TW201827167A - Rotary wrench structure for achieving better strength - Google Patents

Abstract

The present invention relates to a rotary wrench structure, which comprises: a main body, a driving head, a first screwing member and a second screwing member. The main body is configured with a first pivoting hole. The driving head is configured with a first pivoting portion. The first screwing member is configured with a fourth screwing portion and a third pivoting portion. The first pivoting portion of the driving head is protruded into the first pivoting hole of the main body. The fourth screwing portion of the first screwing member is screwed with the first screwing portion of the main body. The third pivoting portion of the first screwing member is pivoted with the first pivoting portion. Although the first pivoting hole of the main body and the first pivoting portion of the driving head are assembled through the first screwing member, the first pivoting portion is protruded into the range of the first pivoting hole. The structure is provided with a first branch arm and the first screwing member at the first pivoting portion, and the first pivoting portion, the first branch arm, the first screwing member and the first pivoting portion are provided with three-layered ring structure to achieve better strength.

Description

 Rotary wrench structure  

The invention relates to a rotary wrench structure, in particular to a first pivot portion of a driving head of a rotary wrench structure protruding in a first pivot hole of the body, the first pivot portion having the first branch The arm, the first screwing member and the first pivot portion have a three-layer annular structure and have better strength.

As previously known by us, the conventional rotary wrench structure, such as U.S. Patent No.: US7987746B2, Taiwan Patent Application No.: 098115020, certificate number: I351335, patent name: sleeve puller, the patent structure is: a set The barrel puller includes a trigger body 10 including a first end 101 and a second end 102. The first end 101 of the trigger body 10 is provided with an accommodating space 15; a cylindrical member 20 is located at the trigger body 10. The accommodating space 15 includes an axial slanting hole 21 and a through slot 22, and a bottom portion of the slanting hole 21 forms a spurring portion 211; a ratchet member 30 includes a first end 301, The second end 302 is adjacent to the intermediate portion 303. The intermediate portion 303 is adjacent to the end surface of the first end 301 to form a ratchet portion 33. The ratchet member 30 is axially provided with a set of holes 31, and the radial direction of the opposite ends of the ratchet member 30 Each of the two ends is provided with a hole 32, the hole 32 is communicated with the sleeve 31, and the ratchet portion 33 of the ratchet member 30 is selectively engaged with the ratchet portion 211 of the tubular member 20; There is a latching device 41, and the connector 40 is disposed in the sleeve hole 31 of the ratchet member 30. The latching device 41 at one end of the connector 40 is stuck to the spine. The hole 32 of the member 30, the latching device 41 at the other end of the connector 40 exposes the ratchet member 30; a fixing member 50 is locked to the tubular member 20, and the fixing member 50 limits the ratchet member 30 and the joint 40 does not come out.

However, the missing structure of this conventional rotary wrench is:

1. In addition, as shown in the third figure of the bulletin, the pivot 11 and the tubular member 20 are assembled by the restricting member 13, but the restricting member 13 is provided with a threaded portion at one end for screwing to the pivot hole. 12, the limiting member 13 is provided with a circular portion at the other end for pivoting in the recessed hole 231, that is, the pivoting portion 11 and the tubular member 20 are not coincident with each other, and between the pivoting lug 11 and the tubular member 20 When the vertical force is applied, the vertical force is completely received by the section of the limiting member 13, the limiting member 13 is relatively easy to break, and the vertical force is received at the intersection of the threaded portion and the round portion of the limiting member 13, The restraining member 13 is more susceptible to breakage and the overall service life is shorter.

2, as shown in FIG. 2, the elastic member 141 and the engaging member 142 are received at the pivoting end 11, and the engaging member 142 is clamped to the tubular member 20 by the elastic force of the elastic member 141. At a positioning hole 232, but with the elastic force of the elastic member 141, when the cylindrical member 20 and the pivoting ear 11 have a positioning function, the cylindrical member 20 can be automatically rotated with respect to the pivoting ear 11 by a slight force. The positioning effect is insufficient.

In view of the above-mentioned lack of the structure of the conventional rotary wrench, the inventors have been engaged in the manufacturing, production and design experience of related industries for many years, and finally have a product that can solve the drawbacks of the rotary wrench structure.

The problem to be solved by the invention is that the pivots of the conventional structure and the tubular members are assembled by the limiting member, and the pivoting ears and the tubular members are free of phase overlapping portions, and if the vertical force is between the two, the vertical The force is completely received by the section of the limiting member, and the limiting member is relatively easy to be broken. The first pivot portion of the driving head of the present invention protrudes into the first pivot hole of the body. The fourth screwing portion of the first screwing member is screwed with the first screwing portion, and the third pivot portion is pivoted with the first pivot portion, although the first pivot hole and the first pivoting portion The first pivoting portion is assembled from the first screwing member, but the first pivoting portion is protruded into the first pivoting hole, and the first pivoting portion is coupled to the first pivoting arm The first screwing member and the first pivot portion have a three-layer annular structure and have better strength.

The technical means for solving the problem: a rotary wrench structure, comprising: a body, a driving head, a first screwing member and a second screwing member, the system is provided with a first pivot hole, the driving head system a first pivoting portion is disposed, the first screwing portion is provided with a fourth screwing portion and a third pivot portion, and the first pivoting portion of the driving head protrudes from the first pivot hole of the body The fourth screwing portion of the first screwing member is screwed with the first screwing portion of the body, and the third pivoting portion of the first screwing member is pivoted with the first pivoting portion. The first pivoting portion and the first pivoting portion of the driving head are required to be assembled by the first screwing member, but the first pivoting portion is protruded into the first pivoting hole. The first arm, the first screw member and the first pivot portion are coupled to the first pivot portion, and the first arm, the first screw member and the first pivot portion have The three-layered annular structure has better strength.

According to the effect of the prior art, the first pivot portion of the driving head protrudes into the first pivot hole of the body, and the fourth screw portion of the first screwing member and the first screw portion The third pivot portion is pivoted with the first pivot portion. Although the first pivot hole and the first pivot portion are required to be assembled by the first screw member, the The first pivot portion is protruded into the first pivot hole, and the first pivot portion is coupled to the first pivot arm, the first screw member and the first pivot portion, and the first pivot portion The arm, the first screw member and the first pivot portion have a three-layer annular structure and have better strength.

The structure and composition of the present invention are described in conjunction with the drawings and the drawings, and the following description is only for explaining the implementation of the present invention. For example, it is not intended to limit the invention in any way, and any modifications made by the present invention are still within the scope of the invention.

10‧‧‧ Ontology

11‧‧‧First arm

12‧‧‧second arm

13‧‧‧First pivot hole

14‧‧‧First screwing

15‧‧‧Second pivot hole

16‧‧‧through slot

17‧‧‧ first plane

18‧‧‧Rotating slot

19‧‧‧Second screw joint

20‧‧‧Drive head

21‧‧‧ First pivot

22‧‧‧Second pivot

23‧‧‧ Third screw joint

24‧‧‧ First end

25‧‧‧ positioning slot

26‧‧‧ second plane

27‧‧‧ Included

30‧‧‧First screw fitting

31‧‧‧ Fourth screw joint

32‧‧‧ Third pivot

40‧‧‧Washers

50‧‧‧

51‧‧‧ first head

55‧‧‧Flexible components

60‧‧‧Rotating parts

61‧‧‧ third pivot hole

62‧‧‧ first position

63‧‧‧second position

64‧‧‧ third position

70‧‧‧Second screw

71‧‧‧ Fifth screw joint

72‧‧‧second end

73‧‧‧ second head

80‧‧‧ Third screw

81‧‧‧ Sixth screw joint

82‧‧‧fourth pivot hole

The first figure is an exploded perspective view of the structure of the rotary wrench of the present invention.

The second figure is a perspective view of a rotary member of the rotary wrench structure of the present invention.

The third figure is a three-dimensional combination diagram of some components of the rotary wrench structure of the present invention.

The fourth figure is a three-dimensional combination diagram of the rotary wrench structure of the present invention.

Fig. 5 is a side view showing the structure of the rotary wrench of the present invention.

Figure 6 is a cross-sectional view taken along line A-A of the fifth embodiment of the present invention.

Figure 7 is a cross-sectional view showing a second operational state at a fifth embodiment A-A of the present invention.

Figure 8 is a perspective view showing a third operational state of the rotary wrench structure of the present invention.

Figure 9 is a perspective view showing a fourth operational state of the rotary wrench structure of the present invention.

Figure 10 is a perspective exploded view of a second embodiment of the present invention.

Figure 11 is a perspective exploded view of a third embodiment of the present invention.

Figure 12 is a side view of a third embodiment of the present invention.

Figure 13 is a cross-sectional view taken along line A-A of Figure 12 of the present invention.

Referring first to the first and second figures, the first drawing is an exploded perspective view of the rotary wrench structure of the present invention, and the second drawing is a perspective view of the rotary wrench structure rotating member 60 of the present invention. The present invention relates to a rotary wrench. The structure includes: a body 10, the body 10 is provided with a first arm 11 and a second arm 12, and the first arm 11 and the second arm 12 are opposite and away from each other, so that the structure The first arm 11 is provided with a first pivot hole 13 , and the first pivot hole 13 is formed in a circular hole shape. The first pivot hole 13 is internally provided with a first body. The first screwing portion 14 is internally threaded, and the second arm 12 is provided with a second pivot hole 15 which is opposite to the first pivot hole 13 The second pivot hole 15 is coincident with the axial center of the first pivot hole 13. The second pivot hole 15 has a circular hole shape. The diameter of the second pivot hole 15 is smaller than the first pivot hole. The diameter of the second pivot hole 15 is provided with a through groove 16 which is formed in a through groove shape. The diameter of the through groove 16 is smaller than the diameter of the second pivot hole 15 , and the second branch Outside of arm 12 The first plane 17 is provided. The second pivot hole 15 and the opening of the through slot 16 are flush with the first plane 17. The body 10 is provided with a rotating slot 18, and the rotating slot 18 is The first arm 11 is connected to the second arm 12, and the rotating slot 18 is in the shape of a circular groove. The driving head 20 is pivotally mounted on the first arm 11 of the body 10. And the first arm portion 21 is disposed at one end of the driving head 20, and the first pivot portion 21 is pivotally disposed at the first pivot hole 13 The first pivot portion 21 has a convex cylindrical shape, and the outer diameter of the first pivot portion 21 is smaller than the inner diameter of the first pivot hole 11, and the first pivot portion 21 The length protruding into the first pivot hole 13 is twice the distance between the driving head 20 and the first arm 11 and the second arm 12. The driving head 20 is provided with a second end. The second pivot portion 22 is opposite to the second pivot hole 15 , and the second pivot portion 22 has a convex cylindrical shape, and the second pivot portion 22 has the same shape as the second pivot hole 15 . Diameter, the second pivot portion 22 has a phase with the first pivot portion 21 A third screwing portion 23 is formed in the second pivot portion 22, and the third screw portion 23 is internally threaded, and the first end portion 24 is disposed at the end of the second pivot portion 22, The first end portion 24 can be received or not disposed in the second pivot hole 15 . The driving head 20 is provided with a plurality of positioning slots 25 , and each positioning slot 25 can be respectively opposite to the through slot 16 . The plurality of positioning grooves 25 are arranged in an annular shape with the second pivot portion 22 as an axis. Each of the positioning grooves 25 has a circular groove shape. The driving head 20 is provided with a second plane 26, and the plurality of positioning grooves 25 are provided. The second flat surface 26 is formed in a plane shape, and the driving head 20 is convexly provided with a fitting portion 27 on the side of the driving head 20, and the fitting portion 27 is in the shape of a quadrangular head. The 27 series can be sleeved to rotate the screwing member, and the driving head 20 can be the first arm portion 21 and the second pivot portion 22 as the axis of the first arm 11 and the second arm The driving head 20 is rotated about the first pivot portion 21 and the second pivot portion 22, and the sleeve portion 27 can pass the rotating slot 18 to make the driving head 20 opposite to the body. The 10 series is rotated by three hundred and sixty degrees; a first screwing member 30 is screwed to the first pivot hole 13 , and the first screwing member 30 is provided with a fourth screwing portion 31 and a third pivot portion 32 . The fourth screwing portion 31 is screwed to the first screwing portion 14 , and the fourth screwing portion 31 is externally threaded. The third pivot portion 32 is slightly protruded from the first pivot hole 13 . The third pivot portion 32 is pivotally disposed with the first pivot portion 21, and the third pivot portion 32 has a circular groove shape. The total length of the first screw member 30 is greater than the length of the first pivot hole 13. a washer 40 is sleeved on the first pivot portion 21, and the washer 40 is abutted between the drive head 20 and the first screw member 30. The washer 40 is in the shape of a ring. And having a slight elasticity, the driving head 20 has elastic resistance when swinging at the first arm 11 and the second arm 12; a tip body 50, the tip body 50 is disposed through the through slot 16 and The driving head 20 has a positioning function in the positioning slot 25 of the driving head 20, and the first head portion 51 is protruded from the first head portion 51. Outside the slot 16, the tip body 50 is in the shape of a round rod; an elastic element 55, the elastic member 55 is sleeved on the tip body 50, the elastic member 55 is elastically abutted between the first plane 17 of the body 10 and the first head portion 51 for the tip body 50 to return; A rotating member 60 is pivotally disposed at the second pivot hole 15 , and the rotating member 60 is provided with a third pivot hole 61 , and the third pivot hole 61 is provided. Opposite to the second pivot hole 15, the third pivot hole 61 has the same diameter as the second pivot hole 15, and the rotating member 60 is provided with a first position 62, a second position 63 and a third position 64. The first position 62 and the second position 63 are separated from each other. The second position 63 has a deeper depth than the first position 62. The third position 64 is connected to the first position 62 and the second position 63. Rotating the rotating member 60, the first position 62 is aligned with the tip body 50, and the tip body 50 compresses the elastic member 55. The end portion of the tip body 50 can be accommodated in a positioning groove 25 thereof. The rotating member 60 causes the second position 63 to align with the tip body 50. The tip body 50 is displaced by the elastic restoring force of the elastic member 55. The end portion of the tip body 50 is not accommodated in a positioning groove 25 thereof. Inside, The driving head 20 is pivoted by the first pivot hole 13 and the second pivot hole 15; a second screwing member 70, the second screwing member 70 is provided with a fifth screwing portion 71, and a second The end portion 72 and the second head portion 73 are screwed to the third screwing portion 23 of the driving head 20, and the second end portion 72 abuts against the first end portion 24 The second screwing member 70 is pivoted for the third pivot hole 61, and the second head portion 73 restricts the rotating member 60 from coming out of the second screwing member 70.

The body 10, the driving head 20, the first screwing member 30, the washer 40, the tip body 50, and the elastic member 55 are assembled as shown in the third figure, and the third figure is the rotary wrench of the present invention. The three-dimensional combination diagram of the structural components, after the rotating member 60 and the second screwing member 70 are assembled at the second arm 12, as shown in the fourth figure, the fourth figure is the rotary wrench of the present invention. A three-dimensional combination of structures.

Please refer to the fifth and sixth figures. The fifth drawing is a side view of the rotary wrench structure of the present invention, and the sixth drawing is a cross-sectional view of the fifth drawing AA of the present invention, which is clearly shown by the figure. The fourth screwing portion 31 is screwed to the first screwing portion 14 , and the third pivot portion 32 is pivoted to the first pivot portion 21 , and the tip body 50 is disposed through the through slot 16 and the In a positioning slot 25 of the driving head 20, the first position 62 of the rotating member 60 is aligned with the tip body 50, so that the driving head 20 has a positioning function relative to the body 10, and the fifth screwing portion 71 is screwed. The third screwing portion 23 of the driving head 20 is engaged.

Referring to the seventh figure, the seventh drawing is a cross-sectional view of the second operating state of the fifth drawing AA of the present invention. The rotating member 60 is rotated to align the second position 63 with the tip body 50. The end portion of the tip body 50 is not disposed in a positioning groove 25, and the driving head 20 is configured by the first pivot hole 13 and the second pivot hole 15 When the shaft is rotated, the driving head 20 can be positioned at a plurality of positions relative to the body 10. The eighth figure is a perspective view of the third operating state of the rotating wrench structure of the present invention, and the ninth drawing is the fourth operating state of the rotating wrench structure of the present invention. In the perspective view of the ninth figure, the sleeve portion 27 of the drive head 20 is received in the rotation groove 18.

Referring to the tenth figure, the tenth figure is an exploded perspective view of the second embodiment of the present invention. The second arm 12 of the body 10 is not provided with the through slot 16 and the first plane 17. The driving head 20 is not provided with a plurality of positioning grooves 25, and the tip body 50, the elastic member 55 and the rotating member 60 are not provided. The driving head 20 is detachable from the first arm 11 and the second arm. 12 three hundred and sixty degrees free to rotate.

Referring to the eleventh to thirteenth drawings, the eleventh drawing is an exploded perspective view of a third embodiment of the present invention, and the twelfth is a side view of the third embodiment of the present invention, and the thirteenth drawing The second pivot hole 15 is provided with a second screwing portion 19, and the second pivot hole 15 and the second screwing portion 19 are connected to the first pivot. The hole 13 and the first screwing portion 14 are identical in structure, and the second pivot hole 15 and the second screwing portion 19 and the first pivot hole 13 and the first screwing portion 14 are symmetrical with respect to the body 10 The third screwing member 80 is provided with a sixth screwing portion 81 and a fourth pivot hole 82. The sixth screwing portion 81 is screwed to the second screwing portion. 19, the second screwing member 70 extends through the fourth pivot hole 82, so that the fifth screwing portion 71 is screwed to the third screwing portion 23, and when combined, it is like the twelfth As shown in the figure, the cross-section is as shown in Figure 13.

The advantages of the rotary wrench structure of the present invention are:

1. The first pivot portion 21 of the driving head 20 protrudes from the first pivot hole 13 of the body 10, and the first screw member 30 is provided. The fourth screwing portion 31 is screwed to the first screwing portion 14 , and the third pivot portion 32 is pivoted to the first pivot portion 21 , and the first pivot hole 13 and the first pivot portion 21 . The first screw portion 21 is formed to protrude from the first pivot hole 13 , and the first pivot portion 21 is configured to be the first The arm 11, the first screwing member 30 and the first pivot portion 21 have a three-layer annular structure and have better strength.

The first position 62 of the rotating member 60 limits the end of the tip 50 to be received in a positioning slot 25. The tip 50 is limited to the first position 62. The less organic rate is removed from the positioning groove 25, and the driving head 20 can be fixed at an angle with respect to the body 10, and has a fixed angle of safety.

3. The rotating member 60 is rotated such that the second position 63 is aligned with the tip body 50. The tip body 50 is displaced by the elastic restoring force of the elastic member 55, and the end portion of the tip body 50 is not allowed to be In a positioning slot 25, the driving head 20 is adjusted to a desired angle by pivoting the first pivot hole 13 and the second pivot hole 15 as a shaft.

4, rotating the rotating member 60, the first position 62 or the second position 63 is aligned with the tip body 50, the driving head 20 is fixed at an angle relative to the body 10, or the driving head 20 is Freely rotating.

5. The body 10 is provided with the rotating slot 18, and the sleeve portion 27 can pass the rotating slot 18 to rotate the driving head 20 360 degrees relative to the body 10, and the driving head 20 is not rotated when rotated. Limited to the body 10.

Therefore, the structure of the rotary wrench of the present invention has industrial utilization, novelty and advancement, and can meet the application requirements of the invention patent, and submits an application according to law.

Claims (12)

 A rotary wrench structure comprising: a body, the system is provided with a first arm and a second arm, the first arm and the second arm are relatively positive and away from each other, so that the system is The first arm is provided with a first pivot hole, the first pivot hole is formed in a circular hole shape, and the first pivot hole is provided with a first screwing portion, the first screw The second arm is provided with a second pivot hole, and the second pivot hole is opposite to the first pivot hole, and the second pivot hole and the axis of the first pivot hole The second pivot hole is formed in a circular hole shape; a driving head is pivotally disposed at the first arm and the second arm, and the driving head is provided with a first end a first pivot portion is pivotally disposed in the first pivot hole, the first pivot portion is protruded in the first pivot hole, and the first pivot portion is in a convex cylindrical shape. The outer diameter of the first pivot portion is smaller than the inner diameter of the first pivot hole, and the second end portion of the driving head is provided with a second pivot portion, the second pivot portion is aligned with the second pivot hole, and the second portion The pivotal system has a convex cylindrical shape, The second pivot portion is provided with a third screwing portion, the third screwing portion is internally threaded, and the second end portion is provided with a first end portion, and the first end portion can be accommodated Or the second pivot hole is not disposed in the second pivot hole, the driving head is provided with a sleeve portion; a first screwing member is screwed to the first pivot hole of the body, the first a screwing member is provided with a fourth screwing portion, the fourth screwing portion is screwed with the first screwing portion, and the fourth screwing portion is externally threaded, and the first screwing portion is a third pivot portion is disposed, the third pivot portion is slightly protruded from the first pivot hole, and the third pivot portion is pivoted with the first pivot portion of the driving head, and the third pivot portion is a second screwing member, the second screwing member is provided with a fifth screwing portion and a second end portion, the fifth screwing portion is screwed to the third screwing of the driving head At the portion, the second end is abutted against the first end.    The rotary wrench structure of claim 1, wherein the diameter of the second pivot hole is smaller than the diameter of the first pivot hole.    The rotary wrench structure of claim 1, wherein the second pivot hole is provided with a through groove, the through groove is formed in a through groove shape, and the diameter of the through groove is smaller than the diameter of the second pivot hole. The driving head is provided with a plurality of positioning slots, each of which is respectively opposite to the through slot, and the plurality of positioning slots are arranged in an annular shape with the second pivot portion as an axis, and each positioning slot is a circular groove, the driving head is provided with a second plane, the plurality of positioning grooves are disposed on the second plane, the second plane is planar, and a tip body is disposed, and the tip system is disposed in the slot And a positioning slot of the driving head, the driving head has a positioning function relative to the body, the first body of the tip body is provided with a first head, and the first head is exposed outside the slot, the tip The system is in the shape of a round rod; an elastic member is disposed on the tip body, and the elastic member is elastically engaged between the body and the first head for returning the body; a rotating member, the rotating member is pivotally disposed at the second pivot hole, and the rotating member is provided with a third pivot hole, the third pivot hole Opposite to the second pivot hole, the third pivot hole has the same diameter as the second pivot hole, and the rotating member is provided with a first position, a second position and a third position, the first position and the first The two positions are far apart, the second position has a deeper depth than the first position, the third position is connected to the first position and the second position, and the rotating member is rotated to align the first position with the tip The tip system compresses the elastic member, and the end portion of the tip body is accommodated in a positioning groove thereof, and the rotating member is rotated to align the second position with the tip body, and the tip body is subjected to the elastic member The elastic restoring force is displaced, and the end of the tip body is not disposed in a positioning groove thereof, and the driving head is pivoted about the first pivot hole and the second pivot hole.    The rotary wrench structure of claim 3, wherein the second arm is provided with a first plane, and the second pivot hole and the opening of the slot are flush with the first plane.    The rotary wrench structure of claim 1, wherein the system is provided with a rotating slot, the rotating slot is disposed between the first arm and the second arm, and the rotating slot is in the shape of a circular groove. The sleeve is in the shape of a quadrangular head, and the driving head is configured such that the first pivot portion and the second pivot portion are pivoted at the first arm and the second arm, when the driving head The first pivot portion and the second pivot portion are pivoted, and the sleeve portion can rotate the driving head by three hundred and sixty degrees with respect to the system through the rotating slot.    The rotary wrench structure of claim 1, wherein the length of the first pivot portion protruding into the first pivot hole is a distance between the driving head and the first arm and the second arm Double.    The rotary wrench structure of claim 1, wherein the second pivot portion has the same diameter as the second pivot hole.    The rotary wrench structure of claim 1, wherein the second pivot portion has the same diameter as the first pivot portion.    The rotary wrench structure of claim 1, wherein a washer is disposed on the first pivot portion, the washer is abutted between the drive head and the first screw member, the washer The utility model has a circular body shape and is slightly elastic, so that the driving head has elastic resistance when oscillating at the first arm and the second arm.    The rotary wrench structure of claim 3, wherein the second screwing member is provided with a second head portion, the second screwing member is configured to pivot the third pivot hole, and the second head portion limits the The rotating member is out of the second screwing member.    The rotary wrench structure of claim 1, wherein the second pivot hole is provided with a second screwing portion, and a third screwing member is provided, and the third screwing member is provided with a sixth screwing portion. And a fourth pivoting hole, the sixth screwing portion is screwed to the second screwing portion, and the second screwing member extends through the fourth pivot hole to screw the fifth screwing portion At the third screwing portion.    The rotary wrench structure of claim 11, wherein the second pivot hole and the second screw portion are identical in structure to the first pivot hole and the first screw portion, and the second pivot hole and The second screwing portion and the first pivot hole and the first screwing portion are symmetric with respect to the system.