GB2256035A

GB2256035A - Structure for expansion and contraction of a guard baton

Info

Publication number: GB2256035A
Application number: GB9210807A
Authority: GB
Inventors: Hideyuki Ashihara
Original assignee: Individual
Current assignee: Individual
Priority date: 1991-05-21
Filing date: 1992-05-21
Publication date: 1992-11-25
Also published as: JPH04344098A; IT1256835B; CA2067308A1; NL9200802A; FR2676804A1; ZA922924B; CN1067115A; DK66092A; GB9210807D0; ITTO920433A1; DK66092D0; SE9201559L; ITTO920433A0; SE9201559D0; DE4216637A1; AU1529392A; KR920021964A

Description

23 5 t, 'i -);, 1

SPECIFICATION

Title of the Invention

Structure for Expansion and Contraction of a Guard Baton Background of the Invention Field of the Invention

The present invention concerns a structure for expansion and contraction tube guard baton using a telescopic pipe constitution and, more in particular, it relates to a structure for expansion and contraction of a guard baton capable of extending and contracting extremely smoothly, with neither rattling nor deviation and having improved durability.

Description of the Prior Art

As an existent structure for expansion and contraction of guard batons of this type, there has been known, for example, such a structure that a plurality of cylindrical members each of different diameter are combined in a telescopic manner, in which an inclined outer surface at the rear end of an inner cylindrical member is engaged to an inclined inner surface at the top end of-a cylindrical member just outside thereto in an anti-slip off fashion.

2 Ld This is a key holder of a telescopic structure which is not the guard baton itself but is applicable thereto (US Patent No. 4,752,072). However, in the structure of this prior art, both of the outer surface and the inner surface at the top end of the outer cylindrical member are formed as inclined surfaces tapered as far as the top end, while both of the outer surface and the inner surface at the rear end of the inner cylindrical member are also formed as inclined surfaces tapered as far as the rear end. Therefore, this structure involves the following problems. (1) The top end of the inclined inner surface of the outer cylindrical member is in a sliding contact with the cylindrical outer surface of the inner cylindrical member substantially along an annular line of contact, and the rear end of the inclined outer surface of the inner cylindrical member is also in a sliding contact with the cylindrical inner surface of the outer cylindrical member substantially along an annular line of contact and they are guided in this state upon extension and contraction. Accordingly, the top end of the guide of the outer cylindrical member and the rear end of the guide of the inner cylindrical member are liable to be abraded and, as a result, a clearance at the guide portion is increased tending to cause rattling or deviation. (2) The rigidity of the guard baton, when it is extended,

3 0 ft has been insufficient and this is assumed to be caused by the rattling described above. In particular, a force or impact may sometimes be exerted on the guard baton in the direction in perpendicular to the axis of the baton and it is considered that such a force or impact, being coupled with the rattling, makes the rigidity of the baton insufficient in a state where it is extended. (3) If the wall thickness of the cylindrical member is decreased for the reduction of the weight, the inclined inner surface of the outer cylindrical member is pushed by the inclined outer surface of the inner cylindrical member and tends to be opened outward when the baton is extended under an intense force. Therefore, the inner diameter is enlarged to make the inner cylindrical member slip out of the outer cylindrical member.

Further, a guard baton of an expansible and contractible structure is disclosed in Japanese Patent Utility Model Laid-Open Sho 61-181996, in which the inner and outer members have a plane-to-plane contact portion. However, in an extended state, a return stopper resiliently protruded outward formed by notching an inner tubular member engages the top end surface of the outer tubular member thereby preventing the inner tubular member from returning. Accordingly, there is a problem for the strength of the notched portion.

4 0 k 1 Further, although an expansible and contractible mechanism is also disclosed in Japanese Utility Model Laid-Open Sho 63-90796, no detailed inner structure is mentioned or disclosed.

Summary of the Invention

It is, accordingly, an object of the present inven tion to overcome the foregoing problems in the prior art and provide a structure for expansion or contraction of a guard baton which causes less rattling or deviation even after repeating use and which is free from the worry of slipping off caused by an extending force even if the weight is reduced.

The foregoing object of the present invention can be attained by a structure for expansion and contraction of a guard baton comprising a plurality of cylindrical members each of different diameter combined in a telescopic manner in which an inclined surface at the rear end of an inner cylindrical member is made engageable with an inclined surface at the top end of a cylindrical member just outside thereto in an extended state, wherein the top end of the outer cylindrical member has an outer circumferential cylindrical surface in parallel with the cylindrical axis and an inner surface having a conically inclined surface tapered toward the top end and a circum- 0 1 ferential cylindrical slide gu-4de surface in contiguous with the top end of the conically inclined surface and in parallel with the cylindrical axis, and the rear end of the inner cylindrical member has an outer circumferential cylindrical slide guide surface in parallel with the cylindrical axis and a conically inclined surface tapered toward the top end and in contiguous with the slide guide surface, in which the slide guide surface of the outer cylindrical member is put to a slidable contact with the outer circumferential surface of the inner cylindrical member and the slide guide surface of the inner cylindrical member is put to a slidable contact with the inner circumferential surface of the outer cylindrical member respectively, and a vent hole may be disposed to at least one position of the guard baton.

In a preferred embodiment of the present invention, a step is disposed between the inner circumferential surface and the base of the conically inclined surface of the outer cylindrical member and another step is also disposed between the slide guide surface and the conically inclined surface of the inner cylindrical member for enabling engagement at the steps.

In another embodiment, an abrasion resistant layer is formed to the inner surface of the outer cylindrical member and the outer surface of the inner cylindrical 6 1 - member.

In a further embodiment, a ring made of an abrasion resistant material and having a slide guide surface is attached to the top end of the outer cylindrical member.

In a further embodiment, a ring made of an abrasion resistant material and having a slide guide surface is attached to the rear end of the inner cylindrical member.

In a further embodiment, an angle of inclination for each of the conical engaging surfaces of the outer cylindrical member and the inner cylindrical member is defined as within a range of 10 to 20.

Upon extension and contraction, the slide guide surface formed cylindrically to the outer cylindrical_ member is put to a plane-to-plane contact with the cylindrical outer surface of the inner cylindrical member, and the slide guide surface formed cylindrically to the inner cylindrical member is put to a plane-to-plane contact with the cylindrical inner surface of the outer cylindrical surface, respectively, and they are guided in this state. Therefore, rattling or deviation can be reduced remarkably as compared with the structure in the prior art. Further, the structure causes less abrasion even after repeating extension and contraction and can suppress the rattling or deviation to a reduced level even after long time use.

Further, even if the wall thickness of the cylindrical 7 member is decreased, as a whole, to reduce the weight, only the top end of the outer cylindrical member is formed cylindrical at the outer surface to increase the wall thickness locally. Accordingly, even when a large extending forces is applied, the member has a great resistance against the forceof opening the top end of the cylindrical member outward, to prevent the inner cylindrical member from slipping off. In a case where the outer cylindrical member and the inner cylindrical member are engaged by way of the steps, the anti-slipping function i further improved. Further, if the angle of inclination for each of the conical engaging surfaces of the outer cylindrical member and the inner cylindrical member is made greater than 10. There is no worry that the inner cylindrical member slips off due to slight dimensional error upon fabrication.

Furthermore, the durability of the structure can be improved remarkably by providing a means such as forming an abrasion resistant layer to the inner surface of the outer cylindrical member or the outer surface of the inner cylindrical member, attaching a ring made of an abrasion resistant material and having a slide guide surface to the top end of the outer cylindrical member or attaching a ring made of an abrasion resistant material and having a slide guide surface to the rear end of the inner cylindrical 8 a k k'O' member.

Particularly, since the guard baton has a sufficient rigidity in an extended state. The present invention is particularly effective when it is applied to a guard baton with a cross handle, to which compressive force is possibly exerted intensely.

DESCRIPTION OF THE APPENDED DRAWINGS

Fig. 1 is an entire perspective view of an expansion and contraction type guard baton with a crosshandle as a first embodiment of the present invention; Fig. 2 is a vertical cross sectional view of the guard baton shown in Fig. 1; Fig. 3 is an enlarged cross sectional view of a portion for explaining a structure for expansion and contraction; Fig. 4 is a side elevational view partially in cross section of a modified embodiment of the guard baton shown in Fig. 1; Fig. 5 is a cross sectional view for a portion of a structure for expansion and contraction of a guard baton main body 1 in a second embodiment of the present invention; Fig. 6 is a cross sectional view for a portion of a third embodiment of the present invention; 9 Fig. 7 is a front elevational view for an abrasion resistant member in a fourth embodiment of the present invention; Fig. 8 is a cross sectional view for a portion of a fourth embodiment of the present invention; Fig. 9 is a front (t,,levational view for a portion of an abrasion resistant member in a fifth embodiment of the present invention; and Fig. 10 is a side elevational view of the member shown in Fig. 9.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT

Description will now be made to preferred embodiments of the present invention with reference to the drawings. Fig. 1 is an entire perspective view of an expansion and contraction type guard baton with a crosshandle as a first embodiment of the present invention, Fig. 2 is a vertical cross sectional view thereof and Fig. 3 is an enlarged cross sectional view of a portion for illustrating a structure for expansion and contraction.

In Fig. 1, a baton main body 1 is shown by a solid line in a contracted state and by a dotted chain in a state extended to a length L. The baton main body 1 has a crosshandle 2 with a length as can be gripped by one hand, which is branched in perpendicular from the baton 1 4 main body 1 at a position displaced somewhat from the center to one end in the longitudinal direction of the baton main body 1, that is, at a position near a hilt A disposed at one end of the baton main body 1. The hilt A comprises a cylindrical member AI made of a synthetic resin, wood or light metal through which the baton main body 1 is inserted.

As shown in Fig. 2, the crosshandle 2 of this embodiment has a support shaft 6 extended vertically from a mounting base 5 for securing to the baton main body 1 in perpendicular to the baton main body 1 and it is constituted as an upper/lower rotational type crosshandle, comprising a relatively rotational lower m ember 7 rotatably put fit around a base end 6a of the support shaft 6, an relatively rotational upper member 8 rotatably put around a top end Cb of the support shaft 6 and a static member 9 through which an intermediate portion 6c of the support shaft 6 is inserted and which is secured to the support shaft 6 at a position between the relatively rotational upper and lower members 7 and 8.

The baton main body 1 has a telescopic structure comprising a plurality of (three in the illustrated embodiment) cylindrical members 25, 26, and 27 each of different diameter. The outer cylinder 25 of the greatest diameter has female threads 28 formed at the inner circum- 0 A ferential surface on the side of the rear end being extended from the opening to the inside, a plug 29 having outer circumferential threads and screwed at the inside, and a cap 30 screwed at the rear end opening as a cover. In the outer cylinder 25, the outer circumferential surface comprises a cylindricalsurface 25a formed in parallel with the cylindrical axis, and an inner circumferential surface comprises an inclined surface 25d at the top end, being tapered (converged) toward the top end. An intermediate cylinder 26 contained at the inside of the outer cylinder 25, as an inner cylindrical member, has an inclined surface 26f formed to the outer surface on the rear end, and the outer diameter thereof is slightly enlarged toward the rear end opening so as to be engageable with the inclined surface 25d of the outer cylinder 25. The top end of the intermediate cylinder 26 has an inclined surface 26d formed to the inner circumferential surface, being tapered to the top end. An inner cylinder 27 contained at the inside of the intermediate cylinder 26 has an inclined surface 27f to the outer surface of the rear end and the outer diameter thereof is slightly enlarged toward the rear end opening so as to be engageable with the inclined surface 26d at the top end of the intermediate inner cylinder 26. Female threads are formed at the inner surface of the top end opening to which a cap 36 is 12 04 I- screwed. The rear end of the inner cylinder 27 has such an inner diameter as capable of engaging a forked spring 38, which is screw-set to the plug 29 when the guard baton is contracted. The base of the cap 36 at the top end has such a size capable of engaging the top end of the intermediate cylinder 26.

Referring more specifically to the structure for expansion and contraction of the baton main body 1 with reference to the enlarged cross sectional view of Fig. 3, the outer cylinder 25 as the outer cylindrical member and the intermediate cylinder 26 (an outer cylindrical member to the inner cylinder 27) are shaped at their top end portions, such that each of their outer surfaces 25a (26a) has no inclination in the axial direction, that is, as a cylindrical shape having a circumferential surface in parallel with the cylindrical axis. On the other hand, at the inner surface of each of the top end portions, there are formed conically inclined tapered surfaces 25d (26d) and a cylindrical slide guide surface 25c (26c) having a circumferential surface in parallel with the cylindrical axis and contiguous to the top end of the conically inclined surface 25d (26d). On the other hand, each of the intermediate cylinder 26 as the inner cylindrical member (inner cylindrical member to the outer cylinder 25) and the inner cylinder 27 has, at the outer surface of the 1 04 I- rear end, a cylindrical slide guide surface 26e (27e) as a circumferential surface in parallel with the cylindrical axis and a conically inclined tapered surface 26f (27F) in contiguous with the slide guide surface 26e (27e), orderly from the rear end.

The slide guide surface 25c at the inner surface on the top end of the outer cylinder 25 and the cylindrical outer circumferential surface 26a of the intermediate cylinder 26 in parallel with the cylindrical axis are fit to each other with a slight clearance, and the slide guide surface 26e on the outer surface at the rear end of the intermediate cylinder 26 and the cylindrical inner circumferential surface 25b of the outer cylinder 25 in parallel with the cylindrical axis are fit to each other with a slight clearance. Further, the slide guide surface 26c on the inner surface at the top end of the intermediate cylinder 26 and the cylindrical outer circumferential surface 27a of the inner cylinder 27 in parallel with the cylindrical axis are fit to each other with a slight clearance, and the slide guide surface 27e on the outer surface at the rear end of the inner cylinder 27 and the cylindrical inner circumferential surface 26b of the intermediate cylinder 26 in parallel with the cylindrical axis are fit to each other with a slight clearance.

14 At least one bent hole 31 is formed to the circumferential side of the outer cylinder 25. Alternatively, the bent hole 31 may be disposed to the intermediate cylinder 26 or the inner cylinder 27, to the cap 30 attached to the rear end of the outer cylinder or to the cap 36 attached to the top end of the inner cylinder 27, or the hole may be replaced with a groove or slit, so long as air can flow freely between the inside and the outside of the cylindrical member of the baton main body 1 to ensure smooth extending and contracting operation.

In this embodiment, an angle of inclination for the conically inclined surface 25d of the outer cylinder, each of the conically inclined surfaces 26d and 26f of the intermediate cylinder and the conical inclined surface 27f of the inner cylinder 27 is preferably within a range from 10 to 20. If the angle is smaller than 10, it requires a large force for releasing engagement between each of the inclined surfaces and containing the intermediate cylinder 26 in the outer cylinder 25 and the inner cylinder 27 in the intermediate cylinder 26. respectively, thereby making it dificult to contract the baton main body 1. Further, depending on the fabrication error, there may be a worry that the inner cylindrical member slips and flies out of the outer cylindrical member by the swinging force upon extending the baton main body 1. On the other hand, if 1 r, 1 0 the angle of inclination is greater than 20, engagement between each of the inclined surfaces is weakened in an extended state to bring about a worry that the engagement is released by the reaction of thrusting an opponent, to contract the baton main body 1. By the way, baton main bodies 1 were experimentally manufactured with the angle of inclination (tapered angle) being varied to three steps, that is, 10, 1.50 and 20 and the relationship between the tensile load and the maximum compression load in the axial direction were determined. Test data are shown in Table 1 As the test method, the manufactured main body 1 was used as a test piece, which was set to a universal material tester, applied with an axial tensile load from the both ends, then compressed in the opposite direction, and the maximum compression load was measured. The test was entrusted to the Prefectural Industrial Technical Center of Ehime.

16 Table 1

Tensile (0 load (Kgf) 250 300 350 400 450 500 550 600 Maximum Compression Load (Kgf) Taper 1.00 Taper 1.50 Taper 2.00 iOO 155 180 260 315 340 385 410 555 540 100 130 215 185 310 315 310 390 400 470 110 125 155 180 205 240 280 290 365 350 When the expansion and contraction type guard baton is actually used, the baton main body 1 is swung by a hand to thrust out and extend the inner cylindrical member. The extending force in this case corresponds to the tensile load shown in Table 1. Further, for contracting the extended baton main body 1, the top end of the baton main body 1 is hit and pressed, to house the inner cylindrical member. The pressing force in this case corresponds to -1 04 the maximum compression load in Table 1. It can be seen from the table that when the inner cylindrical member is thrusted out by a force corresponding, for example, to 300 Kgf of the tensile load, 260 Kgf of a force is required for contracting it in a case of the tapered angle of 10 but it may be reduced to a force of 180 Kgf in a case of the tapered angle of 20. In other words it is apparent that a greater force has to be applied for contraction if the tapered angle is smaller than 10 and that contraction is difficult after the cylindrical member with a smaller tapered angle has been thrusted with a large force. On the contrary, if the tapered angle exceeds 20, the compression load is further reduced and the inner cylindrical member is contracted after it is thrusted strongly and the function of the guard baton can not be attained.

Description will be made to the operation.

When a centrifugal force is applied to the baton main body 1 by gripping the crosshandle 2 or the grip A in a state where each of the cylinders 25, 26 and 27 is contained successively in a telescopic fashion (Fig. 2), the intermediate cylinder 26 and the inner cylinder 27 are thrusted out and extended. In this case, the cylindrical outer circumferential surface 26a of the intermediate cylinder 26 in parallel with the cylindrical axis is guided, being in a slight plane-to-plane contact, along the slide guide 18 a t face 25c at the top end of the outer cylinder 25, and the slide guide surface 26e at the rear end of the intermediate cylinder 26 is guided, while being in a slight plane-toplane contact, along the cylindrical inner circumferential surface 25b of the outer cylinder 25 in parallel with the cylindrical axis. In the same way, the cylindrical outer circumferential surface 27a of the inner cylinder 27 in parallel with the cylindrical axis is guided, while being in a slight plane-to-plane contact, along the slide guide surface 26c at the top end of the inner cylinder 26, and the slide guide surface 27e at the rear end of the inner cylinder 27 is guided, while being in a slight plane-toplane contact, along the cylindrical inner circumferential surface 26b of the intermediate cylinder 26 in parallel with the cylindrical axis. Accordingly, the intermediate cylinder 26 and the inner cylinder 27 can move extremely smoothly with neither rattling nor deviation. Further, since the slide guide surfaces 25c, 26e, 26c and 27e are put to plane-to- plane contact with each other, their abrasion is reduced extremely as compared with case of line-to-line contact in the prior art even when the baton is put to repeating extending and contracting operation for a long period of time, the working life can be improved greatly.

When they are completely extended, the inclined surface 26f at the rear end of the intermediate cylinder 26 thrusted T 19 of out of the outer cylinder 25 engages the inclined surface 25d at the top end of the outer cylinder 25, and the inclined surface 27f at the rear end of the inner cylinder 27 thrusted out of the intermediate cylinder 27 engages the inclined surface 26b at the top end of the intermediate cylinder 26 and they are retained from slipping off. Upon engagement, a strong impact is applied to the outer cylinder 25 as the outer cylindrical member (and the inner cylinder 26) at the inclined surface 25d (and 26d) at the top end portion, and the component of the force along the inclined surface is exerted in the direction of opening outward. In the present invention, since the outer surface of the outer cylinder 25 (and the inner cylinder 26) is made cylindrical as far as the top end so that the wall thickness at the top end which was liable to suffer from deformation in the existent structure is locally increased, it is less deformed even if a large force is exerted in the direction of opening outward. Therefore, if the baton main body 1 is thrusted out with a large force, it can be prevented from slipping off. In addition, the wall thickness for each of the cylindrical members can be decreased, as a whole, to reduce the weight.

Fig. 4 shows a modified structure of the first embodiment, in which a guard portion 40 is attached instead of the crosshandle to the baton main body 1. The structure 4.0 for expansion and contraction of the baton main body 1 is the same as in the first embodiment.

Fig. 5 shows a portion of a structure for expansion and contraction of the baton main body 1 in a second embodiment of the present invention.

In this embodiment, a step 51 is formed between an inner circumferential surface 25b (26b) at the top end and the base of an inclined surface 25d (and 26d) of an outer cylinder 25 as an outer cylindrical member (and an intermediate cylinder 26), while another step 62 engageable with the step 51 is disposed between a slide guide surface 26e (27e) and an inclined surface 26f (27f) of the intermediate cylinder 26 as an inner cylindrical member (and an inner cylinder 27). This modified embodiment has a merit of providing a further improved effect for preventing slipping off by the engagement of the steps 51 and 52 to each other.

Fig. 6 shows a portion of a third embodiment of the present invention.

In this embodiment, a ring 55 made of an abrasion resistant material and having a slide guide surface 25c (26c) is attached to the top end of an outer cylinder 25 as an outer cylindrical member (and an intermediate cylinder 26). As the abrasion resistant material, titanium alloy or like other hard metal or a synthetic resin of low 21 frictional resistance such as a fluoro resin is preferred.

Figs. 7 and 8 show a portion for a fourth embodiment of the present invention.

In this embodiment, a ring 56 made of the same abrasion resistant material as described above and having a slide surface guide 26e (27e) is fit to the rear end of an intermediate cylinder 26 as the inner cylindrical member (and an inner cylinder 27) and fixed by screwing a threadclamping ring 57. The sliding guide surface 26e (27e) is spherically protruded at a plurality of portions (four portions in the illustrated embodiment) from the outer circumferential surface of the abrasion resistant ring 56.

Fig. 9 shows a fifth embodiment according to the present invention, which is different from the fourth embodiment shown in Figs. 7 and 8 in that the slide guide surface 26e (27e) of the abrasion resistant ring 59 is formed as a cylindrical surface.

Each of the third to fifth embodiments has a merit capable of outstandingly improving the durability by forming the slide guide surface with the abrasion resistant material separately from the cylindrical member.

Although not illustrated in the drawings, the inner surfaces of the outer cylinder 25 as the outer cylindrical member and the intermediate cylinder 26 and the outer surfaces of the intermediate cylinder 26 and the inner 22 cylinder 27 as the inner cylindrical member may be formed with an abrasion resistant layer, for example, by applying nitriding treatment or a coating with a titanium alloy layer, for improving the durability.

As has been described above, in the expansion and contraction type guard baton according to the present invention, since a slide guide surface is formed at each of the ends of the inclined surfaces of the outer cylindrical member and the adjacent inner cylindrical member along which they are engaged, in a plane-to-plane contact with the circumferential surface of the cylindrical member, it can provide an advantageous effect of providing an extremely smooth extending and contracting operation and reducing abrasion at the end of the inclined surface even after repeating use, thereby preventing rattling or deviation for a long period of time. Further, since the abrasion resistance of the slide guide surface and the contact surface thereof is enhanced, it can provide an effect capable of outstandingly improving the durability as compared with the existent structure. Further, since the outer surface at the top end of the outer cylindrical member is formed cylindrically and the inner surface thereof is disposed with the conically inclined surface tapered toward the top end and a cylindrical slide guide surface in contiguous to the top end of the conically inclined 1 23 surface, thereby increasing the wall thickness locally at the top end, it can provide an advantageous effect that the top end of the outer cylindrical member is less opened upon extension, thereby preventing the inner cylindrical member from slipping off even if a strong impact is applied to the top end of the outer cylindrical member. Further,since the steps are formed at the engaging portion between the inner and the outer cylindrical members thereby restricting the angle of inclination for each of the inclined surfaces, this can provide a further improved anti-slip off effect.

In particular, when the structure for expansion and contraction of the present invention is applied to a guard baton with a crosshandle, it can provide a sufficient rigidity in the extended state of the guard baton to attain high reliability.

(Q 24 of

Claims

1. A baton comprising an outer cylindrical member and an inner cylindrical member combined in a telescopic fashion, such that the inner member can be retracted within the outer member or can project from the outer member with an end portion thereof retained within an end portion of the outer member; the said end portion of the outer member comprising a radially internal cross-section comprising a axially outer portion having parallel sides of a relatively small separation and defining a first surface, an axially intermediate portion having inclined sides and defining a frustoconical surface of greatest diameter at its axially innermost end and an axially inner portion having parallel sides of a relatively large CD separation and defining a second surface; the said end portion of the inner member having a radially outer cross-section comprising an axially outer portion having sides of a relatively large separation and defining a third surface, a intermediate portion having inclined sides defining a frustoconical surface of greatest radial diameter at its axially outermost end, and an axially inner portion having sides of a relatively small separation and defining a fourth surface; the said frustoconical surfaces being adapted to mate; the said first surface being adapted to slide against the said fourth surface; and the said third surface being adapted to slide against second surface.

(a

2. A structure for expansion and contraction of a guard baton comprising a plurality of cylindrical members each of different diameter combined in a telescopic manner, in which an inclined surface at the rear end of an inner cylindrical member is made engageable with an inclined surface at the top end of a cylindrical member just outside thereto in an extended state, wherein the top end of said outer cylindrical member has an outer circumferential cylindrical surface in parallel with the cylindrical axis and an inner surface having a conically inclined surface tapered toward the top end and a circum ferential cylindrical slide guide surface in contiguous with the top end of said conically inclined surface and in parallel with the cylindrical axis, and the rear end of the inner cylindrical member has an outer circumferential cylindrical slide guide surface in parallel with the cylindrical axis and a conically inclined surface tapered toward the top end and in contiguous with said slide guide surface, in which the slide guide surface of the outer cylindrical member is put to a slidable contact with the outer circumferential surface of the inner cylindrical member and the slide guide surface of the inner cylindrical member is put to a slidable contact with the inner 26 circumferential surface of the outer cylindrical member respectively.

9

3. A structure for expansion and contraction of a guard baton as defined in claim 2, wherein a step is formed between the inner circumferential surface and the base of the conically inclined surface of the outer cylindrical member, and another step is formed between th slide guide surface and-the conically inclined surface of the inner cylindrical member.

4. A structure for expansion and contraction of a guard baton as defined in claim 2 or 3, wherein an abrasion resistant layer is formed to the inner surface of the outer cylindrical member and the outer surface of the inner cylindrical member.

5. A structure for expansion and contraction of a guard baton as defined in any one of claims 2 to 3, wherein a ring made of an abrasion resistant material and having a slide guide surface is attached to the top end of the outer cylindrical member.

6. A structure for expansion and contraction of a guard baton as defined in any one of claims 2 to 5, wherein 27 a ring made of an abrasion resistant material and having a slide guide surface is attached to the rear end of the inner cylindrical member.

7. A structure for expansion and contraction of a guard baton as defined in any one of claims 2 to 6, wherein the angle of inclination for each of the conical engaging surfaces of the outer cylindrical member and the inner cylindrical member is defined as within a range of 10 to 20

8. A structure for expansion and contraction of a guard baton as defined in any one of claims 2 to 7, wherein the guard baton is a guard baton with a crosshandle.

9. A structure for expansion and contraction of a guard baton as defined in any one of claims 2 to 8, which further comprises a vent hole being disposed to at least one position of the guard baton.

10. A baton substantially as herein described with reference to any one of Figures 1 to 3, or 4, 5 or 6 or 7 and 8 or 9 and 10 of the accompanying drawings.