Power assembly for launching unmanned aerial vehicle

Abstract

The invention relates to the technical field of unmanned aerial vehicle launching, in particular to an unmanned aerial vehicle launching power assembly which comprises a box body, a cover plate is rotatably connected to the top of the box body, a launching cylinder is arranged in the box body, a sliding block is slidably connected to the interior of the launching cylinder through an energy storage spring, and the bottom of the sliding block extends to the outer side of the launching cylinder through a movable groove. One end of the bottom of the box body is rotatably connected with a connecting rod through a limiting rod, the limiting rod is slidably connected with the connecting rod and the box body, one end of the connecting rod is rotatably connected with the bottom of the sliding block, and a locking mechanism for limiting the sliding block and a releasing mechanism for releasing limiting are installed in the launching cylinder; through the arrangement of the box body and the cover plate, shielding protection on the launching cylinder is achieved, when the launching cylinder is upwards lifted during rotation, the sliding block overcomes the elastic force of the energy storage spring to slide till the sliding block is limited by the locking mechanism, and through control over the releasing mechanism, the releasing mechanism drives the locking mechanism and releases limiting of the locking mechanism, so that the launching cylinder is locked. And the unmanned aerial vehicle in the launching cylinder is pushed out and launched.

Description

Technical Field

[0001] This invention relates to a power assembly, specifically a power assembly for launching unmanned aerial vehicles (UAVs), and belongs to the field of UAV launch technology. Background Technology

[0002] With the rapid development of drone technology, the application fields of drones have expanded from military reconnaissance and terrain mapping to many civilian and commercial scenarios such as fire rescue, logistics distribution, agricultural plant protection, and aerial filming. When performing many tasks, especially in situations where space is limited (such as vehicle-mounted or shipborne platforms) or rapid deployment is required, drones often cannot rely solely on vertical takeoff and landing (VTOL) or runway takeoff. Instead, they need to be launched into the air using specific launch devices to gain initial speed and altitude, thereby quickly entering the predetermined flight path, saving energy and improving operational efficiency.

[0003] Currently, the power sources for UAV catapult launchers mainly include several forms such as air pressure (pneumatic catapult), electromagnetic (electromagnetic catapult), rocket booster, and mechanical energy storage (such as spring catapult).

[0004] Pneumatic catapults require high-pressure gas sources, valves, and gas tanks, making the system relatively complex and posing a risk of pressure leakage. Furthermore, carrying and replenishing high-pressure gas is inconvenient, especially in field or harsh environments. While electromagnetic catapult technology offers rapid response and precise control, it relies on high-power power supplies and complex control systems, resulting in high costs, large size, and weight, hindering its widespread adoption on portable or low-cost platforms. Rocket-assisted launch systems present safety hazards, emit light and smoke, have high single-use costs, and are cumbersome to handle after launch. In contrast, mechanical energy storage (especially spring-powered) launchers, with their relatively simple structure, short preparation time, low cost, high reliability, reusability, immunity to electromagnetic interference, and absence of open flames and smoke, show great potential for launching small to medium-sized fixed-wing or hybrid-layout UAVs. However, the lack of external safety protection on the launch tube makes it susceptible to impact and deformation during transportation or handling, affecting subsequent launch results.

[0005] Therefore, developing a compact, reliable, quick-unlocking, portable, and easy-to-operate power component for UAV launchers, with good environmental adaptability and protection capabilities, is of great significance for promoting the efficient and reliable deployment of small UAVs in diverse scenarios. Summary of the Invention

[0006] The purpose of this invention is to provide a power assembly for launching unmanned aerial vehicles (UAVs) to solve the above-mentioned problems. The assembly includes a housing and a cover plate to protect the launch tube. When the launch tube rotates and tilts upwards, the slider overcomes the elastic force of the energy storage spring and slides until it is limited by the locking mechanism. By controlling the release mechanism, the release mechanism drives the locking mechanism, releasing the locking mechanism. At this point, the energy storage spring instantly resets and drives the slider upwards, thus launching the UAV from inside the launch tube.

[0007] The present invention achieves the above-mentioned objectives through the following technical solution: a power assembly for launching a drone, comprising a housing, a protective mechanism and an energy storage mechanism installed on the housing, the protective mechanism including a cover plate, the top of the housing being rotatably connected to the cover plate, the energy storage mechanism including a launch tube, the launch tube being disposed inside the housing, one end of the launch tube being rotatably connected to one end inside the housing, a slider being slidably connected inside the launch tube via an energy storage spring, the bottom of the slider extending to the outside of the launch tube via a movable groove, a connecting rod being rotatably connected to one end of the bottom of the housing via a limiting rod, the limiting rod being slidably connected to the connecting rod and the housing, one end of the connecting rod being rotatably connected to the bottom of the slider, and a locking mechanism for limiting the slider and a release mechanism for releasing the limiting mechanism being installed inside the launch tube.

[0008] Preferably, the locking mechanism includes a connecting sleeve, a connecting sleeve is installed at the center of one side of the slider, a column is installed inside one end of the launching tube, the inner sidewall of the connecting sleeve is provided with symmetrical slots, a symmetrical locking pin is installed inside one end of the column, the locking pin is slidably connected to the inside of the column by multiple compression springs, the locking pin has an "L" shaped structure, one end of the locking pin extends to the outside of the column, one end of the locking pin has a trapezoidal structure, and a release mechanism is installed on the column.

[0009] Preferably, a positioning sleeve is installed on the outer side of one end of the column, and the diameter of the positioning sleeve is larger than the outer diameter of the connecting sleeve.

[0010] Preferably, the release mechanism includes a sliding sleeve, which is slidably connected to the outer side of the column. A drive groove is provided on the inner sidewall of one end of the sliding sleeve. Two pressure rods are slidably connected inside one end of the column. One end of the pressure rod is perpendicularly connected to the end of the locking pin, and the other end of the pressure rod extends to the outer side of the column. The other end of the pressure rod has a hemispherical structure and is located inside the drive groove.

[0011] Preferably, a guide groove is provided on the inner side of one end of the column, and a sliding plate is slidably connected inside the guide groove. The two ends of the sliding plate extend to the outside of the column and connect to the inside of the connecting sleeve.

[0012] Preferably, a return spring is installed between one side of the skateboard and the guide groove. A control rod is slidably connected inside the upright column. One end of the control rod passes through the return spring and is connected to the skateboard. The other end of the control rod extends to the outside of the launch tube, and the control rod is slidably connected to the inner side of the launch tube.

[0013] Preferably, a handle is installed on the outside of the launch tube, and a handle is installed on the top of the cover plate.

[0014] Preferably, a connecting block is snap-connected to one end of the launch tube. The connecting block has a "convex" shape structure. A fixed seat is installed inside the box body, and the connecting block is rotatably connected to the fixed seat.

[0015] Preferably, a plurality of sponge blocks are installed inside the box body and at the bottom of the cover plate. One end of the sponge block is in an arc structure.

[0016] Preferably, a plurality of support plates are rotatably connected to the bottom edge of the box body through rotation grooves. A plurality of fixing holes are provided on the support plates, and rubber blocks are installed inside the rotation grooves.

[0017] The beneficial effects of the present invention are as follows: Through the setting of the box body, it is beneficial to store the launch tube. By closing the cover plate, the launch tube is shielded and protected, preventing the launch tube from being knocked and deformed, which affects the subsequent launch of the drone. With the cooperation of the limiting rod and the connecting rod, it is beneficial to connect the slider inside the launch tube. When the launch tube rotates and tilts upward, the slider slides against the elastic force of the energy storage spring until the slider is limited by the locking mechanism. After the slider is limited, by pulling out the limiting rod, the connecting rod is in a freely sliding state. By placing the drone inside the top of the launch tube and then swinging the launch tube at a certain angle as needed, through the control of the release mechanism, the release mechanism drives the locking mechanism, and the locking mechanism releases the limit. At this time, the energy storage spring instantly resets, and the energy storage spring drives the slider to push upward, realizing the launch of the drone inside the launch tube. BRIEF DESCRIPTION OF THE DRAWINGS

[0018] Figure 1 It is a schematic diagram of the overall structure of the present invention;

[0019] Figure 2 The structure diagram of the launch tube and the box body of the present invention unfolded;

[0020] Figure 3 It is a schematic diagram of the connection structure between the launch tube and the box body of the present invention;

[0021] Figure 4 It is a schematic diagram of the connection structure between the slider and the launch tube of the present invention;

[0022] Figure 5 It is a schematic diagram of the connection structure between the control rod and the upright column of the present invention;

[0023] Figure 6 This is a schematic diagram of the connection structure between the locking pin and the column of the present invention.

[0024] In the diagram: 1. Housing; 2. Protective mechanism; 201. Cover plate; 202. Handle; 203. Rotary groove; 204. Rubber block; 205. Support plate; 206. Fixing hole; 207. Sponge block; 3. Energy storage mechanism; 301. Limiting rod; 302. Launch tube; 303. Handle; 304. Connecting rod; 305. Connecting block; 306. Fixing seat; 307. Sliding block; 308. Energy storage spring; 309. Movable groove; 4. Locking mechanism; 401. Connecting sleeve; 402. Column; 403. Locking pin; 404. Locking groove; 405. Positioning sleeve; 406. Compression spring; 5. Release mechanism; 501. Control rod; 502. Guide groove; 503. Sliding sleeve; 504. Pressure rod; 505. Drive groove; 506. Slide plate; 507. Return spring. Detailed Implementation

[0025] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0026] Please see Figures 1-6 As shown, a power assembly for launching a drone includes a housing 1, on which a protective mechanism 2 and an energy storage mechanism 3 are installed. The protective mechanism 2 includes a cover plate 201, which is rotatably connected to the top of the housing 1. The energy storage mechanism 3 includes a launch tube 302, which is located inside the housing 1. One end of the launch tube 302 is rotatably connected to the inside of the housing 1. A slider 307 is slidably connected inside the launch tube 302 via an energy storage spring 308. The bottom of the slider 307 extends to the outside of the launch tube 302 via a movable groove 309. A connecting rod 304 is rotatably connected to the bottom of the housing 1 via a limiting rod 301. The limiting rod 301 is slidably connected to the connecting rod 304 and the housing 1. One end of the connecting rod 304 is rotatably connected to the bottom of the slider 307. A locking mechanism 4 for limiting the slider 307 and a release mechanism 5 for releasing the limit are installed inside the launch tube 302.

[0027] As a technical optimization of the present invention, the locking mechanism 4 includes a connecting sleeve 401. The connecting sleeve 401 is installed at the center of one side of the slider 307. A column 402 is installed inside one end of the launching tube 302. The inner sidewall of the connecting sleeve 401 is provided with symmetrical slots 404. A symmetrical locking pin 403 is installed inside one end of the column 402. The locking pin 403 is slidably connected to the inside of the column 402 by multiple compression springs 406. The locking pin 403 has an "L" shaped structure. One end of the locking pin 403 extends to the outside of the column 402, and the other end of the locking pin 403 has a trapezoidal structure. The structure includes a release mechanism 5 installed on the column 402. With the installation of the connecting sleeve 401 and the cooperation of the column 402, when the slider 307 stores energy, the connecting sleeve 401 is engaged with the outer side of the column 402. At the same time, with the cooperation of the compression spring 406, the two locking pins 403 will be retracted by abutment, so that the connecting sleeve 401 and the column 402 are engaged at a designated position. Under the abutment of the compression spring 406, the locking pins 403 are reset and inserted into the slot 404, so as to limit the connection between the connecting sleeve 401 and the column 402, thereby preventing the slider 307 from releasing the stored energy.

[0028] As a technical optimization of the present invention, a positioning sleeve 405 is installed on the outer side of one end of the column 402. The diameter of the positioning sleeve 405 is larger than the outer diameter of the connecting sleeve 401. The installation of the positioning sleeve 405 facilitates the positioning function when the connecting sleeve 401 is fitted with the outer side of the column 402, ensuring that the locking pin 403 can be smoothly inserted into the slot 404 for internal positioning.

[0029] As a technical optimization of the present invention, the release mechanism 5 includes a sliding sleeve 503. The sliding sleeve 503 is slidably connected to the outer side of the column 402. A drive groove 505 is provided on the inner side wall of one end of the sliding sleeve 503. Two pressure rods 504 are slidably connected inside one end of the column 402. One end of the pressure rod 504 is perpendicularly connected to the end of the locking pin 403, and the other end of the pressure rod 504 extends to the outer side of the column 402. The other end of the pressure rod 504 has a hemispherical structure and is located inside the drive groove 505. In the sliding sleeve 503, with the cooperation of the drive groove 505, the sliding sleeve 503 slides and the drive groove 505 inside the sliding sleeve 503 abuts against the two pressure rods 504. The pressure rods 504 are squeezed down and the two pressure rods 504 simultaneously abut against the two locking pins 403. The locking pins 403 are freed from the elastic force of the compression spring 406 and slide, realizing the separation of the locking pins 403 from the locking groove 404, thereby releasing the limit between the connecting sleeve 401 and the column 402, and allowing the slider 307 to release energy.

[0030] As a technical optimization of the present invention, a guide groove 502 is provided on the inner side of one end of the column 402. A sliding plate 506 is slidably connected inside the guide groove 502. Both ends of the sliding plate 506 extend to the outside of the column 402 and connect to the inside of the connecting sleeve 401. With the opening of the guide groove 502 and the cooperation of the sliding plate 506, the sliding sleeve 503 can slide smoothly and play a guiding role.

[0031] As a technical optimization of the present invention, a return spring 507 is installed between one side of the slide plate 506 and the guide groove 502. A control rod 501 is slidably connected inside the column 402. One end of the control rod 501 passes through the return spring 507 and connects to the slide plate 506. The other end of the control rod 501 extends to the outside of the launch tube 302. The control rod 501 is slidably connected to the inside of the launch tube 302. The installation of the return spring 507 facilitates the contact with the sliding sleeve 503, so that the sliding sleeve 503 will not contact the pressure rod 504 to release the limit when there is no external force driving it, thus playing a protective and reset role. At the same time, the installation of the control rod 501 realizes the driving control of the slide plate 506, thereby realizing the control of the sliding sleeve 503, realizing the release of the limit and the release of energy.

[0032] As a technical optimization of the present invention, a handle 303 is installed on the outside of the launch tube 302, and a handle 202 is installed on the top of the cover plate 201. The installation of the handle 303 facilitates the pulling of the launch tube 302, which facilitates the energy storage of the slider 307 and the adjustment of the elevation angle of the launch tube 302. The installation of the handle 202 enables the opening and closing control of the cover plate 201, and the entire housing 1 can be moved in advance after the cover plate 201 is locked.

[0033] As a technical optimization of the present invention, a connecting block 305 is engaged with one end of the launching tube 302. The connecting block 305 has a "convex" shaped structure. A fixing seat 306 is installed inside the housing 1. The connecting block 305 is rotatably connected to the fixing seat 306. By installing the connecting block 305, it is easy to rotatably connect with the fixing seat 306, so as to realize the rotation of the launching tube 302 and the inside of the housing 1. At the same time, the connecting block 305 and the launching tube 302 can be detachably engaged, which is convenient for subsequent disassembly and maintenance.

[0034] As a technical optimization of the present invention, multiple sponge blocks 207 are installed inside the housing 1 and at the bottom of the cover plate 201. One end of the sponge block 207 has an arc-shaped structure. The installation of the sponge block 207 helps to support the bottom of the launch tube 302. After the cover plate 201 is closed with the housing 1, the sponge block 207 abuts against the top side, so that the launch tube 302 will not shake inside the housing 1.

[0035] As a technical optimization of the present invention, multiple support plates 205 are rotatably connected to the bottom edge of the housing 1 via a rotating groove 203. The support plates 205 are provided with multiple fixing holes 206. A rubber block 204 is installed on the inner side of the rotating groove 203. Through the cooperation of the rotating groove 203, the support plates 205 can be stored and hidden at the bottom of the housing 1. By rotating the support plates 205, the support plates 205 extend to the outside of the housing 1, which facilitates the stable support of the bottom of the housing 1. At the same time, through the cooperation of the multiple fixing holes 206, it is easy to use bolts and nails to fix them, making the housing 1 more stable when placed on the ground, which is conducive to the stable launch of the UAV. The installation of the rubber block 204 helps to stabilize the support plates 205 after they are stored.

[0036] In use, the invention first unfolds the multiple support plates 205 at the bottom of the housing 1 by rotation and then fixes them to the ground with nails. Next, the cover plate 201 is opened, and the limiting rod 301 is inserted into the housing 1, penetrating the bottom of the connecting rod 304. Then, by stepping on the bottom edge of the housing 1 and pulling the handle 303, the launching tube 302 rotates upwards. With the cooperation of the connecting rod 304, the slider 307 overcomes the elastic force of the energy storage spring 308 and slides until the connecting sleeve 401 on the outside of the slider 307 is inserted into the outside of the column 402. At this point, with the cooperation of the compression spring 406, the two locking pins 403 are retracted, allowing the connecting sleeve 401 to engage with the column 402 at a designated position. The locking pins 403, under the resistance of the compression spring 406, reset and insert into the slot 404, limiting the connection between the connecting sleeve 401 and the column 402, thus preventing the slider 307 from releasing its energy. After the slider 307 is limited, the energy is released by pulling out the limiting rod. Position lever 301 allows connecting rod 304 to slide freely, facilitating the subsequent release of slider 307. Pulling handle 303 adjusts the elevation angle of the placement plate, and the drone is placed inside the top of launch tube 302. When launching the drone, pushing control lever 501 at the bottom of launch tube 302 causes sliding plate 506 to break free from the elastic force of return spring 507, thereby allowing sliding sleeve 503 to slide. The drive groove 505 inside sliding sleeve 503 abuts against two pressure rods 504, squeezing the pressure rods 504 downwards. Simultaneously, the two pressure rods 504 abut against two locking pins 403, causing locking pins 403 to break free from the elastic force of compression spring 406, separating locking pins 403 from locking grooves 404, thus releasing the limiting position of connecting sleeve 401 and column 402. At this time, energy storage spring 308 instantly resets, driving slider 307 upwards to launch the drone inside launch tube 302.

[0037] The energy storage spring 308 of this device is a cylindrical helical spring 406, hereinafter referred to as the spring. Its core function is to provide power for UAV launch through three stages: "energy storage, energy retention, and energy release." The specific principle is as follows: 1. Energy Storage: External force compresses and stores energy. Initially, the spring naturally elongates, storing no energy. After fixing the housing 1, pulling the handle 303 of the launch tube 302 causes it to tilt upwards. This drives the slider 307 to slide via the connecting rod 304. The slider 307 compresses the spring, causing it to shorten and deform. The operator's pulling force is converted into the elastic potential energy of the spring until the slider 307 reaches the preset position, completing energy storage. 2. Energy Retention: The locking mechanism 4 locks the energy. When the slider 307 reaches the energy storage endpoint, its connecting sleeve 401 is fitted into the column 402. The connecting sleeve 401 first compresses the locking pin 403 on the column 402 to retract it. Once the slot 404 of the connecting sleeve 401 aligns with the locking pin 403, the locking pin 403 pops out and inserts into the slot 404, locking the slider 307. At this time, although the spring is compressed, the slider 307 cannot move, and the energy is stably maintained; 3. Energy release: unlock the launcher. After the drone is placed in, push the control lever 501 to drive the sliding sleeve 503 to slide. The sliding sleeve 503 squeezes the pressure rod 504 through the drive groove 505, causing the locking pin 403 to exit the slot 404, releasing the slider 307 from the lock. The spring instantly resets, and the elastic potential energy is converted into the kinetic energy of the slider 307. The slider 307 slides quickly to push the drone to launch.

[0038] It will be apparent to those skilled in the art that the present invention is not limited to the details of the exemplary embodiments described above, and that the invention can be implemented in other specific forms without departing from its spirit or essential characteristics. Therefore, the embodiments should be considered in all respects as exemplary and non-limiting, and the scope of the invention is defined by the appended claims rather than the foregoing description. Thus, all variations falling within the meaning and scope of equivalents of the claims are intended to be included within the present invention. No reference numerals in the claims should be construed as limiting the scope of the claims.

[0039] Furthermore, it should be understood that 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, and 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.

Claims

1. A power assembly for launching a UAV, comprising a box (1), a protection mechanism (2) and an energy storage mechanism (3) are installed on the box (1), the protection mechanism (2) comprises a cover plate (201), the box (1) is rotationally connected with the cover plate (201) at the top, characterized in that: The energy storage mechanism (3) includes a launching barrel (302), the inside of the box (1) is provided with a launching barrel (302), one end of the launching barrel (302) is rotatably connected with one end of the inside of the box (1), a sliding block (307) is slidably connected with the inside of the launching barrel (302) through an energy storage spring (308), the bottom of the sliding block (307) extends to the outside of the launching barrel (302) through a movable slot (309), one end of the bottom of the box (1) is rotatably connected with a connecting rod (304) through a limiting rod (301), the limiting rod (301) is slidably connected with the connecting rod (304) and the box (1), one end of the connecting rod (304) is rotatably connected with the bottom of the sliding block (307), the inside of the launching barrel (302) is provided with a locking mechanism (4) for limiting the sliding block (307) and a release mechanism (5) for releasing the limitation.

2. The power assembly for launching a UAV of claim 1, wherein: The locking mechanism (4) includes a connecting sleeve (401), the connecting sleeve (401) is installed on one side of the center of the sliding block (307), a stand (402) is installed at one end of the inside of the launching barrel (302), symmetrically arranged clamping grooves (404) are formed in the inner side wall of the connecting sleeve (401), symmetrically arranged clamping pins (403) are installed at one end of the inside of the stand (402), the clamping pins (403) are slidably connected with the inside of the stand (402) through a plurality of compression springs (406), the clamping pins (403) are "L" shaped structures, one end of the clamping pins (403) extends to the outside of the stand (402), one end of the clamping pins (403) is a trapezoidal structure, and the stand (402) is provided with the release mechanism (5).

3. The power pack for launching a UAV according to claim 2, wherein: One end of the stand (402) is provided with a positioning sleeve (405), and the diameter of the positioning sleeve (405) is greater than the outer diameter of the connecting sleeve (401).

4. The power pack for launching a UAV according to claim 2, wherein: The release mechanism (5) includes a sliding sleeve (503), the sliding sleeve (503) is slidably connected with the outside of the stand (402), a driving groove (505) is formed in the inner side wall of one end of the sliding sleeve (503), two pressing rods (504) are slidably connected with the inside of one end of the stand (402), one end of the pressing rods (504) is perpendicularly connected with the end portion of the clamping pins (403), the other end of the pressing rods (504) extends to the outside of the stand (402), the other end of the pressing rods (504) is a hemispherical structure, and the other end of the pressing rods (504) is located in the inside of the driving groove (505).

5. The power pack for launching a UAV according to claim 4, wherein: The inside of one end of the stand (402) is provided with a guide groove (502), a sliding plate (506) is slidably connected with the inside of the guide groove (502), and the sliding plate (506) extends to the inside of the connecting sleeve (401) from the outside of the stand (402) at both ends.

6. The power pack for launching a UAV according to claim 5, wherein: A reset spring (507) is installed between one side of the sliding plate (506) and the guide groove (502), a control rod (501) is slidably connected with the inside of the stand (402), one end of the control rod (501) penetrates through the reset spring (507) and is connected with the sliding plate (506), the other end of the control rod (501) extends to the outside of the launching barrel (302), and the control rod (501) is slidably connected with the inside of the launching barrel (302).

7. The power pack for launching a UAV according to claim 1, wherein: The launching barrel (302) is externally provided with a handle (303), and the top of the cover plate (201) is provided with a handle (202).

8. The power pack for launching a UAV according to claim 1, wherein: One end of the launching barrel (302) is clamped and connected with a connecting block (305), the connecting block (305) is a "convex" structure, the inside of the box body (1) is provided with a fixing seat (306), and the connecting block (305) is rotationally connected with the fixing seat (306).

9. The power pack for launching a UAV according to claim 1, wherein: The inside of the box body (1) and the bottom of the cover plate (201) are provided with a plurality of sponge blocks (207), and one end of the sponge block (207) is an arc structure.

10. The power pack for launching a UAV according to claim 1, wherein: A plurality of supporting plates (205) are rotationally connected with the box body (1) through rotating grooves (203) at the bottom edges, a plurality of fixing holes (206) are arranged on the supporting plates (205), and rubber blocks (204) are arranged on the inside of the rotating grooves (203).

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