CN210082844U

CN210082844U - Light-weight manual double-hook traction seat

Info

Publication number: CN210082844U
Application number: CN201822265349.4U
Authority: CN
Inventors: 程铸; 祁景岗; 丁家良; 张良
Original assignee: HEFEI JIUXIANG MACHINERY Co Ltd
Current assignee: HEFEI JIUXIANG MACHINERY Co Ltd
Priority date: 2018-12-31
Filing date: 2018-12-31
Publication date: 2020-02-18
Anticipated expiration: 2028-12-31

Abstract

The utility model discloses a manual double hook of lightweight pulls seat, half latch hook plate can be around the fixed axle rotation to foldeing the position or open the position, when two half latch hook plates are in when foldeing the position, two half latch hook holes constitute jointly and pull the pinhole, the shift fork of U type control fork is located between backstop ear and the perforation of ear, when two half latch hook plates are in when opening the position, the mouth that opens of two half latch hook holes is corresponding with the towing pin position of trailer, the shift fork of U type control fork is located shift fork accommodate opening, the backstop ear is located the perforation of ear. The utility model discloses in, conveniently open or lock the towing pin, compare single-hook traction seat long distance swing and removal, the mechanism is more reasonable reliable and the difficult hairpin of operation, and the double-hook traction seat is convenient for adjust with the centre bore size of trailer towing pin cooperation department during the assembly, uses the manual double-hook traction seat of the lightweight of secondary adjustment size of being convenient for after the centre bore wearing and tearing for a long time to compare single-hook traction seat materials still less, reduce weight realizes the lightweight.

Description

Light-weight manual double-hook traction seat

Technical Field

The utility model relates to a traction seat technical field, more specifically say, in particular to manual double hook traction seat of lightweight.

Background

With the rapid development of economy in China and the great investment of China in highway construction, highway transportation has become a main transportation mode in China. The semi-trailer tractor serves as main equipment for road transportation, and is widely applied due to the advantages of strong specialization, large loading capacity and quick transportation. The fifth wheel is the coupling between the tractor head and the semitrailer, and is not a very complicated and attractive part, but is the most important safety device of a semitrailer, which may cause serious safety accidents if the tractor is operated incorrectly or maintained improperly.

The traction seat in the prior art is basically of a single-hook traction seat structure, when the single-hook traction seat needs to be opened or closed, a lock hook needs to deflect, a lock block moves in two steps to realize the single-hook traction seat, the stroke is relatively long, and the operation is inconvenient; the hole center of the locking hook of the single-hook traction seat and the center of the traction pin on the trailer are difficult to ensure to be concentric; and simultaneously, after the lock hook is worn, the center of the lock hook can be eccentric relative to the traction pin hole.

Meanwhile, with the development of the automobile industry, the whole automobile needs to be lightened, the material of the truck traction seat cannot be directly thinned when the weight of the truck traction seat is lightened, if the raw material is directly thinned, the requirements of lightening and reducing cost can be met, but the performance requirements of the traction seat such as strength cannot be met.

SUMMERY OF THE UTILITY MODEL

An object of the utility model is to provide a both can conveniently open or lock the towing pin, compare single-hook traction seat long distance swing and removal, the mechanism is more reasonable reliable and the difficult hairpin of operation, and the adjustment of being convenient for during the assembly is drawn seat and the centre bore size of trailer towing pin cooperation department, the manual double-hook traction seat of the lightweight of the secondary adjustment size of being convenient for after long-term use centre bore wearing and tearing.

In order to achieve the above purpose, the utility model adopts the following technical scheme: a light-weight manual double-hook traction seat comprises a traction seat plate, wherein the traction seat plate is provided with a supporting part and an opening part, the traction seat plate further comprises an opening mechanism, a prepressing device, a tension spring, a U-shaped control fork, a shifting fork limiting plate and a pair of half-locking hook plates, the half-locking hook plates jointly form a hook plate, the upper ends of the half-locking hook plates are provided with spring mounting holes, the lower ends of the half-locking hook plates are provided with stopping lug parts, one side of each half-locking hook plate is provided with a half-locking hook hole, the other side of each half-locking hook plate is provided with a shifting fork accommodating opening, the upper parts of the half-locking hook plates are further provided with rotating shaft holes, the half-locking hook plates are connected with the traction seat plate through fixed shafts, the spring mounting holes in the two half-locking hook plates are connected through the tension spring, the U-shaped control fork is arranged outside the two half-, the shifting fork limiting plate is fixedly connected with the traction seat plate, ear through holes capable of accommodating the stop ears to penetrate through are formed in the shifting fork limiting plate opposite to the stop ears, a fixing part on the prepressing device is installed on the traction seat plate, a pressing part on the prepressing device is connected with the U-shaped control fork and used for pressing the U-shaped control fork towards the two half-latch hook plates, and the opening mechanism is connected with the traction seat plate and used for driving the U-shaped control fork to be far away from the two half-latch hook plates;

half latch hook plate can be rotatory to the position of foldeing or open the position around the fixed axle, when two half latch hook plates are in the position of foldeing, two half latch hook holes constitute jointly and pull the pinhole, and pull the position of pinhole and pull the towing pin recess on the bedplate concentric, the shift fork of U type control fork is located between backstop ear and the perforation of ear, when two half latch hook plates are in the position of opening, the mouth of opening in two half latch hook holes is corresponding with the towing pin position of trailer, the shift fork of U type control fork is located shift fork accommodate opening, backstop ear is located the perforation of ear.

Furthermore, the pre-pressing device comprises a guide rod and a first compression spring, one end of the guide rod penetrates through a bending surface on the side surface of the traction seat plate, the other end of the guide rod is connected with the U-shaped shifting fork, and the first compression spring is further arranged on the guide rod in a penetrating mode.

Furthermore, the upper end of the guide rod is provided with threads, and the guide rod penetrates through a bending surface on the side surface of the traction seat plate and then is in threaded connection with a limiting nut.

Further, the opening mechanism comprises a mechanism plate, a first hinged pore plate and a handle rod, the first hinged pore plate is arranged on the inner side of the bending surface of the side surface of the traction seat plate on one side of the guide rod, a first hinged pore plate, a second hinged pore plate and a guide groove are arranged on the mechanism plate, one side of the first hinged pore plate is a driving part, the other side of the first hinged pore plate is a driven part, a second hinged pore plate is arranged on the driving part, the guide groove extends to the middle part of the driving part from the lower end of the driven part, the guide groove is arranged between the first hinged pore plate and the second hinged pore plate, the mechanism plate is hinged with the first hinged pore plate through the first hinged pore plate, the mechanism plate is hinged with one end of the handle rod through the second hinged pore plate, the other end of the handle rod extends to the outside of the traction seat plate on one side far away from the second hinged pore plate, a spring stop pin is arranged on the handle rod, and a second compression spring is sleeved on the handle rod, one end of the second compression spring is stopped on the spring stopping pin, the other end of the second compression spring is stopped on the supporting frame connected with the traction seat plate, a first shifting rod is arranged at the joint of the U-shaped shifting fork and the guide rod, and the first shifting rod extends into the guide groove.

Further, still install the safety mechanism on the traction seat board, the safety mechanism includes the articulated orifice plate of second, bumper bar and second driving lever, the traction seat board side of guide bar opposite side is bent the face inboard and is installed the articulated orifice plate of second, the articulated orifice plate of second is articulated with the one end of bumper bar, and the torsional spring is still installed to articulated department, the other end of bumper bar stretch to U type control fork position, just the second driving lever is installed the bumper bar side, just the second driving lever is located the outside of the driven part of mechanism board.

Furthermore, the lower end of the safety rod is bent towards the direction of the guide rod.

Furthermore, the lower end of the shifting fork limiting plate inclines towards the middle of the traction seat plate.

Further, two the couple board of butterfly structure is constituteed jointly to half lock hook board, every slope incision has all been seted up on half lock hook board upper portion, and is a pair of the slope incision is constituteed the extension spring jointly and is held the chamber, the extension spring sets up in the extension spring holds the chamber, shift fork holding opening upper portion is provided with slope backstop face.

When the traction pin needs to be connected, a worker operates the opening mechanism to move the U-shaped control fork upwards, a shifting fork on the U-shaped control fork does not block a stopping lug part any more, the two half latch hook plates are subjected to the elastic action of a tension spring and rotate around a fixed shaft to be opened, the stopping lug part penetrates into a lug hole, and after the two half latch hook plates are opened, the traction pin can move to the position of the traction pin hole in the traction seat plate through an opening part in the traction seat plate; then the worker loosens the opening mechanism, the traction pin enters the half latch hook hole positions of the two half latch hook plates which are opened, the inner side ends of the half latch hook holes are pushed, the half latch hook plates are driven to rotate back around the fixed shaft, the two half latch hook plates are folded, the stopping lug parts retract from the lug part through holes, the U-shaped control fork is driven by the pre-pressing device to move downwards and stop between the stopping lug parts and the lug part through holes; and keeping the two half latch hook plates at the folding position, thereby realizing the locking of the towing pin.

Compared with the prior art, the utility model has the advantages of: conveniently open or lock the towing pin, compare single-hook traction seat long distance swing and removal, the difficult hairpin of mechanism more reasonable reliable and operation, the double-hook traction seat is convenient for adjust with the central hole size of trailer towing pin cooperation department during the assembly, the manual double-hook traction seat of the lightweight of the secondary adjustment size of being convenient for after long-term use central hole wearing and tearing to compare single-hook traction seat materials still less, reduce weight realizes the lightweight.

Drawings

In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the drawings used in the description of the embodiments or the prior art will be briefly described below, it is obvious that the drawings in the following description are only some embodiments of the present invention, and for those skilled in the art, other drawings can be obtained according to these drawings without creative efforts.

Fig. 1 is a schematic structural view of a half latch hook plate in a lightweight manual double-hook traction seat according to the present invention at a folding position;

fig. 2 is a schematic structural view of a half-locking hook plate in a lightweight manual double-hook traction seat according to the present invention, when the half-locking hook plate is in an open position.

FIG. 3 is a schematic structural view of the position of the middle half latch hook plate of the present invention;

FIG. 4 is a schematic structural view of a pre-pressing device of the present invention;

fig. 5 is a schematic structural diagram of the mechanism plate of the present invention.

Detailed Description

The preferred embodiments of the present invention will be described in detail below with reference to the accompanying drawings, so that the advantages and features of the present invention can be more easily understood by those skilled in the art, and the scope of the present invention can be more clearly and clearly defined.

Referring to fig. 1 and 2, the utility model provides a light-weight manual double-hook traction seat, which comprises a traction seat plate 1, a support frame 106 welded on the traction seat plate, a support part 101 and an opening part 102 arranged on the traction seat plate 1, a traction pin on a trailer entering a traction pin groove 104 through the opening part 102, an opening mechanism 2, a pre-pressing device 3, a tension spring 4, a U-shaped control fork 5, a shifting fork limit plate 6 and a pair of half-lock hook plates 7, wherein the pair of half-lock hook plates 7 jointly form a hook plate, referring to fig. 3, a spring mounting hole 71 is arranged at the upper end of the half-lock hook plate 7, a stop lug 72 is arranged at the lower end of the half-lock hook plate 7, a half-lock hook hole 73 is arranged at one side of the half-lock hook plate 7, a shifting fork receiving opening 74 is arranged at the other side of the half-lock hook plate 7, a rotating shaft hole 75 is arranged at the upper part of the half-lock hook plate 7, the half-lock hook plates 7 can rotate around a fixed shaft 8, the two half-lock hook plates 7 are folded to form a hook plate together and can clamp a traction pin, the traction pin can be separated from the two half-lock hook plates 7 after the two half-lock hook plates 7 are separated, the spring mounting holes 71 on the two half-lock hook plates 7 are connected through a tension spring 4, the tension spring 4 can drive the two half-lock hook plates 7 to be separated to an opening position, the U-shaped control fork 5 is clamped outside the two half-lock hook plates 7, when the two half-lock hook plates 7 are in the closing position, the U-shaped control fork 5 stops the half-lock hook plates 7 from two sides to keep the two half-lock hook plates in the closing position, the shifting fork limiting plates 6 are further arranged outside the two shifting forks 51 of the U-shaped control fork 5, the shifting fork limiting plates 6 are used for guiding and limiting the shifting forks 51 on the U-shaped control fork, and the shifting fork limiting, generally, the integrated welding with the supporting frame 106 is direct, the lug penetrating hole 61 capable of accommodating the lug part 72 to penetrate is formed in the shifting fork limiting plate 6 opposite to the lug part 72, when the plate hook plate 7 is located at the opening position, the lug part 72 can penetrate through the lug penetrating hole 61, the fixing part on the pre-pressing device 3 is installed on the traction plate seat 1, the pressing part on the pre-pressing device 3 is connected with the U-shaped control fork 5, the U-shaped control fork 5 is pressed towards the two half hook plates 7, the two half hook plates 7 are kept at the closing position, the opening mechanism 2 is connected with the traction plate seat 1, the U-shaped control fork 5 is driven to be far away from the two half hook plates 7, and the two half hook plates 7 can be opened to the opening position.

When the two half latch hook plates 7 are in the closed position, the two half latch hook holes 73 jointly form a traction pin hole, the position of the traction pin hole is concentric with a traction pin groove 104 on the traction seat plate 1, the shifting fork 51 of the U-shaped control fork 5 is positioned between the stop lug 72 and the lug through hole 61, when the two half latch hook plates 7 are in the open position, the opening of the two half latch hook holes 73 corresponds to the position of a pin shaft guide groove 103 on the traction seat plate 1, the shifting fork 51 of the U-shaped control fork 5 is positioned in the shifting fork accommodating opening 74, and the stop lug 72 is positioned in the lug through hole 61.

When a traction pin needs to be connected, a worker operates the opening mechanism 2 to move the U-shaped control fork 5 upwards, the shifting fork 51 on the U-shaped control fork 5 does not block the stopping lug part 72 any more, the two half-locking hook plates 7 are subjected to the elastic action of the tension spring 4 and rotate around the fixed shaft 8 to be opened, the stopping lug part 72 penetrates into the lug through hole 61, and after the two half-locking hook plates 7 are opened, the traction pin can move to the position of the traction pin hole in the traction seat plate 1 through the opening part in the traction seat plate 1; then, the worker releases the opening mechanism 2, the traction pin enters the position of the half latch hook hole 73 of the two half latch hook plates 7 which are opened, the inner end of the half latch hook hole 73 is pushed, the half latch hook plates 7 are driven to rotate around the fixed shaft 8, the two half latch hook plates 7 are folded, the stopping lug 72 retracts from the lug penetrating hole 61, and the U-shaped control fork 5 is driven by the pre-pressing device 3 to move downwards to be stopped between the stopping lug 72 and the lug penetrating hole 61; keeping the two half latch hook plates 7 in the closed position, so that when locking the tow pin, the tow pin axis remains on the midperpendicular of the tow seat plate 1, compared to a traditional single hook tow pin, which would be eccentric after wear.

The lower end of the shifting fork limiting plate 6 inclines towards the middle of the traction seat plate 1. The purpose is that the closer the U-shaped control fork 5 is pressed down, the tighter the two half latch hook plates 7 are closed.

Referring to fig. 4, the pre-pressing device 3 includes a guide rod 31 and a first compression spring 32, one end of the guide rod 31 passes through the bending surface 105 of the side surface of the traction seat plate 1, the other end of the guide rod 31 is connected with the U-shaped shifting fork 5, and the guide rod 31 is further provided with the first compression spring 32 in a penetrating manner. The U-shaped shifting fork 5 can be pre-tightened downwards by the first compression spring 32, so that the U-shaped shifting fork 5 is prevented from sliding upwards in use; when the two half latch hook plates 7 are in a closed state, a gap can be formed between the two half latch hook plates, particularly after long-term use, the inner wall of the half latch hook hole 73 is abraded, the U-shaped shifting fork 5 moves downwards, the gap is reduced, the half latch hook plates 7 can continuously clamp the towing pin, self-adaption after abrasion is achieved, and the concentricity of the half latch hook plates and the towing pin can be kept.

The upper end of the guide rod 31 is provided with threads, and the guide rod 31 penetrates through a bending surface 105 on the side surface of the traction seat plate 1 and then is in threaded connection with a limit nut 33. The limit travel of the downward movement of the guide rod 31 can be adjusted by adjusting the position of the limit nut 33. For example, when the half latch hook hole 73 is worn too much, the nut is unscrewed upwards, the downward stroke of the U-shaped shifting fork is lengthened, and the two half latch hook plates 7 can be further extruded inwards, so that the two half latch hook plates 7 can be folded more tightly, the half latch hook hole 73 is reduced, and the towing pin is clamped.

Specifically, the opening mechanism 2 includes a mechanism plate 21, a first hinge hole plate 22 and a handle rod 23, the mechanism plate 21 may be substantially triangular, the first hinge hole plate 22 is mounted inside the bending surface 105 of the side surface of the traction seat plate 1 on one side of the guide rod 31, referring to fig. 5, the mechanism plate 21 is provided with a first hinge hole 211, a second hinge hole 212 and a guide groove 213, the longitudinal direction of the first hinge hole 211 is taken as an axis, one side of the first hinge hole 211 is a driving part 21a, the other side of the first hinge hole 211 is a driven part 21b, the driving part 21a is provided with the second hinge hole 212, the guide groove 213 extends from the lower end of the driven part 21b to the middle part of the driving part 21a, the guide groove 213 is disposed between the first hinge hole 211 and the second hinge hole 212, a transition arc may be further disposed above the middle part of the guide groove 213, and is used for positioning the first shift lever 26 after the mechanism plate 21 rotates, the mechanism plate 21 is hinged to the first hinged hole plate 22 through a first hinged hole 211, the mechanism plate 21 is hinged to one end of the handle rod 23 through a second hinged hole 212, the other end of the handle rod 23 extends out of the traction seat plate 1 far away from one side of the second hinged hole 212, a spring stop pin 24 is arranged on the handle rod 23, a second compression spring 25 is sleeved on the handle rod 23, one end stop of the second compression spring 25 is arranged on the spring stop pin 24, the other end stop is arranged on a supporting frame 106 connected with the traction seat plate 1, a first shifting lever 26 is arranged at the joint of the U-shaped shifting fork 5 and the guide rod 31, and the first shifting lever 26 extends into the guide groove 213. When the traction seat needs to be opened, a driver can pull the handle rod 23, the second compression spring 25 is compressed, the handle rod 23 pulls the mechanism plate 21 to rotate anticlockwise, and the first shift lever 26 moves in the guide groove 213 and drives the guide rod 31 to move upwards, so that the U-shaped shifting fork 5 is driven to move upwards. The two half latch plates 7 are separated by the tension spring 4.

Referring to fig. 4, a safety mechanism 9 is further installed on the traction seat plate 1, the safety mechanism 9 includes a second hinged hole plate 91, a safety rod 92 and a second shift lever 93, the second hinged hole plate 91 is installed on the inner side of the bending surface 105 of the side surface of the traction seat plate 1 on the other side of the guide rod 31, the second hinged hole plate 91 is hinged to one end of the safety rod 92, a torsion spring is further installed at the hinged position, the torsion spring is used for driving the safety rod 92 to move clockwise, the other end of the safety rod 92 extends to the position of the U-shaped control fork 5, the second shift lever 93 is installed on the side surface of the safety rod 92, and the second shift lever 93 is located on the outer side of the driven portion 21b of the mechanism plate 21. When the U-shaped control fork 5 is in the lower position, the safety rod 92 is stopped at the upper part of the U-shaped control fork 5, so that the U-shaped control fork 5 is prevented from moving upwards due to vibration during running of a vehicle, and the semi-latch hook plate 7 is prevented from being pulled out of a traction pin. When the mechanism plate 21 rotates, the side surface of the mechanism plate 21 pushes the second shift lever 93 from the side direction, and the safety lever 92 is driven to rotate counterclockwise, so that the safety lever moves out from the position above the U-shaped control fork 5, and the U-shaped control fork 5 can move upward.

Preferably, the lower end of the safety lever 92 is bent toward the guide bar 31. The purpose is to stop the U-shaped control fork 5 from moving upwards to impact the safety lever 92 during the running process of the vehicle, so that the impact anticlockwise rotation of the safety lever 92 is removed. Further, two the couple board of butterfly structure is constituteed jointly to half lock hook plate 7, every slope incision 76 has all been seted up on half lock hook plate 7 upper portion, and is a pair of slope incision 76 constitutes the extension spring jointly and holds the chamber, extension spring 4 sets up in the extension spring holds the chamber, conveniently holds the extension spring in the little space, shift fork holding opening 74 upper portion is provided with slope backstop face 77. The purpose is that the inclined stop surface 77 can be supported against the fork inner wall of the U-shaped control fork 5 for a stop when the half latch hook plate 7 is in the disengaged position.

Although the embodiments of the present invention have been described with reference to the accompanying drawings, various changes and modifications can be made by the owner within the scope of the appended claims, and the protection scope of the present invention should not be exceeded by the claims.

Claims

1. The utility model provides a manual double hook of lightweight pulls seat, is including pulling the bedplate, pull and have supporting part and opening on the bedplate, its characterized in that: the device comprises an opening mechanism, a prepressing device, a tension spring, a U-shaped control fork, a shifting fork limiting plate and a pair of half-lock hook plates, wherein the pair of half-lock hook plates jointly form a hook plate, the upper ends of the half-lock hook plates are provided with spring mounting holes, the lower ends of the half-lock hook plates are provided with stopping lugs, one side of each half-lock hook plate is provided with a half-lock hook hole, the other side of each half-lock hook plate is provided with a shifting fork accommodating opening, the upper parts of the half-lock hook plates are also provided with rotating shaft holes, the half-lock hook plates are connected with a traction seat plate through fixed shafts, the spring mounting holes in the two half-lock hook plates are connected through the tension spring, the U-shaped control fork is arranged on the outer sides of the two half-lock hook plates, the outer sides of the two shifting forks of the U-shaped control fork are also provided with the shifting fork limiting plate which is fixedly connected with the traction seat, the opening mechanism is connected with the traction seat plate and used for driving the U-shaped control fork to be far away from the two half-locking hook plates;

2. The light-weight manual double hook fifth wheel according to claim 1, wherein: the lower end of the shifting fork limiting plate inclines towards the middle of the traction seat plate.

3. The light-weight manual double hook fifth wheel according to claim 2, wherein: the pre-pressing device comprises a guide rod and a first compression spring, one end of the guide rod penetrates through a bending surface on the side surface of the traction seat plate, the other end of the guide rod is connected with the U-shaped shifting fork, and the guide rod is further provided with the first compression spring in a penetrating mode.

4. The light-weight manual double hook fifth wheel according to claim 3, wherein: the upper end of the guide rod is provided with threads, and the guide rod penetrates through a bending surface on the side surface of the traction seat plate and then is in threaded connection with the limiting nut.

5. The light-weight manual double hook fifth wheel according to claim 3, wherein: the opening mechanism comprises a mechanism plate, a first hinged pore plate and a handle rod, wherein the first hinged pore plate is arranged on the inner side of a bent surface on the side of a traction seat plate on one side of the guide rod, a first hinged pore plate, a second hinged pore plate and a guide groove are arranged on the mechanism plate, one side of the first hinged pore plate is a driving part, the other side of the first hinged pore plate is a driven part, a second hinged pore plate is arranged on the driving part, the guide groove extends to the middle part of the driving part from the lower end of the driven part, the guide groove is arranged between the first hinged pore plate and the second hinged pore plate, the mechanism plate is hinged with the first hinged pore plate through the first hinged pore plate, the mechanism plate is hinged with one end of the handle rod through the second hinged pore plate, the other end of the handle rod extends to the outside of the traction seat plate on one side far away from the second hinged pore plate, a spring stop pin is arranged on the handle rod, and a second compression spring is sleeved on the handle rod, one end of the second compression spring is stopped on the spring stop pin,

the other end of the U-shaped shifting fork is stopped on a supporting frame connected with the traction seat plate, a first shifting rod is arranged at the joint of the U-shaped shifting fork and the guide rod, and the first shifting rod extends into the guide groove.

6. The light-weight manual double hook fifth wheel of claim 5, wherein: still install the safety mechanism on the traction bedplate, the safety mechanism includes the articulated orifice plate of second, bumper bar and second driving lever, the traction bedplate side face of guide bar opposite side is bent the inboard and is installed the articulated orifice plate of second, the articulated orifice plate of second is articulated with the one end of bumper bar, and the torsional spring is still installed to articulated department, the other end of bumper bar stretches to U type control fork position, just the second driving lever is installed the bumper bar side, just the second driving lever is located the outside of the driven part of mechanism board.

7. The light-weight manual double hook fifth wheel of claim 6, wherein: the lower end of the safety rod is bent towards the direction of the guide rod.

8. The light-weight manual double hook fifth wheel according to claim 1, wherein: two the couple board of butterfly structure is constituteed jointly to half lock hook board, every slope incision has all been seted up on half lock hook board upper portion, and is a pair of slope incision is constituteed the extension spring jointly and is held the chamber, the extension spring sets up in the extension spring holds the chamber, shift fork holding opening upper portion is provided with slope backstop face.