CN101338649A

CN101338649A - Telescopic ladder

Info

Publication number: CN101338649A
Application number: CNA2008101202452A
Authority: CN
Inventors: 王万兴
Original assignee: Individual
Current assignee: Ningbo Xingfu Tools Co Ltd
Priority date: 2008-08-14
Filing date: 2008-08-14
Publication date: 2009-01-07
Anticipated expiration: 2028-08-14
Also published as: CN101338649B

Abstract

The present invention relates to an extension ladder which comprises a left grab rod (1) and a right grab rod (2) which are oppositely arranged, and a plurality of rungs (3) between the left grab rod and the right grab rod, wherein, the left grab rod and the right grab rod consist of a plurality of sections of flexible folding left sectional rod and right sectional rod (11 and 12) which are sleeved and jointed orderly; the rungs (3) are installed between two opposite left sectional rod and right sectional rod; a left locking mechanism (4) and a right locking mechanism (5) are arranged in the rungs (3) to prevent the ladder from contracting and folding; the left locking mechanism and the right locking mechanism are respectively provided with a left operating button and a right operating button (6 and 7). The extension ladder is characterized in that the left operating button and the right operating button (6 and 7) are arranged at the middle parts of the rungs (3) and are adjacent to each other, thereby being convenient for one hand to operate two operating buttons at the same time to ensure that the rungs (3) is unlocked from the corresponding sectional rods. When operating, only the thumb and the first finger of the same hand are required to stretch, the thumb touches the right operating button, the first finger touches the left operating button, and then the thumb and the first finger energize inwards at the same time to drive the left operating button and the right operating button to move oppositely, so the extension ladder is very convenient for operating.

Description

A kind of extension ladder

Technical field

The present invention relates to a kind of ladder, particularly relate to a kind of some can slip relatively and mutually nested together the extension ladder of terraced bar that include.

Background technology

When maintenance or maintenance task take place for dwelling house, apartment, farm, factory and other places, often need the use ladder.Ladder must be covered up obsolete the time somewhere.Long ladder can allow people arrive higher height, but but is not easy to carry and can takies more space in collection.And telescopic ladder just can extend ladder in use, and when collection ladder is folded up.

Disclose a kind of extension ladder of similar structures in EP-A-0527766, this ladder comprises the terraced bar that is divided into by putting forward the shelves section of being interconnected to, and the diameter of terraced bar upwards reduces.It is characterized in that the maintaining body in U.S.'s bench is designed to when terraced grade of the ladder shelves next one below being positioned at descend, automatically the higher bench of release.This means that along with the release of bottom bench, follow-up bench is automatically released, thereby ladder is flexible.This patent has extension ladder advantage easily, but also there is the dangerous defective that easily has an accident of use in it, the injury that caused by extruding especially takes place, when this ladder in use, the careless switch that descends bench most that touches of the third party is arranged, can cause above each bench all to discharge automatically, this can bring danger to the user.

Therefore, the extension ladder that ladder could be folded up of the existing the sort of button that must press one at a time on each crosspiece is in use safer on the contrary.

Have No. one for the U.S. Patent Publication of US7048094 a kind of safe extension ladder easy to use, this ladder comprises: the first terraced bar, the second terraced bar and extend in the first terraced bar and the second terraced bar between some crosspieces; The first terraced bar includes first pole and second pole, and this first pole includes an inner surface, and second pole connects into the stretching structure of a relative motion along its length by the nested mode and first pole; One locking mechanism is selectively tight with the relative first segment lever lock of second pole; One button is operatively coupled on the locking mechanism, is used to control this locking mechanism; This patent is characterised in that, described button is arranged on the position near first pole, and have one can with the suitable recess of thumb finger tip size, the thumb finger tip is placed in this recess and can promotes button and cancel the locking of locking mechanism to second pole along the direction from first pole toward second pole; One sleeve pipe is set on the external surface of second pole; This sleeve pipe has and the contacted outer spigot surface of the inner surface of first pole.

Compare with the existing extension ladder of safety that uses, the technical characterictic that this claim is the most outstanding is " button " and " sleeve pipe " wherein, and mainly how solution makes button control more convenient and how to reduce friction and wear problem between the adjacent pole.

People are by common-sense reasoning, think generally button along with being convenient to user's operational lock structure more near the pole position, so that feature is shunk, because the button on each crosspiece respectively has two, and be located at the end positions place of crosspiece respectively, therefore must make when operating and with the hands grip the first terraced bar, the second terraced bar stretches out the thumb actuation button simultaneously and comes the operational lock structure, that is to say to make the operating process that with the hands just can finish simultaneously two buttons.And in fact this structure also is not that easily we control button.

In sum, existing extension ladder also can be further improved.

Summary of the invention

Technical problem to be solved by this invention is to provide a kind of one-handed performance of being convenient to control the extension ladder that button makes crosspiece and corresponding pole release at above-mentioned prior art present situation, and this ladder has use advantage more convenient to operate.

Second technical problem to be solved by this invention is: provide a kind of preventing to break away from next joint joint bar at the state bottom left pole that spurs pole fast, and the extension ladder that can indicate the pulling of user's pole whether to put in place.

The present invention solves the problems of the technologies described above the technical scheme that is adopted: a kind of extension ladder, include two left terraced bars that are oppositely arranged and right terraced bar, and a plurality of this left sides that are arranged on, crosspiece between the right terraced bar, wherein left terraced bar is made up of the left pole of more piece telescopic folding socket successively, right terraced bar is made up of the right pole of more piece telescopic folding socket successively, crosspiece then is installed in two relative left sides, between the right pole, and in crosspiece, be provided with when ladder launches with crosspiece with on the left locking mechanism of left pole locking of a joint, reach right locking mechanism with the right pole locking of a crosspiece and a last joint, folding to prevent that ladder from shrinking, this left side, right locking mechanism has a left side respectively, button is controlled on the right side; It is characterized in that: the described left and right button of controlling is positioned at the crosspiece central part and is arranged in close proximity to each other, and is convenient to a hand and operates these two simultaneously and control button and make this crosspiece and corresponding pole release.

Above-mentioned left locking mechanism also comprises the left adapter sleeve that is connected the crosspiece left end, this left side adapter sleeve interconnects the top of crosspiece and corresponding left pole, be located at the left latch in the crosspiece, this left side latch can move also relative to the crosspiece horizontal cross can stretch out the crosspiece left hand external, be arranged with first spring that left latch is remained expose outside crosspiece left hand external trend on the described left latch, a described left side is controlled button and is linked to each other with this left side latch, corresponding, described left pole top has first lock hole that passes for left latch, and the middle part of left pole also has second lock hole that inserts for left latch; Described right locking mechanism also comprises the right adapter sleeve that is connected the crosspiece right-hand member, this right side adapter sleeve interconnects the top of crosspiece and corresponding right pole, be located at the right pin in the crosspiece, this right pin can move also relative to the crosspiece horizontal cross can stretch out the crosspiece right hand external, be arranged with second spring that right pin is remained expose outside crosspiece right hand external trend on the described right pin, the described right side is controlled button and is linked to each other with this right pin, corresponding, described right pole top has the 3rd lock hole that passes for right pin, and the middle part of right pole also has the 4th lock hole that inserts for right pin.

The parts that aforementioned locking mechanism relates to are few, so it is a comparatively simply locking mechanism of a kind of structure, this locking mechanism also can adopt the various lock modes in the existing extension ladder certainly.

The left side has first spring base in the above-mentioned crosspiece, this first spring base is passed in described left latch activity, described first spring is located in this first spring base, and this first spring, one end is resisted against the right side inwall of first spring base, and the other end is resisted against on the convex shoulder at left latch middle part; The right side has second spring base in the described crosspiece, this second spring base is passed in described right pin activity, described second spring is located in this second spring base, and this second spring, one end is resisted against the inner left wall of second spring base, and the other end is resisted against on the convex shoulder at right pin middle part.Described spring base not only plays the purpose of putting spring, but also has the effect of supporting latch.

The left side has the left limit piece in the above-mentioned crosspiece, and this left limit piece is passed in described left latch activity, and fixed interval has two baffle rings of joining with left limit piece end face retaining on the left latch, and described two baffle rings are positioned at left limit piece both sides; The right side has the right limit piece in the described crosspiece, and this right limit piece is passed in described right pin activity, and fixed interval has two baffle rings of joining with right limit piece end face retaining on the right pin, and described two baffle rings are positioned at right limit piece both sides.By limited block spacing to latch, can control the left and right button of controlling well and in a suitable scope, move, it is that a kind of latch is moved carried out spacing structure certainly.

For solving second technical problem of the present invention, the middle part of described left pole outer peripheral face is arranged with the left limit ring, this left limit ring is between the left pole of adjacent two joints, corresponding, described left adapter sleeve has annular surface, and this annular surface forms socket, this socket and left pole upper periphery close-fitting, described socket inwall upper end forms the interior omoplate that can join with left limit ring retaining, also has the through hole that passes and connect with described socket for left latch on the left adapter sleeve; The middle part of described right pole outer peripheral face is arranged with the right limit ring, this right limit ring is between the right pole of adjacent two joints, corresponding, described right adapter sleeve has annular surface, this annular surface forms socket, this socket and right pole upper periphery close-fitting, described socket inwall upper end form the interior omoplate that can join with right limit ring retaining, also have the through hole that passes and connect with described socket for right pin on the right adapter sleeve.

When pole after upwards pulling puts in place, the gear by omoplate on spacing ring and the adapter sleeve cooperates, and the prevention pole further is drawn out, and omoplate was obstructed in spacing ring was run into, and promptly can not easily spur under the pole state again, just indicated the user, this moment, pole put in place, stopped drag pole.

The spacing mode on pole of spacing ring can adopt following pole: have first breach relative with described first lock hole on the described left limit ring, and the inwall of described left limit ring has several protuberances, correspondence, described left pole middle part perisporium has the hole that several snap in for described protuberance; Have second breach relative on the described right limit ring, and the inwall of described right limit ring has several protuberances with described the 3rd lock hole, correspondence, described right pole middle part perisporium has the hole that several snap in for described protuberance.This pole can make spacing ring convenient and firm spacing at the pole middle part, operates to make along the breach direction and breaks spacing ring into two with one's hands, spacing ring is buckled in the pole outer peripheral face, and protuberance is snapped in the corresponding hole, spacing ring can be installed.

Above-mentioned left pole lower ending opening place is arranged with a left pipe box, and the outer surface of upper of this left side pipe box contacts with the left pole inner face of next joint, and the lower external face of described left pipe box is tapered; Described right pole lower ending opening place is arranged with a right pipe box, and the outer surface of upper of this right side pipe box contacts with the right pole inner face of next joint, and the lower external face of described right pipe box is tapered.The outer surface of upper of right pipe box contacts with the right pole inner face of next joint, play the damping action when between adjacent pole, relatively moving, it is too fast to prevent that pole from relatively moving, avoid colliding energetically mutually between the adjacent crosspiece and damage crosspiece, and can reduce the noise that crosspiece produces because of collision mutually; Be convenient to us and will go up a joint joint bar and be inserted in next joint joint bar and the lower external face of right pipe box is tapered.

The upper inside surface of above-mentioned left pipe box has several salient points, correspondence, and described left pole bottom perisporium has several locating holes that snaps in for described salient point; The upper inside surface of described right pipe box has several salient points, correspondence, and described right pole bottom perisporium has several locating holes that snaps in for described salient point.Cooperation by salient point and locating hole just can be installed to pipe box the pole lower end, and this pole that puts in place is simple, easy to assembly.

Control button for ease of us with finger manipulation, the right side that button is controlled on an above-mentioned left side has is convenient to the stopper that finger tip is set up; The left side that button is controlled on the described right side has is convenient to the stopper that finger tip is set up.Stopper is located at the inboard of controlling button, can reduces the operation span between finger, finger can better be exerted all one's strength to controlling button, operates lighter.

Compared with prior art, the invention has the advantages that: this extension ladder is with a left side, the right side is controlled button and is located at the crosspiece central part and is arranged in close proximity to each other, only need open same thumb and forefinger on hand during former the operation, thumb is controlled button with the right side and is contacted, forefinger is controlled button with a left side and is contacted, firmly drive a left side then simultaneously inwardly, the right side is controlled button and is moved in opposite directions, to operate a left side, right locking mechanism is removed a crosspiece and a corresponding left side, locking between the right pole, it is quite convenient to operate, remaining another hand can grip pole, allow pole slowly move down, avoid the bump between adjacent rungs, operating process is steadily carried out.

Description of drawings

Fig. 1 is the perspective view of the embodiment of the invention;

Fig. 2 is the sectional view of the embodiment of the invention;

Fig. 3 is the A place enlarged drawing of Fig. 2;

Fig. 4 is the B place enlarged drawing of Fig. 2;

Fig. 5 is the C place enlarged drawing of Fig. 2;

Fig. 6 is the D place enlarged drawing of Fig. 2;

Fig. 7 is the E place enlarged drawing of Fig. 2;

Fig. 8 is the F place enlarged drawing of Fig. 2;

Fig. 9 is the three-dimensional exploded view of the embodiment of the invention;

Figure 10 is a scheme of installation between spacing ring and pipe box and the pole in the embodiment of the invention.

The specific embodiment

Embodiment describes in further detail the present invention below in conjunction with accompanying drawing.

Be depicted as a preferred embodiment of the present invention as Fig. 1～10.

A kind of extension ladder, include two left terraced bars 1 that are oppositely arranged and right terraced bar 2, and a plurality of crosspieces 3 that are arranged between this left and right

terraced bar

1,2, wherein left terraced bar 1 is formed and is formed a stretching structure by the left pole 11 of more piece telescopic folding socket successively, right terraced bar 2 is made up of the right pole 21 of more piece telescopic folding socket successively and is formed a stretching structure, the tubulose that described left and

right pole

11,21 is roughly.

3 of described crosspieces are installed between two relative left and

right poles

11,21, crosspiece 3 is the rectangular-shaped of hollow, be provided with in the described crosspiece 3 when ladder launches with crosspiece 3 with on the left locking mechanism 4 of left pole 11 lockings of a joint, and with the right locking mechanism 5 of crosspiece 3 with right pole 21 lockings of a last joint, folding to prevent that ladder from shrinking, this left and right locking mechanism 4,5 has the left and

right button

6,7 of controlling that is used to operate these two latch-up structures respectively.

As Fig. 3, shown in 7, described left locking mechanism 4 also comprises the left adapter sleeve 41 that is connected crosspiece 3 left ends, this left side adapter sleeve 41 interconnects the top of crosspiece 3 with corresponding left pole 11, be located at the left latch 42 in the crosspiece 3, this left side latch 42 can move also relative to crosspiece 3 horizontal cross can stretch out crosspiece 3 left hand external, be arranged with first spring 43 that left latch 42 is remained expose outside crosspiece 3 left hand external trend on the described left latch 42, the left side has first spring base 44 in the crosspiece 3, this first spring base 44 is passed in described left latch 42 activities, described first spring 43 is located in this first spring base 44, these first spring, 43 1 ends are resisted against the right side inwall of first spring base 44, and the other end is resisted against on the convex shoulder 421 at left latch 42 middle parts; The left side has left limit piece 45 in described crosspiece 3, this left limit piece 45 is passed in described left latch 42 activities, and fixed interval has two baffle rings 46 of joining with left limit piece 45 end faces retaining on the left latch 42, and described two baffle rings 46 are positioned at left limit piece 45 both sides; A described left side is controlled button 6 and is linked to each other with this left side latch 42, correspondence, and described left pole 11 tops have first lock hole 111 that passes for left latch 42, and the middle part of left pole 11 also has second lock hole 112 that inserts for left latch 42.

As Fig. 4, shown in 8, described right locking mechanism 5 also comprises the right adapter sleeve 51 that is connected crosspiece 3 right-hand members, this right side adapter sleeve 51 interconnects the top of crosspiece 3 with corresponding right pole 21, be located at the right pin 52 in the crosspiece 3, this right pin 52 can move also relative to crosspiece 3 horizontal cross can stretch out crosspiece 3 right hand external, be arranged with second spring 53 that right pin 52 is remained expose outside crosspiece 3 right hand external trend on the described right pin 52, the right side has second spring base 54 in the crosspiece 3, this second spring base 54 is passed in described right pin 52 activities, described second spring 53 is located in this second spring base 54, these second spring, 53 1 ends are resisted against the inner left wall of second spring base 54, and the other end is resisted against on the convex shoulder 521 at right pin 52 middle parts; The right side has right limit piece 55 in described crosspiece 3, this right limit piece 55 is passed in described right pin 52 activities, and fixed interval has two baffle rings 56 of joining with right limit piece 55 end faces retaining on the right pin 52, and described two baffle rings 56 are positioned at right limit piece 55 both sides; The described right side is controlled button 7 and is linked to each other with this right pin 52, correspondence, and described right pole 21 tops have the 3rd lock hole 211 that passes for right pin 52, and the middle part of right pole 21 also has the 4th lock hole 212 that inserts for right pin 52.

The described left and

right button

6,7 of controlling is positioned at crosspiece 3 central parts and is arranged in close proximity to each other, have at crosspiece 3 middle parts promptly that two confessions are left and right controls the left and

right groove

31,32 that

button

6,7 passes, it is left and right that to control

button

6,7 spacing respectively in left and

right groove

31,32, and can distinguish relative to left and

right groove

31,32 and laterally move, be convenient to a hand like this and operate these two simultaneously and

control button

6,7 and make crosspiece 3 and corresponding

pole

11,21 releases.The right side that button 6 is controlled on a described left side has is convenient to the stopper 61 that finger tip is set up; The left side that button 7 is controlled on the described right side has is convenient to the stopper 71 that finger tip is set up.

Middle part at left pole 11 outer peripheral faces is arranged with left limit ring 8, this left limit ring 8 is between the left pole 11 of adjacent two joints, corresponding, described left adapter sleeve 41 has annular surface, this annular surface forms socket 411, this socket 411 and left pole 11 upper periphery close-fittings, and connect by connector, described socket 411 inwalls upper end forms the interior omoplate 412 that can join with left limit ring 8 retainings, also has the through hole 413 that passes and connect with described socket 411 for left latch 42 on the left adapter sleeve 41; Have on the described left limit ring 8 one with the first relative breach 81 of described first lock hole 111, and the inwall of described left limit ring 8 has several protuberances 82, correspondence, described left pole 11 middle part perisporiums have several holes 113 that snaps in for described protuberance 82.

The middle part of described right pole 21 outer peripheral faces is arranged with right limit ring 9, this right limit ring 9 is between the right pole 21 of adjacent two joints, corresponding, described right adapter sleeve 51 has annular surface, this annular surface forms socket 511, this socket 511 and right pole 21 upper periphery close-fittings, and connect by connector, described socket 511 inwalls upper end forms the interior omoplate 512 that can join with right limit ring 9 retainings, also has the through hole 513 that passes and connect with described socket 511 for right pin 52 on the right adapter sleeve 51; Have on the described right limit ring 9 one with the second relative breach 91 of described the 3rd lock hole 211, and the inwall of described right limit ring 9 has several protuberances 92, correspondence, described right pole 21 middle part perisporiums have several holes 213 that snaps in for described protuberance 92.

Shown in Fig. 9,10, described left pole 11 lower ending opening places are arranged with a left pipe box 10, and the outer surface of upper 101 of this left side pipe box 10 contacts with left pole 11 inner faces of next joint, and the lower external face 102 of described left pipe box 10 is tapered; The upper inside surface of described left pipe box 10 has several salient points 103, correspondence, and described left pole 11 bottom perisporiums have several locating holes 114 that snaps in for described salient point 103.

Described right pole 21 lower ending opening places are arranged with a right pipe box 12, and the outer surface of upper 121 of this right side pipe box 12 contacts with right pole 21 inner faces of next joint, and the lower external face 122 of described right pipe box 12 is tapered; The upper inside surface of described right pipe box 12 has several salient points 123, correspondence, and described right pole 21 bottom perisporiums have several locating holes 214 that snaps in for described salient point 123.

The operating principle and the process of the embodiment of the invention are as follows:

This only with left pole 11 wherein, right pole 21, the crosspiece 3 that links to each other with this left and

right pole

11,21, on the course of action of a working cell constituting of the left and

right pole

11,21 of a joint be example.

The locking process of right pole 21: on draw right pole 21, when right pole 21 after upwards pulling puts in place, gear by omoplate 512 on right limit ring 9 and the right adapter sleeve 51 cooperates, stop right pole 21 further to be drawn out, and omoplate 512 was obstructed in right limit ring 9 was run into, just indicate the user, this moment, right pole 21 put in place, stopped drag right pole 21.At this moment, the 4th lock hole 212 at right pole 21 middle parts that this is pulled saves right pole 21 tops the 3rd lock hole 211 with next and is positioned on the same axis, therefore, save at next that the right pin 52 in the crosspiece 3 ejects between the right pole 21 under the effect of second spring 53, pass the through hole 513 on the right adapter sleeve 51 successively, insert in the 4th lock hole 212 the 3rd lock hole 211 backs, the right pole 21 of crosspiece 3 with a last joint locked together, and crosspiece 3 is to fix with another right pole 21, so crosspiece 3, the right pole 32 that links to each other with crosspiece 3, the right pole 32 of a last joint locks mutually.

The locking process of locking process and the right pole 21 of left side pole 11 is identical and carry out simultaneously.

Releasing process: open same thumb and forefinger on hand, thumb is controlled button 7 with the right side and is contacted, forefinger is controlled button 6 with a left side and is contacted, firmly driving simultaneously the left and

right button

6,7 of controlling then inwardly moves in opposite directions, left and

right latch

42,52 moves simultaneously in opposite directions, left and

right latch

42,52 breaks away from second, four lock holes 112,212 on the left and

right pole

11,21 of a last joint simultaneously, remove the locking between this crosspiece 3 and the left and

right pole

11,21 of a last joint, the another hand can grip pole.

Left and

right pole

11,21 inner face CONTACT WITH FRICTION are saved in the outer surface of upper 101,121 of left and

right sleeve pipe

10,12 and next in the lower end of the left and

right pole

11,21 of a last joint, left and

right sleeve pipe

10,12 plays damping action, prevent that the left and

right pole

11,21 of a joint from saving left and

right pole

11,21 relative to next and moving too fast, avoid colliding energetically mutually between the adjacent crosspiece 3 and damage crosspiece 3, and can reduce the noise that crosspiece 3 produces because of collision mutually.

Claims

1, a kind of extension ladder, include two left terraced bars (1) that are oppositely arranged and right terraced bar (2), and a plurality of this left sides that are arranged on, right terraced bar (1,2) crosspiece between (3), wherein left terraced bar (1) is made up of the left pole (11) of more piece telescopic folding socket successively, right terraced bar (2) is made up of the right pole (21) of more piece telescopic folding socket successively, crosspiece (3) then is installed in two relative left sides, right pole (11,21) between, and in crosspiece (3), be provided with when ladder launches the left locking mechanism (4) of crosspiece (3) with left pole (11) locking of a last joint, and with the right locking mechanism (5) of crosspiece (3) with right pole (21) locking of a last joint, folding to prevent that ladder from shrinking, this left side, right locking mechanism (4,5) has a left side respectively, button (6 is controlled on the right side, 7); It is characterized in that: the described left and right button (6,7) of controlling is positioned at crosspiece (3) central part and is arranged in close proximity to each other, and is convenient to a hand and operates these two simultaneously and control button (6,7) and make this crosspiece (3) and corresponding pole (11,21) release.

2, extension ladder according to claim 1, it is characterized in that: described left locking mechanism (4) also comprises the left adapter sleeve (41) that is connected crosspiece (3) left end, this left side adapter sleeve (41) interconnects the top of crosspiece (3) with corresponding left pole (11), be located at the left latch (42) in the crosspiece (3), this left side latch (42) can move also relative to crosspiece (3) horizontal cross can stretch out crosspiece (3) left hand external, be arranged with first spring (43) that left latch (42) is remained expose outside crosspiece (3) left hand external trend on the described left latch (42), a described left side is controlled button (6) and is linked to each other with this left side latch (42), corresponding, described left pole (11) top has first lock hole (111) that passes for left latch (42), and the middle part of left pole (11) also has second lock hole (112) that inserts for left latch (42);

Described right locking mechanism (5) also comprises the right adapter sleeve (51) that is connected crosspiece (3) right-hand member, this right side adapter sleeve (51) interconnects the top of crosspiece (3) with corresponding right pole (21), be located at the right pin (52) in the crosspiece (3), this right pin (52) can move also relative to crosspiece (3) horizontal cross can stretch out crosspiece (3) right hand external, be arranged with second spring (53) that right pin (52) is remained expose outside crosspiece (3) right hand external trend on the described right pin (52), the described right side is controlled button (7) and is linked to each other with this right pin (52), corresponding, described right pole (21) top has the 3rd lock hole (211) that passes for right pin (52), and the middle part of right pole (21) also has the 4th lock hole (212) that inserts for right pin (52).

3, extension ladder according to claim 2, it is characterized in that: the left side has first spring base (44) in the described crosspiece (3), this first spring base (44) is passed in described left latch (42) activity, described first spring (43) is located in this first spring base (44), these first spring (43) one ends are resisted against the right side inwall of first spring base (44), and the other end is resisted against on the convex shoulder (421) at left latch (42) middle part;

The interior right side of described crosspiece (3) has second spring base (54), this second spring base (54) is passed in described right pin (52) activity, described second spring (53) is located in this second spring base (54), these second spring (53) one ends are resisted against the inner left wall of second spring base (54), and the other end is resisted against on the convex shoulder (521) at right pin (52) middle part.

4, extension ladder according to claim 2, it is characterized in that: the left side has left limit piece (45) in the described crosspiece (3), this left limit piece (45) is passed in described left latch (42) activity, and left latch (42) is gone up fixed interval two baffle rings (46) of joining with left limit piece (45) end face retaining, and described two baffle rings (46) are positioned at left limit piece (45) both sides;

The interior right side of described crosspiece (3) has right limit piece (55), this right limit piece (55) is passed in described right pin (52) activity, and right pin (52) is gone up fixed interval two baffle rings (56) of joining with right limit (55) piece end face retaining, and described two baffle rings (56) are positioned at right limit piece (55) both sides.

5, extension ladder according to claim 2, it is characterized in that: the middle part of described left pole (11) outer peripheral face is arranged with left limit ring (8), this left limit ring (8) is positioned between the adjacent two left poles of joint (11), corresponding, described left adapter sleeve (41) has annular surface, this annular surface forms socket (411), this socket (411) and left pole (11) upper periphery close-fitting, described socket (411) inwall upper end forms the interior omoplate (412) that can join with left limit ring (8) retaining, also has the through hole (413) that passes and connect with described socket (411) for left latch (42) on the left adapter sleeve (41);

The middle part of described right pole (21) outer peripheral face is arranged with right limit ring (9), this right limit ring (9) is positioned between the adjacent two right poles of joint (21), corresponding, described right adapter sleeve (51) has annular surface, this annular surface forms socket (511), this socket (511) and right pole (21) upper periphery close-fitting, described socket (511) inwall upper end forms the interior omoplate (512) that can join with right limit ring (9) retaining, also has the through hole (513) that passes and connect with described socket (511) for right pin (52) on the right adapter sleeve (51).

6, extension ladder according to claim 5, it is characterized in that: have first breach (81) relative on the described left limit ring (8) with described first lock hole (111), and the inwall of described left limit ring (8) has several protuberances (82), correspondence, described left pole (11) middle part perisporium has the hole (113) that several snap in for described protuberance (82);

Have second breach (91) relative on the described right limit ring (9) with described the 3rd lock hole (211), and the inwall of described right limit ring (9) has several protuberances (92), correspondence, described right pole (21) middle part perisporium has the hole (213) that several snap in for described protuberance (92).

7, according to the described extension ladder of arbitrary claim in the claim 1～6, it is characterized in that: described left pole (11) lower ending opening place is arranged with a left pipe box (10), the outer surface of upper (101) of this left side pipe box (10) contacts with left pole (11) inner face of next joint, and the lower external face (102) of described left pipe box (10) is tapered;

Described right pole (21) lower ending opening place is arranged with a right pipe box (12), and the outer surface of upper (121) of this right side pipe box (12) contacts with right pole (21) inner face of next joint, and the lower external face (122) of described right pipe box (12) is tapered.

8, extension ladder according to claim 7, it is characterized in that: the upper inside surface of described left pipe box (10) has several salient points (103), correspondence, described left pole (11) bottom perisporium have several locating holes (114) that snaps in for described salient point (103);

The upper inside surface of described right pipe box (12) has several salient points (123), correspondence, and described right pole (21) bottom perisporium has several locating holes (214) that snaps in for described salient point (123).

9, extension ladder according to claim 1 is characterized in that: the right side that button (7) is controlled on a described left side has the stopper (71) of being convenient to finger tip and setting up; The left side that button (8) is controlled on the described right side has the stopper (81) of being convenient to finger tip and setting up.