TWM665848U - Anti-fall device for the locking teeth of the lifting ring connection - Google Patents

Abstract

A fall arrester with a lifting ring connected to a locking tooth is provided with a lifting ring opening and a rope outlet at the top and bottom of an outer shell, a lifting ring of a lifting ring assembly is inserted into the lifting ring opening, a lifting ring seat is connected to the bottom of the lifting ring, the lifting ring seat is embedded in the top of the outer shell and connected to a locking tooth, a main shaft and a rotating hub which is sleeved on the main shaft and can rotate are fixed in the outer shell, a spiral spring is connected between the rotating hub and the main shaft, and a spring is connected to the rotating hub. A rope body is combined with a plurality of circles wound around the swivel, and the rope body passes through the outer shell through the opening of the hanging ring. A brake assembly is combined with the installation part on one side of the swivel, and the brake assembly is configured to be engaged with the locking tooth. Since the locking tooth is provided on the hanging ring assembly for the brake assembly to engage, it is not necessary to set a ratchet wheel for braking the swivel on the main shaft, which can reduce the volume of the anti-fall device and the simplified structure is conducive to reducing the production cost.

Description

Anti-fall device for the locking teeth of the lifting ring connection

This creation is related to safety protection equipment; in particular, it is a fall arrester with a lifting ring connected to a locking tooth.

The existing fall arrester has a main shaft fixed in an outer shell, a rotating hub and a ratchet wheel rotatably connected to the main shaft, a brake assembly connected to one side of the rotating hub, and a rope body wound around the rotating hub for multiple turns connected around the rotating hub.

When the above-mentioned fall arrester is used, the outer shell is fixed at one place, and one end of the rope body passing through the outer shell is connected to the backpack safety belt worn by the human body. When the human body wearing the backpack safety belt falls from the air, the rope body will be pulled to make the rotating hub inside the fall arrester rotate rapidly, so that the braking assembly connected to the rotating hub changes from a state that cannot be engaged with the ratchet to a state that can be engaged with the ratchet due to the centrifugal force of the rapid rotation. When the braking assembly is engaged with the ratchet, it will prevent the rotating hub from continuing to rotate and release the rope body, which can prevent the human body from continuing to fall down, and achieve the effect of safe fall prevention.

Although the above-mentioned existing fall arrester has the effect of preventing the human body from falling, since the ratchet and the wheel hub in the fall arrester are mounted on the main shaft fixed in the outer shell, such a setting makes it impossible to reduce the length of the main shaft and the volume of the outer shell, and the volume of the fall arrester cannot be effectively miniaturized.

In view of this, the purpose of this invention is to redesign the structure of the brake assembly that can be engaged with the rotating hub to make the internal structure of the fall arrester more streamlined, and to achieve the effect of reducing the size of the fall arrester and reducing the production cost.

In order to achieve the above-mentioned purpose, the invention provides a fall arrester with a hanging ring connected to a locking tooth, comprising an outer shell, a hanging ring assembly, and a fall arrester body. The top of the outer shell has a hanging ring opening, the bottom of the outer shell has a rope outlet, the inner part of the outer shell has an installation space, the installation space is communicated with the rope outlet and the hanging ring opening respectively, and the outer shell forms a hanging ring seat embedding groove at a portion adjacent to the inner side of the hanging ring opening. The hanging ring assembly comprises a hanging ring seat, a locking tooth and a hanging ring; the hanging ring seat is embedded in the hanging ring seat embedding groove; the locking tooth is connected to one side of the hanging ring seat; the middle of the hanging ring is inserted into the hanging ring mouth and is connected to the hanging ring seat with its inner end. The anti-fall device body includes a main shaft, a rotating hub, a spiral spring, a rope body and a brake assembly; the main shaft is fixed in the installation space; the rotating hub is rotatably fitted around the main shaft, one side of the rotating hub has a mounting portion and a spiral spring chamber inside; the spiral spring is arranged in the spiral spring chamber and connected between the main shaft and the rotating hub; one end of the rope body is combined with the rotating hub and is wound around the rotating hub for multiple turns, and the other end of the rope body passes through the rope outlet; the brake assembly is combined with the mounting portion and is configured to be engaged with the locking tooth.

The effect of the invention is that the locking tooth is arranged on the ring seat at the bottom of the ring assembly so that the locking tooth is located on the upper side of the installation space, and the locking tooth is then engaged with the brake assembly coupled to one side of the turning hub, thereby producing a braking effect on the turning hub and the rope body released by the turning hub. In this way, there is no need to provide a ratchet on the main shaft or the inner side of the outer shell for the brake assembly to engage, which can reduce the length of the main shaft and the volume of the outer shell along the extension direction of the main shaft. In addition to miniaturizing the volume of the invention, the internal structure of the outer shell can be simplified by only providing the rotating hub and the brake assembly around the main shaft, which is also beneficial to reduce the production cost of the invention.

In order to more clearly explain the invention, a preferred embodiment is given and described in detail with reference to the drawings. Please refer to FIGS. 1 to 5 , which are a preferred embodiment of the invention, a fall arrester 100 with a hanging ring connected to a locking tooth, comprising an outer shell 10, a hanging ring assembly 20, and a fall arrester body 30. The hanging ring assembly 20 is combined with the outer shell 10, and the fall arrester body 30 is installed in the outer shell 10. According to the arrangement method of hanging the housing 10 and the fall arrester body 30 at a certain place through the hanging ring assembly 20, the two sides of the housing 10 corresponding to the upper and lower directions are respectively called the top side and the bottom side, and the following description is based on the above-defined directions.

The outer shell 10 includes two half shells 10A and has an installation space S inside. The two half shells 10A are connected by screws so that the two half shells 10A can be detached. In other preferred embodiments, the two half shells 10A can also be connected by hooks or tenons. Each half shell 10A has a side wall 12 and a peripheral wall 14 connected to the side wall 12, and the two side walls 12 of the two half shells 10A are opposite to each other. A hanging ring recess 161 is formed at the edge of the top side of each peripheral wall 14. The two hanging ring recesses 161 are semicircular and merge to form a hanging ring opening 16. The hanging ring opening 16 is communicated with the installation space S and has a positioning flange 162 around the hanging ring opening 16. The housing 10 forms a hanging ring seat embedding groove 163 at the top of the installation space S adjacent to the inner side of the hanging ring opening 16. A rope threading notch 181 is formed at the edge of the bottom side of each peripheral wall 14 . The two rope threading notches 181 are combined to form a rope outlet 18 . The rope outlet 18 is communicated with the installation space S. A guide ring 182 is fixed around the rope outlet 18 .

The lifting ring assembly 20 includes a lifting ring seat 22, a locking tooth 24 and a lifting ring 26. The lifting ring seat 22 is embedded in the lifting ring seat embedding groove 163 of the housing 10, and the lifting ring seat 22 has a top plate 221 and a surrounding plate 222 connected to the top plate 221. The middle of the top plate 221 has a lifting ring seat hole 223, and the lifting ring seat hole 223 is located directly below the lifting ring opening 16. The locking tooth 24 is a ratchet and is connected to one side of the lifting ring seat 22. Specifically, the locking tooth 24 is connected to one side of the surrounding plate 222.

The hanging ring 26 includes a rod 261, a ring 262 and a pin 263. The rod 261 is inserted into the hanging ring opening 16 and has a positioning groove 2611 around it. The positioning flange 162 around the hanging ring opening 16 is embedded in the positioning groove 2611 to fix the position of the rod 261. The bottom end of the rod 261 passes through the hanging ring seat hole 223 of the hanging ring seat 22. A buckling flange 2612 is formed around the bottom end of the rod 261. The buckling flange 2612 abuts against the bottom end of the hanging ring seat hole 223. The top end of the rod 261 passes through an inner pin hole 2613 in a transverse direction. The ring portion 262 is inverted C-shaped and has two lugs 2621 on both sides. A pair of outer pin holes 2622 are inserted through the two lugs 2621. The pin 263 is inserted through the outer pin holes 2622 and fixed to the inner pin hole 2613.

The anti-fall device body 30 includes a bracket 32, a main shaft 34, a pivot 36, a spiral spring 38, a rope body 31 and a brake assembly 33. The bracket 32 includes two discs 321, which are hollow discs and are embedded in the middle of each side wall 12 by insert injection molding. The center of each disc 321 has a through hole 322, and each through hole 322 penetrates each side wall 12. The two through holes 322 are both set as non-circular holes. In other preferred embodiments, only one of the through holes 322 can be set as a non-circular hole.

The direction in which the axis of the main shaft 34 extends defines an axis direction L, which is perpendicular to the up-down direction. The two ends of the main shaft 34 form an end portion 341, respectively. The shape of the periphery of each end portion 341 conforms to the shape of the corresponding through hole 322. Each end portion 341 is embedded in each through hole 322 and the outer end of each end portion 341 has a screw hole 342. A fixing screw 35 is screwed in each screw hole 342. Each fixing screw 35 has a head 351. Each head 351 abuts against the periphery of each through hole 322, thereby fixing the main shaft 34 to the installation space S of the housing 10, and the main shaft 34 cannot rotate relative to the housing 10.

The rotating hub 36 is rotatably sleeved around the main shaft 34. The rotating hub 36 has a rope groove 361 around it and a coil spring chamber 362 inside it. The rotating hub 36 has a mounting portion 37 on one of the two sides corresponding to the axial direction L. The mounting portion 37 includes a mounting surface 363 and a fixing plate 37A screwed to the mounting surface 363. The mounting surface 363 has an inner plate embedding groove 364 in the middle, and the inner surface of the inner plate embedding groove 364 has a limit block 365. The fixed plate 37A has an outer plate 371 and an inner plate 372 connected in sequence along the axial direction L. The inner plate 372 is concentrically connected to the center of the outer plate 371. The inner plate 372 is embedded in the inner plate embedding groove 364 and has a limiting groove 3721. The limiting groove 3721 is fitted on the limiting block 365 for fixation. The center of the fixed plate 37A has a fixed plate shaft hole 371A. The fixed plate shaft hole 371A passes through the center of the outer plate 371 and the inner plate 372 and can be rotatably fitted on the main shaft 34.

3 and 5 to 8, the outer plate 371 of the fixed plate 37A is provided with two pawl grooves 373 arranged in a surrounding and spaced manner. In the preferred embodiment, the two pawl grooves 373 are located on opposite sides of the main shaft 34, and each pawl groove 373 is adjacent to the mounting surface 36 along one of the two sides of the axial direction L. 3, and the other side has a side wall 374. One side of each pawl groove 373 forms an inner wall 375, and the other side forms a spring bottom groove 3751. Each side wall 374 has a shaft hole 376. Each shaft hole 376 is located between each inner wall 375 and each spring bottom groove 3751, and each shaft hole 376 is adjacent to each inner wall 375.

The coil spring 38 is disposed in the coil spring chamber 362. The coil spring 38 has two ends, one end of which is coupled to the main shaft 34, and the other end is coupled to the pivot 36. Thus, when the pivot 36 rotates relative to the main shaft 34, the coil spring 38 provides a restoring force for the pivot 36 to rotate and return to its original position. The rope body 31 has two ends and one end is coupled to the hub 36. The rope body 31 is accommodated in the rope groove 361 and is wound around the hub 36 for multiple turns. The other end of the rope groove 361 passes through the rope outlet 18 of the housing 10 from the inner side of the guide ring 182. When the rope body 31 is pulled outward from the rope outlet 18 by an external force, the rope body 31 drives the hub 36 to rotate with the main shaft 34 as the rotation center. At this time, the rotation direction of the hub 36 is defined as forward rotation. On the contrary, when the tension for pulling the rope body 31 outward no longer exists, the spiral spring 38 provides a restoring force for the rotating hub 36 to rotate back to its original position. At this time, the rotating hub 36 will rotate in the opposite direction and retract the rope body 31 that is pulled outward into the outer shell 10.

The brake assembly 33 includes a number of pawl blocks 33A equal to the number of the pawl grooves 373. In the preferred embodiment, the brake assembly 33 includes two pawl blocks 33A. The pawl blocks 33A are respectively accommodated in the pawl grooves 373. Each pawl block 33A includes a base 331 and a body 332 connected to each other. Each base 331 has a shaft 3311. The shaft 3311 is rotatably inserted into each shaft hole 376. Each body 332 is close to each inner wall 375, and each body 332 rotates in the positive direction corresponding to the rotating hub 36. A pawl 3321 and a spring groove 3322 are formed on the two sides of the reverse rotation, respectively. Please refer to Figures 3 and 8. A compressed return spring 333 is set in each spring groove 3322 and each spring bottom groove 3751. Each return spring 333 keeps each pawl block 33A at a first position P1, that is, the position where each body 332 is close to each inner wall 375.

Please refer to Figures 5 and 7 to 9. When the rope 31 is pulled outward by the force and drives the rotating hub 36 to rotate in the forward direction, if the rotation speed of the pawl blocks 33A of the braking assembly 33 along with the rotation of the rotating hub 36 exceeds a predetermined speed, the centrifugal force received by each pawl block 33A exceeds the elastic force biased by each return spring 333 of each pawl block 33A. At this time, each pawl block 33A will rotate around with each shaft 3311 as the rotation center to a second position P2. When each pawl block 33A is at the second position P2, each body 332 is rotated outward from each inner wall 375 and each pawl 3321 extends out of each pawl groove 373. At this time, the trajectory of the pawls 3321 rotating with the rotating hub 36 interferes with the position of the locking tooth 24, so that the pawl 3321 of one of the pawl blocks 33A rotating to the top engages with the locking tooth 24, so that the rotating hub 36 stops rotating immediately. When the rotating hub 36 stops rotating, it also stops releasing the rope body 31 outward. At this time, the other pawl block 33A at the bottom is pushed by the corresponding return spring 333, and thus returns to the first position P1 from the second position P2 rotated outward.

The value of the predetermined rotation speed for rotating the pawl blocks 33A from the first position P1 to the second position P2 is set to match the application scenario of the invention in which the housing 10 is hung at a fixed place by the hanging ring 26, and the other end of the rope body 31 passing through the rope outlet 18 is connected to a backpack safety belt worn by a human body. The value of the predetermined rotation speed is generally set to be higher than the rotation speed of the turning hub 36 when the rope body 31 is pulled out from the rope outlet 18 by the hand or the movement of the human body; the value of the predetermined rotation speed is lower than the rotation speed of the turning hub 36 when the human body falls from the air and the turning hub 36 is rotated by the rope body 31 during the falling process. In this way, the fall arrester 100 connected to the locking teeth of the hanging ring can prevent the human body from falling continuously when the human body falls from the air, but under normal conditions, the rope body 31 can be pulled out by human hands or human body movement, and the rotating hub 36 can be rolled back into the rope body 31 when the rope body 31 is not continuously pulled out, so as not to hinder the movement of the user during work.

The effectiveness of the above-mentioned preferred embodiment of the present invention lies in that the locking tooth 24 is provided on the ring seat 22 at the bottom of the ring assembly 20, so that the locking tooth 24 is provided on the top side of the installation space S and above the brake assembly 33, and then the locking tooth 24 is engaged with the brake assembly 33 coupled to one side of the swivel hub 36, thereby producing a braking effect on the swivel hub 36. Such a structure makes it unnecessary for the anti-fall device 100 with the hanging ring connected to the locking tooth to be provided with a ratchet or similar brake structure for the brake assembly 33 to engage around the main shaft 34 or on the inner side of the outer shell 10. Therefore, compared with the structure in which the ratchet must be provided on the main shaft 34, the length of the main shaft 34 and the volume of the outer shell 10 along the axial direction L can be reduced. In addition to miniaturizing the volume of the anti-fall device 100 with the hanging ring connected to the locking tooth, simplifying the internal structure of the anti-fall device 100 with the hanging ring connected to the locking tooth is also conducive to reducing the production cost.

In addition to the above-mentioned preferred embodiment, the present invention forms two pawl grooves 373 around the fixed plate 37A in a surrounding and spaced arrangement, and then sets two of the above-mentioned pawl blocks 33A in the two pawl grooves 373. In other preferred embodiments, more than three pawl grooves 373 can be formed around the fixed plate 37A in a surrounding and spaced arrangement, and in this case, the brake assembly 33 sets more than three of the above-mentioned pawl blocks 33A in the more than three pawl grooves 373.

The above is only the best feasible embodiment of the present invention. Any equivalent changes made by applying the description of the present invention and the scope of patent application should be included in the patent scope of the present invention.

100: Anti-fall device for connecting the lifting ring to the locking tooth 10: Outer shell 10A: Half shell 12: Side wall 14: Peripheral wall 16: Lifting ring opening 161: Lifting ring recess 162: Positioning flange 163: Lifting ring seat groove 18: Rope outlet 181: Rope threading recess 182: Guide ring 20: Lifting ring assembly 22: Lifting ring seat 221: Top plate 222: Enclosure plate 223: Lifting ring seat hole 24: Locking tooth 26: Lifting ring 261: Rod 2611: Positioning groove 2612: Buckle flange 2613: Inner pin hole 262: Ring 2621: Lug 2622: Outer pin hole 263: Pin 30: Anti-fall device body 31: Rope body 32: Brake 321: Disc body 322: Through hole 33: Brake assembly 33A: Pawl block 331: Base 3311: Shaft 332: Body 3321: Pawl 3322: Spring groove 333: Return spring 34: Spindle 341: End 342: Screw hole 35: Fixing screw 351: Head 36: Hub 361: Rope groove 362: Spring chamber 363: Mounting surface 364: Disk embedded in groove 365: Stopper 37: Mounting part 37A: Fixed disk 371: Outer disk 371A: Fixed disk shaft hole 372: Inner disk 3721: Stopper groove 373: Pawl groove 374: Side wall 375: Inner wall 3751: Spring bottom groove 376: Rotating shaft hole 38: Spring L: Axis direction P1: First position P2: Second position S: Mounting space

Figure 1 is a three-dimensional view of a preferred embodiment of the present invention. Figure 2 is an exploded view of the preferred embodiment of the present invention. Figure 3 is an exploded view of the pivot and brake assembly in Figure 2. Figure 4 is a left side view of the preferred embodiment of the present invention. Figure 5 is a cross-sectional view in the direction of 5-5 of Figure 4. Figure 6 is a front view of the preferred embodiment of the present invention. Figure 7 is a cross-sectional view in the direction of 7-7 of Figure 6. Figure 8 is a cross-sectional view in the direction of 8-8 of Figure 6. Figure 9 is a schematic diagram of the action of the pawl block rotated to the upper side in Figure 8 engaging with the locking tooth.

100: Anti-fall device for the locking tooth of the lifting ring connection

10: Shell

10A: Half shell

12: Side wall

14: Peripheral wall

16: Hanging ring mouth

161: Ring notch

162: Positioning flange

18: Rope exit

181: Rope threading notch

182:Guide ring

20: Ring assembly

22: Ring seat

221: Top plate

222: Hoardings

24: Locking teeth

261: Rod

2611: Positioning groove

262: Environmental Protection Department

2621: Lugs

30: Fall arrester body

31: Rope body

32: Bracket

321: Plate

322: Perforation

33: Brake assembly

33A: Ratchet block

341: End

342: screw hole

35:Fixing screws

351:Head

36: Transformation

363: Installation surface

37: Installation Department

37A: Fixed plate

S: Installation space

Claims (10)

A fall arrester with a hanging ring connected to a locking tooth, comprising: an outer shell, the top of which has a hanging ring opening, the bottom of which has a rope outlet, the interior of which has an installation space, the installation space is communicated with the rope outlet and the hanging ring opening respectively, and the outer shell forms a hanging ring seat embedding groove at a portion adjacent to the inner side of the hanging ring opening; a hanging ring assembly, comprising a hanging ring seat, a locking tooth and a hanging ring; the hanging ring seat is embedded in the hanging ring seat embedding groove; the locking tooth is connected to one side of the hanging ring seat; the middle of the hanging ring is inserted into the hanging ring opening and is connected to the hanging ring seat with its inner end; and A fall arrester body includes a main shaft, a rotating hub, a spiral spring, a rope body and a brake assembly; the main shaft is fixed in the installation space; the rotating hub is rotatably fitted around the main shaft, one side of the rotating hub has a mounting portion and a spiral spring chamber inside; the spiral spring is arranged in the spiral spring chamber and connected between the main shaft and the rotating hub; one end of the rope body is coupled to the rotating hub and is wound around the rotating hub for multiple turns, and the other end of the rope body passes through the rope outlet; the brake assembly is coupled to the mounting portion and is configured to be engaged with the locking tooth. The anti-fall device with a lifting ring connected to a locking tooth as described in claim 1, wherein the periphery of the lifting ring mouth has a positioning flange; the lifting ring has a rod portion and a ring portion, the periphery of the rod portion has a positioning groove, the positioning flange is embedded in the positioning groove for fixation, the top end of the rod portion laterally penetrates an inner pin hole, the two sides of the ring portion have two lugs, a pair of outer pin holes are penetrated through the two lugs, and a pin is penetrated and fixed through the pair of outer pin holes and the inner pin hole. A fall arrester with a hanging ring connected to a locking tooth as described in claim 2, wherein the hanging ring seat has a top plate and a surrounding plate connected to the top plate, the top plate has a hanging ring seat hole in the middle, the bottom end of the rod passes through the hanging ring seat hole, and a buckle flange is formed around the bottom end of the rod, and the buckle flange rests against the periphery of the bottom end of the hanging ring seat hole. A fall arrester with a hanging ring connected to a locking tooth as described in claim 3, wherein the outer shell includes two half shells, and the two half shells are connected in a detachable manner; the top side of each half shell has a hanging ring recess, and the two hanging ring recesses of the two half shells are combined to form the hanging ring opening; the bottom side of each half shell has a rope threading recess, and the two rope threading recesses of the two half shells are combined to form the rope outlet. The anti-fall device with a hanging ring connected to a locking tooth as described in claim 4, wherein each half shell has a side wall and a peripheral wall connected to the side wall; each hanging ring recess is formed on the edge of the top side of each peripheral wall; each rope threading recess is formed on the edge of the bottom side of each peripheral wall. The anti-fall device with a hanging ring connected to a locking tooth as described in claim 5, wherein the anti-fall device body includes a bracket, and the bracket includes two discs, and the two discs are respectively embedded in the middle of each side wall and have a through hole, and at least one of the two through holes is a non-circular hole; the two ends of the main shaft respectively form an end portion, each of the end portions is embedded in each through hole and has a screw hole, and a fixing screw is screwed in each screw hole, and each of the fixing screws has a head, and each of the heads is fixed against the periphery of each through hole. The anti-fall device of the hanging ring connected to the locking tooth as described in claim 1, wherein the braking assembly includes a plurality of pawl blocks; the pawl blocks respectively include a base and a body connected to each other, the pawl blocks are pivotally connected to the periphery of the installation part through the bases in a surrounding and spaced arrangement, and the bodies of the pawl blocks respectively have a pawl; a reset spring is respectively arranged between each pawl block and the installation part, Each of the return springs keeps each of the pawl blocks at a first position; when the rotation speed of the pawl blocks rotating with the hub exceeds a predetermined rotation speed, each of the pawl blocks rotates to a second position due to centrifugal force; when each of the pawl blocks is at the second position, the tracks of the pawls rotating with the hub interfere with the position of the locking tooth, thereby enabling the pawl of one of the pawl blocks to engage with the locking tooth. The anti-fall device with a hanging ring connected to a locking tooth as described in claim 7, wherein the main shaft has an axial direction; the mounting portion includes a mounting surface and a fixed plate coupled to the mounting surface, the center of the fixed plate has a fixed plate shaft hole, and the fixed plate shaft hole can be rotatably fitted on the main shaft; a plurality of pawl grooves are formed around the fixed plate in a surrounding and spaced arrangement, one side of each pawl groove forms an inner wall, and the other side forms a spring bottom groove; one of the two sides of each pawl groove along the axial direction is adjacent to the mounting surface, and the other side has a side wall; each of the side walls has a rotating shaft hole, and the The shaft hole is located between the inner wall and the spring bottom groove; the pawl blocks are respectively accommodated in the pawl grooves, the base of each pawl block has a shaft, and the shaft is rotatably inserted into the shaft hole, each pawl is formed on one side of each body, and a spring groove is formed on the other side of each body, and each return spring is compressed and arranged between each spring groove and each spring bottom groove; when each pawl block is in the first position, each body leans against each inner wall; when each pawl block is in the second position, each body rotates outward from each inner wall and each pawl extends out of each pawl groove. The anti-fall device with a hanging ring connected to a locking tooth as described in claim 8, wherein the middle of the mounting surface has an inner plate embedding groove; the fixed plate has an outer plate, the pawl grooves are formed around the outer plate, the middle of the outer plate is connected to an inner plate, and the inner plate is embedded in the inner plate embedding groove. As described in claim 9, the anti-fall device with a hanging ring connected to a locking tooth has a limit block on the inner surface of the inner plate embedding groove; the inner plate has a limit groove, and the limit groove is fitted on the limit block for fixing.

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