description

Technical Field

[0001] This utility model relates to the field of aerial rail transit technology, and in particular to a drive mechanism for a small overhead crane. Background Technology

[0002] Suspended rail transit (skyrail) boasts significant advantages due to its unique design, including low construction costs, short construction periods, and strong spatial adaptability. Requiring only supporting columns, it can be adapted to mountainous and densely populated urban areas, and is also environmentally friendly, energy-efficient, and low-noise. These characteristics make it widely applicable in various scenarios such as urban commuter trunk lines, tourism, airport connections, and industrial logistics.

[0003] However, existing suspended railcars typically use a traction wheel suspended on the track, relying on friction between the traction wheel and the track to move the car, or a synchronous belt with the car fixed to a fixed position on the belt, the belt's rotation driving the car's movement. These drive structure designs have the following drawbacks: Using a traction wheel suspension means the traction wheel acts as both the power wheel and the suspension support wheel for the entire car, resulting in the traction wheel bearing significant pressure, making it prone to damage, having a short service life, and requiring frequent maintenance. Meanwhile, synchronous belt drives are only suitable for short-distance, single-track reciprocating movement and are unsuitable for aerial network rail transit systems.

[0004] Based on the above needs, the industry urgently needs to provide a miniaturized aerial rail transit system, especially a drive mechanism that is low-cost, easy to maintain, has a long service life, and is easy to integrate into a networked rail transit system. Utility Model Content

[0005] The purpose of this invention is to address the shortcomings of existing suspended overhead rail systems. There is no system that can flexibly adjust track surface pressure, provide high thrust, enable the locomotive to climb steep gradients, and flexibly accommodate drive devices of different power and size. This invention provides a drive mechanism for a small overhead crane to overcome these deficiencies. It solves the technical problems of existing suspended rail trolley drive mechanisms, which rely solely on the locomotive's weight for track surface pressure, cannot provide high thrust, cannot achieve steep gradients, cannot flexibly accommodate drive devices of different power and size, and have the locomotive drive device placed inside the track cavity, resulting in various size limitations.

[0006] To achieve the above objectives, the present invention adopts the following technical solution:

[0007] An embodiment of this utility model provides a drive mechanism for a small overhead crane, which includes: an aerial track, a power unit, a support frame, and a drive wheel assembly. The power unit and the drive wheel assembly are both connected to the support frame, and the power unit is used to drive the drive wheel assembly to rotate.

[0008] The bottom of the aerial track is provided with a friction surface, and the drive wheel set includes a power wheel. The wheel surface of the power wheel abuts against the friction surface, and the power wheel is located below the aerial track.

[0009] The drive wheel assembly includes the power wheel and several support wheels. The power wheel includes a driving wheel and a driven wheel. The support wheels are located between the driving wheel and the driven wheel, and the driving wheel, the driven wheel, and the support wheels are all rotatably connected to the bracket.

[0010] The drive wheel assembly further includes a transmission belt assembly, which is sleeved on the drive wheel and the driven wheel, and its middle part is abutted by the support wheel. The drive wheel is driven to the power unit.

[0011] The transmission belt assembly includes a first transmission belt and a second transmission belt, with a preset gap between the first transmission belt and the second transmission belt.

[0012] The support frame is also equipped with at least two lifting components, which are respectively positioned near both ends of the drive wheel assembly. The lifting components are used to drive the drive wheel assembly to move vertically closer to or away from the aerial track.

[0013] The lifting component is an elastic element arranged in the vertical direction.

[0014] The lifting assembly is a pneumatic cylinder, a hydraulic cylinder, or an electric cylinder.

[0015] The drive mechanism of the small overhead crane also includes a suspension roller assembly, and the top of the aerial track is provided with a guide surface. The suspension roller assembly is connected to the drive wheel assembly and rolls against the guide surface.

[0016] The suspended roller assembly includes: a connecting frame, a plurality of guide rollers rotatably connected to the connecting frame, and a hanging plate connected to the connecting frame, the hanging plate passing through the aerial track and connected to the lifting assembly.

[0017] The aerial track includes a first track and a second track that are parallel and at the same height. A guide gap is provided between the first track and the second track. The hanging plate passes through the guide gap, and the wheel surface of the guide roller is simultaneously attached to the guide surfaces of the first track and the second track.

[0018] This utility model discloses a drive mechanism for a small overhead crane. The drive unit is suspended from the overhead track via a roller suspension assembly housed within the track cavity, while the power unit, including the drive rollers, is located outside the track cavity. This significantly reduces the track's cross-sectional dimensions and construction cost. The external location of the power unit also facilitates maintenance, further lowering operating and maintenance costs. Furthermore, the external location of the power unit allows for compatibility with different drive device models. The lifting assembly also allows for flexible adjustment of the contact pressure with the track, enabling steep gradient ascents.

[0019] The above description is only an overview of the technical solution of this utility model. In order to better understand the technical means of this utility model, it can be implemented according to the contents of the specification. In order to make the above and other objects, features and advantages of this utility model more obvious and easy to understand, the following are preferred embodiments, which are described in detail below. Attached Figure Description

[0020] Figure 1 This is a schematic diagram of the overall structure of the drive mechanism of the small overhead crane according to an embodiment of the present invention.

[0021] Figure 2 for Figure 1 A magnified schematic diagram of part A in the middle.

[0022] Figure 3 This is a schematic diagram of the overall structure of the drive mechanism of the small overhead crane according to another embodiment of the present invention.

[0023] Figure 4 This is a schematic diagram of the aerial track and suspension roller assembly of the drive mechanism of the small overhead crane according to an embodiment of the present invention.

[0024] Figure 5 for Figure 4 The diagram shows a magnified view of part B.

[0025] Figure 6 and Figure 7 These are schematic diagrams of the drive unit portion of the drive mechanism of the small overhead crane according to an embodiment of the present invention from different perspectives.

[0026] Explanation of reference numerals in the attached figures:

[0027] The small overhead crane includes a drive mechanism 100, an aerial track 1, a suspension roller assembly 2, a drive unit 3, a first track 11, a second track 12, a hanger 13, a guide gap 14, a connecting frame 21, a guide roller 22, a hanging plate 23, a bracket 31, a drive wheel assembly 32, a transmission belt assembly 33, a power unit 34, a belt 35, a lifting assembly 36, a support plate 37, a first guide surface 111, a friction surface 112, a second guide surface 121, a friction surface 122, a drive wheel 321, a driven wheel 322, a support wheel 323, a first transmission belt 331, a second transmission belt 332, and a preset gap 333. Detailed Implementation

[0028] To make the objectives, technical solutions, and advantages of this utility model clearer, the present utility model will be further described in detail below with reference to the accompanying drawings and specific embodiments.

[0029] The technical solutions of the present utility model will be clearly and completely described below with reference to the accompanying drawings of the embodiments. Obviously, the described embodiments are only some embodiments of the present utility model, and not all embodiments. Based on the embodiments of the present utility model, all other embodiments obtained by those skilled in the art without creative effort are within the protection scope of the present utility model.

[0030] In the description of this utility model, it should be understood that the terms "center", "longitudinal", "lateral", "length", "width", "thickness", "upper", "lower", "front", "rear", "left", "right", "vertical", "horizontal", "top", "bottom", "inner", "outer", "clockwise", "counterclockwise", etc., indicate the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings. They are only for the convenience of describing this utility model and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation. Therefore, they should not be construed as limitations on this utility model.

[0031] Furthermore, the terms "first" and "second" are used for descriptive purposes only and should not be construed as indicating or implying relative importance or implicitly specifying the number of technical features indicated. Thus, a feature defined as "first" or "second" may explicitly or implicitly include one or more of that feature. In the description of this utility model, "a plurality of" means two or more, unless otherwise explicitly specified.

[0032] In this utility model, unless otherwise explicitly specified and limited, the terms "installation," "connection," "joining," and "fixing," etc., should be interpreted broadly. For example, they can refer to a connection, a detachable connection, or an integral part; they can refer to a mechanical connection or an electrical connection; they can refer to a direct connection or an indirect connection through an intermediate medium; they can refer to the internal communication of two components or the interaction between two components. Those skilled in the art can understand the specific meaning of the above terms in this utility model according to the specific circumstances.

[0033] In this invention, unless otherwise explicitly specified and limited, "above" or "below" the second feature can include direct contact between the first and second features, or contact between the first and second features through another feature between them. Furthermore, "above," "over," and "on top" of the second feature includes the first feature directly above or diagonally above the second feature, or simply indicates that the first feature is at a higher horizontal level than the second feature. "Below," "below," and "under" the second feature includes the first feature directly below or diagonally below the second feature, or simply indicates that the first feature is at a lower horizontal level than the second feature.

[0034] In the description of this specification, the references to terms such as "one embodiment," "some embodiments," "example," "specific example," or "some examples," etc., indicate that a specific feature, structure, material, or characteristic described in connection with that embodiment or example is included in at least one embodiment or example of the present invention. The illustrative expressions of the above terms in this specification should not be construed as necessarily referring to the same embodiment or example. Furthermore, the specific features, structures, materials, or characteristics described may be combined in any suitable manner in one or more embodiments or examples.

[0035] Suspended rail transit (skyrail) boasts significant advantages due to its unique design, including low construction costs, short construction periods, and strong spatial adaptability. Requiring only supporting columns, it can be adapted to mountainous and densely populated urban areas, and is also environmentally friendly, energy-efficient, and low-noise. These characteristics make it widely applicable in various scenarios such as urban commuter trunk lines, tourism, airport connections, and industrial logistics.

[0036] However, existing suspended railcars typically use a traction wheel suspended on the track, relying on friction between the traction wheel and the track to move the car, or a synchronous belt drive where the car is fixedly suspended at a fixed position on the synchronous belt, and the belt's rotation drives the car. These drive structure designs have the following drawbacks: Using a traction wheel suspension means the traction wheel is both the power wheel and the suspension support wheel for the entire car, leading to easy damage, short service life, and frequent maintenance and replacement. Synchronous belt drives are only suitable for short-distance, single-track reciprocating movement and are unsuitable for aerial network rail transit. There is an urgent need in the industry for a miniaturized aerial rail transit system, particularly a low-cost, easy-to-maintain, long-service-life drive mechanism that facilitates network rail transit systems. Therefore, based on these needs, this embodiment provides a drive mechanism 100 for a small overhead crane.

[0037] Please see Figures 1 to 7 This embodiment discloses a drive mechanism 100 for a small overhead crane, which has the following characteristics in its application scenarios:

[0038] The suspended aerial vehicle features a monorail structure, unlike existing dual-rail structures. The total weight of the suspended aerial vehicle, including its own weight and load capacity, does not exceed 100 kg. Depending on the application requirements, the number of axles and wheel sets can be increased, and it can also be a cascaded box structure. Its design goal is to reduce the requirements of the track by tailoring the vehicle to specific application scenarios, keeping the track's load-bearing capacity within the range of 100-150 kg / m, thereby reducing track costs and facilitating large-scale commercialization.

[0039] The drive mechanism 100 of the small overhead crane in this embodiment includes: an overhead track 1, a suspension roller assembly 2, and a drive unit 3. The suspension roller assembly 2 is attached to the overhead track 1, and the drive unit 3 is connected to the suspension roller assembly 2 and rolls against the bottom of the overhead track 1. The friction between the drive unit 3 and the overhead track 1 drives the car connected to the drive unit 3 to move along the overhead track. The suspension roller assembly 2 provides longitudinal tension to the drive unit 3 and the car.

[0040] In this embodiment, the suspension roller assembly 2 is supported on the top of the aerial track 1, while the drive unit 3 abuts against the bottom of the aerial track 1. That is, the longitudinal suspension of the aerial vehicle is supported by the top surface of the aerial track 1, while the power to drive the carriage along the aerial track 1 is provided by the drive unit 3 from the bottom of the aerial track 1 via friction. Since the suspension and power are provided from different surfaces of the aerial track 1, the advantages of this design are: the suspension roller assembly 2 is located inside the cavity of the aerial track 1, while the drive unit 3 is located outside the cavity of the aerial track 1, which is different from the design scheme in the prior art where both the suspension and drive mechanism are located inside the track cavity. On the one hand, it greatly reduces the cross-sectional size of the cavity of the aerial track 1, reducing the cost of the track. At the same time, the most complex drive device of the locomotive is located outside the cavity, which facilitates maintenance, reduces operating costs, and improves the efficiency of operation and maintenance. On the other hand, the drive unit 3 is located outside the cavity of the aerial track 1, which is not limited by size and facilitates compatibility with different types of drive devices.

[0041] Specifically, the drive mechanism 100 of the small crane includes a power unit 34, a support 31, and a drive wheel set 32. The power unit 34 and the drive wheel set 32 ​​are both connected to the support 31, and the power unit 34 is used to drive the drive wheel set 32 ​​to rotate.

[0042] In this embodiment, the power unit 34 is a drive motor that can provide rotational power. The drive motor drives the drive wheel set 32, and the drive wheel set 32 ​​relies on the friction between its wheel surface and the air track to make the drive component 3 move along the air track 1.

[0043] The bottom of the aerial track 1 is provided with a friction surface 122 (112). The drive wheel set 32 ​​includes a power wheel, the wheel surface of which abuts against the friction surface 122 (112), and the power wheel is located below the aerial track 1. This transmission method differs from the existing transmission method that abuts against the top surface of the track or is fixed to a synchronous belt. The weight of the drive unit 3 is not loaded onto the aerial track 1 from the top, which simplifies the structural design of the drive unit 3 and reduces wear and tear on the drive unit 3, so that the drive mechanism can operate reliably for a long time and reduce the cost of use and maintenance.

[0044] Please refer to it again. Figure 6 and Figure 7The drive wheel assembly 32 includes the power wheel and several support wheels 323. The power wheel includes a drive wheel 321 and a driven wheel 322. The support wheels 323 are located between the drive wheel 321 and the driven wheel 322, and the drive wheel 321, the driven wheel 322, and the support wheels 323 are all rotatably connected to the bracket 31. The highest points of the wheel surfaces of the drive wheel 321, the driven wheel 322, and the support wheels 323 are all located on the same plane, so that the wheel surfaces of the drive wheel 321, the driven wheel 322, and the support wheels 323 always abut against the bottom friction surface 122 (112) of the aerial track 1.

[0045] The drive wheel assembly 32 further includes a transmission belt assembly 33, which is sleeved on the driving wheel 321 and the driven wheel 322, and its middle portion is abutted by the support wheel 323. The driving wheel 321 is driveably connected to the power unit 34. That is, in this embodiment, the drive unit 3 can also move via friction transmission between the transmission belt assembly 33 and the overhead track 1. The transmission belt assembly 33 is made of a wear-resistant material with a high coefficient of friction.

[0046] like Figure 2 and Figure 7 As shown, the transmission belt assembly 33 includes a first transmission belt 331 and a second transmission belt 332. A preset gap 333 is provided between the first transmission belt 331 and the second transmission belt 332. The preset gap 333 is used for the connecting component of the guide roller assembly 2 to pass through.

[0047] like Figure 6 As shown, the bracket 31 is also provided with at least two lifting components 36. The lifting components 36 are respectively located near the two ends of the drive wheel assembly 32. The lifting components 36 are used to drive the drive wheel assembly 32 to move closer to or away from the aerial track 1. The lifting components 36 can lift the drive wheel assembly 32, causing the pressure on the friction surface 122 (112) between it and the aerial track 1 to change. According to the friction calculation formula, when the friction coefficient is the same, different pressures will cause the magnitude of the friction between the two to change. The advantage of using the lifting components 36 to adjust the magnitude of the friction between the drive wheel assembly 32 and the aerial track 1 in this embodiment is that when the trolley is running on the horizontal section of the aerial track 1, the lifting components 36 can be adjusted to descend, reducing the friction between it and the aerial track 1. At this time, the power required for the trolley to move is sufficient, which can reduce the wear between the transmission belt assembly 33 and the aerial track 1 and improve the service life. When the trolley is running on the non-horizontal section of the overhead track 1, in order to improve its operational reliability, the lifting assembly 36 can be adjusted to increase the pressure between the transmission belt assembly 33 and the overhead track, thereby increasing the friction between the two and thus improving its operational safety and reliability.

[0048] In one embodiment, the lifting assembly 36 is an elastic element, such as a spring, arranged vertically. Multiple elastic elements can be provided, arranged in a rectangular pattern, so that the drive wheel assembly 32 can dynamically adjust the pressure with the overhead track 1 according to the actual working conditions. At the same time, the structure of dynamically adjusting the pressure with elastic elements can also reduce costs.

[0049] In one embodiment, the lifting assembly 36 is a pneumatic cylinder, hydraulic cylinder, or electric cylinder. A lifting mechanism using a pneumatic, hydraulic, or electric cylinder can actively adjust the pressure between the drive wheel assembly 32 and the overhead track 1 as needed, ultimately adjusting the friction between them. Compared to a lifting assembly 36 using an elastic element, the lifting assembly 36 in this embodiment has active adjustment characteristics.

[0050] like Figure 6 As shown, the lifting assembly 36 has two sets. The first set consists of four elastic elements or linear drive cylinders arranged in a rectangle and located at the front end of the drive wheel assembly 32. The second set also consists of four elastic elements or linear drive cylinders arranged in a rectangle and located at the rear end of the drive wheel assembly 32. The distribution of the first and second sets can improve the uniformity of pressure regulation and avoid damage to the transmission belt caused by excessive local pressure.

[0051] In summary, the drive mechanism 100 of this small overhead crane uses a suspension roller assembly 2 and a drive wheel assembly 32 to grip the upper and lower surfaces of the overhead track 1, and the pressure can be adjusted via the lifting assembly 36. Specifically, it adjusts the contact pressure between the drive wheel assembly 32 and the friction surface of the overhead track 1, unlike traditional drive methods that rely solely on the locomotive's gravity. This drive method can dynamically adjust the contact force between the drive wheel assembly 32 and the wheel tread (friction surface) of the overhead track 1, enabling it to climb steep inclines.

[0052] The output shaft of the power unit 35 is connected to the drive wheel 321 via the belt 35. The drive wheel 321 drives the driven wheel 322. When the power unit 34 drives the transmission belt group 33 to rotate, the trolley moves relative to the track by relying on the friction between the transmission belt group 33 and the air track 1.

[0053] Please refer to it again. Figures 3 to 5 The drive mechanism 100 of the small crane also includes a suspension roller assembly 2, and the top of the aerial track 1 is also provided with a guide surface. The suspension roller assembly 2 is connected to the drive wheel set 32 ​​and rolls against the guide surface.

[0054] The suspended roller assembly 2 includes: a connecting frame 21, a plurality of guide rollers 22 rotatably connected to the connecting frame 21, and a hanging plate 23 connected to the connecting frame 21. The hanging plate 23 passes through the aerial track 1 and is connected to the lifting assembly 36. The hanging plate 23 passes through the reserved gap 333, and a support plate 37 is connected to its bottom. The fixed part of the lifting assembly 36 is connected to the support plate 37.

[0055] The aerial track 1 includes a first track 11 and a second track 12 that are parallel and at the same height. A guide gap 14 is provided between the first track 11 and the second track 12. The hanging plate 23 passes through the guide gap 14, and the wheel surface of the guide roller 22 is simultaneously attached to the guide surfaces of the first track 11 and the second track 12.

[0056] Specifically, the first track 11 has a first guide surface 111 at the top and a friction surface 112 at the bottom; the second track 12 has a second guide surface 121 at the top and a friction surface 122 at the bottom. The guide rollers 22 are rolled on the first guide surface 111 and the second guide surface 121. A hanging plate 23 is positioned between adjacent guide rollers 22 and passes through a guide gap 14. The hanging plate 23 and the guide gap 14 form a limiting effect. As the guide rollers 22 roll along the guide surfaces, they will not derail because the hanging plate 23 limits their movement within the guide gap 14. Furthermore, the wheel surfaces of the guide rollers 22 are respectively attached to the first guide surface 111 and the second guide surface 121, resulting in a relatively balanced force distribution between them and the overhead track 1.

[0057] The first track 11 and the second track 12 are connected and fixed from above by a number of hangers 13. The hangers 13 are then suspended by steel cables or other support mechanisms to form an aerial track network.

[0058] In this embodiment, the transmission belt assembly 33 is provided with a first transmission belt 331 and a second transmission belt 332. The first transmission belt 331 abuts against the friction surface 112 at the bottom of the first track 11, and the second transmission belt 332 abuts against the friction surface 122 at the bottom of the second track 12. The increased friction area between the transmission belt assembly 33 and the overhead track 1 can further improve its operational stability and durability.

[0059] The drive mechanism of this utility model for a small overhead crane suspends the drive unit on an aerial track via a roller suspension assembly. The drive rollers for the trolley movement are located at the bottom of the aerial track, and the trolley is driven to move along the aerial track by friction from the bottom of the track. The load-bearing guidance and drive are set separately, thereby reducing damage to components, increasing their service life, reducing operating costs, and improving the convenience of operation and maintenance.

[0060] The above examples are merely illustrative of the technical content of this utility model to facilitate reader understanding, but do not imply that the implementation of this utility model is limited to these embodiments. Any technical extensions or re-creations made based on this utility model are protected by this utility model. The scope of protection of this utility model is defined by the claims.

Claims

1. A drive mechanism for a small overhead crane, characterized in that, include: The system includes an aerial track, a power unit, a support frame, and a drive wheel assembly. Both the power unit and the drive wheel assembly are connected to the support frame, and the power unit is used to drive the drive wheel assembly to rotate. The bottom of the aerial track is provided with a friction surface, and the drive wheel set includes a power wheel. The wheel surface of the power wheel abuts against the friction surface, and the power wheel is located below the aerial track.

2. The drive mechanism of the small overhead crane according to claim 1, characterized in that, The drive wheel assembly includes the power wheel and several support wheels. The power wheel includes a driving wheel and a driven wheel. The support wheels are located between the driving wheel and the driven wheel, and the driving wheel, the driven wheel and the support wheels are all rotatably connected to the bracket.

3. The drive mechanism of the small overhead crane according to claim 2, characterized in that, The drive wheel assembly also includes a transmission belt assembly, which is sleeved on the drive wheel and the driven wheel, and its middle part is abutted by the support wheel. The drive wheel is driven to the power unit, and the transmission belt assembly abuts against the friction surface.

4. The drive mechanism of the small overhead crane according to claim 3, characterized in that, The transmission belt assembly includes a first transmission belt and a second transmission belt, with a preset gap between the first transmission belt and the second transmission belt.

5. The drive mechanism of the small overhead crane according to any one of claims 1 to 4, characterized in that, The support is also equipped with at least two lifting components, which are respectively located near the two ends of the drive wheel assembly. The lifting components are used to drive the drive wheel assembly to move vertically closer to or away from the aerial track.

6. The drive mechanism of the small overhead crane according to claim 5, characterized in that, The lifting assembly is an elastic element arranged in the vertical direction.

7. The drive mechanism of the small overhead crane according to claim 5, characterized in that, The lifting assembly is a pneumatic cylinder, hydraulic cylinder, or electric cylinder.

8. The drive mechanism of the small overhead crane according to claim 5, characterized in that, The drive mechanism of the small overhead crane also includes a suspension roller assembly, and the top of the aerial track is provided with a guide surface. The suspension roller assembly is connected to the drive wheel assembly and rolls against the guide surface.

9. The drive mechanism of the small overhead crane according to claim 8, characterized in that, The suspension roller assembly includes: a connecting frame, a plurality of guide rollers rotatably connected to the connecting frame, and a hanging plate connected to the connecting frame, the hanging plate passing through the aerial track and connected to the lifting assembly.

10. The drive mechanism of the small overhead crane according to claim 9, characterized in that, The aerial track includes a first track and a second track that are parallel and at the same height. A guide gap is provided between the first track and the second track. The hanging plate passes through the guide gap, and the wheel surface of the guide roller is simultaneously attached to the guide surfaces of the first track and the second track.

Images