CN214388744U - Transmission device of double-shaft type sports equipment and double-shaft type sports equipment - Google Patents

Abstract

The utility model discloses a transmission and two-axis sports equipment of two-axis sports equipment, this two-axis sports equipment's transmission contain a first wheelset and a second wheelset. The first wheel set comprises a first driving wheel, a first driving wheel and a first driving belt which is connected with the first driving wheel and the first driving wheel in a surrounding mode. The second wheel set is connected with the first wheel set along the left-right direction and comprises a second driving wheel, a second driving wheel and a second driving belt, wherein the second driving wheel and the first driving wheel are mutually spaced in the top-bottom direction and the left-right direction, the second driving wheel and the second driving belt are connected to the second driving wheel and the second driving wheel in a surrounding mode and connected to the first driving wheel, so that one of the first wheel set and the second wheel set drives the other to rotate, and the rotating direction of the first wheel set is opposite to the rotating direction of the second wheel set.

Description

Transmission device of double-shaft type sports equipment and double-shaft type sports equipment

Technical Field

The utility model relates to a training equipment, in particular to transmission and two-axis sports equipment of two-axis sports equipment.

Background

Treadmills, gliders, indoor bicycles, and the like are exercise equipment for training leg muscles, and are popular among consumers because of convenient use and good exercise effect. However, since the above-mentioned leg exercise machines are trained by stepping up and down, only the muscles on the front and rear sides of the thigh can be exercised, and there is a demand for exercise machines that can train the inside and outside of the thigh in the market.

SUMMERY OF THE UTILITY MODEL

Therefore, the present invention provides a transmission device for a two-axis sports apparatus using a transversely treaded two-axis circular motion.

Therefore, the transmission device of the double-shaft sports apparatus of the present invention comprises a first wheel set and a second wheel set. The first wheel set comprises a rotatable first driving wheel, a first driving wheel and a first driving belt, wherein the first driving wheel and the first driving wheel are arranged at intervals along a left-right direction, the first driving belt is connected to the first driving wheel and the first driving wheel in a surrounding mode, the first driving wheel is provided with a first joint portion connected to the first driving belt, and a second joint portion is arranged at intervals along a front-back direction with the first joint portion. The second wheel set is connected with the first wheel set along the left-right direction, and comprises a second driving wheel which is adjacent to the first driving wheel and is mutually spaced from the first driving wheel in a top-bottom direction and the left-right direction, a second driving wheel which is far away from the first wheel set, and a second driving belt which is connected with the second driving wheel and the second driving wheel in a surrounding way and is connected with a second joint part of the first driving wheel.

Therefore, another object of the present invention is to provide a biaxial exercise device capable of training the medial and lateral muscle groups.

Therefore, the double-shaft sports equipment of the utility model comprises a base unit, the transmission device and two operating parts. The transmission device is rotatably arranged on the base unit. The operating members are respectively connected to the first driving wheel and the second driving wheel and are used for driving the first driving wheel and the second driving wheel to rotate so as to drive the first transmission belt and the second transmission belt to rotate, and the operating members simultaneously perform circular motion in opposite directions.

The utility model has the advantages that: utilize one of them person of this first wheelset and this second wheelset to drive the rotation of another person, make the rotation direction of this first wheelset opposite with the rotation direction of this second wheelset to make these operating parts carry out the circular motion with opposite direction simultaneously, the utility model discloses a biaxial sport equipment borrows the biaxial circular motion of transversely trampling, can train the inside and outside muscle crowd of both legs or both arms, and then reach the effect of motion or rehabilitating.

Drawings

FIG. 1 is a perspective view of a first embodiment of a two-axis exercise apparatus of the present invention;

FIG. 2 is a right side view of the first embodiment;

FIG. 3 is a top view of the first embodiment;

FIG. 4 is a fragmentary cross-sectional view taken along line IV-IV in FIG. 3;

FIG. 5 is a rear schematic view of a transmission of the first embodiment;

FIG. 6 is a perspective view of the transmission;

FIG. 7 is a schematic view of the use of the first embodiment;

FIG. 8 is a rear side schematic view of a variation of the first embodiment;

FIG. 9 is a schematic front view of a second embodiment of the dual-axis exercise apparatus of the present invention;

FIG. 10 is a perspective view of a third embodiment of the dual-axis exercising apparatus of the present invention;

FIG. 11 is a partially exploded perspective view of the third embodiment;

FIG. 12 is a rear side schematic view illustrating a resistance unit of the third embodiment;

FIG. 13 is a fragmentary perspective view from the rear illustrating the connection of the resistance unit of the third embodiment to the transmission; and

fig. 14 is a perspective view of a fourth embodiment of the biaxial exercise machine of the present invention.

[ notation ] to show

1 base unit 213 bearing 24 first drive belt

11 base 22 first drive wheel 241 first internal teeth

12, the main frame 221, the stop edge 242 and the first external teeth

120, a containing space 222, meshing teeth 25 and a second transmission wheel

13 casing 23 first driving wheel 251 third joint part

2 transmission 231, first joint 252 and fourth joint

201 first wheel set 232 second joint 26 second axle set

202, second wheel set 233, base wall 27, second drive wheel

21 first set of shafts 234 annular wall 28 second drive belt

211, shaft 235, outer wall 281, second inner teeth

212, sleeve 236, engaging teeth 282, second outer teeth

3 operating group 41 resistance sheet 49 resistance belt

31 rotary disc 42 knob L1 first axis

311 connecting hole 43, pulley L2, second axis

312 mounting hole 44, magnetic control wheel C1, first center line

32 operating member 45, belt C2, second centerline

321 reference surface 46 adjustment group X in the left-right direction

322, a body 461, a magnetic resistance sheet Y, a front and back direction

323 positioning lever 462, brake line Z, and top-bottom direction

324 bearing 463 elastic element 9 chair

33 reinforcing rod 47 friction wheel

4. 4', 4', resistance unit 48, support plate

Detailed Description

To further illustrate the embodiments, the present invention provides the accompanying drawings. The accompanying drawings, which are incorporated in and constitute a part of this disclosure, illustrate embodiments of the invention and, together with the description, serve to explain the principles of the embodiments. With these references, one of ordinary skill in the art will appreciate other possible embodiments and advantages of the present invention. Elements in the figures are not drawn to scale and like reference numerals are generally used to indicate like elements.

The present invention will now be further described with reference to the accompanying drawings and detailed description.

Referring to fig. 1 to 3, the first embodiment of the dual-axis exercise device of the present invention comprises a base unit 1, a transmission device 2 rotatably disposed on the base unit 1, two operation sets 3 operable to drive the transmission device 2, and a resistance unit 4 for adjusting exercise resistance. In the first embodiment, the dual-axis exercise apparatus is illustrated as a foot pedal, and in some embodiments, the dual-axis exercise apparatus can also be a hand trainer.

The base unit 1 includes a base 11 for placing on a plane such as the ground, and a main frame 12 extending obliquely upward from the base 11 in a top-bottom direction Z, the main frame 12 having a receiving space 120 formed at a top end thereof.

First, each direction is defined by an XYZ coordinate system in the diagram shown in fig. 1, which is established when the biaxial exercise equipment of the embodiment is put in use in exercise, and a plane on which a bottom surface is located is an XY plane, and a Z axis is perpendicular to the XY plane; the arrangement direction of the first wheel set 201 and the second wheel set 202 is the left-right direction X, the vertical direction of the plane of the bottom surface is the front-back direction Y, and the vertical direction of the plane of the bottom surface is the top-bottom direction Z. It should be noted that the directions in which the components are arranged are not strictly the directions of the coordinate system, but exist according to the inclination angle. The transmission device 2 is rotatably disposed on the main frame 12 of the base unit 1, and includes a first wheel set 201 and a second wheel set 202 engaged with the first wheel set 201 along a left-right direction X. The first wheel set 201 includes a first shaft set 21 extending along a front-back direction Y and erected at one end of the main frame 12, a first driving wheel 22 sleeved on the first shaft set 21 and located in the accommodating space 120, a first driving wheel 23 spaced from the first driving wheel 22 along the left-right direction X, and a first driving belt 24 coupled around the first driving wheel 22 and the first driving wheel 23.

Referring to fig. 3 to 5, the first shaft set 21 includes a shaft 211 passing through the main frame 12 and the first driving wheel 22 along a first axis L1, two shaft sleeves 212 respectively located at the front and rear ends of the first driving wheel 22 and installed between the main frame 12 and the shaft 211, and a plurality of bearings 213 respectively rotatably disposed between the shaft sleeves 212 and the shaft 211. When the first shaft set 21 rotates, the first driving wheel 22 is driven to rotate relative to the main frame 12 about the first axis L1, and the first driving belt 24 is driven to drive the first driving wheel 23 to rotate about a first center line C1, the first center line C1 and the first axis L1 are parallel to each other and extend along the front-back direction Y, and preferably, the first center line C1 is higher than the first axis L1 in the top-bottom direction Z. Preferably, the diameter of the first driving wheel 22 is larger than the diameter of the first driving wheel 23, and the thickness of the first driving wheel 23 is larger than the thickness of the first driving wheel 22.

Referring to fig. 4 to 6, in the first embodiment, the first driving wheel 22 and the first driving wheel 23 are respectively a gear, and the first driving belt 24 is a timing belt. The first driving wheel 22 has two retaining edges 221 formed on the front and rear peripheries and surrounding the first axis L1, and a plurality of engaging teeth 222 located between the two retaining edges 221 and surrounding the first axis L1, wherein the two retaining edges 221 are used for preventing the first driving belt 24 from being accidentally disengaged from the first driving wheel 22. The first driving wheel 23 has a first engaging portion 231 engaged with the first driving belt 24, and a second engaging portion 232 spaced from the first engaging portion 231 in the front-rear direction Y. The first driving wheel 23 has a base wall 233 and an annular wall 234 extending from the base wall 233 along the front-rear direction Y and surrounding the first center line C1, the base wall 233 has an outer wall surface 235 far away from the annular wall 234, the annular wall 234 has a plurality of circumferentially surrounding engaging teeth 236, and the engaging teeth 236 are divided into the first engaging portion 231 and the second engaging portion 232. The first driving belt 24 has a plurality of first inner teeth 241 located on an inner surface for engaging the engaging teeth 222 of the first driving wheel 22 with the engaging teeth 236 of the first driving wheel 23, and a plurality of first outer teeth 242 located on an outer surface.

Referring to fig. 3, 5 and 6, the second wheel set 202 includes a second driving wheel 25 adjacent to the first driving wheel 23 and spaced from the first driving wheel 23 in the top-bottom direction Z and the left-right direction X, a second shaft set 26 extending along the front-back direction Y and erected at the other end of the main frame 12, a second driving wheel 27 rotatably sleeved on the first shaft set 26 and located in the accommodating space 120, and a second driving belt 28 coupled around the second driving wheel 27 and the second driving wheel 25 and coupled to the second coupling portion 232 of the first driving wheel 23. When the second shaft set 26 rotates, the second driving wheel 27 is driven to rotate around a second axis L2 with respect to the main frame 12, and the second driving belt 28 is linked to drive the second driving wheel 25 to rotate around a second center line C2, and the components and connection relationship of the second shaft set 26 are the same as those of the first shaft set 21, which is not described herein again. The second centerline C2 and the second centerline L2 are parallel to each other and extend along the front-back direction Y, and preferably, the heights of the first axis L1 and the second axis L2 in the top-bottom direction Z are substantially the same, and the second centerline C2 is lower than the second axis L2 and the first centerline C1 in the top-bottom direction Z. Preferably, the thickness of the second transmission wheel 25 is greater than the thickness of the second driving wheel 27, the diameter of the second driving wheel 27 is equal to the diameter of the first driving wheel 22, and the diameter of the second transmission wheel 25 is equal to the diameter of the first driving wheel 23. The second transmission wheel 25 has a third engaging portion 251 engaged with the second transmission belt 28, and a fourth engaging portion 252 spaced from the third engaging portion 251 along the front-rear direction Y and engaged with the first external teeth 242 of the first transmission belt 24.

In the first embodiment, the second driving wheel 27 and the second driving wheel 25 are gears respectively, and the second transmission belt 28 is a timing belt. The structure of the second driving wheel 27 is the same as that of the first driving wheel 22, and the structure of the second driving wheel 25 is the same as that of the first driving wheel 23, which will not be described again. The second belt 28 has a plurality of second inner teeth 281 disposed on the inner surface for engaging the second driving wheel 27 with the second driving wheel 25, and a plurality of second outer teeth 282 disposed on the outer surface for engaging the first driving wheel 23.

The utility model discloses a transmission 2 utilizes one of them one of these first wheelset 201 and this second wheelset 202 to drive another person and rotates, and the rotation direction of this first wheelset 201 is opposite with the rotation direction of this second wheelset 202, and its transmission mode explains as follows:

referring to fig. 5, when one of the driving wheels, for example, the first driving wheel 22, rotates clockwise, the first driving belt 24 is driven to drive the first driving wheel 23 to rotate clockwise, the first driving belt 24 is also driven to drive the second driving wheel 25 to rotate counterclockwise, and the rotation of the second driving wheel 25 drives the second driving belt 28 to drive the second driving wheel 27 to rotate counterclockwise; on the contrary, when the first driving wheel 22 of the transmission device 2 rotates in the counterclockwise direction, the first driving belt 24 is driven to drive the first driving wheel 23 to rotate in the counterclockwise direction, the first driving belt 24 is also driven to drive the second driving wheel 25 to rotate in the clockwise direction, and the rotation of the second driving wheel 25 drives the second driving belt 28 to drive the second driving wheel 27 to rotate in the clockwise direction, so as to achieve the reverse rotation of the first wheel set 201 and the second wheel set 202.

Referring to fig. 1, fig. 3 and fig. 4, the two operation sets 3 are respectively connected to the first wheel set 201 and the second wheel set 202 and are used for driving the first wheel set 201 and the second wheel set 202 to rotate. The right operating set 3 includes a rotating plate 31 connected to the first shaft set 21 for driving the first driving wheel 22 to rotate, and an operating member 32 eccentrically disposed on the rotating plate 31 for driving the rotating plate 31 to rotate. The left operating set 3 includes a rotating plate 31 connected to the second shaft set 26 for driving the second driving wheel 27 to rotate, and an operating member 32 eccentrically disposed on the left rotating plate 31 for driving the rotating plate 31 to rotate. Each of the operating members 32 of the first embodiment is a pedal, each of the operating members 32 has a reference surface 321, and the reference surface 321 in the first embodiment is a stepping surface of the pedal. Further, each of the rotating discs 31 has a connecting hole 311 for the first shaft set 21 or the second shaft set 26 to pass through, and a mounting hole 312 spaced from the connecting hole 311. Each of the operating members 32 has a main body 322 with the reference surface 321, a positioning rod 323 passing through the main body 322 and the corresponding mounting hole 312 of the turntable 31, and two bearings 324 rotatably disposed between the positioning rod 323 and the main body 322, so that the main body 322 can freely pivot relative to the positioning rod 323.

The resistance unit 4 serves to hinder the transmission of the transmission 2, thereby generating a movement resistance when operating the operating member 32. Preferably, the resistance unit 4 includes a resistance plate 41 simultaneously in frictional contact with the outer wall surfaces 235 of the first and second transmission wheels 23 and 25, and a knob 42 connected to the resistance plate 41 and extending along the front-rear direction Y to be exposed to the base unit 1, wherein the position of the resistance plate 41 in the front-rear direction Y can be changed by rotating the knob 42, and the first embodiment frictionally contacts the transmission device 2 via the resistance unit 4 to generate a movement resistance when the operating element 32 is operated. In addition to using friction as the exercise resistance, in other variations, the resistance unit 4 can be formed on the first wheel set 201 or the second wheel set 202 and using air resistance such as wind wheel or magnetic resistance such as magnetic control wheel as the exercise resistance, or the resistance unit 4 can be omitted and the foot coordination can be trained only in the non-resistance state, but not limited thereto.

Referring to fig. 7 and 8, during training, the user sits on a chair 9 and places the present invention on the ground, and the two operating members 32 are alternately trampled on the left and right sides of the user's feet, so that the two operating members 32 perform a circular motion of transversely trampling in opposite directions simultaneously, and the first wheel set 201 and the second wheel set 2020 can be driven to continuously move in opposite directions simultaneously, thereby achieving a transverse trampling motion of simultaneous outward rotation or simultaneous inward rotation of both legs. As shown in FIG. 8, when the two operation members 32 are simultaneously rotated outwards, they can train the outer sides of the thighs of both feet. On the contrary, when the two operation members 32 are rotated inwards at the same time, the exercise device has the function of training the inner sides of the thighs of the feet. The user can freely select the circular motion of the internal rotation or the external rotation and rotate the knob 42 to increase or decrease the resistance to the motion, thereby achieving the exercise or rehabilitation function.

In some embodiments, the rotating plate 31 can be omitted and the operating member 32 and the first shaft set 21 and the second shaft set 26 can be connected by a crank, so that the operating member 32 can simultaneously perform a circular motion of transversely stepping in opposite directions.

In some embodiments, the two-axis exercise apparatus can also be a hand trainer that can train both arms' internal and external muscles through a transverse two-axis circular motion.

Referring to fig. 9, a second embodiment of the dual-axis exercise apparatus of the present invention is similar to the first embodiment, and the main differences are:

the transmission device 2 uses a chain and a chain wheel to replace a belt and a gear, and the first wheel set 201 and the second wheel set 202 can move in the same direction, so as to achieve the transverse pedaling movement of training both feet to simultaneously outward rotate or inward rotate, and further exercise the muscle groups on the inner side and the outer side of the thigh.

Referring to fig. 10 to 12, a third embodiment of the dual-axis exercise apparatus of the present invention is similar to the first embodiment, and the main difference is:

the base unit 1 further comprises two housings 13 which are mutually involutory and which enclose the transmission 2.

Each of the operation sets 3 further includes two reinforcing rods 33 crossing each other and disposed on the respective rotating discs 31, and the first shaft rod set 21 and the second shaft rod set 26 penetrate the reinforcing rods 33 and the rotating discs 31, so as to improve the structural strength of each of the operation sets 3 and facilitate the manufacturing.

Referring to fig. 11 to 13, the resistance unit 4 'uses magnetic resistance as the motion resistance, and the resistance unit 4' includes a belt pulley 43 (damping transmission wheel) axially connected to the second transmission wheel 25, a magnetic control wheel 44 lower than the belt pulley 43 and rotatably disposed on the base unit 1, a belt 45 (damping transmission belt) rotatably sleeved on the belt pulley 43 and the magnetic control wheel 44, an adjustment set 46 adjustably disposed on the main frame 12, and the knob 42 rotatably disposed on the base unit 1 and connected to the adjustment set 46. The second transmission wheel 25 can drive the belt pulley 43 to rotate so as to drive the belt 45 and the magnetic control wheel 44 to rotate. The adjusting set 46 has a magnetic resistance sheet 461 facing the outer periphery of the magnetron wheel 44 and used for cooperating with the magnetron wheel 44 to generate magnetic resistance, a brake wire 462 for pulling the magnetic resistance sheet 461, and an elastic member 463 for moving the magnetic resistance sheet 461 in a direction away from the magnetron wheel 44, by rotating the knob 42, the brake wire 462 can be tightened or loosened to make the magnetic resistance sheet 461 get away from or close to the magnetron wheel 44, thereby changing the motion resistance.

Referring to fig. 14, a fourth embodiment of the dual-axis exercise apparatus of the present invention is similar to the first embodiment, and the main differences are:

the resistance unit 4 ″ includes a friction wheel 47 (damping transmission wheel) axially connected to the first transmission wheel 23, a support sheet 48 slidably disposed on the main frame 12 and higher than the friction wheel 47, a resistance belt 49 (damping transmission belt) in a closed ring shape and sleeved between the support sheet 48 and the friction wheel 47, and the knob 42 connected to the support sheet 48, wherein the resistance belt 49 is an elastic transmission belt made of elastic material such as cow belt or rubber belt for the friction wheel 47 to rotate and contact to generate friction force. The knob 42 is rotatably screwed to the main frame 12 and is used to drive the supporting plate 48 to move up and down, and the distance between the supporting plate 48 and the friction wheel 47 can be changed by rotating the knob 42, so as to tighten or loosen the resistance belt 49. When the first driving wheel 23 rotates, the friction wheel 47 is driven to rotate, and the friction wheel 47 rotates relative to the resistance belt 49 to generate friction force, so that by rotating the knob 42, the magnitude of the friction force between the resistance belt 4 and the friction wheel 47 can be changed, thereby adjusting the motion resistance.

While the invention has been particularly shown and described with reference to a preferred embodiment, it will be understood by those skilled in the art that various changes in form and detail may be made therein without departing from the spirit and scope of the invention as defined by the appended claims.

Claims (10)

1. A transmission device for a two-axis exercise machine, comprising:

a first wheel set including a rotatable first driving wheel, a first driving wheel spaced from the first driving wheel along a left-right direction, and a first driving belt coupled to the first driving wheel and the first driving wheel in a surrounding manner, the first driving wheel having a first coupling portion coupled to the first driving belt and a second coupling portion spaced from the first coupling portion along a front-rear direction; and

a second wheel set, which is connected with the first wheel set along the left-right direction and comprises a second driving wheel which is adjacent to the first driving wheel and is mutually spaced from the first driving wheel in a top-bottom direction and the left-right direction, a second driving wheel which is far away from the first wheel set, and a second driving belt which is connected with the second driving wheel and the second driving wheel in a surrounding way and is connected with a second joint part of the first driving wheel, wherein the second driving wheel is provided with a third joint part which is connected with the second driving belt and a fourth joint part which is arranged at a distance from the third joint part along the front-back direction and is connected with the first driving belt, so that one of the first wheel set and the second wheel set drives the other wheel set to rotate, and the rotation direction of the first wheel set is opposite to that of the second wheel set.

2. The transmission of a biaxial exercise machine as defined in claim 1, wherein: the first driving wheel and the first driving wheel are meshed with the inner surface of the first driving belt, the second driving wheel is meshed with the outer surface of the first driving belt, the second driving wheel and the second driving wheel are meshed with the inner surface of the second driving belt, and the first driving wheel is meshed with the outer surface of the second driving belt.

3. The transmission of a biaxial exercise machine as defined in claim 1, wherein: this first driving belt is a timing belt with this second drive belt respectively, this first action wheel, this first drive wheel, this second action wheel and this second drive wheel are a gear respectively, this first driving belt has a plurality of first internal teeth that supply this first action wheel and this first drive wheel interlock, and a plurality of first external teeth that are in reverse direction to this first internal tooth and supply this second drive wheel interlock, this second drive belt has a plurality of second internal teeth that supply this second action wheel and this second drive wheel interlock, and a plurality of second external teeth that are in reverse direction to this second internal tooth and supply this first drive wheel interlock.

4. The transmission of a biaxial exercise machine as defined in claim 1, wherein: the first driving wheel and the second driving wheel respectively rotate by taking a first axis and a second axis as centers, the first driving wheel and the second driving wheel respectively rotate by taking a first center line and a second center line as centers, the heights of the first axis and the second axis in the top-bottom direction are substantially the same, the first center line is higher than the first axis in the top-bottom direction, and the second center line is lower than the second axis in the top-bottom direction.

5. The transmission of a biaxial exercise machine as defined in claim 1, wherein: the diameter of the first driving wheel is substantially equal to that of the second driving wheel, and the diameter of the first driving wheel is larger than that of the first driving wheel and that of the second driving wheel.

6. A two-axis exercise apparatus, comprising a base unit, further comprising:

a drive arrangement according to any one of claims 1 to 5, the drive arrangement being rotatably mounted on the base unit; and

two operation parts connected to the first driving wheel and the second driving wheel separately to drive the first driving wheel and the second driving wheel to rotate and to drive the first driving belt and the second driving belt to rotate, and the two operation parts perform circular motion in opposite directions simultaneously.

7. The dual-axis exercise apparatus of claim 6, wherein: the operating unit comprises a first wheel set, a second wheel set and an operating member, wherein the first wheel set and the second wheel set are respectively arranged on the operating member, and the operating member is used for driving the first wheel set and the second wheel set to rotate.

8. The dual-axis exercise apparatus of claim 7, wherein: each rotating disc is provided with a connecting hole for connecting the first wheel set or the second wheel set and a mounting hole arranged at an interval with the connecting hole, and each operating piece is provided with a body, a positioning rod penetrating through the body and the mounting hole of the corresponding rotating disc and at least one bearing rotatably arranged between the positioning rod and the body.

9. The dual-axis exercise apparatus of claim 6, wherein: the resistance unit can generate motion resistance when the operating piece is operated.

10. The dual-axis exercise apparatus of claim 9, wherein: the resistance unit comprises a resistance sheet which is in friction contact with the first transmission wheel and the second transmission wheel simultaneously, and a knob which is connected with the resistance sheet and exposed out of the base unit, and the position of the resistance sheet in the front-back direction can be changed by rotating the knob.

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