KR940005867B1 - Anti-skid device for automobile tires - Google Patents

Abstract

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Description

Anti-skid device for car tire

1 is an explanatory view showing the assembled state of the anti-skid device of the tire for an automobile of the present invention.

2 is a plan view of a non-slip device main body of an anti-slip device of a tire for automobiles according to the present invention.

3 is a partial view showing a bent state by connecting the non-slip device body with a hook.

4 is an explanatory diagram showing a state in which the fixing device is released in the anti-skid device of a tire for a vehicle according to the present invention.

5 is a plan view of a plate of the fixture.

6 is an explanatory diagram showing an assembly state of the fixing device.

7 is an explanatory diagram of a dedicated jig for rotating and fixing the stator.

8 is an explanatory diagram showing a state in which the fixing device is fixed in the anti-skid device of a tire for a vehicle according to the present invention.

9 (a), 9 (b) and 9 (c) are explanatory diagrams showing respective parts of the second hook of the fastener.

10 is a cross-sectional view showing a state in which the fixture is fixed.

11 and 12 are explanatory views showing the assembling process of the anti-skid device of a tire for automobiles according to the present invention.

13 is an explanatory diagram of another embodiment of the fastener;

14 is a plan view of a non-slip device body of a conventional automobile tire.

15 is an explanatory diagram showing an assembled state of a non-slip device of a conventional vehicle tire.

* Explanation of symbols for main parts of the drawings

1: tire 2: slipper body

3, 3 ': joint hook 4: connection protrusion

4 ': buffer member 5: first hook

6: 2nd hook 7: plate

8: third hook 9: elastic member

10,11,12: hole 10 ', 11', 12 ': protrusion

13: dedicated jig 14: locking projection

The present invention relates to an anti-skid device of a tire for an automobile. An anti-slip device for automobile tires, which has been mainly used in the past, is disclosed in Japanese Unexamined Patent Application No. 58-13337 or 58-49366. In these examples, as shown in FIG. 14, the inner rope C is installed on the inner surface of the tire anti-skid net body B directly or through the inner metal member G, and the tire anti-slip net body (B) is attached to the tire (T) by the inner rope (C) fixed to the tread (Tread) of the tire, by connecting the both ends of the net body (B) in a suitable manner so that the net body (B) in an annular shape do. The inner surface of the net body B is then clamped with a rope C, and the outer surface of the net body is clamped with a setting strap D provided as shown in FIG.

However, this method takes a long time and takes a lot of stamina to fill the setting straps D one by one on the plurality of outer metal members E.

And the setting strap (D) is designed to be different without a lot of effort in consideration of the female user. Another reason why the setting strap (D) is made as mentioned above is that if the setting strap (D) is installed too hard, the rope (C) installed on the inner side of the net body (B) is broken. For this reason, setting the setting strap D too hard has become impossible. Therefore, if a centrifugal force is applied to the tire anti-slip net body B while the wheel is rotating, the setting strap D is expanded so that the net body B is lifted up and partially slipped. As a result, the net body B becomes loose with respect to the tire T, and the change of the position of the net body and concentration of the partial load causes the net body B to be partially broken or displaced, making it difficult to use such an anti-skid device. .

In particular, in the case of the non-metallic net anti-slip device which is the mainstream of this kind of anti-slip device, lifting of the tire anti-slip net body B from the tire T by centrifugal force may reduce the durability of the device. It lowers and the net main body B swells and contacts the inner surface of the fender, and causes the net body B to be damaged. These problems suggest an important point of anti-skid device design.

In other words, in order to prevent the lifting of the net body (B), it is necessary to increase the level of the clamping force applied to the entire setting strap (D). However, in the conventional non-slip device, the tension of the setting strap (D) that can be easily filled by hand to the outer metal member (E) is limited, so the tension of the single setting strap (D) is the net when the tire (T) is rotated Lifting of the net body B from the tire T caused by the centrifugal force appearing in the main body B cannot be prevented.

Therefore, two to three setting straps are generally used which are installed at a very limited range of levels in which the setting strap D can be hand filled to the outer metal member. However, the continuous filling of an increased number of setting straps (D) one by one into a plurality of outer metal members one by one increases the time and effort required to install the anti-slip device on the tire or to remove the anti-slip device from the tire. . This makes it difficult to expand the prevalence of this kind of anti-skid device that is being reconsidered in view of the expected total closure of spike tires.

The conventional sliding net body B for a tire shown in FIG. 15 is in a flat shape as shown in FIG. The fastening portion of the net body to be applied to the inner side of the tire T is set to the pitch lu 'at which these fastening portions are finally held by the tire using the inner metal member G. Looking at the fastening portion of the net body B applied to the outer surface of the tire T, the diameter of the circle connecting these fastening portions fills the setting strap D with the outer metal member E to the outside of the tire T. The setting straps were closed so that the lo of the fastening portion of the net body in the flat state was reduced to lo '.

If the pitch of the fastening portion of the tire anti-slip net body B corresponding to the outer surface of the tire is not secured to a sufficient size, the net body B cannot be installed in the tire. Therefore, the net body B having an outer fastening portion spaced at the pitch lo formed in the flat state of the fastening portion of the net body B is provided in the tire. Therefore, a large amount of energy is required to reduce the pitch of the fastening portion corresponding to the outside of the tire to the level where these fastening portions are finally held in the tire. In the conventional method, installing the net body on the tire and fixing it by centrifugal force Make the fastening part largely flat.

It is an object of the present invention to provide a sliding device for an automobile tire that solves the problems mentioned above.

An automobile tire anti-slip device according to the present invention comprises an anti-slip device body and joint hooks connected to both ends of the device body, wherein the anti-slip device body is configured to cover the side surface of the tire when the device body is mounted on the tire. A plurality of mutually spaced end portions extending inwardly, the ends of adjacent fastening ends of these fastening ends being connected to each other by a fastener, the length between the ends being freed by the fastener. It is smaller than the length, and the length of the fastener is variable, and the variable length fastener has a hook, one end of which is connected to the opposite fastening end, a hole in the base, and the other end of the hook in its different hole to be rotatable. A plate supported, the length between said opposite fastening ends pivoting said plate To decrease as characterized.

The above and other objects and features of the present invention will become apparent from the description of the embodiments described below in conjunction with the drawings.

EXAMPLE

Hereinafter, embodiments of the present invention will be described with reference to the drawings. An anti-skid device for an automobile tire according to the present invention has four non-slip device body members connected together to joint hooks 3 and 3 'at four locations on the outer circumference of the tire, as shown in FIG. It has a divided nonmetal antiskid body 2. Two of the joint hooks 3 'among these four joint hooks can be attached to or detached from the apparatus body member.

As shown in FIG. 2, the anti-skid body 2 has a plurality of mutually spaced fastening ends extending inward along the side of the tire when the apparatus body 2 is mounted to the tire, The connecting projections 4 extending from the first and fourth fastening ends of the fastening ends spaced at pitch lo on the outer side toward each other are integrally formed. The length of the connecting protrusion 4 is lo ', and the free end of the connecting protrusion 4 is finally connected to the adjacent fastening end by the first hook 5, as shown in FIG. The connecting projection 4 has two holes at its free end, as shown in Figs. 2-4, and the fastening end is connected to a hole near the adjacent fastening end by the hook 5. Thus, the link portion formed to bend the formed connection portion.

An automobile tire anti-slip device according to the present invention has respective fasteners composed of a second hook 6 and a plate 7, each fastener having a non-slip device body having an outer fastening end thereof on the outer surface of the tire. Power doublers are provided for reducing the length lo in the free state, which is installed on the tire, to the length lo ', which is the level required when these fastening ends are finally installed. The above-mentioned bendable link part moves with the rotation of the plate 7.

Each device body member of the quadrant anti-slip device body 2 is formed flat as shown in FIG. The pitch lo of the part of the apparatus body member 2 on the outside of the tire and the pitch lu of the part of the member on the inside of the tire are the same.

As shown in FIG. 3, the non-slip main body 2 is connected together using a connecting hook 4 and a fastening end using a first hook 5 and a third hook 8 on the inner side of the tire. In this case, the apparatus main body 2 is assembled to have a three-dimensional curved structure.

The length of the third hook 8 is the pitch lo ', lu' corresponding to the pitch lo, lu when the non-slip device main body 2 member is installed on the tire, i.e., when the condition shown in FIG. It is set to be the same.

In the automobile tire anti-skid device according to the present invention, a plurality of fasteners used on the outer surface of the tire are made in advance to the length required when the device body is finally installed. Accordingly, the fasteners on the outer side of the tire are made to be easily coupled to and detached from the device body 2.

In the fastener which performs the function of the power booster used in the present invention, one end of the second hook 6 is such that the hook 6 extends in the same direction as the connecting projection 4 as shown in FIG. It is connected to the end of the connecting projection 4 on the outside of the tire. The other ends of the second hooks 6 extending toward each other are rotatably fixed to two holes formed at a distance r away from the base of the plate 7. As shown in FIG. 5, the plate 7 forms a flat plate with a plurality of holes and is integrally coupled with the elastic member 9 as shown in FIG.

The plate 7 is provided with a first hole 10 at the center of its rotational movement, symmetrically arranged second and third holes 11 and 12 are separated by a distance r, and FIG. It can be rotated by a dedicated plate pivot jig 13 provided with projections 10 ', 11', 12 'corresponding to the holes 10, 11, 12 as shown in FIG. have. Moreover, the dedicated jig 13 is provided with the plate rotation handle of length M. As shown in FIG. When the handle of the dedicated jig 13 having the projections 10'-12 'of the dedicated jig inserted into the three holes 10-12 of the corresponding plate 7 is turned about the hole 10, the force of the handle Is amplified at a rate of M / m around the first hole 10 and works in the direction of the distance Lo shown in FIG. When the plate 7 is inverted to 180 ° and rotated in the state shown in FIG. 8, the distance Lo is reduced to lo '= Lo-2r. The connection protrusion 4 and the fastening end are connected together to form a bendable link portion by the first hook 5. Therefore, the distance 2r reduced by the rotation of the plate 7 is evenly divided between the fastening portions of the device body. When the plate 7 is rotated, the distance between the fastening portions of the device body is uniformly reduced as the angle α between the first hook 5 and the corresponding fastening ends is reduced, and in the state shown in FIG. 8, The distance between opposite fastenings of the device body is equal to lo, which is the final required level.

In the automobile tire anti-skid device according to the present invention, the distance between opposing fastening portions is set to Lo, which is somewhat shorter than the pitch lo of the fastening end of the fastening end of the device body in the flat state shown in FIG. That is, the distance including the distance r between the outermost holes and the length of the hook 6 in the initial release state. Therefore, the connection protrusions can be easily attached or detached to the tire even when the device body is fixedly installed at a lo 'length while the device body is finally installed on the tire.

When the plate 7 is rotated so Lo becomes lo ', the apparatus body is fixed to the tire as shown in FIG. In addition, the fastening portion of the apparatus main body forms a closed loop of force so that the apparatus main body obtains a stable fixed state.

In this state, since the first hook 5 faces the rotational center of the tire, the tension force toward this center is applied to the fastening end to which the hook 5 is fastened, thereby making the anti-skid device stable.

The length of the deformable part of the anti-skid device is calculated below using the 165R13 tire as a general size.

The outer diameter of the 165R13 tire is 596 mm, and the diameter of the circle in contact with the outer and inner fastening portions of the anti-skid device to be installed on this tire is equally 464 mm. If the length of each joint hook 3, 3 'for connecting the members of the anti-slip device main body 2 is set to 30 mm, the length lo' in the device shown in FIG.

Then, the length lo of the apparatus body in the flat state shown in FIG.

Therefore, the reduction length of the device body for each fastening portion requires lo-lo '= 35 mm. The length of each connection projection 4 is set to lo 'required from the beginning in the state where the apparatus main body is finally engaged. The first hook 5 to which the fastening ends of the connection protrusions 4 are connected together acts like a link. Therefore, when the first hook 5 forms an angle α as shown in FIG. 4, the length of the fastening portion of the connection protrusion 4 increases by S so as to be lo '+ S.

On the other hand, the length of the fastening portion of the plate 7 is reduced by the distance 2S so that L = Lo-2S. Since the length of the first hook 5 is set to satisfy the relationship of lo '+ S = L, the distance between the three fastening portions is the same. Looking at the fixture acting as a booster, Lo is extended to 43 mm more than the lo = 146 length in its free state, taking into account the need for the fixture to be detachable from the device body, as shown in FIG. It is set to 189 mm.

That is, the difference in length Lo-lo '= 189-111 = 78mm is distributed evenly (by 78/3 = 26mm each) in the three fastening portions.

As a result, the distance between the fastening portions of the opposing connecting projections is lo '+ 26 = 137 mm, and the distance between the fastening portions of the plate 71 is L = Lo-2S = 189-2 × 26 = 137 mm, and lo' + S = L Therefore, when the plate 71 is rotated so as to hide the distance Lo to lo ', the distance between the three fastening portions becomes the same. That is, reduced to lo '.

In order to reduce the distance of the fastening portion of the device body from Lo = 189mm to lo '= 111mm by the fastener, r should be set to (180-111) / 2 = 39mm.

If the length M of the handle of the rotating jig of the dedicated plate is set to M = 160m, the rotational force applied around the center of rotation is amplified by four times. That is, M / r = 160/39/4. The lengths r = 39mm and M = 160mm can be secured without any problem in size.

If the distance m between the plate turning holes is m = 20mm, the rotational force generated by the handle becomes r / m = 39/20 ≒ 2. Thus, a force twice that of the force applied to the hole in which the second hook 6 is rotatably supported by the plate 7 is applied to the plate turning holes 11 and 12 and the plate projection of the handle. As a result, the compartments are large enough.

In the conventional case, the final tightening force required to clamp the fastening part using a rubber belt is about 20 kgf. If this force is obtained using the handle of the plate pivot jig, the force increased by 4 times as mentioned above, so the rotational force is 5 kgf. This level of torque can be easily aesthetically generated by a weak person, including a woman, in the general case, in terms of the nature of the work. The rotational force exerted on the plate turning holes 11 and 12 in this work is 10 kgf, which the antiskid device body can withstand sufficiently, which does not cause any problem.

The first hole 10 and the projection 10 'are provided corresponding to the center of the handle of the plate 7 and the plate pivot jig 13. Since the handle is pivoted about the center, the handle pivoting operation can be performed smoothly, and the projections 11 'and 12' of the handle can be prevented from being separated from the plate pivoting holes 11 and 12. .

Each second hook 6 has the shape shown in FIGS. 9 (a) -9 (c), and the cross section of the fastener in the fixed state is shown in FIG.

As is apparent from FIG. 8, when the locking projection 14 is formed on the plate 7 integrally with the elastic member 9 and as part of it, the fixing member is in a fixed state. , Each support point (B) (C) of the second hook (6) rotatably supported on the plate is locked, these support points (B) (C) is the end of the connecting projection (4) of the shaft (6) It is maintained on the conditions which shift | deviate with respect to the line which connects the support point A (D) in between.

That is, since the support points (B) and (C) are at positions displaced from each other in the direction in which the device body is rotated and fixed, a force for rotating the fixture in the opposite direction to the holder in the released direction is applied to the support points (B) and (C), A force to increase the device body tightening distance lo 'is applied to the support points (A) (D).

As shown in FIG. 10, the portion of the second hook 6 between the fastening portions of the hook both ends is engaged with the locking projection 14 to the surface of the plate 7 on the opposite side of the tire surface. Therefore, when the force that separates the entire anti-skid device from the tire surface is generated by the centrifugal force generated when the tire rotates, the plate 7 larger than the mass of the second hook 6 pushes the hook 6 up. This prevents the second hook 6 from deviating from the locking projection 14 and allows the second hook 6 to reliably lock. The plate 7 is rotated while being pressed against the tire surface in order for the second hook 6 to lock over the protrusion 14. As a result, the free end of the fastening portion of the hook 6 is pressed against the tire surface, and the entire plate 7 including the locking projection 14 is pressed below the tire surface by the elasticity of the tire. Thus, the locking of the second hook can be made easily. Release of the second hook 86 is also easily accomplished by pivoting the plate 7 in the release direction while pressing against the tire surface.

Looking at each hook used in the automobile tire anti-slip device according to the present invention, each hook fastening hole portion of the anti-slip device body is spaced from the surface of the tire by a thickness corresponding to the thickness of the hook, as shown in FIG. It has a stepped portion. Therefore, the surface of the hook which is in contact with the tire and the surface of the body which is in contact with the tire is the surface with a small curvature of the hook due to the anti-slip device clamping force generated when the anti-slip device is firmly fixed around the tire. In order to prevent the tire from being concentrated on the surface of the tire, i.e. the tire pressure is not generated in the hook and the tire in contact with each other, thereby preventing the tire from being damaged while the wheel is rotating. Is set.

The method for fixing the anti-slip device according to the present invention will be set hereinafter. First, as shown in FIG. 11, the members of the anti-skid body 2 are temporarily mounted on the tire 1. At this time, the four fasteners are placed in the released state with the plate 7 in the state shown in FIG. The plate 7 of the fixture is then rotated to the position shown in FIG. 8 and fixed in the fastened state. During temporary mounting of the device body, pivoting the plate 7 can be easily done by hand without using any special tools. During the operation, the center of curvature of each member of the apparatus body 2 and the center of the tire 1 lie in a straight line with each other. The tire 1 is then rotated about one quarter. During the operation of mounting the apparatus body, the rotation and fixing of the plate 7 are satisfactorily made only at two spaces spaced from each other in the rotational direction of the tire 1.

On the other hand, in the conventional anti-slip device shown in FIGS. 14 and 15, one setting strap D is temporarily filled with several outer metal members E, after which the tire 1 is 1/4 Is rotated. Since the diameter of the set strap in the free state is small, tension is applied to the outer fastening portion of the apparatus body during the setting strap temporarily filling the apparatus body. As a result, the tension between the outer fastening portions and the inner fastening portions is lost. In addition, the setting strap D is moved on the outer metal member E when the tire 1 rotates. Due to these problems, when the tire rotates, the anti-slip net body B deviates from the center of the tire 1. This makes it difficult to carry out the setting strap tightening operation.

In the device according to the invention, the shrinkage ratios of the inner and outer fastening portions of the device body are the same. Thus, the lengths of these fastening portions having four fasteners in the clamped state are the same. Therefore, these inner and outer tensions are well balanced. And no displacement of the device occurs when the tire rotates.

After the tire is rotated a quarter turn, the joint hooks 3 'on the inner side of the tire are fastened in order to seamlessly connect the inner fastening portion. At this time, the members of the anti-skid body 2 are lowered to the inner side of the tire so that the fastening of the joint hook 3 'is easily performed. If the fastener is set to the released state again and the two outer joint hooks 3 'facing each other are set as shown in Fig. 12, seamless contact of the inner part of the apparatus body is satisfactory.

The setting of the first hook 5 and the setting of the length Lo, which form the link mechanism with the corresponding connection protrusion 4 described with reference to FIG. 4, set the members of the anti-slip device body 2 on the inner side of the tire. This operation, which is carried out on the inside of the tire, is facilitated, and the work of smoothly connecting the four-part apparatus body member on the outer surface of the tire is smoothed by fastening the outer joint hook 3 'described below to the member of the anti-slip device 2. To be done. After the inner joint hook 3 'is fastened to the member of the apparatus body, the apparatus body 2 is pulled out of the tire.

Then, the two joint hooks 3 'are fastened to the members of the apparatus main body so as to seamlessly connect the apparatus body divided into four on the outer surface of the tire and the four fasteners are rotated arbitrarily to complete the work. In this state, the outer fastening portions of the device body form a closed rope of force, and the fastening portions are fixed integrally. Therefore, even when the tire is slipped, the fastening portions of the apparatus body 2 are not displaced and the apparatus body is not displaced or deviated from the tire 1.

Since the fastening portions on both the outer and inner sides of the tire are fixed using the same system, the tension on the inner and outer sides of the apparatus body is balanced. In addition, since the expansion of the fastening portion hardly occurs, the resistance of the anti-skid device against centrifugal force and its durability are remarkably enhanced in comparison with that of the anti-skid device employing a rubber strap.

When the fixture is fixed, its reduction distance is constant in any case. In order to offset the difference in the diameter of the outer fastening portion due to the difference in tire size or the slight displacement of the anti-slip device fixed on the tire, and to create a tension slightly higher than that of the inner fastening portion at the outer fastening portion, 4) is composed of a buffer structure using a material or structure having an elastic energy, which is preferably formed to have a length slightly smaller than lo '. The cushioning structure of the anti-skid body 2 of the present invention including the connecting projection 4 is formed integrally with, for example, an elastic body of a polyurethane elastic body. If the connection projection is formed to have a cross-sectional size which can extend further than the inner fastening portion and the tread cover portion of the anti-slip device body, a satisfactory buffer connection projection 4 can be obtained. The connecting projection 4 may also be provided with a spring-type shock absorbing member 4 'extending longitudinally in the middle portion thereof, as shown in FIG. As described above, the device according to the present invention has excellent fastening ability, that is, the ability to be mounted on a tire without much time and effort. In addition, this prevents the expansion of the fastening portion of the device body caused by the centrifugal force which has been a problem in this kind of conventional device, improves the durability of the device and prevents the device body from being displaced or deviated from the tire.

These advantages of the present invention are listed as follows.

(1) Since the anti-skid device is temporarily fixed to the tire and the tire is rotated, the position of the device is not changed so that the fastening portion of the device and the center of the tire are easily matched.

(2) In the conventional anti-slip device, the time and effort required to fill the rubber strap with the outer metal member is omitted.

(3) The tightening force of the inner and outer fastening portions of the tire device is improved, and the durability of the device is improved.

(4) Since the fastening portion is fixed integrally, displacement and deviation of the apparatus main body from the tire hardly occur.

(5) Since the hook for filling the rubber strap need not be provided, the entire anti-slip body does not need to extend radially into the inside of the tire. Thus, the device can be mounted in a low profile tire that does not differ much between the outer diameter of the tire and the outer diameter of the wheel body such that the fastening portion does not contact the wheel body. This can prevent the wheel body from being damaged.

In this embodiment, a net-type anti-slip device main body was used. However, the present invention is directed to the axial direction of the tire type disclosed in Japanese Patent Application Laid-Open No. 60-68909 or Japanese Patent Application Laid-Open No. 67-178909, or the tire disclosed in Japanese Patent Application Laid-Open No. 63-28509 or Japanese Patent Application Laid-Open No. 54-138203. Ladder anti-skid devices may also be used, in which a number of elongated non-slip plates are secured to the tread of the tire by fastening lines.

Claims (8)

A non-slip device body 2 and a detachable joint hook 3 'which connects both ends of the anti-slip device body 2 to each other, the anti-slip device body 2 is mounted on the tire 1 When there are a plurality of fastening ends spaced apart from each other extending inward along the side of the tire (1), the adjacent fastening ends of the fastening ends are not fixed to the length (lo ') between the fastening ends fixed by the fasteners Connected to each other by a fastener so as to be smaller than the length lo between the fastening ends, the length of the fastener being variable, the fastener being variable length and having a hook 6 connected at one end thereof to the opposite fastening end. It consists of a plate 7 which has holes in its base and rotatably supports the other end of the hook 6 in different holes, so that the opposite fastening end is rotated by rotating the plate 7. Anti-skid device for automobile tires for the length thereof decreases. The hook according to claim 1, wherein the hook is inserted between the fastening end to which the variable length fasteners are connected and the variable length fastener and connected in a radial direction of the tire 1 along the side of the tire 1; An anti-skid device for a vehicle tire further comprising a bent link portion connected to the fastening end via (5). 2. An anti-slip of a motor vehicle tire according to claim 1, wherein the respective fastening ends are elastically stretched when the length between the fastening ends connected through the fasteners is reduced by the rotation of the plate 7 of the fasteners. Device. 2. The holes (11) (12) according to claim 1, wherein said variable length retainer is formed in a symmetrical position away from the hole (10) formed at the center of rotation of said plate (7) and the center of rotation of said plate (7). Anti-skid device for automobile tires composed of 2. The hole portion of the anti-skid body 2 for fastening the hooks 5 to 8 corresponds to the thickness of the hooks 5 to 8 so that the hooks do not directly contact the surface of the tire. An anti-skid device for an automobile tire having a stepped portion spaced from the surface of the tire by a distance. The projection (14) according to claim 1, wherein the projection (14) is formed on the plate (7) to fix the plate (7) in a pivoted state with the hook (6) rotatably inserted in the hole of the plate (7). Anti-skid device for a vehicle tire further comprising a locking means consisting of. 7. The process according to claim 6, wherein the projections (14) are formed on the surface of the plate (7) on the opposite side of the tire surface so as to contact the hooks (6), so that the locking force of the locking means is applied to the centrifugal force generated when the tire rotates. Anti-skid device for automobile tires increased by Automobile tire anti-slip device composed of three projections 10'-12 'corresponding to three holes 10-12 on the rotation plate 7 of the variable length holder for rotating the rotation plate 7. Dedicated jig for tightening fasteners.