Transmission structure of synchronous driving mechanism

Abstract

The utility model discloses a transmission structure of a synchronous driving mechanism, which comprises a driving gear set, a transmission gear set and a deflection gear, the transmission gear set comprises a fixed gear and a swing gear meshed with the fixed gear, the fixed gear is in transmission connection with the driving gear set, the swing gear rotates around the fixed gear, and the deflection gear is meshed with the fixed gear. The driving gear set is located outside the rotation range of the swing gear. When the axial distance between the deflection gear and the fixed gear is changed, the deflection gear is in transmission connection with the driving gear set through the swing gear. The synchronous transmission device can meet the synchronous transmission requirement that the distance between shafts changes.

Description

Technical Field

[0001] The utility model belongs to the technical field of gear transmission, and in particular relates to a transmission structure of a synchronous drive mechanism. Background Art

[0002] When two shafts are synchronously driven, gear sets or synchronous belts are often used to achieve the linkage of the two shafts. Gear sets have better synchronization effects and are often preferred. However, in actual applications, when the spacing between the two drive shafts needs to change, the position of the linkage gear between the two shafts also needs to change adaptively, and neither conventional gear sets nor conventional synchronous belts can meet the use requirements.

[0003] Based on this, there is an urgent need for a transmission structure that can adapt to the change in the spacing between the two shafts. Utility Model Content

[0004] The utility model aims to provide a transmission structure of a synchronous drive mechanism, which can adapt to the synchronous transmission requirements with a change in the shaft spacing.

[0005] The technical solution adopted by the utility model to solve its technical problem is to propose a transmission structure of a synchronous drive mechanism, including a driving gear group, a transmission gear group, and a shift gear, the transmission gear group includes a fixed gear and a swing gear meshing with the fixed gear, the fixed gear is transmission connected to the driving gear group, the swing gear rotates around the fixed gear, and the driving gear group is located outside the rotation range of the swing gear; when the axial spacing between the shift gear and the fixed gear changes, the shift gear is transmission connected to the driving gear group through the swing gear.

[0006] Furthermore, the maximum value of the axial spacing between the shifting gear and the fixed gear is the sum of the axial spacing when the shifting gear is meshed with the swinging gear and the axial spacing between the swinging gear and the fixed gear; the minimum value of the axial spacing between the shifting gear and the fixed gear is the axial spacing when the shifting gear is meshed with the fixed gear.

[0007] Furthermore, the driving gear set includes a power wheel set and a transfer gear. The power wheel set is transmission-connected to the driving end, and the power wheel set is meshed with the transfer gear, and the transfer gear is meshed with the fixed gear.

[0008] Furthermore, the transmission gear is located directly below the fixed gear, and the transmission gear is located outside the rotation range of the swing gear.

[0009] Furthermore, the power wheel group includes a driving wheel, a passive wheel, and a transmission belt. The driving wheel is connected to the driving end in transmission. The transmission belt is mounted on the driving wheel and the passive wheel, thereby driving the passive wheel to rotate synchronously with the driving wheel. The passive wheel is equipped with a passive gear, and the passive gear is meshed with the transmission gear. The passive gear is located below the transmission gear.

[0010] Furthermore, it also includes a swing arm, the swing gear is assembled on the swing arm, the swing arm is rotationally connected to the rotating shaft of the fixed gear, the swing gear and the fixed gear are located on the same side of the swing arm, so that the swing gear rotates around the fixed gear when it is meshed with the fixed gear.

[0011] Furthermore, the swing arm is extended toward the outside of the fixed gear to form a limit plate for limiting the swing range of the swing arm.

[0012] Furthermore, it also includes a base plate, the fixed gear is arranged on the base plate, the limit plate is parallel to the base plate, the limit plate is provided with a swing arc groove, the base plate is provided with a positioning pin corresponding to the swing arc groove, and the positioning pin limits the swing of the swing arm in the swing arc groove.

[0013] Furthermore, the swing arc groove is a strip-shaped circular arc groove, and the swing arc groove is opened with the rotating shaft of the fixed gear as the center.

[0014] Furthermore, a displacement groove is provided on the base plate, and the shifting gear is mounted in the displacement groove through a displacement mechanism. The shifting gear is displaced back and forth along the direction of the displacement groove, so that the distance between the shifting gear and the fixed gear changes; the displacement groove is vertically located above the fixed gear.

[0015] Preferably, the driving gear set is arranged on the base plate. The rotating shaft of the transmission gear, the rotating shaft of the shifting gear and the rotating shaft of the positioning gear are all power output ends.

[0016] The beneficial effects of the utility model are:

[0017] The utility model provides a transmission structure of a synchronous drive mechanism, designs a transmission gear set so that the meshing spacing is adjustable, and performs transmission meshing on two sets of gears with varying shaft spacing, thereby meeting the synchronous transmission requirement with varying shaft spacing.

[0018] The transmission gear set includes a fixed gear and a swinging gear. The swinging gear is always meshed with the fixed gear. The swinging gear is set to rotate around the fixed gear. The fixed gear is used to mesh with the gear with a fixed position, and the swinging gear is used to mesh with the gear with a variable position (variable gear). When the axial distance between the two sets of gears that need to be connected for transmission changes, that is, the position of the variable gear changes, the swinging gear rotates on the fixed gear to a position that meshes with the variable gear, thereby adapting to the transmission connection with the change in axial distance.

[0019] In the present application, the transmission gear set has a certain range of application when the position of the shifted gear is changed, and the maximum axial spacing between the shifted gear and the fixed gear is the sum of the axial spacing when the shifted gear is meshed with the swing gear and the axial spacing between the swing gear and the fixed gear; the minimum axial spacing between the shifted gear and the fixed gear is the axial spacing when the shifted gear is meshed with the fixed gear. BRIEF DESCRIPTION OF THE DRAWINGS

[0020] The accompanying drawings, which are incorporated into the specification and constitute a part of the specification, illustrate embodiments of the utility model and are used together with the description to explain the principles of the utility model. In these drawings, similar reference numerals are used to represent similar elements. The drawings described below are some embodiments of the utility model, rather than all embodiments. For those of ordinary skill in the art, other drawings can be obtained based on these drawings without paying creative work.

[0021] Figure 1 It is a front and side view of a transmission structure of a synchronous drive mechanism according to an embodiment of the utility model;

[0022] Figure 2 A partial cross-sectional view of a transmission structure of a synchronous drive mechanism according to an embodiment of the utility model;

[0023] Figure 3 A rear view of a transmission structure of a synchronous drive mechanism according to an embodiment of the utility model;

[0024] Figure 4 Schematic diagram of meshing when the gear spacing changes.

[0025] In the figure: 1, base plate; 2, fixing plate; 3, connecting plate; 4, driving motor; 5, first driving shaft; 6, first rotating shaft; 7, second rotating shaft; 8, third rotating shaft; 9, second driving shaft; 11, first through slot; 12, fixing screw; 13, displacement slot; 14, second through slot; 15, arc slide slot; 16, connecting slide slot; 21, connecting screw; 31, positioning screw; 32, third through slot; 33, nut; 34, adjusting screw; 35, fixing block; 36, slider; 41, reducer; 42, driving shaft; 43, belt; 44, tensioning device; 51, fourth gear; 61, first gear; 71, second gear; 81, third gear; 82, swing arm; 83, swing arc through slot; 84, positioning pin; 85, circular slider; 91, fifth gear. DETAILED DESCRIPTION

[0026] In order to more clearly illustrate the embodiments of the utility model and the technical solutions in the prior art, the specific implementation methods of the utility model will be described below with reference to the accompanying drawings. Obviously, the accompanying drawings described below are only some embodiments of the utility model. For ordinary technicians in this field, other drawings and other implementation methods can be obtained based on these drawings without creative work. In addition, the design orientation only represents the relative position relationship between the components, not the absolute position relationship.

[0027] An embodiment of the utility model provides a transmission structure of a synchronous drive mechanism, including a driving gear group, a transmission gear group, and a shift gear. The transmission gear group includes a fixed gear and a swing gear meshing with the fixed gear. The fixed gear is transmission connected to the driving gear group, the swing gear rotates around the fixed gear, and the driving gear group is located outside the rotation range of the swing gear. When the axial spacing between the shift gear and the fixed gear changes, the shift gear is transmission connected to the driving gear group through the swing gear.

[0028] In this application, the position of the displacement gear is not fixed and is displaced in a certain direction; and the transmission gear set realizes the transmission meshing between the driving gear set and the displacement gear on this basis. However, it should be clear that when the transmission gear set transmits between gears with a change in the shaft spacing, the change in the shaft spacing should be within a specific range, rather than unlimited.

[0029] In a specific example, the maximum axial spacing between the shifting gear and the fixed gear is the sum of the axial spacing when the shifting gear is meshed with the swinging gear and the axial spacing between the swinging gear and the fixed gear; the minimum axial spacing between the shifting gear and the fixed gear is the axial spacing when the shifting gear is meshed with the fixed gear.

[0030] When the position of the shifting gear changes, the axial distance between the shifting gear and the fixed gear changes (increases or decreases). At this time, you only need to rotate the swinging gear around the fixed gear. During the rotation of the swinging gear, it is always engaged with the fixed gear. When the swinging gear rotates to engage with the shifting gear, the shifting gear and the fixed gear can be re-engaged.

[0031] In the present application, the driving gear set is a fixed gear set, and the function of the transmission gear set is to establish a transmission connection between the variable gear and the fixed gear, so that meshing transmission can still be achieved after the axis spacing changes within a variable range.

[0032] In the embodiment of the present application, the driving gear set includes a power wheel set and a transmission gear, the power wheel set is transmission-connected to the driving end, the power wheel set is meshed with the transmission gear, and the transmission gear is meshed with the fixed gear. The transmission gear is located directly below the fixed gear, and the transmission gear is located outside the rotation range of the swing gear.

[0033] The power wheel group includes a driving wheel, a passive wheel, and a transmission belt. The driving wheel is connected to the driving end, and the transmission belt is mounted on the driving wheel and the passive wheel, thereby driving the passive wheel and the driving wheel to rotate synchronously. The passive wheel is equipped with a passive gear, which is meshed with the transmission gear. The passive gear is located below the transmission gear.

[0034] In the present application, the rotation range of the swing gear is limited so that it does not interfere with other gears meshed with the fixed gear. The limit can be implemented synchronously based on the rotation relationship between the swing gear and the fixed gear.

[0035] In a specific implementation, the swing gear is assembled on the swing arm 82, and the swing arm 82 is rotationally connected to the rotating shaft of the fixed gear. The swing gear and the fixed gear are located on the same side of the swing arm 82, so that the swing gear rotates around the fixed gear when it is meshed with the fixed gear.

[0036] The swing arm 82 is extended to the outside of the fixed gear to be provided with a limit plate for limiting the swing range of the swing arm 82. The limit plate and the swing arm 82 can be at a right angle, and the rotation range of the swing arm 82 can be limited by limiting the limit plate.

[0037] In a feasible embodiment, the fixed gear is arranged on the base plate 1, and the base plate 1 may be provided with a stop groove, the limit plate is located in the stop groove, and the groove wall of the stop groove is used to limit the rotation range of the limit plate. Preferably, the limit plate may be a vertical plate, vertically suspended on the base plate 1, and located in the stop groove; or a shaft structure, parallel suspended on the base plate 1, and located in the stop groove.

[0038] In another feasible embodiment, the fixed gear is arranged on the base plate 1, the limit plate is parallel to the base plate 1, a swing arc groove 83 is opened on the limit plate, and a positioning pin 84 is arranged on the base plate corresponding to the swing arc groove 83, and the positioning pin 84 limits the swing of the swing arm 82 in the swing arc groove 83.

[0039] Exemplarily, the swing arc groove 83 is a strip-shaped circular arc groove, and the swing arc groove 83 is opened with the rotating shaft of the fixed gear as the center. A displacement groove 13 is opened on the base plate 1, and the shifting gear is mounted in the displacement groove 13 through a displacement mechanism. The shifting gear moves back and forth along the direction of the displacement groove 13, so that the distance between the shifting gear and the fixed gear changes; the displacement groove 13 is vertically located above the fixed gear.

[0040] It can be understood that the position change of the shifting gear can be in the vertical direction, in the horizontal direction, or along a circular arc trajectory, depending on the actual situation.

[0041] But for the displacement mechanism, it can be a telescopic drive structure or a swinging drive structure. The telescopic drive structure can be set based on the substrate 1, and can be specifically a cylinder, a drive motor, etc.; it can directly push the rotating shaft of the displacement gear to produce displacement; specifically, a sleeve can be set on the rotating shaft of the displacement gear, and the telescopic structure pushes the sleeve to drive the displacement gear to produce displacement. The swinging drive structure can be set based on the substrate 1, and can be specifically in the form of a swing arm plus a cylinder or a drive motor. One end of the swing arm is rotatably connected to the substrate 1, and the other end is driven by the telescopic structure to realize the controllable rotation of the swing arm, and the displacement gear can be rotatably set on the swing arm.

[0042] It is understandable that after the position of the shifting gear is adjusted, its position stability should be ensured and no changes will occur, so that the meshing relationship between the swing gear and the shifting gear is stable. Under this basic requirement, a manual adjustment method can be set to adjust the displacement of the shifting gear.

[0043] See also Figure 1-Figure 4 The transmission structure of a synchronous drive mechanism proposed in the present application can be implemented on a substrate 1. The shifting gear is a fifth gear 91, and the fifth gear 91 is arranged on a second drive shaft 9. The second drive shaft 9 is the rotating shaft of the shifting gear. A displacement groove 13 is opened on the substrate 1, and the second drive shaft 9 passes through the displacement groove 13 to the front side of the substrate 1. The fifth gear 91 is arranged on the front side of the substrate 1.

[0044] The fixed gear is the second gear 71 and the swinging gear is the third gear 81. The second gear 71 is arranged on the second rotating shaft 7, the second rotating shaft 7 is arranged on the substrate 1, and the second gear 71 is located on the front side of the substrate 1; the third gear 81 is arranged on the third rotating shaft 8, and the third rotating shaft 8 is arranged on the swing arm 82. The third gear 81 and the second gear 71 are both located between the swing arm 82 and the substrate 1, and are always meshed.

[0045] The transmission gear is the first gear 61, the first gear 61 is arranged on the first rotating shaft 6, the first rotating shaft 6 is arranged on the front side of the substrate 1, and the first gear 61 is located on the front side of the substrate 1; the first gear 61 is always in a meshing state with the second gear 71; the driving wheel can correspond to the driving shaft 42, the driven wheel can correspond to the first driving shaft 5, the driven gear is the fourth gear 51, the transmission belt is the belt 43, the transmission end may include a driving motor 4 and a reducer 41, the driving motor 4 is connected to the driving shaft 42 through the reducer 41, and the belt 43 is sleeved on the driving shaft 42 and the first driving shaft 5.

[0046] The driving shaft 42 may be provided with a driving roller body, the first driving shaft 5 may be provided with a friction roller body and a fourth gear 51 in sequence, the belt 43 is sleeved on the driving roller body and the friction roller body, the fourth gear 51 and the friction roller body may be in synchronous rotation without mutual interference. The belt 43 may be provided with a tensioning device 44 to stabilize the transmission effect of the belt 43 and the driving roller body and the friction roller body.

[0047] Specifically, the first drive shaft 5 and the second drive shaft 9 are arranged on the base plate 1, the middle part of the first drive shaft 5 is rotatably mounted on the base plate 1, and the middle part of the second drive shaft 9 is rotatably mounted on the fixed plate 2 fixed on the base plate 1. The linkage ends of the first drive shaft 5 and the second drive shaft 9 are both located on the front side of the base plate 1. A first gear 61, a second gear 71 and a third gear 81 that mesh in sequence are arranged between the first drive shaft 5 and the second drive shaft 9 on the base plate 1. A fourth gear 51 is fixedly sleeved on the linkage end of the first drive shaft 5, and the fourth gear 51 is connected to the first gear 61 and the third gear 81 is connected to the first gear 61. 1 is meshed; a fifth gear 91 is fixedly sleeved on the linkage end of the second driving shaft 9, and the fifth gear 91 is meshed with the third gear 81; wherein, the first gear 61 and the second gear 71 are rotatably mounted on the base plate 1, and the third gear 81 is rotatably mounted on the swing arm 82, the third gear 81 is located at one end of the swing arm 82, and the other end of the swing arm 82 is rotatably mounted on the second gear 71 and is detachably fixedly connected to the base plate 1 through a locating pin 84, and the rotating shaft of the swing arm 82 and the rotating shaft of the second gear 71 are coaxially arranged to ensure that the second gear 71 and the third gear 81 are always meshed together.

[0048] See also Figure 4A swing arc groove 83 is opened on the swing arm 82 at a position corresponding to the positioning pin 84. When the swing arm 82 swings, the positioning pin 84 can adjust its position in the swing arc groove 83; when the fixed plate 2 drives the second drive shaft 9 to move in a direction perpendicular to the second drive shaft 9 (that is, when the second drive shaft 9 is away from the first drive shaft 5), the positioning pin 84 is loosened, the swing arm 82 is swung, and the third gear 81 is always engaged with the fifth gear 91.

[0049] In order to improve the stability of the swing arm 82, an arc-shaped slide groove 15 is provided at a position corresponding to the third gear 81 on the base plate 1, the center of which is located on the axis of the second gear 71, and a circular slider 85 is fixedly connected to the rotating shaft of the third gear 81, and the circular slider 85 is located in the arc-shaped slide groove 15 and slidably cooperates with the arc-shaped slide groove 15. When the swing arm 82 swings, the circular slider 85 moves along the arc-shaped slide groove 15.

[0050] To facilitate the movement of the second driving shaft 9, the fixed plate 2 is located on the back side of the base plate 1 and fits therewith, one end of the fixed plate 2 is fixedly connected to the base plate 1 by a fixing screw 12, a first strip-shaped through groove 11 is provided at a position corresponding to the fixing screw 12 on the base plate 1, and the fixing screw 12 is penetrated in the first through groove 11; a second strip-shaped through groove 14 is provided at a position corresponding to the other end of the fixed plate 2 on the base plate 1, a connecting screw 21 is penetrated in the second through groove 14, the fixed plate 2 is fixedly connected to the connecting plate 3 provided on the front side of the base plate 1 by the connecting screw 21, the connecting plate 3 fits with the front side of the base plate 1, a plurality of third strip-shaped through grooves 32 are provided on the connecting plate 3, positioning screws 31 are penetrated in the third through grooves 32, and the connecting plate 3 is fixedly connected to the base plate 1 by the positioning screws 31.

[0051] In order to facilitate fine adjustment of the moving distance of the fixed plate 2, a nut 33 is fixedly connected to the connecting plate 3, and the nut 33 is threadedly matched with one end of the adjusting screw 34. A fixing block 35 is fixedly connected to the other end of the adjusting screw 34 on the base plate 1. The adjusting screw 34 is rotatably mounted on the fixing block 35. After loosening the fixing screw 12 and the positioning screw 31, the adjusting screw 34 is rotated to fine-tune the distance between the connecting plate 3 and the fixing block 35, thereby adjusting the moving distance of the fixing plate 2 and the second driving shaft 9. In order to ensure the stability of the movement of the connecting plate 3, a slider 36 is provided on the connecting plate 3 at a position between the connecting plate 3 and the base plate 1, and a connecting groove 16 matching the slider 36 is provided at a position corresponding to the slider 36 on the base plate 1. The slider 36 is located in the connecting groove 16 and slidably matches with it.

[0052] The above-mentioned displacement mechanism for implementing the displacement behavior of the shifting gear is manually adjusted.

[0053] A driving shaft 42 is provided through the base plate 1 and rotates therewith. A driving motor 4 is fixedly provided on the base plate 1. The driving motor 4 drives the driving shaft 42 after passing through a reducer 41. The driving shaft 42 and the first driving shaft 5 are linked by a belt 43. A tensioning device 44 is provided on the belt. The tensioning device 44 is fixedly mounted on the base plate 1.

[0054] When the above specific embodiment is in use, the driving motor 4 drives the active shaft 42, and the active shaft 42 drives the first driving shaft 5 through the belt 43. The free end of the first driving shaft 5 serves as the power output end. The fourth gear 51 of the first driving shaft 5 is linked with the fifth gear 91 after passing through the first gear 61, the second gear 71 and the third gear 81 in sequence. The fifth gear 91 drives the second driving shaft 9 to rotate, and the free end of the second driving shaft 9 serves as the second power output end; the first gear 61 and the first rotating shaft 6 are fixedly connected, and the first rotating shaft 6 is used as the third driving shaft. The third driving shaft passes through the base plate 1 and rotates therewith, and the free end of the third driving shaft serves as the third power output end.

[0055] It should be noted that, in this article, relational terms such as first and second, etc. are only used to distinguish one entity or operation from another entity or operation, and do not necessarily require or imply any such actual relationship or order between these entities or operations. Moreover, the terms "include", "comprise" or any other variants thereof are intended to cover non-exclusive inclusion, so that a process, method, article or device comprising a series of elements includes not only those elements, but also other elements not explicitly listed, or also includes elements inherent to such process, method, article or device. In the absence of further restrictions, the elements defined by the statement "comprise a ..." do not exclude the presence of other identical elements in the process, method, article or device comprising the elements.

[0056] The above contents are further detailed descriptions of the present invention in combination with specific preferred implementation methods, and the specific embodiments of the present invention cannot be considered to be limited to these descriptions. For ordinary technicians in the technical field to which the present invention belongs, several simple deductions or substitutions can be made without departing from the concept of the present invention, which should be regarded as falling within the protection scope of the present invention.

Claims

1. A transmission structure of a synchronous drive mechanism, characterized in that: It includes a driving gear set, a transmission gear set, and a shifting gear, wherein the transmission gear set includes a fixed gear and a swing gear meshing with the fixed gear, the fixed gear is in transmission connection with the driving gear set, the swing gear rotates around the fixed gear, and the driving gear set is located outside the rotation range of the swing gear; When the axial distance between the shifting gear and the fixed gear changes, the shifting gear is transmission-connected to the driving gear set via the swing gear.

2. The transmission structure of a synchronous drive mechanism according to claim 1, characterized in that: The maximum value of the axial spacing between the shifting gear and the fixed gear is the sum of the axial spacing when the shifting gear is meshed with the swinging gear and the axial spacing between the swinging gear and the fixed gear; the minimum value of the axial spacing between the shifting gear and the fixed gear is the axial spacing when the shifting gear is meshed with the fixed gear.

3. The transmission structure of a synchronous drive mechanism according to claim 1, characterized in that: The driving gear set includes a power wheel set and a transfer gear. The power wheel set is transmission-connected to the driving end, and the power wheel set is meshed with the transfer gear, and the transfer gear is meshed with the fixed gear.

4. The transmission structure of a synchronous drive mechanism according to claim 3, characterized in that: The transmission gear is located directly below the fixed gear, and the transmission gear is located outside the rotation range of the swing gear.

5. The transmission structure of a synchronous drive mechanism according to claim 3, characterized in that: The power wheel group includes a driving wheel, a passive wheel, and a transmission belt. The driving wheel is connected to the driving end in a transmission manner. The transmission belt is sleeved on the driving wheel and the passive wheel, thereby driving the passive wheel to rotate synchronously with the driving wheel. The passive wheel is equipped with a passive gear, the passive gear is meshed with the transmission gear, and the passive gear is located below the transmission gear.

6. The transmission structure of a synchronous drive mechanism according to claim 1, characterized in that: It also includes a swing arm (82), the swing gear is mounted on the swing arm (82), the swing arm (82) is rotationally connected to the rotating shaft of the fixed gear, the swing gear and the fixed gear are located on the same side of the swing arm (82), so that the swing gear rotates around the fixed gear when in a state of meshing with the fixed gear.

7. The transmission structure of a synchronous drive mechanism according to claim 6, characterized in that: The swing arm (82) is extended toward the outside of the fixed gear to be provided with a limit plate for limiting the swing range of the swing arm (82).

8. The transmission structure of a synchronous drive mechanism according to claim 7, characterized in that: It also comprises a base plate (1), the fixed gear is arranged on the base plate (1), the limit plate is parallel to the base plate (1), a swing arc groove (83) is provided on the limit plate, and a positioning pin (84) is provided on the base plate (1) corresponding to the swing arc groove (83), and the positioning pin (84) limits the swing of the swing arm (82) in the swing arc groove (83).

9. The transmission structure of a synchronous drive mechanism according to claim 8, characterized in that: The swing arc groove (83) is a strip-shaped circular arc groove, and the swing arc groove (83) is opened with the rotating shaft of the fixed gear as the center of the circle.

10. The transmission structure of a synchronous drive mechanism according to claim 8, characterized in that: The base plate (1) is provided with a displacement groove (13), the displacement gear is mounted in the displacement groove (13) via a displacement mechanism, and the displacement gear is reciprocated along the direction of the displacement groove (13), so that the distance between the displacement gear and the fixed gear changes; the displacement groove (13) is vertically located above the fixed gear.

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