Double-drive spiral intelligent blast hole filling vehicle

Abstract

This utility model relates to the technical field of mining operation equipment, and in particular to a dual-drive spiral intelligent blast hole filling vehicle, including a vehicle body, on which multiple sets of filling mechanisms are installed in sequence. The filling mechanism includes a discharge hood, a hopper, and a discharge hood. The discharge hood is fixedly installed on the vehicle body, and the hopper is fixedly installed on the top of the discharge hood, with the opening at the bottom of the hopper connected to the top of the discharge hood. A discharge port is opened on one side of the discharge hood, and the discharge hood is hinged to the discharge port on the side of the discharge hood. Multiple sets of guide spiral assemblies extending to the bottom opening of the hopper are evenly arranged inside the discharge hood. A baffle is fixedly installed on the top of the hopper, and multiple sets of inverted V-shaped baffle bars are installed at equal intervals between the baffles. This utility model can improve the filling efficiency of blast holes, and the anti-clogging design of the guide spiral assembly can effectively avoid material jamming, making it more durable than conveyor belts and belt conveyors.

Description

Technical Field

[0001] This utility model relates to the field of mining operation equipment technology, and in particular to a dual-drive spiral intelligent blast hole filling vehicle. Background Technology

[0002] In surface blasting operations in various mining areas, borehole filling is a crucial step in ensuring operational safety and efficiency. After loading explosives, the boreholes must be filled and sealed. However, this step currently relies mainly on manual operation, requiring operators to manually shovel and load materials such as stones and drill cuttings for filling. This process not only poses high safety risks but is also inefficient and labor-intensive, directly leading to increased operating costs and extended time. Furthermore, traditional filling devices have significant limitations: they are difficult to cover boreholes in multiple directions, requiring frequent adjustments to vehicle position; and problems such as material blockage or uneven filling can easily occur during the filling process. In view of this, this application proposes a dual-drive spiral intelligent borehole filling vehicle. Utility Model Content

[0003] In view of the shortcomings of the existing technology, the purpose of this utility model is to provide a dual-drive spiral intelligent blast hole filling vehicle to solve the problems mentioned in the background technology.

[0004] To achieve the above objectives, this utility model is implemented through the following technical solution: a dual-drive spiral intelligent borehole filling vehicle, comprising a vehicle body, on which multiple sets of filling mechanisms are sequentially installed. The filling mechanism includes a discharge hood, a hopper, and a discharge hood. The discharge hood is fixedly installed on the vehicle body, and the hopper is fixedly installed on the top of the discharge hood, with the opening at the bottom of the hopper connected to the top of the discharge hood. A discharge port is provided on one side of the discharge hood, and the discharge hood is hinged to the discharge port on the side of the discharge hood. Multiple sets of guide spiral assemblies extending to the bottom opening of the hopper are evenly arranged inside the discharge hood. A baffle is fixedly installed on the top of the hopper, and multiple sets of inverted V-shaped baffle rods are installed at equal intervals between the baffles.

[0005] Optionally, an inclined feeding plate is fixedly installed inside the feeding hood, with the lower end of the feeding plate extending to the bottom of the feeding port. The bottom of the feeding plate is equidistantly equipped with fixed frames of the same number as the guide spiral assemblies. Each set of guide spiral assemblies passes through the feeding plate and the fixed frames in sequence. Two fourth bearings are fixedly installed between each fixed frame, and the inner ring wall of each fourth bearing is fixedly sleeved on the corresponding guide spiral assembly.

[0006] Optionally, a motor is fixedly installed at the left end of the discharge hood, and a rotating shaft extending into the interior of the discharge hood is fixedly connected to the output end of the motor. The same number of bevel gears as the flow guide spiral assembly are installed on the rotating shaft at equal intervals. A support plate is fixedly installed inside the discharge hood and below the rotating shaft. The same number of openings as the flow guide spiral assembly are opened at equal intervals on the support plate, and a first bearing is fixedly installed in each opening. A transmission gear is inserted between the inner ring walls of each first bearing. The upper half of the transmission gear is a bevel gear, and the lower half of the transmission gear is a cylindrical gear. The bevel gear in the upper half of each transmission gear meshes with the corresponding bevel gear.

[0007] Optionally, the flow guide spiral assembly includes a rod body, a stirring blade, and a spur gear. The rod body is divided into an upper rod and a lower rod. The lower rod is rotatably connected to the bottom end of the upper rod, and the upper rod is inserted through the material discharge plate and the fixed frame. The stirring blade is fixedly installed at the top end of the upper rod, and the spur gear is fixedly installed at the bottom end of the lower rod. The spur gear in each flow guide spiral assembly meshes with the spur gear of the lower half of the corresponding transmission gear.

[0008] Optionally, the top of the lower rod has a groove, in which a third bearing is fixedly installed. The bottom of the upper rod is connected to a connecting rod that is fixedly inserted between the inner ring walls of the third bearing. Both sides of the bottom of the connecting rod are fixedly installed with stop bars. The bottom of the groove has two rod slots, in which insert rods are movably inserted. A blocking block is fixedly installed at the top of each insert rod. One side of the top of the blocking block is set as an inclined surface, and the side of the blocking block can contact the stop bar. A spring sleeved on the insert rod is fixedly connected between the bottom of the blocking block and the groove.

[0009] Optionally, a fixing block is fixedly installed at both ends of the discharge hood near the discharge port, and a fixing shaft is fixedly installed at one end of the discharge hood near the discharge hood. The two ends of the fixing shaft are respectively rotatably inserted between the two fixing blocks. A sleeve is fitted on the right end of the fixing shaft, and the right end of the rotating shaft passes through the right side of the discharge hood. A transmission component is provided between the right end of the rotating shaft and the sleeve.

[0010] Optionally, the inner wall of the sleeve is provided with an annular groove, and a second bearing is fixedly installed in the annular groove. The right end of the fixed shaft is fixedly inserted between the inner ring walls of the second bearing, and a first toothed groove is provided at the right end of the fixed shaft. A second toothed groove is provided at the right end of the sleeve. A matching limiting gear is movably inserted in the second toothed groove. The left end of the limiting gear can be inserted into the first toothed groove at the right end of the fixed shaft. A hydraulic rod is fixedly installed at the right end of the sleeve. The telescopic end of the hydraulic rod extends into the second toothed groove and connects with the limiting gear.

[0011] Optionally, the transmission assembly includes two sprockets and a chain. The two sprockets are fixedly mounted on the right end of the rotating shaft and the sleeve, respectively, and the chain drive is sleeved between the two sprockets.

[0012] The beneficial effects of this utility model are:

[0013] By starting the motor and rotating it in the opposite direction, multiple bevel gears on its output shaft mesh with the corresponding transmission gears on the support plate. The transmission gears then drive the spur gears that mesh with them to rotate. The rotation of the spur gears causes the lower rod to rotate at the bottom of the upper rod, so that the vertical surfaces of the two blocking blocks in the groove contact the stop bar at the bottom of the connecting rod. This causes the entire rod to rotate, which in turn causes multiple sets of guide spiral assemblies to rotate inside the feeding hood, enabling uniform material distribution and discharge.

[0014] Furthermore, when the rotating shaft rotates in the reverse direction, the hydraulic rod is controlled to push the limiting gear to engage between the first and second tooth grooves, allowing the fixed shaft to rotate together with the sleeve. The power generated by the rotating shaft is then transmitted to the sleeve through the transmission assembly, causing the sleeve to rotate together with the fixed shaft. This, in turn, causes the discharge hood to flip, allowing the material in the hopper to be discharged into the borehole through the discharge hood and the discharge hood. Once the discharge hood is opened, the hydraulic rod is controlled to separate the limiting gear from the first tooth groove on the right end of the fixed shaft, preventing the rotation of the rotating shaft from causing the discharge hood to flip. The guide spiral assembly can then continue to convey the material.

[0015] When the discharge hood is retracted, the hydraulic rod is controlled again to push the limit gear to engage between the first and second tooth grooves. Then, the motor is started to rotate in the forward direction, which will cause the discharge hood to flip to the side of the hopper. When the blocking block in the lower rod rotates, the inclined surface at the top of the blocking block will contact the stop rod. The stop rod will squeeze the inclined surface of the blocking block, causing the blocking block to slide under the stop rod. This will prevent the guide spiral assembly from rotating inside the discharge hood.

[0016] Several baffles arranged at equal intervals in the enclosure can screen materials, and oversized materials are discharged along both sides of the slope, thereby preventing larger materials from entering the hopper and affecting the normal discharge of materials inside the hopper. Attached Figure Description

[0017] Other features, objects, and advantages of this invention will become more apparent from the following detailed description of non-limiting embodiments with reference to the accompanying drawings:

[0018] Figure 1 This is a schematic diagram of the overall structure of this utility model;

[0019] Figure 2 This is a schematic diagram of the connection between the material feeding cover, the hopper, and the discharge cover of this utility model;

[0020] Figure 3 This is a schematic diagram of the connection between the discharge hood and the rotating shaft of this utility model;

[0021] Figure 4 This is a cross-sectional structural diagram of the connection between the fixed shaft and the sleeve of this utility model;

[0022] Figure 5 This is a schematic diagram of the connection between the material feeding cover, the guide spiral assembly, and the rotating shaft of this utility model;

[0023] Figure 6 This is a schematic diagram of the connection between the flow guide spiral assembly and the rotating shaft of this utility model;

[0024] Figure 7 This is a schematic diagram of the connection between the bevel gear and the spur gear of this utility model;

[0025] Figure 8 This is a schematic diagram of the flow guiding spiral assembly of this utility model;

[0026] Figure 9 This is an enlarged structural diagram of point A in this utility model;

[0027] Figure 10 This is a schematic diagram of the structure of the blocking block and the stop bar of this utility model;

[0028] Figure 11 This is a schematic diagram of the structure of the support plate of this utility model;

[0029] In the diagram: 1. Vehicle body; 2. Discharge hood; 21. Fixing block; 3. Hopper; 4. Enclosure; 41. Baffle rod; 5. Discharge hood; 51. Fixing shaft; 511. First tooth groove; 6. Motor; 61. Rotating shaft; 62. Bevel gear; 63. Support plate; 64. First bearing; 65. Transmission gear; 7. Transmission assembly; 8. Sleeve; 81. Second bearing; 82. Hydraulic rod; 83. Second tooth groove; 84. Limiting gear; 9. Guide spiral assembly; 91. Rod body; 92. Stirring blade; 93. Column gear; 911. Upper rod; 912. Lower rod; 913. Groove; 914. Connecting rod; 915. Third bearing; 916. Insert rod; 917. Blocking block; 918. Spring; 919. Baffle rod; 10. Fixing frame; 101. Fourth bearing. Detailed Implementation

[0030] To make the technical means, creative features, objectives and effects of this utility model easier to understand, the following describes this patent in conjunction with specific embodiments.

[0031] Please see Figures 1-11This utility model provides a technical solution: a dual-drive spiral intelligent borehole filling vehicle, including a vehicle body 1. Multiple sets of filling mechanisms are installed sequentially on the vehicle body 1. The number of filling mechanisms can be customized according to the situation. The filling mechanism includes a discharge hood 2, a hopper 3, and a discharge hood 5. The discharge hood 2 is fixedly installed on the vehicle body 1, and the hopper 3 is fixedly installed on the top of the discharge hood 2. The opening at the bottom of the hopper 3 is connected to the top of the discharge hood 2. A discharge port is opened on one side of the discharge hood 2. The discharge hood 5 is hinged to the discharge port on the side of the discharge hood 2. Multiple sets of guide spiral assemblies 9 extending to the bottom opening of the hopper 3 are evenly arranged inside the discharge hood 2. A baffle 4 is fixedly installed on the top of the hopper 3, and multiple sets of inverted V-shaped baffle rods 41 are installed at equal intervals between the baffles 4. The guide spiral assemblies 9 can effectively stir and transport the material in the discharge hood 2, and can achieve uniform material distribution and discharge.

[0032] like Figure 5 , Figure 6 and Figure 7 As shown, an inclined feeding plate is fixedly installed inside the feeding hood 2, and the lower end of the feeding plate extends to the bottom of the feeding port. The bottom of the feeding plate is equidistantly installed with the fixed frame 10. Each set of guide spiral assembly 9 passes through the feeding plate and the fixed frame 10 in sequence. Two fourth bearings 101 are fixedly installed between each fixed frame 10. The inner ring wall of each fourth bearing 101 is fixedly sleeved on the corresponding guide spiral assembly 9. Through the fourth bearings 101 in the fixed frame 10, the position of the rod 91 in the guide spiral assembly 9 can be fixed, so that it can rotate and feed normally inside the feeding hood 2.

[0033] like Figure 5 , Figure 6 and Figure 7 As shown, a motor 6 is fixedly installed at the left end of the discharge hood 2. A rotating shaft 61 extending into the interior of the discharge hood 2 is fixedly connected to the output end of the motor 6. Bevel gears 62, the same number as the guide spiral assembly 9, are installed at equal intervals on the rotating shaft 61. A support plate 63 is fixedly installed inside the discharge hood 2 and below the rotating shaft 61. The support plate 63 has openings at equal intervals, the same number as the guide spiral assembly 9. A first bearing 64 is fixedly installed in each opening. A transmission gear 65 is inserted between the inner ring walls of each first bearing 64. The upper half of the transmission gear 65 is a bevel gear, and the lower half is a cylindrical gear. The bevel gear in the upper half of each transmission gear 65 meshes with the corresponding bevel gear 62. The support plate 63 provides an installation position for the transmission gear 65 and fixes the position of the transmission gear 65 through the first bearing 64. The operation of the motor 6 drives the bevel gear 62 to mesh and rotate with the transmission gear 65.

[0034] like Figure 7 , Figure 8 and Figure 9 As shown, the guide spiral assembly 9 includes a rod 91, a stirring blade 92, and a spur gear 93. The rod 91 is divided into an upper rod 911 and a lower rod 912. The lower rod 912 is rotatably connected to the bottom end of the upper rod 911, and the upper rod 911 is inserted through the material feed plate and the fixed frame 10. The stirring blade 92 is fixedly installed at the top end of the upper rod 911, and the spur gear 93 is fixedly installed at the bottom end of the lower rod 912. The spur gear 93 in each guide spiral assembly 9 meshes with the spur gear in the lower half of the corresponding transmission gear 65. The transmission gear 65 meshes with the spur gear 93 and rotates, thereby driving the rod 91 and the stirring blade 92 to rotate.

[0035] like Figure 8 , Figure 9 and Figure 10 As shown, the top end of the lower rod 912 has a groove 913, in which a third bearing 915 is fixedly installed. The bottom end of the upper rod 911 is connected to a connecting rod 914, which is fixedly inserted between the inner ring walls of the third bearing 915. Stop rods 919 are fixedly installed on both sides of the bottom end of the connecting rod 914. The bottom of the groove 913 has two rod slots, in which insert rods 916 are movably inserted. A blocking block 917 is fixedly installed at the top of each insert rod 916. One side of the top of the blocking block 917 is sloped, allowing the side of the blocking block 917 to contact the stop rod 919. A sleeved part of the insert rod is fixedly connected between the bottom of the blocking block 917 and the groove 913. When the rotating shaft 61 rotates in the reverse direction, causing the lower rod 912 to rotate, the vertical surfaces of the two blocking blocks 917 in the groove 913 can contact the stop rod 919 and push the stop rod 919, thereby causing the connecting rod 914 and the upper rod 911 to rotate together. When the rotating shaft 61 rotates in the forward direction, causing the lower rod 912 to rotate, the inclined surface of the blocking block 917 contacts the stop rod 919 and is squeezed downward. The insert rod 916 at the bottom of the blocking block 917 moves down in the rod groove, and the blocking block 917 squeezes the spring 918, so it can slide past the bottom of the stop rod 919, thus preventing the connecting rod 914 and the upper rod 911 from rotating together.

[0036] like Figure 2 and Figure 3As shown, the feeding hood 2 has fixed blocks 21 fixedly installed at both ends near the feeding port. The discharge hood 5 has a fixed shaft 51 fixedly installed at one end near the feeding hood 2. The two ends of the fixed shaft 51 are respectively rotatably inserted between the two fixed blocks 21. The right end of the fixed shaft 51 is fitted with a sleeve 8. The right end of the rotating shaft 61 passes through the right side of the feeding hood 2. A transmission assembly 7 is provided between the right end of the rotating shaft 61 and the sleeve 8. The right end of the rotating shaft 61 and the right end of the fixed shaft 51 can be connected together through the transmission assembly 7. In this way, the rotation of the rotating shaft 61 can drive the fixed shaft 51 and the discharge hood 5 to rotate, so as to realize the retraction and expansion of the discharge hood 5.

[0037] like Figure 3 and Figure 4 As shown, an annular groove is formed on the inner wall of the sleeve 8, and a second bearing 81 is fixedly installed in the annular groove. The right end of the fixed shaft 51 is fixedly inserted between the inner ring wall of the second bearing 81, and a first toothed groove 511 is formed on the right end of the fixed shaft 51. A second toothed groove 83 is formed on the right end of the sleeve 8, and a matching limiting gear 84 is movably inserted in the second toothed groove 83. The left end of the limiting gear 84 can be inserted into the first toothed groove 511 on the right end of the fixed shaft 51. A hydraulic rod 82 is fixedly installed on the right end of the sleeve 8, and the telescopic end of the hydraulic rod 82 extends into the second toothed groove 83 and interacts with the limiting gear 84. When the rotating shaft 61 rotates in the reverse direction, the hydraulic rod 82 pushes the limiting gear 84 to engage between the first tooth groove 511 and the second tooth groove 83, allowing the fixed shaft 51 to rotate together with the sleeve 8. In this way, the transmission assembly 7 allows the rotating shaft 61 to drive the fixed shaft 51 and the discharge hood 5 to rotate together. When the discharge hood 5 opens, the hydraulic rod 82 drives the limiting gear 84 to separate from the first tooth groove 511 on the right end of the fixed shaft 51, so that the rotation of the rotating shaft 61 will not continue to drive the discharge hood 5 to flip, while the guide spiral assembly 9 can continue to convey the material.

[0038] like Figure 3 As shown, the transmission assembly 7 includes two sprockets and a chain. The two sprockets are fixedly installed on the right end of the rotating shaft 61 and the sleeve 8, respectively. The chain drive is sleeved between the two sprockets. The transmission assembly 7 can transmit the power generated when the rotating shaft 61 rotates to the sleeve 8. With the help of the limiting gear 84, the fixed shaft 51 can rotate together.

[0039] In the cab of vehicle 1, the driver can control the start and forward / reverse operation of motor 6 through the control button connected to the motor 6 in each packing mechanism, thereby enabling the opening and closing of the discharge hood 5 and the feeding and discharging of materials. Compared with the original multi-person packing operation, it is transformed into intelligent packing performed by a single person, which has the advantages of cost reduction and efficiency improvement.

[0040] Although this specification describes embodiments, not every embodiment contains only one independent technical solution. This narrative style is merely for clarity. Those skilled in the art should consider the specification as a whole. The technical solutions in each embodiment can also be appropriately combined to form other embodiments that can be understood by those skilled in the art.

[0041] The above description is merely a preferred embodiment of this patent and is not intended to limit the scope of this patent. Various modifications and variations can be made to this patent by those skilled in the art. Any modifications, equivalent substitutions, or improvements made within the spirit and principles of this patent should be included within the scope of protection of this patent.

Claims

1. A double drive spiral intelligent blast hole filling vehicle, comprising a vehicle body (1), characterized in that, Multiple sets of filling mechanisms are installed sequentially on the vehicle body (1). The filling mechanism includes a discharge hood (2), a hopper (3), and a discharge hood (5). The discharge hood (2) is fixedly installed on the vehicle body (1). The hopper (3) is fixedly installed on the top of the discharge hood (2), and the opening at the bottom of the hopper (3) is connected to the top of the discharge hood (2). A discharge port is opened on one side of the discharge hood (2). The discharge hood (5) is hinged to the discharge port on the side of the discharge hood (2). Multiple sets of guide spiral assemblies (9) extending to the bottom opening of the hopper (3) are evenly arranged inside the discharge hood (2). A baffle (4) is fixedly installed on the top of the hopper (3), and multiple sets of inverted V-shaped baffle rods (41) are installed at equal intervals between the baffles (4).

2. The double drive screw intelligent borehole filling vehicle according to claim 1, characterized in that, An inclined feeding plate is fixedly installed inside the feeding hood (2), and the lower end of the feeding plate extends to the bottom of the feeding port. The bottom of the feeding plate is equidistantly equipped with the same number of fixed frames (10) as the flow guide spiral assembly (9). Each set of the flow guide spiral assembly (9) passes through the feeding plate and the corresponding fixed frame (10) in sequence. Two fourth bearings (101) are fixedly installed between each fixed frame (10). The inner ring wall of each fourth bearing (101) is fixedly sleeved on the corresponding flow guide spiral assembly (9).

3. The dual-drive spiral intelligent borehole filling vehicle according to claim 2, characterized in that, A motor (6) is fixedly installed at the left end of the discharge hood (2). A rotating shaft (61) extending into the interior of the discharge hood (2) is fixedly connected to the output end of the motor (6). The same number of bevel gears (62) as the flow guide spiral assembly (9) are installed on the rotating shaft (61) at equal intervals. A support plate (63) is fixedly installed inside the discharge hood (2) and below the rotating shaft (61). The same number of openings as the flow guide spiral assembly (9) are opened on the support plate (63) at equal intervals. A first bearing (64) is fixedly installed in each opening. A transmission gear (65) is inserted between the inner ring walls of each first bearing (64). The upper half of the transmission gear (65) is a bevel gear, and the lower half of the transmission gear (65) is a column gear. The bevel gear in the upper half of each transmission gear (65) meshes with the corresponding bevel gear (62).

4. The dual-drive spiral intelligent borehole filling vehicle according to claim 3, characterized in that, The guide spiral assembly (9) includes a rod (91), a stirring blade (92), and a spur gear (93). The rod (91) is divided into an upper rod (911) and a lower rod (912). The lower rod (912) is rotatably connected to the bottom end of the upper rod (911), and the upper rod (911) is inserted through between the feed plate and the fixed frame (10). The stirring blade (92) is fixedly installed at the top end of the upper rod (911), and the spur gear (93) is fixedly installed at the bottom end of the lower rod (912). The spur gear (93) in each group of the guide spiral assembly (9) meshes with the spur gear of the lower half of the corresponding transmission gear (65).

5. The dual-drive spiral intelligent borehole filling vehicle according to claim 4, characterized in that, The lower rod (912) has a groove (913) at its top end, and a third bearing (915) is fixedly installed in the groove (913). The bottom end of the upper rod (911) is connected to a connecting rod (914) that is fixedly inserted between the inner ring walls of the third bearing (915). A stop rod (919) is fixedly installed on both sides of the bottom end of the connecting rod (914). The bottom of the groove (913) has two rod slots, and a plug rod (916) is movably inserted into each of the two rod slots. A blocking block (917) is fixedly installed at the top of each of the two plug rods (916). One side of the top of the blocking block (917) is set as an inclined surface. The side of the blocking block (917) can contact the stop rod (919). A spring (918) sleeved on the plug rod (916) is fixedly connected between the bottom of the blocking block (917) and the groove (913).

6. The dual-drive spiral intelligent borehole filling vehicle according to claim 3, characterized in that, The material discharge hood (2) has fixed blocks (21) fixedly installed at both ends near the material discharge port. The material discharge hood (5) has a fixed shaft (51) fixedly installed at one end near the material discharge hood (2). The two ends of the fixed shaft (51) are respectively rotatably inserted between the two fixed blocks (21). The right end of the fixed shaft (51) is fitted with a sleeve (8). The right end of the rotating shaft (61) passes through the right side of the material discharge hood (2). A transmission assembly (7) is provided between the right end of the rotating shaft (61) and the sleeve (8).

7. A dual-drive spiral intelligent borehole filling vehicle according to claim 6, characterized in that, The inner wall of the sleeve (8) is provided with an annular groove, and a second bearing (81) is fixedly installed in the annular groove. The right end of the fixed shaft (51) is fixedly inserted between the inner ring walls of the second bearing (81). A first tooth groove (511) is provided at the right end of the fixed shaft (51), and a second tooth groove (83) is provided at the right end of the sleeve (8). A matching limiting gear (84) is movably inserted in the second tooth groove (83). The left end of the limiting gear (84) can be inserted into the first tooth groove (511) at the right end of the fixed shaft (51). A hydraulic rod (82) is fixedly installed at the right end of the sleeve (8). The telescopic end of the hydraulic rod (82) extends into the second tooth groove (83) and is connected to the limiting gear (84).

8. A dual-drive spiral intelligent borehole filling vehicle according to claim 6, characterized in that, The transmission assembly (7) includes two sprockets and a chain. The two sprockets are fixedly installed on the right end of the rotating shaft (61) and the sleeve (8), respectively, and the chain drive is sleeved between the two sprockets.

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