Leg stretching device for fitness training

Abstract

The invention relates to the technical field of fitness training, and discloses a leg stretching device for fitness training, which comprises a lying plate, a main component mounting cavity formed in the lying plate, a rotor through hole formed in one end of the main component mounting cavity, a component mounting opening formed in the center of the lying plate, a friction type linkage mechanism and a controllable driving mechanism, a driving motor which is fixedly mounted on one side of the lying plate and can drive the horizontal rotating shaft to rotate and a motor controller which can control the rotating speed of the driving motor are arranged in the lying plate. According to the leg stretching device for fitness training, the damping effect in the stretching exercise process is improved through the friction force between the parts, the characteristic of stable damping strength is achieved, and therefore accidents caused by the fact that the stretching damping strength of an exerciser is increased in the exercise process are prevented, at the moment, the device is driven by the driving motor to stretch and retract, and the exercise efficiency is improved. And the retraction speed and the retraction strength can be effectively controlled, so that accidents caused by retraction of the pull rope are prevented, and the use safety of equipment is improved.

Description

Technical Field

[0001] The invention relates to the technical field of fitness training equipment, in particular to a leg stretching device for fitness training. Background Art

[0002] Stretching is the favorite exercise of many people during physical fitness training. Stretching can make the body flexible and stretchable. During physical fitness exercise, the muscles being exercised will feel stiff and cramped. Stretching can help the muscles relieve stiffness and cramps. During exercise, it is more effective to use it with a leg stretching training device.

[0003] For example, Chinese patent publication number "CN221655012U" discloses a "leg stretching device," the main structure of which includes a horizontally arranged base plate, with two fixed plates fixed to the right side of the top of the base plate. The left ends of the fixed plates are hinged to a first movable plate that swings up and down, the left ends of the first movable plates are hinged to a second movable plate that swings up and down, and the left ends of the second movable plates are hinged to a slide plate. Both slide plates slide left and right with the base plate. The tops of the slide plates are provided with exercise components for exercising the patient's feet, and the side walls of the base plate are provided with a drive component for driving the slide plates to slide on the top of the base plate. When the leg stretching device is in use, the patient's legs are placed on the two movable plates and the feet are placed on the exercise components, which massage and exercise the patient's feet. Under the action of the drive component, the slide plates are pulled to slide left and right on the top of the base plate, and the two movable plates are converted between horizontal and vertical states, allowing the patient to bend their knees and then lower them, exercising and stretching the patient's legs.

[0004] However, during actual use of the above-mentioned leg stretching device, since it utilizes the elasticity of the coil spring to provide damping for the stretching movement and store kinetic energy, the coil spring will cause the tensile strength to gradually increase when providing damping. In other words, since the damping strength gradually increases during the movement, the potential safety hazards will gradually increase. Once the user cannot accept the subsequent strength, serious accidents will occur. At the same time, once the coil spring in the energy storage state is released, it will contract rapidly, which can easily cause collision damage to the human body by the linkage components. Summary of the Invention

[0005] In response to the shortcomings of the existing technology, the present invention provides a leg stretching device for fitness training, which uses the friction between components to improve the damping effect during stretching exercises, and has the characteristic of stable damping strength, thereby preventing the exerciser from causing accidents due to the increase of stretching damping strength during exercise. At this time, the device uses a driving motor to drive stretching and retraction, which can effectively control the retraction speed and retraction strength, thereby preventing accidents caused by retraction of the pull rope, thereby improving the safety of equipment use and solving the above-mentioned technical problems.

[0006] To achieve the above-mentioned objectives, the present invention provides the following technical solutions: a leg stretching device for fitness training, comprising a lying board with a supporting leg installed on the bottom, a main component installation cavity arranged inside the lying board, a rotor through-hole arranged at one end of the main component installation cavity, and a component installation port arranged at the center of the lying board and connected to the main component installation cavity; and also comprising a friction-type linkage mechanism, wherein a linkage roller installed inside the main component installation cavity and capable of rotating, a horizontal rotating shaft located at the center of the linkage roller and capable of rotating, a conical friction block that can make the linkage roller rotate with the horizontal rotating shaft through friction force, and a coil spring that provides elastic pressure to the conical friction block; and a controllable driving mechanism, wherein a driving motor fixedly installed on one side of the lying board and capable of driving the horizontal rotating shaft to rotate, and a motor controller that can control the rotation speed of the driving motor are provided.

[0007] Preferably, the friction linkage mechanism includes two fixed brackets fixedly mounted inside the main component mounting cavity, each of the fixed brackets is provided with an outer shaft mounting hole with open ends, the two rotating ends of the linkage roller are respectively provided with a hollow rotating shaft with an integral structure therewith, the shaft body of the hollow rotating shaft is mounted inside the outer shaft mounting hole through a bearing, a horizontal component movable cavity is provided inside the linkage roller, the linkage roller is respectively provided with an outwardly expanding conical friction cavity at both ends of the horizontal component movable cavity, the interior of the hollow rotating shaft is provided with an inner shaft mounting hole connecting the external space and one end of the conical friction cavity, a horizontal rotating shaft is installed at the center of the inner shaft mounting hole, the conical friction cavity and the horizontal component movable cavity through a bearing, the center of the two conical friction blocks is provided with a shaft sliding hole that can slide along the shaft body of the horizontal rotating shaft, a coil spring in a compressed state is placed on the outer periphery of the shaft body of the horizontal rotating shaft between the two conical friction blocks, and a No. 1 coupling is fixedly installed on the end of the horizontal rotating shaft facing the rotor through-hole.

[0008] Preferably, the structural shape of the cross section of the shaft body sliding hole is consistent with the structural shape of the cross section of the horizontal rotating shaft, both are polygonal structures, and the structural dimensions of the cross section of the shaft body sliding hole match the structural dimensions of the cross section of the horizontal rotating shaft.

[0009] Preferably, the structural radius of the conical friction cavity at the port facing the inner shaft mounting hole is smaller than the structural radius of the port facing the horizontal component movable cavity.

[0010] Preferably, the structural shape of the conical friction block is consistent with that of the conical friction cavity, both of which are conical platform structures, and the conical friction block can abut against the surface of the conical friction cavity.

[0011] Preferably, the controllable drive mechanism includes a motor fixed shell fixedly mounted on the outside of the drive motor, one end of the motor fixed shell is provided with a No. 1 fixed mounting plate which is an integral structure with it and fixedly mounted on one side of the lying plate, the rotor of the drive motor passes through the rotor through-hole, and a No. 2 coupling is fixedly mounted on the end, the No. 2 coupling is fixedly connected to the No. 1 coupling, and a motor controller is fixedly mounted on the outer circumferential surface of the motor fixed shell.

[0012] Preferably, the control output terminal of the motor controller is connected to the control input terminal of the drive motor via a wire, and the motor controller can control the rotation direction of the rotor.

[0013] Preferably, it also includes a winding-type stretching mechanism, which is internally provided with a winding roller fixedly mounted on the outer circumference of the linkage roller, a pull rope capable of winding and unwinding as the winding roller rotates, and a curved guide tube capable of guiding the pull rope.

[0014] Preferably, the winding-up stretching mechanism includes a mounting cavity arranged at the center of the winding roller and fixedly mounted on the outer circumferential surface of the linkage roller, the outer circumferential surface of the winding roller is provided with a cylindrical protrusion structure integral with it, the interior of the cylindrical protrusion structure is provided with a hemispherical mounting cavity with a concave structure, the cylindrical protrusion structure is provided with a rotatable rotating ball head placed inside the hemispherical mounting cavity, one end of the pull rope is fixedly mounted inside the rotating ball head, the bottom end of the curved guide tube is provided with a No. 2 fixed mounting plate integral with it and fixedly mounted on the surface of the lying board, the interior of the curved guide tube is provided with a curved guide hole with both ends open for guiding the pull rope, and the other end of the pull rope is fixedly mounted with a foot pedal.

[0015] Preferably, the structural radius of the hemispherical mounting cavity matches the structural radius of the rotating ball head, and the depth of the hemispherical mounting cavity is greater than the structural radius of the rotating ball head and smaller than the structural diameter of the rotating ball head.

[0016] Compared with the prior art, the present invention provides a leg stretching device for fitness training, which has the following beneficial effects: The friction between components is used to improve the damping effect during stretching exercises, and the damping strength is stable, thereby preventing the exercisers from causing accidents due to the increase of stretching damping strength during exercise. At this time, the device uses a driving motor to drive the stretching retraction, which can effectively control the retraction speed and retraction strength, thereby preventing accidents caused by the retraction of the rope, thereby improving the safety of the equipment. BRIEF DESCRIPTION OF THE DRAWINGS

[0017] Figure 1 A perspective view of the present invention; Figure 2 It is a three-dimensional cross-sectional view of the present invention at a first viewing angle; Figure 3 is a three-dimensional cross-sectional view of the present invention at a second viewing angle; Figure 4 A three-dimensional diagram of the friction linkage mechanism of the present invention; Figure 5 is a three-dimensional cross-sectional view of the friction linkage mechanism of the present invention; Figure 6 is a three-dimensional cross-sectional view of the controllable drive mechanism of the present invention; Figure 7 It is a three-dimensional diagram of the winding and stretching mechanism of the present invention; Figure 8 It is a three-dimensional cross-sectional view of the winding and stretching mechanism of the present invention.

[0018] Among them: 1. Lay plate; 2. Support legs; 3. Main component installation cavity; 4. Component installation port; 5. Rotor through hole; 6. Friction linkage mechanism; 61. Fixed bracket; 62. Linkage roller; 63. Outer shaft installation hole; 64. Hollow shaft; 65. Horizontal component movable cavity; 66. Conical friction cavity; 67. Inner shaft installation hole; 68. Horizontal rotating shaft; 69. Shaft sliding hole; 610. Conical friction block; 611. Coil spring; 612. No. 1 coupling; 7 , controllable drive mechanism; 71, motor fixed housing; 72, No. 1 fixed mounting plate; 73, drive motor; 74, rotor; 75, No. 2 coupling; 76, motor controller; 8, winding and stretching mechanism; 81, winding roller; 82, mounting cavity; 83, hemispherical mounting cavity; 84, rotating ball head; 85, curved guide tube; 86, curved guide hole; 87, No. 2 fixed mounting plate; 88, pull rope; 89, foot pedal; 810, columnar protrusion structure. DETAILED DESCRIPTION

[0019] The following will clearly and completely describe the technical solutions in the embodiments of the present invention in conjunction with the accompanying drawings. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without making creative efforts are within the scope of protection of the present invention.

[0020] See also Figure 1 、 Figure 2 and Figure 3A leg stretching device for fitness training includes a lying board 1 with a supporting leg 2 installed at the bottom, a main component installation cavity 3 arranged inside the lying board 1, a rotor through-hole 5 arranged at one end of the main component installation cavity 3, and a component installation port 4 arranged at the center of the lying board 1 and connected to the main component installation cavity 3. The user lies on the surface of the lying board 1, then steps both feet on the surface of the foot pedal 89, and then continuously straightens and contracts the legs to perform stretching training.

[0021] To provide the required damping for stretching in the form of friction, see Figure 2 、 Figure 3 、 Figure 4 and Figure 5 , it is necessary to set up a friction linkage mechanism 6, which is provided with a linkage roller 62 installed in the main component installation cavity 3 and capable of rotation, a horizontal rotating shaft 68 located at the center of the linkage roller 62 and capable of rotation, a conical friction block 610 that can make the linkage roller 62 rotate along with the horizontal rotating shaft 68 through friction, and a coil spring 611 that provides elastic pressure to the conical friction block 610. When the user stretches, the foot pedal 89 drives the pull rope 88 to stretch. At this time, the pull rope 88 drives the winding roller 81 to rotate, and The winding roller 81 will drive the linkage roller 62 to rotate. At this time, by controlling the driving motor 73, the rotation direction of the rotor 74 is opposite to the rotation direction of the linkage roller 62 when paying out the line. The conical friction block 610 will rotate relative to the linkage roller 62 on the contact surface of the conical friction chamber 66. Due to the elastic pressure provided by the coil spring 611 between the two, the linkage roller 62 will generate the necessary friction damping when rotating. The friction damping will provide the damping required for stretching in the form of friction, thereby allowing the legs to obtain a stretching exercise effect.

[0022] For the specific structure of the friction linkage mechanism 6, please refer to Figure 4 and Figure 5, including two fixed brackets 61 fixedly mounted inside the main component mounting cavity 3, each of the fixed brackets 61 is provided with an outer shaft mounting hole 63 with open ends, the two rotating ends of the linkage roller 62 are respectively provided with a hollow rotating shaft 64 with an integral structure therewith, the shaft body of the hollow rotating shaft 64 is mounted inside the outer shaft mounting hole 63 through a bearing, a horizontal component movable cavity 65 is provided inside the linkage roller 62, and the linkage roller 62 is provided with an outwardly expanding conical friction cavity 66 at both ends of the horizontal component movable cavity 65, an inner shaft mounting hole 67 connecting the external space and one end of the conical friction cavity 66 is provided inside the hollow rotating shaft 64, a horizontal rotating shaft 68 is installed at the center of the inner shaft mounting hole 67, the conical friction cavity 66 and the horizontal component movable cavity 65 through a bearing, and the two conical friction blocks 610 are arranged in the middle. The center is provided with a shaft sliding hole 69 that can slide along the shaft of the horizontal rotating shaft 68. A coil spring 611 in a compressed state is placed on the outer periphery of the shaft of the horizontal rotating shaft 68 between the two conical friction blocks 610. The horizontal rotating shaft 68 is fixedly installed with a No. 1 coupling 612 at the end facing the rotor through-hole 5. The structural shape of the cross section of the shaft sliding hole 69 is consistent with the structural shape of the cross section of the horizontal rotating shaft 68, both of which are polygonal structures, and the structural dimensions of the cross section of the shaft sliding hole 69 match the structural dimensions of the cross section of the horizontal rotating shaft 68. The structural radius of the port of the conical friction cavity 66 facing the inner shaft mounting hole 67 is smaller than the structural radius of its port facing the horizontal component movable cavity 65. The structural shape of the conical friction block 610 is consistent with the structural shape of the conical friction cavity 66, both of which are conical table structures, and the conical friction block 610 can abut against the surface of the conical friction cavity 66.

[0023] To control the retraction speed of the pull cord 88, refer to Figure 2 and Figure 6 , it is necessary to set up a controllable driving mechanism 7, which is internally provided with a driving motor 73 fixedly installed on one side of the lying plate 1 and capable of driving the horizontal rotating shaft 68 to rotate, and a motor controller 76 capable of controlling the rotation speed of the driving motor 73. By adjusting the corresponding values of the motor controller 76, the speed and direction of the rotor 74 of the driving motor 73 can be adjusted during rotation. By adjusting the rotation speed of the rotor 74, the recovery speed of the pull rope 88 can be adjusted to prevent the pull rope 88 from recovering too fast and causing a serious collision accident.

[0024] For the specific structure of the controllable drive mechanism 7, please refer to Figure 6, including a motor fixed shell 71 fixedly mounted on the outside of the drive motor 73, one end of the motor fixed shell 71 is provided with a No. 1 fixed mounting plate 72 which is an integral structure with it and fixedly mounted on one side of the lying plate 1, the rotor 74 of the drive motor 73 passes through the rotor through-hole 5, and a No. 2 coupling 75 is fixedly mounted on the end thereof, the No. 2 coupling 75 is fixedly connected to the No. 1 coupling 612, and a motor controller 76 is fixedly mounted on the outer circumference of the motor fixed shell 71, the control output end of the motor controller 76 is connected to the control input end of the drive motor 73 through a wire, and the motor controller 76 can control the rotation direction of the rotor 74.

[0025] In order to reduce the bending and twisting of the drawstring 88 during the winding and unwinding process, please refer to Figure 1 、 Figure 2 、 Figure 3 、 Figure 7 and Figure 8 , it is necessary to set up a winding and stretching mechanism 8, which is internally provided with a winding roller 81 fixedly mounted on the outer circumference of the linkage roller 62, a pull rope 88 that can produce winding and unwinding functions as the winding roller 81 rotates, and a curved guide tube 85 that can guide the pull rope 88. During the process of unwinding and pulling the rope, the rotating ball head 84 can adaptively rotate inside the hemispherical mounting cavity 83. At the same time, the curved guide tube 85 can ensure the bending transition of the pull rope 88 during the movement, thereby reducing the degree of bending and twisting of the pull rope 88 during the winding and unwinding process.

[0026] For the specific structure of the winding and stretching mechanism 8, please refer to Figure 3 、 Figure 7 and Figure 8 , including a mounting cavity 82 provided at the center of the winding roller 81 and fixedly mounted on the outer circumference of the linkage roller 62, the outer circumference of the winding roller 81 is provided with a cylindrical protrusion structure 810 with an integral structure therewith, the interior of the cylindrical protrusion structure 810 is provided with a hemispherical mounting cavity 83 with an inner concave structure, the cylindrical protrusion structure 810 is provided with a rotatable rotating ball head 84 placed inside the hemispherical mounting cavity 83, one end of the pull rope 88 is fixedly mounted inside the rotating ball head 84, the curved The bottom end of the guide tube 85 is provided with a second fixed mounting plate 87 which is an integral structure with it and fixedly mounted on the surface of the lying board 1. The interior of the curved guide tube 85 is provided with a curved guide hole 86 with both ends being open and used to guide the pull rope 88. The other end of the pull rope 88 is fixedly mounted with a foot pedal 89. The structural radius of the hemispherical mounting cavity 83 matches the structural radius of the rotating ball head 84, and the depth of the hemispherical mounting cavity 83 is greater than the structural radius of the rotating ball head 84 and smaller than the structural diameter of the rotating ball head 84.

[0027] During use, the speed and direction of rotation of the rotor 74 of the drive motor 73 can be adjusted by adjusting the corresponding values through the motor controller 76. By adjusting the rotation speed of the rotor 74, the recovery speed of the pull rope 88 can be adjusted. When the user performs an extension movement, the foot pedal 89 will drive the pull rope 88 to extend. At this time, the pull rope 88 will drive the winding roller 81 to rotate, and the winding roller 81 will drive the linkage roller 62 to rotate. At this time, by controlling the drive motor 73, the rotation direction of the rotor 74 is opposite to the rotation direction of the linkage roller 62 when paying out the line. The conical friction block 610 will rotate relative to the contact surface of the linkage roller 62 in the conical friction cavity 66. Due to the elastic pressure provided by the coil spring 611 between the two, the linkage roller 62 will generate the necessary friction damping when rotating. This friction damping will provide the damping required for stretching in the form of friction, thereby allowing the legs to obtain a stretching exercise effect.

[0028] While embodiments of the present invention have been shown and described, it will be appreciated by those skilled in the art that various changes, modifications, substitutions, and variations may be made to these embodiments without departing from the principles and spirit of the invention, and that the scope of the invention is defined by the appended claims and their equivalents.

Claims

1. A leg stretching device for fitness training, comprising a lying plate (1) with a supporting leg (2) mounted on the bottom, a main component mounting cavity (3) arranged inside the lying plate (1), a rotor through-hole (5) arranged at one end of the main component mounting cavity (3), and a component mounting opening (4) arranged at the center of the lying plate (1) and communicating with the main component mounting cavity (3), characterized in that: Also includes, A friction-type linkage mechanism (6) is provided with a linkage roller (62) installed in the main component installation cavity (3) and capable of rotation, a horizontal rotation shaft (68) located at the center of the linkage roller (62) and capable of rotation, a conical friction block (610) capable of causing the linkage roller (62) to rotate along the horizontal rotation shaft (68) through friction, and a coil spring (611) for providing elastic pressure to the conical friction block (610); and a controllable drive mechanism (7), which is internally provided with a drive motor (73) fixedly mounted on one side of the lying plate (1) and capable of driving the horizontal rotating shaft (68) to rotate, and a motor controller (76) capable of controlling the rotation speed of the drive motor (73).

2. A leg stretching device for fitness training according to claim 1, characterized in that: The friction linkage mechanism (6) comprises two fixed brackets (61) fixedly mounted inside the main component mounting cavity (3), each of the fixed brackets (61) is provided with an outer shaft mounting hole (63) with both ends being open, the two rotating ends of the linkage roller (62) are respectively provided with a hollow rotating shaft (64) with an integral structure therewith, the shaft body of the hollow rotating shaft (64) is mounted inside the outer shaft mounting hole (63) through a bearing, the linkage roller (62) is provided with a horizontal component active cavity (65), the linkage roller (62) is provided with an outwardly expanding conical friction cavity (66) at both ends of the horizontal component active cavity (65), the hollow rotating shaft An inner shaft mounting hole (67) communicating with the external space and one end of the conical friction chamber (66) is provided inside (64); a horizontal rotating shaft (68) is mounted on the hollow rotating shaft (64) through a bearing at the center of the inner shaft mounting hole (67), the conical friction chamber (66) and the horizontal component movable chamber (65); a shaft sliding hole (69) capable of sliding along the shaft of the horizontal rotating shaft (68) is provided at the center of the two conical friction blocks (610); a coil spring (611) in a compressed state is placed on the outer periphery of the shaft of the horizontal rotating shaft (68) between the two conical friction blocks (610); and a No. 1 coupling (612) is fixedly mounted on the end of the horizontal rotating shaft (68) facing the rotor through hole (5).

3. A leg stretching device for fitness training according to claim 2, characterized in that: The structural shape of the cross section of the shaft body sliding hole (69) is consistent with the structural shape of the cross section of the horizontal rotating shaft (68), both of which are polygonal structures, and the structural dimensions of the cross section of the shaft body sliding hole (69) match the structural dimensions of the cross section of the horizontal rotating shaft (68).

4. A leg stretching device for fitness training according to claim 3, characterized in that: The structural radius of the conical friction cavity (66) at the port facing the inner shaft body mounting hole (67) is smaller than the structural radius of the port facing the horizontal component movable cavity (65).

5. A leg stretching device for fitness training according to claim 4, characterized in that: The structural shape of the conical friction block (610) is consistent with the structural shape of the conical friction cavity (66), both of which are conical platform structures, and the conical friction block (610) can abut against the surface of the conical friction cavity (66).

6. A leg stretching device for fitness training according to claim 5, characterized in that: The controllable drive mechanism (7) includes a motor fixed housing (71) fixedly mounted on the outside of the drive motor (73), one end of the motor fixed housing (71) is provided with a No. 1 fixed mounting plate (72) which is an integral structure with the motor fixed housing and fixedly mounted on one side of the lying plate (1), a rotor (74) of the drive motor (73) passes through the rotor through-hole (5), and a No. 2 coupling (75) is fixedly mounted on the end thereof, the No. 2 coupling (75) is fixedly connected to the No. 1 coupling (612), and a motor controller (76) is fixedly mounted on the outer circumferential surface of the motor fixed housing (71).

7. A leg stretching device for fitness training according to claim 6, characterized in that: The control output end of the motor controller (76) is connected to the control input end of the drive motor (73) via a wire, and the motor controller (76) is capable of controlling the rotation direction of the rotor (74).

8. A leg stretching device for fitness training according to any one of claims 2 to 7, characterized in that: The invention also includes a winding-type stretching mechanism (8), which is internally provided with a winding roller (81) fixedly mounted on the outer circumference of the linkage roller (62), a drawstring (88) capable of generating winding and unwinding functions as the winding roller (81) rotates, and a curved guide tube (85) capable of generating a guiding function for the drawstring (88).

9. The leg stretching device for fitness training according to claim 8, characterized in that: The winding stretching mechanism (8) comprises a mounting cavity (82) arranged at the center of the winding roller (81) and fixedly mounted on the outer circumference of the linkage roller (62); the outer circumference of the winding roller (81) is provided with a cylindrical protrusion structure (810) integral with the winding roller; the interior of the cylindrical protrusion structure (810) is provided with a hemispherical mounting cavity (83) with an inner concave structure; the cylindrical protrusion structure (810) is provided with a hemispherical mounting cavity (83) disposed inside the hemispherical mounting cavity (83); A rotating ball head (84) is provided, one end of the pull rope (88) is fixedly mounted inside the rotating ball head (84), the bottom end of the curved guide tube (85) is provided with a second fixed mounting plate (87) which is integrally formed with the bottom end of the curved guide tube (85) and fixedly mounted on the surface of the lying board (1), the interior of the curved guide tube (85) is provided with a curved guide hole (86) with both ends being open and used to guide the pull rope (88), and the other end of the pull rope (88) is fixedly mounted with a foot pedal (89).

10. The leg stretching device for fitness training according to claim 9, characterized in that: The structural radius of the hemispherical mounting cavity (83) matches the structural radius of the rotating ball head (84), and the depth of the hemispherical mounting cavity (83) is greater than the structural radius of the rotating ball head (84) and smaller than the structural diameter of the rotating ball head (84).

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