Patient leg rehabilitation device for surgical nursing

Abstract

The invention discloses a patient leg rehabilitation device for surgical nursing, and relates to the technical field of medical rehabilitation, the patient leg rehabilitation device comprises three first half cylinders and two second half cylinders, the top of one of the first half cylinders and the second half cylinders is provided with four fixing belts, and an adjusting buckle is arranged between every two fixing belts in a sleeving manner; and two L-shaped frames are arranged at the bottom of one of the first half cylinders. Through the arrangement of an adjusting rack, two adjusting gears, two U-shaped limiting rods and an arc-shaped abutting plate, the position of a massage mechanism is adjusted according to the knee bending degree of a patient, the initial, middle and later rehabilitation periods of the patient are judged according to the knee bending degree of the patient, and through the arrangement of a one-way rack, a wedge-shaped block and an abutting spring, the rehabilitation effect of the patient is improved. The maximum massage strength which can be adapted to a patient is recorded and limited, the massage strength is adjusted in a self-adaptive mode according to the rehabilitation stage of the patient, the muscle fatigue recovery time is shortened, meanwhile, blood circulation is promoted, and the fascia adhesion or fibrosis risk is reduced.

Description

Technical Field

[0001] The present invention relates to the technical field of medical rehabilitation, and in particular to a patient leg rehabilitation device for surgical care. Background Art

[0002] For patients with lower limb joint movement disorders, improving the range of motion of their lower limb joints, strengthening leg muscle strength and improving the coordinated movement function of leg muscles are important means to improve their physical functions.

[0003] Existing technology allows patients to use fixed equipment while adjusting training resistance to adapt to training intensities at different rehabilitation stages. However, for patients in the rehabilitation stage, their muscle tolerance recovery speed is far slower than that in healthy periods. If they do not recover properly after training, it is easy to cause muscle fatigue and secondary injury, aggravating the condition. In addition, the recovery time required for different training intensities needs to be adapted and adjusted, which is cumbersome. Summary of the Invention

[0004] The technical solution of the present invention addresses the technical problem that the existing technical solutions are too simple, and provides a solution that is significantly different from the existing technology. Specifically, the purpose of the present invention is to provide a patient leg rehabilitation device for surgical care to solve the problems raised in the above background technology.

[0005] To achieve the above-mentioned objectives, the present invention provides the following technical solutions: a patient leg rehabilitation device for surgical care, comprising three first half-cylinders and two second half-cylinders, wherein the top of each of the first half-cylinders and the second half-cylinder is provided with four fixing straps, and adjustment buckles are provided between each of the fixing straps, and the bottom of one of the first half-cylinders is provided with two L-shaped frames, the side walls of the two L-shaped frames are fixedly provided with servo motors, the ends of the output shafts of the two servo motors are rotatably provided with training mechanisms, the side walls of the two L-shaped frames are fixedly provided with timing mechanisms for adaptively adjusting the massage time according to the training intensity, both side walls of the first half-cylinder are provided with a one-way mechanism, the side walls of the two training mechanisms are provided with an adjustment mechanism, and a massage mechanism is provided inside the adjustment mechanism, and one of the first half-cylinders is slidably sleeved on the two L-shaped frames.

[0006] Preferably, both of the two training mechanisms include a torsion spring, a first rotating shaft, a first connecting plate, a second connecting plate and a circular block, the circular block is fixedly arranged at the end of the servo motor output shaft, one end of the first rotating shaft is rotatably arranged at the end of the circular block, one end of the torsion spring is fixedly arranged on the circular block, the other end of the torsion spring is fixedly connected to the first rotating shaft, the first connecting plate is fixedly arranged at the end of the first half-cylinder located below, the second connecting plate is fixedly arranged at the end of the second half-cylinder located below, the second connecting plate is fixedly connected to the other end of the first rotating shaft, and the first connecting plate is rotatably matched with the first rotating shaft.

[0007] Preferably, the adjustment mechanism includes two adjustment racks, two adjustment gears, two U-shaped limit rods and an arc-shaped contact plate. The two adjustment gears are fixedly arranged on the first rotating shaft, the two U-shaped limit rods are slidingly limited on the two L-shaped frame side walls, the two adjustment racks are respectively fixedly arranged on the ends of the two U-shaped limit rods, and the arc-shaped contact plate is fixedly arranged on the two adjustment rack side walls.

[0008] Preferably, the two one-way mechanisms each include a one-way rack, a wedge block and a resistance spring, and the two side walls of the first half cylinder are provided with a receiving groove, one end of the resistance spring is fixedly arranged on the side wall of the receiving groove, the wedge block is fixedly arranged on the other end of the resistance spring, and the one-way rack is fixedly arranged on the bottom of the first half cylinder located above.

[0009] Preferably, two side walls of the wedge-shaped blocks are fixedly provided with special-shaped reset rods.

[0010] Preferably, the massage mechanism includes a massage motor, a cam, a rotating column, a plurality of plug-in slots, a plurality of massage blocks and an arc-shaped massage plate. The massage motor is arranged inside the first half-cylinder located at the bottom, the rotating column is fixedly arranged at the end of the output shaft of the massage motor, the cam is fixedly arranged on the rotating column, the arc-shaped massage plate is plugged into the top of the first half-cylinder located at the bottom, a plurality of the plug-in slots are arranged in a linear array on the middle first half-cylinder, and a plurality of the massage blocks are fixedly arranged in a linear array on the top of the arc-shaped massage plate.

[0011] Preferably, the timing mechanism includes two U-shaped timing rods, two piston cylinders, two piston plates, two one-way valves, two connecting pipes and a timing assembly. The timing assembly is arranged at the top of the first half cylinder located at the bottom, the two U-shaped timing rods are respectively fixed on the top of the two U-shaped limit rods, the two piston plates are respectively fixed on the bottom of the two U-shaped timing plates, the two piston cylinders are respectively fixed on the two L-shaped frame side walls, the two one-way valves are respectively arranged on the two piston plates, and one end of the two connecting pipes are respectively connected and arranged at the bottom of the piston cylinder.

[0012] Preferably, the timing assembly includes a hollow plate, a micropore, a curved plate, a reset spring, a limit plate and a limit gear. The hollow plate is fixedly connected and arranged at the other end of the two connecting tubes. The reset spring is arranged inside the hollow plate. The micropore is arranged at the end of the hollow plate. The curved plate is fixedly arranged at the end of the reset spring. The limit gear is fixedly arranged at the end of the rotating column. The limit plate is fixedly arranged on a side wall of the curved plate close to the limit gear.

[0013] Compared with the prior art, the present invention has the following beneficial effects:

[0014] (1) The present invention adjusts the position of the massage mechanism according to the patient's knee flexion degree by setting an adjustment rack, two adjustment gears, two U-shaped limit rods and an arc-shaped contact plate, so as to judge the initial, middle and late stages of the patient's rehabilitation according to the patient's knee flexion degree. The present invention also records and limits the maximum massage intensity that the patient can adapt to by setting a one-way rack, a wedge block and a contact spring, and adaptively adjusts the massage intensity according to the patient's rehabilitation stage, thereby shortening the muscle fatigue recovery time and promoting blood circulation to reduce the risk of fascia adhesion or fibrosis.

[0015] (2) The present invention realizes the adjustment of the deformation of the torsion spring by the servo motor through the arrangement of the torsion spring, the first rotating shaft, the first connecting plate, the second connecting plate and the circular block, thereby adjusting the training resistance to meet the training requirements of different people at different rehabilitation stages and ensuring the training effect;

[0016] (3) The present invention realizes the adaptive adjustment of the massage time of the massage mechanism according to the patient's training time and rehabilitation stage through the arrangement of a U-shaped timing rod, two piston cylinders, two piston plates, two one-way valves, two connecting pipes, a hollow plate, a micropore, an arc-shaped plate, a reset spring, a limit plate and a limit gear, a through groove and an oil filling port, without the need for manual judgment, which not only allows the patient to accelerate the recovery of muscle fatigue, but also avoids the situation where the patient causes muscle soreness due to excessive massage, thereby further shortening the patient's leg rehabilitation period. BRIEF DESCRIPTION OF THE DRAWINGS

[0017] Figure 1 It is a schematic diagram of the overall structure of the present invention;

[0018] Figure 2 It is a structural diagram of the training mechanism of the present invention;

[0019] Figure 3 It is a cross-sectional structural diagram showing the positional relationship between the adjustment mechanism and the timing mechanism of the present invention;

[0020] Figure 4 For the present invention Figure 3 Enlarged view of point A in the middle;

[0021] Figure 5 It is a schematic cross-sectional structural diagram of the one-way mechanism of the present invention;

[0022] Figure 6 It is a schematic cross-sectional view of the massage mechanism of the present invention.

[0023] Figure: 1, first half cylinder; 2, second half cylinder; 3, adjustment buckle; 31, fixing belt; 4, training mechanism; 41, torsion spring; 42, first rotating shaft; 43, first connecting plate; 44, second connecting plate; 45, circular block; 5, timing mechanism; 51, U-shaped timing rod; 52, piston cylinder; 53, piston plate; 54, one-way valve; 55, connecting pipe; 56, hollow plate; 561, micropore; 57, curved plate; 58, return spring; 59, limit Plate; 510, limit gear; 6, one-way mechanism; 61, one-way rack; 62, wedge block; 63, resistance spring; 7, L-shaped frame; 8, adjustment mechanism; 81, adjustment rack; 82, adjustment gear; 83, U-shaped limit rod; 84, arc-shaped resistance plate; 9, massage mechanism; 91, massage motor; 92, cam; 93, rotating column; 94, plug-in slot; 95, massage block; 96, arc-shaped massage plate; 10, servo motor; 11, special-shaped reset rod. DETAILED DESCRIPTION

[0024] 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.

[0025] See also Figures 1-6, the present invention provides an embodiment: a patient leg rehabilitation device for surgical nursing, comprising three first half-cylinders 1 and two second half-cylinders 2, wherein the top of each of the first half-cylinder 1 and the second half-cylinder 2 is provided with four fixing straps 31, and adjustment buckles 3 are sleeved between the fixing straps 31, and two L-shaped frames 7 are provided at the bottom of the first half-cylinder 1, and servo motors 10 are fixedly provided on the side walls of the two L-shaped frames 7, and training mechanisms 4 are rotatably provided on the ends of the output shafts of the two servo motors 10, and timing mechanisms 5 for adaptively adjusting the massage time according to the training intensity are fixed on the side walls of the two L-shaped frames 7, one of the first half-cylinder 1 is provided with a one-way mechanism 6 on both side walls, and an adjustment mechanism 8 is provided on the side walls of the two training mechanisms 4, and a massage mechanism 9 is provided inside the adjustment mechanism 8, and one of the first half-cylinders 1 is slidably sleeved on the two L-shaped frames 7. First, the patient's thigh and calf are tied tightly by the fixing belt 31, and then the training resistance is adjusted by rotating the output shaft of the servo motor 10. The patient performs reciprocating knee flexion training, driving the training mechanism 4 to work, and the training mechanism 4 drives the adjustment mechanism 8 to move up and down. The adjustment mechanism 8 resists the first half cylinder 1 at the bottom and moves up. After the first half cylinder 1 moves up, it is limited by the one-way mechanism 6. The adjustment mechanism 8 drives the massage mechanism 9 to move up synchronously, thereby adjusting the massage intensity. At the same time, the adjustment mechanism 8 moves up and down to drive the timing mechanism 5 to perform timing. When the training is fatigued or the training is completed, the massage mechanism 9 is used to pat and massage the patient's thigh hamstrings to relax. When the massage time reaches the training time recorded by the timing mechanism 5, the massage mechanism 9 is limited and locked. At this time, the fixing belt 31 is pulled out from the adjustment buckle 3 to unlock the first half cylinder 1 and the second half cylinder 2 and remove the device.

[0026] Specifically, the two training mechanisms 4 each include a torsion spring 41, a first rotating shaft 42, a first connecting plate 43, a second connecting plate 44 and a circular block 45. The circular block 45 is fixedly arranged at the end of the output shaft of the servo motor 10, and one end of the first rotating shaft 42 is rotatably arranged at the end of the circular block 45. One end of the torsion spring 41 is fixedly arranged on the circular block 45, and the other end of the torsion spring 41 is fixedly connected to the first rotating shaft 42. The first connecting plate 43 is fixedly arranged at the end of the first half cylinder 1 located below, and the second connecting plate 44 is fixedly arranged at the end of the second half cylinder 2 located below. The second connecting plate 44 is fixedly connected to the other end of the first rotating shaft 42, and the first connecting plate 43 is rotatably matched with the first rotating shaft 42. The patient's knee flexion drives the second half cylinder 2, the second connecting plate 44, and the first rotating shaft 42 located in the first connecting plate 43 to rotate, and the rotation of the first rotating shaft 42 drives the torsion spring 41 to deform, thereby providing the patient with knee flexion training resistance; the deformation degree of the torsion spring 41 is adjusted by the servo motor 10, thereby adjusting the training resistance to meet the training requirements of different people at different rehabilitation stages, thereby ensuring the training effect.

[0027] Specifically, the adjustment mechanism 8 includes two adjustment racks 81, two adjustment gears 82, two U-shaped limit rods 83 and an arc-shaped contact plate 84. The two adjustment gears 82 are fixedly mounted on the first rotating shaft 42, the two U-shaped limit rods 83 are slidingly mounted on the two side walls of the L-shaped frame 7, the two adjustment racks 81 are fixedly mounted on the ends of the two U-shaped limit rods 83, and the arc-shaped contact plate 84 is fixedly mounted on the side walls of the two adjustment racks 81. The adjustment gears 82 are rotated by the first rotating shaft 42, and the adjustment gears 82 rotate and the adjustment racks 81 move upward. The upward movement of the adjustment racks 81 drives the U-shaped limit rods 83 and the arc-shaped contact plate 84 upward, and the arc-shaped contact plate 84 moves upward and contacts the first half-cylinder 1 at the bottom, which moves upward synchronously. The position of the massage mechanism 9 is adjusted according to the patient's knee flexion degree, so that the patient's rehabilitation stage can be judged according to the patient's knee flexion degree, thereby adaptively adjusting the appropriate massage intensity.

[0028] Specifically, the two one-way mechanisms 6 each include a one-way rack 61, a wedge block 62, and a resistance spring 63. Receiving slots are provided on both side walls of the first half-cylinder 1. One end of the resistance spring 63 is fixedly mounted on the side wall of the receiving slot, and the wedge block 62 is fixedly mounted on the other end of the resistance spring 63. The one-way rack 61 is fixedly mounted on the bottom of the upper first half-cylinder 1. The wedge block 62 presses against the one-way rack 61 to compress the resistance spring 63, forcing the first half-cylinder 1 at the bottom to move only upward, thereby recording and limiting the maximum massage intensity that the patient can adapt to.

[0029] Specifically, the side walls of the two wedge-shaped blocks 62 are fixedly provided with special-shaped reset rods 11; by pressing the special-shaped reset rods 11, the wedge-shaped blocks 62 are driven to compress the resistance spring 63, so that the first half cylinder 1 at the bottom is reset under the action of gravity, which is convenient for next use.

[0030] Specifically, the massage mechanism 9 includes a massage motor 91, a cam 92, a rotating column 93, a plurality of insertion slots 94, a plurality of massage blocks 95, and a curved massage plate 96. The massage motor 91 is disposed within the first half-cylinder 1 at the bottom. The rotating column 93 is fixedly mounted at the end of the output shaft of the massage motor 91. The cam 92 is fixedly mounted on the rotating column 93. The curved massage plate 96 is inserted into the top of the first half-cylinder 1 at the bottom. The insertion slots 94 are arranged in a linear array on the middle first half-cylinder 1. The massage blocks 95 are fixedly mounted in a linear array on the top of the curved massage plate 96. The output shaft of the massage motor 91 drives the rotating column 93 and the cam 92 to rotate. The cam 92 rotates, causing the curved massage plate 96 to move upward and then fall under the action of gravity. The curved massage plate 96 synchronizes with the massage blocks 95 to move back and forth synchronously, thereby patting and massaging the patient's hamstring muscles. This achieves massage relaxation for the patient's hamstring muscles, promotes blood circulation, accelerates muscle fatigue recovery, and shortens the leg rehabilitation period.

[0031] Specifically, the timing mechanism 5 includes two U-shaped timing rods 51, two piston cylinders 52, two piston plates 53, two one-way valves 54, two connecting pipes 55 and a timing assembly. The timing assembly is arranged at the top of the first half cylinder 1 located at the bottom. The two U-shaped timing rods 51 are respectively fixed on the tops of the two U-shaped limit rods 83, the two piston plates 53 are respectively fixed on the bottoms of the two U-shaped timing plates, the two piston cylinders 52 are respectively fixed on the side walls of the two L-shaped frames 7, the two one-way valves 54 are respectively arranged on the two piston plates 53, and one ends of the two connecting pipes 55 are respectively connected and arranged at the bottoms of the piston cylinders 52.

[0032] Specifically, the timing assembly includes a hollow plate 56, a micropore 561, an arc plate 57, a return spring 58, a limit plate 59 and a limit gear 510. The hollow plate 56 is fixedly connected and arranged at the other end of the two connecting tubes 55. The return spring 58 is arranged inside the hollow plate 56. The micropore 561 is arranged at the end of the hollow plate 56. The arc plate 57 is fixedly arranged at the end of the return spring 58. The limit gear 510 is fixedly arranged at the end of the rotating column 93. The limit plate 59 is fixedly arranged on a side wall of the arc plate 57 close to the limit gear 510. The movement of the U-shaped limit rod 83 drives the U-shaped timing rod 51 to move up and down synchronously, and the reciprocating movement of the U-shaped timing rod 51 drives the piston plate 53 to move synchronously. Moreover, since the ventilation direction of the one-way valve 54 is to flow from the bottom of the piston plate 53 to the top of the piston plate 53, when the piston plate 53 moves up, a negative pressure is formed inside the piston cylinder 52, and the air inside the hollow plate 56 is sucked into the piston cylinder 52 through the connecting pipe 55. When the piston plate 53 moves down, the air inside the piston cylinder 52 is squeezed out from the one-way valve 54, so that the gas inside the hollow plate 56 is sucked out to form a negative pressure inside, thereby driving the arc plate 57 to move toward the connecting pipe 55. After fatigue or training, the negative pressure state inside the hollow plate 56 slowly sucks in the outside air from the micropores 561, so that the arc plate 57 slowly moves toward the limit gear 510 under the elastic force of the reset spring 58, until the arc plate 57 is completely reset to drive the limit plate 59 to be engaged with the limit rack, limiting the limit gear 510, and the massage stops at this time; the massage time of the massage mechanism 9 is adaptively adjusted according to the patient's training time and rehabilitation stage without manual judgment, which not only allows the patient to accelerate muscle fatigue recovery, but also avoids the situation where the patient causes muscle soreness due to excessive massage, further shortening the patient's leg rehabilitation cycle.

[0033] Although the present invention has been described in detail with reference to the aforementioned embodiments, it is still possible for those skilled in the art to modify the technical solutions described in the aforementioned embodiments, or to make equivalent substitutions for some of the technical features therein. Any modifications, equivalent substitutions, improvements, etc. made within the spirit and principles of the present invention should be included in the scope of protection of the present invention.

Claims

1. A patient leg rehabilitation device for surgical nursing, comprising three first half-cylinders (1) and two second half-cylinders (2), wherein the top of each of the first half-cylinder (1) and the second half-cylinder (2) is provided with four fixing straps (31), and adjustment buckles (3) are provided between each of the fixing straps (31), characterized in that: Two L-shaped frames (7) are provided at the bottom of one of the first half-cylinders (1), servo motors (10) are fixedly provided on the side walls of the two L-shaped frames (7), training mechanisms (4) are rotatably provided at the ends of the output shafts of the two servo motors (10), timing mechanisms (5) for adaptively adjusting the massage time according to the training intensity are fixedly provided on the side walls of the two L-shaped frames (7), one of the first half-cylinders (1) is provided with a one-way mechanism (6) on both side walls, and an adjustment mechanism (8) is provided on the side walls of the two training mechanisms (4), and a massage mechanism (9) is provided inside the adjustment mechanism (8), and one of the first half-cylinders (1) is slidably sleeved on the two L-shaped frames (7).

2. A surgical nursing patient leg rehabilitation device according to claim 1, characterized in that: The two training mechanisms (4) each include a torsion spring (41), a first rotating shaft (42), a first connecting plate (43), a second connecting plate (44) and a circular block (45), wherein the circular block (45) is fixedly arranged at the end of the output shaft of the servo motor (10), one end of the first rotating shaft (42) is rotatably arranged at the end of the circular block (45), one end of the torsion spring (41) is fixedly arranged on the circular block (45), the other end of the torsion spring (41) is fixedly connected to the first rotating shaft (42), the first connecting plate (43) is fixedly arranged at the end of the first half-cylinder (1) located below, the second connecting plate (44) is fixedly arranged at the end of the second half-cylinder (2) located below, the second connecting plate (44) is fixedly connected to the other end of the first rotating shaft (42), and the first connecting plate (43) is rotatably matched with the first rotating shaft (42).

3. A surgical nursing patient leg rehabilitation device according to claim 2, characterized in that: The adjustment mechanism (8) comprises two adjustment racks (81), two adjustment gears (82), two U-shaped limiting rods (83) and an arc-shaped contact plate (84); the two adjustment gears (82) are fixedly arranged on the first rotating shaft (42); the two U-shaped limiting rods (83) are limitedly slidably arranged on the side walls of the two L-shaped frames (7); the two adjustment racks (81) are respectively fixedly arranged on the ends of the two U-shaped limiting rods (83); and the arc-shaped contact plate (84) is fixedly arranged on the side walls of the two adjustment racks (81).

4. A surgical nursing patient leg rehabilitation device according to claim 1, characterized in that: The two one-way mechanisms (6) each comprise a one-way rack (61), a wedge block (62) and a resisting spring (63); both side walls of the first half cylinder (1) are provided with a receiving groove; one end of the resisting spring (63) is fixedly arranged on the side wall of the receiving groove; the wedge block (62) is fixedly arranged on the other end of the resisting spring (63); and the one-way rack (61) is fixedly arranged on the bottom of the first half cylinder (1) located above.

5. A surgical nursing patient leg rehabilitation device according to claim 4, characterized in that: Special-shaped reset rods (11) are fixedly provided on the side walls of the two wedge-shaped blocks (62).

6. A surgical nursing patient leg rehabilitation device according to claim 1, characterized in that: The massage mechanism (9) comprises a massage motor (91), a cam (92), a rotating column (93), a plurality of plug-in slots (94), a plurality of massage blocks (95) and an arc-shaped massage plate (96); the massage motor (91) is arranged inside the first half-cylinder (1) at the bottom; the rotating column (93) is fixedly arranged at the end of the output shaft of the massage motor (91); the cam (92) is fixedly arranged on the rotating column (93); the arc-shaped massage plate (96) is plugged into the top of the first half-cylinder (1) at the bottom; the plurality of plug-in slots (94) are arranged in a linear array on the middle first half-cylinder (1); and the plurality of massage blocks (95) are fixedly arranged in a linear array on the top of the arc-shaped massage plate (96).

7. The leg rehabilitation device for surgical nursing patients according to claim 3, characterized in that: The timing mechanism (5) comprises two U-shaped timing rods (51), two piston cylinders (52), two piston plates (53), two one-way valves (54), two connecting pipes (55) and a timing assembly. The timing assembly is arranged on the top of the first half cylinder (1) located at the bottom. The two U-shaped timing rods (51) are respectively fixedly arranged on the tops of two U-shaped limit rods (83). The two piston plates (53) are respectively fixedly arranged on the bottoms of the two U-shaped timing plates. The two piston cylinders (52) are respectively fixedly arranged on the side walls of two L-shaped frames (7). The two one-way valves (54) are respectively arranged on the two piston plates (53). One end of the two connecting pipes (55) is respectively connected and arranged at the bottom of the piston cylinder (52).

8. A leg rehabilitation device for surgical nursing patients according to claim 7, characterized in that: The timing assembly comprises a hollow plate (56), a microhole (561), an arc-shaped plate (57), a reset spring (58), a limit plate (59) and a limit gear (510); the hollow plate (56) is fixedly connected and arranged at the other end of the two connecting tubes (55); the reset spring (58) is arranged inside the hollow plate (56); the microhole (561) is arranged at the end of the hollow plate (56); the arc-shaped plate (57) is fixedly arranged at the end of the reset spring (58); the limit gear (510) is fixedly arranged at the end of the rotating column (93); and the limit plate (59) is fixedly arranged on a side wall of the arc-shaped plate (57) close to the limit gear (510).

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