AU2013216670A1 - Automatic safety device for quick coupler - Google Patents

Abstract

Disclosed therein is an automatic safety device for a quick coupler which is used when an attachment is joined to an arm of heavy equipment, such as excavators. The automatic safety device has a new type latch assembly that is automatically locked and released in liaison with a cylinder actuating a movable hook of the quick coupler for joining and detaching attachments, such as buckets or breakers, thereby securing convenience and safety in work and preventing various accidents by stably keeping the joined state of the attachment even though an external force is frequently applied during work. [Figures] [Fig. 1] 10a10 341 32a , 40 22 o 60 [F21 IFig. 2]

Description

Australian Patents Act 1990 - Regulation 3.2 ORIGINAL COMPLETE SPECIFICATION STANDARD PATENT Invention Title Automatic safety device for quick coupler The following statement is a full description of this invention, including the best method of performing it known to me/us: 5102 BACKGROUND OF THE INVENTION Field of the Invention [01] The present invention relates to an automatic safety device for a quick coupler, and more particularly, to an automatic safety device for a quick coupler which is used when an attachment is joined to an arm of heavy equipment, such as excavators. Background Art [02] In general, heavy equipment, such as excavators, used in construction sites, civil-engineering sites or other sites is construction machinery widely used for road construction, water supply and drain system construction, building groundwork, and work for collecting soil, sand and gravels, and can carry out work selectively using attachments of various kinds according to usage of work. [03] In other words, the heavy equipment can carry out work of various kinds, for instance, excavation work using buckets, concrete building crushing work and cutting work of reinforcing rods using crushers, destruction work of rocks and concrete structures using breakers, carrying work of scrap irons and rocks using grabs, building groundwork of shafts and water supply and drain systems using clamshell buckets, while replacing the attachments of various kinds according to usage. [04] Such an attachment is detachably joined to an arm of an excavator, and is replaceable according to usage of work. Recently, quick couplers which can connect the attachment easily have been developed and widely used. [05] That is, when an excavator driver manipulates a lever to assemble or disassemble the quick coupler, which is mounted at the front end of the arm, to or from a bucket or a breaker, the attachment can be easily handled. (06] Moreover, the quick coupler has a safety device such as a safety pin, so as to prevent various accidents, for instance, to prevent a danger that the attachment is separated due to a trouble of a hydraulic cylinder of the quick coupler or due to a damage of a hydraulic hose during operation. [07] For instance, Korean Utility Model Registration No. 20-0225763 entitled "Coupler for excavator" and Korean Patent No. 10-0397586 entitled "Safety device of clamp for mounting excavator bucket" disclose quick couplers respectively having safety pins. [08] However, in the case of using the safety pin, because an excavator driver or an assistant worker must directly put the safety pin into a safety pin hole of the quick coupler or pull - -2out the safety pin from the safety pin hole, it is very complicated and hard and it takes much time to do so. [09] As described above, the conventional quick couplers have several problems in that they are inconvenient in work because the safety pin is joined to the quick coupler manually, and in that they have a higher risk of accidents, for instance, because the driver sometimes uses the quick coupler without using the safety pin. [10] In order to overcome the above-mentioned problems, Korean Patent No. 10-1096085 discloses a "quick coupler of excavator" including an automatic safety device having an automatic lock cylinder and a retaining protrusion. [11] However, the safety device proposed in the quick coupler of the excavator also has several problems in that it is disadvantageous in structure because it additionally needs a hydraulic cylinder, and in that the safety device is deteriorated in reliability because it still has the above-mentioned problems, such as the trouble of the hydraulic cylinder of the quick coupler or the damage of the hydraulic hose. [12] In consideration of the above problems, Korean Patent No. 10-1210833 entitled "Automatic safety device for quick coupler" discloses a hitch which is a safety device and is automatically locked and released in interlock with a movable hook actuated by a hydraulic cylinder.

[13] In other words, Korean Patent No. 10-1210833 discloses a safety device with a structure that resiliently supports the hitch using a coil type spring standing on the top surface of the front end portion of the hitch mounted on a body. [14] However, the automatic safety device for the quick coupler also has a problem in that an external force is frequently applied in the direction to lift up the hitch when concrete destruction work is carried out using the attachment such as the breaker, and in this instance, in the case that the external force applied to the hitch is greater than elasticity of the spring, the spring is compressed, and hence, the attachment pin is pulled out. [15] Cited References [16] Cited reference 1: Korean Patent No. 10-1210833 (published on December 11, 2012) [17] Cited reference 2: International Patent Laid-open No. W02008/051095 (published on May 02, 2008) SUIMARY OF THE INVENTION [18] Accordingly, the present invention has been made to solve the above-mentioned problems occurring in the prior arts, and it is an object of the present invention to provide an automatic safety device for a quick coupler, which has a new type latch assembly that is automatically locked and released in -4liaison with a cylinder actuating a movable hook of the quick coupler for joining and detaching attachments, such as buckets or breakers, thereby securing convenience and safety in work and preventing various accidents by stably keeping the joined state of the attachment even though an external force is frequently applied during work. [19] To achieve the above objects, the present invention provides an automatic safety device for a quick coupler including: a body connected and assembled to an arm and a link device of an excavator using front and rear pin holes; a fixed hook fixed to the lower portion of the rear of the body; a latch elevatably mounted inside the body just above the fixed hook, the latch holding or releasing an attachment pin together with the fixed hook, the latch having: operating spaces for allowing latch actuating parts to move back and forth in a state where the latch actuating parts respectively put in the operating spaces; and inclined surfaces formed on the operating spaces; a cylinder supported inside the body using a cylinder pin located at the rear end; and a slider connected to a rod of the cylinder using a hook pin so as to move straight in the back and forth direction of the body, the slider having: a movable hook located at the lower portion of the front of the body for holding or releasing the attachment pin according to the straight movement; and latch actuating parts elongated straight toward the rear of the body -5and having upwardly inclined portions formed at ends thereof so as to ascend and descend the latch through a contact motion between the inclined portions and the inclined surfaces of the latch along the straight movement. [20] In this instance, a pair of the latch actuating parts extend from both sides of the front of the slider side by side, the operating spaces of the latch are respectively provided at both sides of the latch, and the latch actuating parts are movable in the back and forth direction in the state where they are respectively put in the operating spaces disposed at both sides of the latch. [21] Here, the latch includes a hook portion formed at the lower end of the latch facing the fixed hook, such that the hook portion surrounds and holds the upper portion of the attachment pin received in the fixed hook. E22] Furthermore, the operating spaces of the latch are respectively formed in a rectangular dent hollowed toward the center of the latch. [23] The automatic safety device for the quick coupler according to the present invention has the following advantages. [24] First, the safety device can automatically lock and release in liaison with the movable hook and the latch actuating parts of the slider operated by the cylinder for joining and detaching the attachment, thereby providing convenience in use -6and preventing a damage of the machines due to the attaching and detaching actions and preventing a risk of accidents. [25] Second, the safety device can enhance safety by stably keeping the joined state of the attachment pins even though the external force is frequently applied during work, because the. latch which is operated in liaison with the latch actuating parts of the slider stands erect and presses the top portion of the attachment pin under the condition that it is restricted in vertical movement by the latch actuating parts. [26] Third, because the automatic safety device adopts the combination of the latch actuating parts formed integrally with the slider and the single latch for joining the attachment pins while ascending and descending by the latch actuating parts, the automatic safety device according to the present invention is simple in structure and advantageous in handling and maintenance. BRIEF DESCRIPTION OF THE DRAWINGS [27] The above and other objects, features and advantages of the present invention will be apparent from the following detailed description of the preferred embodiments of the invention in conjunction with the accompanying drawings, in which: -7- [28] FIG. 1 is an exploded perspective view of a quick coupler having an automatic safety device according to a preferred embodiment of the present invention; [29] FIG. 2 is a perspective view of the quick coupler having the automatic safety device; [30] FIG. 3 is an exploded perspective top view of the quick coupler having the automatic safety device; [31] FIG. 4 is a perspective view of essential parts of the automatic safety device for the quick coupler; [32] FIG. 5 a sectional view of the automatic safety device for the quick coupler; [33] FIG. 6 is a sectional view showing an operating condition that an attachment pin is joined to the automatic safety device for the quick coupler; and [34] FIG. 7 is a sectional view showing an operating condition that the attachment pin is released from the automatic safety device for the quick coupler. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT [35] Reference will be now made in detail to the preferred embodiment of the present invention with reference to the attached drawings. [36] In the detailed description of the preferred embodiment and claims of the present invention, the terms, -8- 'front', 'forward movement', and 'front face', are used on the basis of the direction that a movable hook is mounted, the terms, 'rear', 'backward movement', and 'rear face', are used on the basis of the direction that a fixed hook is mounted, and the terms, 'upper portion' and 'lower portion', are used on the basis of the direction that the fixed hook and the movable hook are mounted and the reverse direction. [37] FIG. 1 is an exploded perspective view of a quick coupler having an automatic safety device according to a preferred embodiment of the present invention, FIG. 2 is a perspective view of the quick coupler having the automatic safety device, FIG. 3 is an exploded perspective top view of the quick coupler having the automatic safety device, FIG. 4 is a perspective view of essential parts of the automatic safety device for the quick coupler, and FIG. 5 a sectional view of the automatic safety device for the quick coupler. [38] As shown in FIGS. 1 to 5, the automatic safety device for the quick coupler has a structure that is automatically operated at the time of joining and using the quick coupler so as to provide convenience in joining and safety in use because it uses a combination of a slide-type movable hook and a latch operated in liaison with the movable hook. -9- [39] For this, the automatic safety device for the quick coupler includes: a body 10 forming the entire outward appearance and having a fixed hook 12; a slider 30 slidably mounted inside the body 10 and having a movable hook 31; a cylinder 20 operating the slider 30; and a latch 40 holding or releasing attachment pins 100a and 100b together with the fixed hook 12 while ascending and descending in liaison with the slider 30. [40] Here, the attachment pins 100a and 100b are mounted on various attachments, such as buckets, crushers, or others, mounted on an excavator arm, and are detachably joined to the fixed hook 12 and the movable hook 31 of the quick coupler. [41] The body 10 includes pin holes 10a and 10b respectively formed at the front and the rear of the upper part to be joined with the arm and a link device of the excavator by pins, and the fixed hook 12 formed integrally at the rear of the lower part for joining the attachment pin. [42] The body 10 has a predetermined space therein, and the cylinder 20 and the slider 30 may be mounted in the space of the body 10. ] [43] Moreover, the body 10 has two slide grooves 11 (in FIG. 5) formed on the inner side walls side by side in the longitudinal direction of the body 10, and the slider 30 has - 10slide protrusions 35 which are formed on both sides thereof and respectively fit into the slide grooves 11 so as to be slidably guided. [44] Furthermore, the body 10 further includes a ring 13 mounted at the upper portion of the front on a plate crossing the space of the body 10 in the width direction. The ring 13 is used for easily carrying workpieces in a state where the quick coupler is mounted on the excavator but the attachment is not attached. [45] The upper part of the body 10 -is finished by a plate type upper cover 50, and the upper cover 50 serves to protect the cylinder 20 mounted therein from external shocks or foreign matters. [46] The cylinder 20 is actuating means for actuating the slider 30, for instance, may be a hydraulic cylinder operated by hydraulic pressure. In this instance, the cylinder 20 is arranged inside the space formed at the lower portion of the inside of the body 10, and is mounted in such a structure that a rod is located in front and the rear end of the cylinder 20 is supported to the body 10. [47] For instance, the cylinder 20 is located horizontally in the inside space of the body 10 in such a way that the rod faces the front, and in the above state, the rear end of the -11cylinder body is joined to the body 10 by a cylinder pin 21, and hence, the cylinder 20 is supported by the cylinder pin 21 of the rear end. For this, the cylinder 20 has a pin joining portion 22b formed integrally at the rear end thereof, such that the cylinder pin 21 penetrates through the pin joining portion 22b. [48] In the meantime, the movable hook 31 forms a pair together with the fixed hook 12 as means for joining the attachment pin. [49] Particularly, differently from the rotation-type movable hook of the conventional quick coupler, the movable hook 31 adopts a slide type which moves straight in the back and forth direction of the body, and hence, can be applied to various attachments, which are different from one another in a distance between attachment pins, through such an operation characteristic. [50J For this, the movable hook 31 is formed integrally to the slider 30 which slides back and forth inside the body 10. [51] The slider 30 is mounted in such a way as to be operated in a state where it is connected to the rod of the cylinder 20. [52] In more detail, the slider 30 has a pair of pin joining portions 33 formed on the front end of the upper face thereof. In this instance, the pin joining portions 22a of the - 12 rod of the cylinder 20 are located between the pin joining portions 33, and the pin joining portions 22a and 33 are joined together by a hook pin 34, such that the attachment pin is hooked or released while the slider 30 slidably moves in the back and forth direction by forward and backward movements of the rod of the cylinder 20 and the movable hook 31 moves back and forth together with the slider 30. [53] Additionally, the slide protrusions 35 are formed on both sides of the slider 30 in the longitudinal direction of the slider 30, and in this instance, the slide protrusions 35 are slidably joined to the slide grooves 11 of the body 10. [54] Accordingly, the slider 30 is guided to move straight using the slide protrusions 35 slidably fit into the slide grooves 11. [55] Meanwhile, the slider 30 is provided with means to operate the latch 40 substantially serving as a safety device to hold or release the attachment pin together with the fixed hook 12. [56] For this, the slider 30 includes a pair of latch actuating parts 32 which are formed at both sides of the rear side by side in the direction that the latch 40 is formed, namely, extend straight toward the rear side of the body 10, and are -13 formed in a bar shape with a rectangular section so as to ascend - and descend the latch 40 along the straight movement of the slider 30. [57] The latch actuating parts 32 includes extended portions 32b and inclined portions 32a. Each of the extended portions 32b is extended to a predetermined length from the side of the slider 30, and each of the inclined portions 32a is upwardly inclined at a predetermined angle at the end portion of the extended portion 32b. [58] Here, the extended portions 32b respectively put through operating spaces 41, which will be described later, of the latch 40 and serve to descend the latch 40 and support the descended latch 40. The inclined portions 32a get in contact with inclined surfaces 42 formed in the operating spaces 41 of the latch 40 so as to ascend the latch 40. [59] The action to ascend and descend the latch 40 through the latch actuating parts 32 and the structure to fix the vertical movement of the latch 40 in the ascended and descended states will be described later in more detail. [60] As described above, the movable hook 31 and the latch actuating parts 32 are formed integrally to the slider 30. Therefore, each attachment pin can be joined to or released from -14the fixed hook 12 and the movable hook 31 in order along the back and forth movements of the slider 30. [61] In the meantime, in the present invention, the latch 40 actually serves as the safety device. [62] The latch 40 holds or releases the attachment pin together with the fixed hook 12, and especially, functions to stably keep the joined state of the attachment in liaison with the latch actuating parts 32 of the slider 30 even though an external force is applied in the vertical direction, for instance, in concrete destruction work. [63] For this, the latch 40 of a rectangular plate form is mounted in a vertically elevatable manner and vertically stands above the fixed hook 12. As described above, the latch 40 performs ascending and descending actions by the latch actuating parts 32 of the slider 30 which slides back and forth inside the body 10. [64] The latch 40 includes a hook portion 43 of a hook shape, which is formed at the lower end of the latch 40 facing the fixed hook 12 and has a round face to surround and hold the upper portion of the attachment pin with a round section put in the fixed hook 12. -15- [65] Moreover, the latch 40 has the operating spaces 41 for allowing the latch actuating parts 32 to elevate the latch 40 while moving in the back and forth direction in a state where the latch actuating parts 32 respectively put through the operating spaces 41. [66] The operating spaces 41 are respectively formed at right and left sides of the latch 40 in the structure that the latch 40 is cut through the whole thickness of the plate of the latch 40, namely, in the structure that the entire thickness of the latch 40 is cut, so that the extended portions 32b of the latch actuating parts 32 respectively penetrate through the latch 40. [67] In more detail, the operating spaces 41 respectively have the structure that the latch 40 is cut in the middle of both sides in the back and forth direction, namely, are formed in a rectangular dent hollowed toward the center of the latch 40 from both sides of the latch 40. [68] In this instance, it is preferable that the operating spaces 41 allow the extended portions 32b of the latch actuating parts 32 to move straight in the back and forth direction in the state where the extended portions 32b are put in the operating spaces 41, and that the latch 40 has a height to restrict the -16vertical movement in the state where the extended portions 32b of the latch actuating parts 32 are put through the operating spaces 41. [69] The upper face of each operating space 41 has an inclined surface 42 corresponding to the inclined portion 32a of the latch actuating part 32, namely, an inclined surface 42 upwardly inclined from the rear face to the front face of the latch 40. Thereby, the latch 40 ascends when the inclined portions 32a of the latch actuating parts 32 get in contact with the inclined surfaces 42 of the operating spaces 41 but descends when the contact state between the inclined portions 32a and the inclined surfaces 42 is removed. [70) In the state where the latch 40 is descended, because the extended portions 32b of the latch actuating parts 32 support the latch 40 in the state where they are put through the operating spaces 41 of the latch 40, the latch 40 is restricted in its vertical movement. [71] In other words, in the descended state of the latch 40, because the extended portions 32b of the latch actuating parts 32 support the latch 40 in the state where they are put through the operating spaces 41 of the latch 40, the latch 40 is restricted in its vertical movement and keeps its fixed state. -17- [72] In the present invention, the latch 40 has a structure to stably ascend and descend inside the body 10. [73] For this, on both side walls of the inner face of the body 10 in which the latch 40 is mounted, two guide protrusions 14 are oppositely formed long in the vertical direction. The guide protrusions 14 are respectively fit to the guide grooves 44 vertically formed at both sides of the latch 40 so as to be guided in slide action. In this instance, the guide protrusions 14 are formed in a rectangular block shape and are joined to the inner walls of the body 10 by bolts. [74] As described above, because the latch 40 slides in a state where the guide protrusions 14 of the body 10 are fit into the guide grooves 44, the latch 40 can stably ascend and descend without any back and forth shaking during the ascending and descending actions. [75] Meanwhile, a cover 60 is mounted on the body 10 right behind the latch 40 so as to finish the rear side of the body 10, and has spaces for allowing the latch actuating parts 32 pass therethrough. The cover 60 has the same shape and structure as D the latch 40 except that the latch 40 has the inclined surfaces 42 and the hook portion 43. - 18- [76] Now, an operational state of the automatic safety device for the quick coupler having the above structure will be described as follows. [77] FIG. 6 is a sectional view showing an operating condition that an attachment pin is joined to the automatic safety device for the quick coupler, and FIG. 7 is a sectional view showing an operating condition that the attachment pin is released from the automatic safety device for the quick coupler. [78] As shown in FIG. 6, first, a lock state that the movable hook 31, the fixed hook 12 and the latch 40 of the quick coupler are joined to the attachment pins 100a and 100b of the both sides will be described as follows. [79] First, the latch actuating parts 32 of the slider 30, in more detail, the inclined portions 32a of the latch actuating parts 32, make in contact with the inclined surfaces of the latch 40 by the maximum forward movement of the cylinder 20, and in this state, the latch 40 opens the fixed hook 12 in the ascended state. In the above condition, the fixed hook 12 holds the bottom side of one 100b of the attachment pins 100a and 100b. [80] Furthermore, when the cylinder 20 is operated to backwardly move the slider 30 to the rear of the body 10, the contact state between the inclined portions 32a of the latch -19actuating parts 32 and the inclined surfaces of the latch 40 is removed, and the latch 40 descends in the state where it is joined to the body 10. Thereby, the hook portion 43 of the latch 40 holds the attachment pin 100b together with the fixed hook 12 while pressing the top portion of the attachment pin 100b (See FIG. 6(b)). [81] In the above state, when the cylinder 20 is operated to move the slider 30 backward more, the movable hook 31 secures a distance to hold the other attachment pin 100a. [82] After that, the joining work is finished when the movable hook 31 hold the attachment pin 100a while the sider 30 slides toward the front of the body 10 by the forward movement of the cylinder 20 (See FIG. 6(C)). [83] When the slider 30 moves inside the body 10 in the back and forth direction and is connected with the latch 40, one 100a of the attachment pins is automatically joined to the latch 40 by the movable hook 31 and the other one 100b is automatically joined to the latch 40 by the fixed hook 12, so that the attachments, such as buckets, can be easily attached and used to the quick coupler. [84] As described above, in the case of the attachment pin 100b joined with the latch 40 by the fixed hook 12, the latch 40 -20is pressed down while keeping its erected state. Moreover, as shown in FIG. 3, the latch 40 is joined in the state where it is restricted in ascending because being caught to the extended portions 32b of the latch actuating parts 32 through the operating spaces 41, so that the joined state of the attachment pin can be kept stably even though the external force is applied in the vertical direction, namely, in the direction to lift up the latch, during the concrete destruction work. [85] Next, the releasing action to release the movable hook 31, the fixed hook 12 and the latch 40 of the quick coupler from the attachment pins 100a and 100b is carried out in the reverse order of the joining action. Referring to FIG. 7, the releasing action will be described as follows. [86] First, in the state that the two attachment pins 100a and 100b are joined to both sides of the quick coupler (See FIG. 7(a)), when the slider 30 slides to the rear of the body 11 by the backward movement of the cylinder 20, the movable hook 31 is separated from the attachment pin 100a (See FIG. 7(b)). (87] In the above state, when the cylinder 20 moves forward to the maximum, the latch actuating parts 32 of the slider 30 are also moved forward, and thereby, the inclined portions 32a of the latch actuating parts 32 get in contact with the inclined -21surfaces of the latch 40, so that the latch 40 ascends and is separated from the other attachment pin 100b (See FIG. 7(c)). [88] As a result, because the attachment pin 100b comes out through an interval between the latch 40 and the fixed hook 12, a user can remove the attachment, such as the bucket, from the quick coupler, or replace the attachment with another one. [89] As described above, according to the present invention, because the safety device, namely, the latch assembly, is automatically operated immediately when the hooks arranged on both sides of the quick coupler are joined to the attachment pins, the automatic safety device for the quick coupler can secure convenience and safety in work. Furthermore, the automatic safety- device for the quick coupler according to the present invention can be applied to attachments of various standards without needing to correct the distance between the hooks of the quick coupler (the distance between the hooks is variable) because the movable hook is the slide type. [90] Particularly, because the latch is restricted in movement by the extended portions of the latch actuating parts under the condition that the latch is descended and holds the attachment pin together with the fixed hook, in the case that the concrete destruction work is carried out using the attachment - 22 such as a breaker, even though the external force is frequently applied, the attachment pins are not separated, and hence, the automatic safety device according to the present invention can enhance safety and efficiency in work. [91] It will be understood by those of ordinary skill in the art that the present invention is not limited to the example embodiment and the attached drawings and that various changes, modifications and alternations may be made therein without departing from the technical idea and the technical scope of the present invention. Throughout this specification and the claims which follow, unless the context requires otherwise, the word "comprise", and variations such as "comprises" and "comprising", will be understood to imply the inclusion of a stated integer or step or group of integers or steps but not the exclusion of any other integer or step or group of integers or steps. The reference in this specification to any prior publication (or information derived from it), or to any matter which is known, _is not, and should not be taken as an acknowledgment or admission or any form of suggestion that that prior publication (or information derived from it) or known matter forms part of the common general knowledge in the field of endeavour to which this specification relates. -23- The reference numerals in the following claims do not in any way limit the scope of the respective claims. -24-

Claims (5)

1. An automatic safety device for a quick coupler comprising: a body(10) connected and assembled to an arm and a link device of an excavator using front and rear pin holes (10a,10b); a fixed hook(12) fixed to the lower portion of the rear of the body(10); a latch(40) elevatably mounted inside the body(10) just above the fixed hook(12), the latch(40) holding or releasing an attachment pin together with the fixed hook(12), the latch(40) having: operating spaces(41) for allowing latch actuating parts(32) to move back and forth in a state where the latch actuating parts(32) respectively put in the operating spaces(41); and inclined surfaces(42) formed on the operating spaces(41); a cylinder(20) supported inside the body(10) using a cylinder pin(21) located at the rear end; and a slider(30) connected to a rod of the cylinder(20) using a hook pin(34) so as to move straight in the back and forth direction of the body(10), the slider(30) having: a movable hook(31) located at the lower portion of the front of the body(10) for holding or releasing the attachment pin according to the straight movement; and latch actuating parts(32) elongated straight toward the rear of the body(10) and having upwardly -25- inclined portions(32a) formed at ends thereof so as to ascend and descend the latch(40) through a contact motion between the inclined portions(32a) and the inclined surfaces(42) of the latch(40) along the straight movement.

2. The automatic safety device according to claim 1, wherein the latch(40) comprises a hook portion(43) formed at the lower end of the latch(40) facing the fixed hook(12), such that the hook portion(43) surrounds and holds the upper portion of the attachment pin received in the fixed hook(12).

3. The automatic safety device according to claim 1, wherein the latch(40) ascends and descends in a state where guide protrusions(14) formed at both sides of the body(10) are fit into guide grooves(44) formed vertically long at both sides of the latch (40).

4. The automatic safety device according to one of claims 1 to 3, wherein a pair of the latch actuating parts(32) extend from both sides of the front of the slider(30) side by side, the operating spaces(41) of the latch(40) are respectively provided at both sides of the latch, and the latch actuating parts(32) are movable in the back and forth direction in the state where they -26- are respectively put in the operating spaces (41) disposed at both sides of the latch(40).

5. The automatic safety device according to claim 4, wherein the operating spaces(41) of the latch(40) are respectively formed in a rectangular dent hollowed toward the center of the latch(40). -27-