WO2008064532A1

WO2008064532A1 - An extensible ladder with anti-pinch device

Info

Publication number: WO2008064532A1
Application number: PCT/CN2007/000376
Authority: WO
Inventors: Wanxing Wang
Original assignee: Wanxing Wang
Priority date: 2006-11-29
Filing date: 2007-02-05
Publication date: 2008-06-05

Abstract

An extensible ladder with anti-pinch device comprises a first vertical post and a second vertical post composed of multilevel sleeves, and several cross pieces with hollow structure. The cross piece is connected with the vertical post by an annular ring (3, 36). A bearing junk ring and a cushion collar are provided in the extensible sleeve (1, 1') of the vertical post. An anti-pinch void is provided between the vertical post and the extremity piece of the base cross piece (28), the base cross piece is connected to the corresponding extensible sleeve by means of an annular ring (36) with an anti-pinch boss on the upper end, and the horizontalplane (363) on the top of the wall of the annular ring (36) is provided with a protrusion (361) for linked unlocking when the ladder is retracted. A sufficient safe interval is placed between the base cross piece and the adjacent cross piece above for anti-pinching when the ladder is retracted.

Description

Title Inventive Safety Retractable Ladder

The present invention relates to the field of ascending ladders, and more particularly to a telescopic ladder having a chain unlocking function and an anti-pinch device. It is suitable for use in a variety of locations where it is necessary to climb up frequently and safely or to take and store items at high altitudes. Background technique

The utility model patent of "a retractable ladder" of the Chinese patent application No. 2-00420091638. 2, which has a crossbar and a vertical rod, the vertical rod is a retractable sleeve a stepped manner, which is telescopically sleeved by a plurality of sleeves, the crossbar being placed horizontally between the two opposing vertical rods, at each end of each of the crossbars Retractable horizontal locking axle pins are respectively provided, which are respectively adapted to the locking positioning sockets corresponding to them in the vertical rod sleeve. The upper end of each of the sleeves forming the vertical rod is sleeved with a nylon annular sleeve, and the sleeve is fixedly coupled to the cross rod. The ends of the cross bar are provided with end pieces with annular slits, and the connection between the end pieces of the cross bar and the vertical rods is fixedly connected by screws. The above-mentioned Chinese patent application No. 200420091638. 2 "The type of telescopic ladder" utility model patent has the advantage that the crossbar acts as both a lever and a pull bar, effectively preventing the ladder from falling apart; and the locking axle pin One end is provided with a wear-resistant member to prevent the shaft pin from wearing the vertical rod; the bottom of the sleeve is provided with a collar, and the cross rod is a hollow structure, and the weight is light.

However, it still has the insufficiency that the connection between the end piece of the cross bar and the vertical rod is fixed by screws, and two bosses are provided on both sides of the ladder; and the screw will loosen in long-term use, or the screw will be used by people. The loosening of the disassembly causes a safety hazard; secondly, the above-mentioned patent still exists - the disadvantage is that when the multi-stage step down movement is collapsed, it becomes a stacking block without safety clearance, and between the crossbars of the various levels There is no safety clearance, and the resulting force will cause a person's hand or finger to be pinched between two adjacent rails at each level. There are insecurities due to unsafe operations. It is a problem for us to suppress and reduce the above-mentioned impulses, so that each step unit forms a damping during the falling of its free fall to reduce the speed and momentum of the slip to avoid pinching the hands or fingers. Summary of the invention

SUMMARY OF THE INVENTION It is an object of the present invention to provide a telescopic ladder using a secure anti-pinch device in order to overcome the deficiencies of the prior art described above. As long as it pushes the elevator button on the basic grade crosspiece of the lower part of the ladder (the penultimate stage), the crosspieces of the entire ladder will be slid down into a pile like a domino. The chain of the entire ladder is unlocked. Due to the action of the damper friction device installed in the telescopic tubes of the vertical rods, the crosspieces of the ladders of each stage are evenly and uniformly slid down when sliding, and the fixed stop horizontally located at the lower part of the ladder with the ladder button is provided. The gear (basic crosspiece) maintains a safety margin against the pinch when it is folded with its adjacent upper rung, so the operation is very safe. The structure of the present invention is as follows: An anti-pinch safety telescopic ladder comprising a telescopic vertical rod which is sleeved by a multi-stage sleeve, which are the first vertical rod and the second vertical rod on the left and right sides, There are multiple levels of horizontally extending crosspieces between the first and second vertical bars. The entire ladder has no locks except for the top level of the horizontal gear. Pin latch. - The lower part of the ladder has a stationary fixed stop rail stage (basic grade rung), on which the rung assemblies are retractable. There is a latching mechanism at the junction of the base level rail and its corresponding vertical rod, the latching mechanism including an unlocking step button for unlocking the upper level rails of the upper level, which performs the initial action of the ladder. It can be push-pull or single push. It is enough to use only one initial action when unlocking the ladder. That is, you only need to enter the fi-secondary operation (pull or single push unlock button) on the unlock button on the basic grade rail, and the basic grade rail The above latches on the crosspieces of the various levels are automatically interlocked to complete the unlocking action.

An unlocking button for realizing the interlocking start action of the chain is provided on the basic crosspiece at the lower part of the ladder. The unlocking button is provided on the lower horizontal side of the stationary fixed base level rail at the lower portion of the ladder, or on both sides of the rail.

The conventional ring on each end of each level of the crosspiece has a separable seam, and the slot is screwed after it is wrapped around the telescopic sleeve. The ring enclosing the telescopic sleeve described in the present invention is an integrally closed loop, and no screws are required for installation, so that the structure is simple and the appearance is better. The crosspiece has an elastic inner protrusion contact point matched with the vertical rod sleeve on the ring wall of the ring, which is formed by cutting the inverted U-shaped groove on the wall surface of the ring ring at both ends of the crosspiece, forming a cantilever elastic protrusion surrounded by an inverted U-shaped groove, the upper end of the cantilever protrusion is inwardly protruding obliquely, having a sloped surface, and the elastic contact point cantilever block on the telescopic sleeve of the vertical rod Corresponding holes or pits that snap into each other when they move into position with each other. The original setting is because the telescopic sleeves of the first vertical rod and the second vertical rod are made of metal aluminum alloy, and the ring on the telescopic sleeve is nylon. This design can ensure the two parts made of different materials. Good fit between the rooms. It suffices to arrange a pair of elastic inward contact points in a certain diameter direction of the loop in a phasewise manner, and of course, the cantilever projections representing the same can also be provided. The crosspiece has a ring (26) made of a nylon material. a chain level unlocking mechanism is provided on the upper level rails of the lower level of the lower level of the lowermost level of the ladder, and includes a button member with a corner shape and a top rod and a button member that can move up and down The horizontal value of the dial. The top surface of the two ends of the crosspieces between the first level rail and the lower base rail is provided with a small hole for the top rod disposed inside and below, and the bottom hole is opened. The lower bottom surface of the two ends of the crosspiece is provided with a small hole for the next stage. The ejector rod in the crosspiece can pass through when it is pushed upward. The end of the outer end of the cross pin can be opened and latched in the pin hole on the wall surface of the sleeve. The end of the cross pin abuts against a compression spring. The ejector rod has a square shape, and the bottom edge thereof is always opposite to the corner of the button member by gravity, and the fixed stop rail at the lower portion of the ladder is upwardly raised on the upper surface of the ring sleeve as the upper horizontal rail When falling, its corner-shaped button member has a lower end that collides with the lower end of the corner portion of the button member, so that the corner portion is lifted up, and the top pushes the top rod, so that the entire button member occurs. Around the rotation of its own fulcrum, its push arm moves inwardly against the pressure of the compression spring through the groove embedded in the middle of the cross pin. At this time, the horizontal end of the cross pin is caused by the horizontal movement of the cross pin. Pulled out from the slotted hole of the first and second vertical rod telescopic tube, at this time, the fixed stop rail level is above the first grade horizontal grade from the nearest first horizontal grade to the uppermost first stage The dominoes are slid down into a pile like the dominoes, forming a chain of the entire ^^ ladder to unlock. The corner-shaped button member constituting the interlocking mechanism of the interlocking mechanism is accommodated in the cavity of each level of the crosspiece, and the pivot point of the rotation is a short column, which is placed on the bottom surface of the inner cavity of the crosspiece in a resting state, and the dial is embedded In the dial in the middle of the horizontal cross pin, the horizontal cross pin is used for the dialing action. The button member has two lower legs, and the vertically arranged ejector pins are also two. The upper and lower horizontal faces of the crosspiece are also respectively opened for the push-pull ejector and the button member to extend under the foot. Two through holes that pass through. Unlocking the entire ladder chain is the unlocking elevator button on the basic grade rail in the lower part of the ladder, which can be push-pull or single push. The push-pull type includes a pull-out unlocking button, a shifting column and a bullet Spring. A positioning and fixing boss is disposed between the sliding plane of the push-pull stepping button and the crosspiece, and the dial and the cross pin are vertically screwed and fixed to each other through the screw hole, and the cylindrical shape of the sliding button is unlocked. Part of it is a spring seat, which accommodates the shifting column and the spring, and the magazine keeps the push-pull stepping button in a state of being in close contact with the lower plane of the crossbar. When operating, first pull out the unlocking push-pull ladder button vertically downwards, let the positioning fixed boss down below the lower plane of the crosspiece, then push the spring in the inward direction, the cross pin will move inward, the lock will be Was opened. At this point, the adjacent grade of the crosspiece is lowered.

If the single push type is used, the structure is as follows: The unlocking and closing button on the basic rail level of the ladder part of the ladder is a single push type unlocking button, which comprises a push handle integrated with the vertical reinforcement. The upper end of the push handle is provided with an open slot which is matched with the slot pin provided in the middle of the cross pin, and the inner end of the cross pin abuts against the spring. : a damping device is fixed in the lower end port of each stage of the first and second vertical rods, and includes a bearing block and a friction ring embedded in the lower end of the bearing block to inwardly shrink the groove, and a pin will be The load bearing block is transversely and fixedly connected to the lower end of the telescopic sleeve. The expansion sleeves at all levels have this friction ring to maintain a constant speed during the movement, which also increases safety. The inner ring of the friction ring at the lower end of the telescopic sleeve is concave. Compared with the prior art, the advantages of the present invention are as follows: 1. The ladder has an anti-pinch device when it is folded, and is safe to use; 2. It has the function of a serial solution, and it is not necessary to add an independent function on the crosspiece of each step. Manual unlock button, good stability and reliability; 3. Buffer function when telescopic ladder is also a safety factor, and the appearance is good, the operation is simple and fast.

DRAWINGS

Figure 1 is a schematic view showing the structure of the extended state of the ladder of the present invention;

2 is a structural view showing the connection of a basic crosspiece and a ring of the end piece thereof according to Embodiment 1 of the present invention;

Figure 3 is a cross-sectional view taken along line A-A of Figure 2;

4 is a view showing an operation state of a chain unlocking mechanism according to Embodiment 1 of the present invention;

Figure 5 is a perspective view of the button member in the interlocking mechanism of Figure 4;

Figure 6 is a perspective view of the second and third stage rails in the first embodiment of the present invention;

7 is a structural diagram of a push button mechanism of a basic level crosspiece pull button type elevator unlocking mechanism according to Embodiment 1;

Figure 8 is a view showing the cooperation between the ring of the uppermost end piece end piece and the telescopic tube of the first embodiment;

Figure 9 is a cross-sectional view showing the structure of the damper device at the lower end of the vertical rod telescopic tube of the embodiment 1; - Figure ίθ is a schematic diagram of the unlocking mechanism of the basic level cross-bar push button type elevator in the embodiment 2;

Figure 11 is a partial view of the push button of the basic level cross-bar push button type unlocking mechanism of the second embodiment.

Figure 12 is a plan view of Figure 11;

13 is a schematic structural view of a horizontal pin in a basic level cross-bar push button type elevator unlocking mechanism according to Embodiment 2;

Figure 14 is a perspective view of the basic level crosspiece plus single push type elevator unlocking button of the second embodiment;

Figure 15 is a schematic structural view of the collapsed state of the present invention;

detailed description

The invention will be further described in detail below with reference to the embodiments of the drawings. - Embodiment 1 is a pinch-proof safety retractable ladder, see Fig. 1, which comprises a telescopic vertical rod which is sleeved by a multi-stage sleeve, and a retractable first vertical rod and a There are multiple levels of horizontally extending crosspieces between the two vertical bars. The second and third stage rails 2' and 2" have their own interlocking latches except for the uppermost level rail 2, and the lower part of the ladder has a fixed position relative to the ground. Basic rung 28, 'with its bounds, in its The upper level rail assemblies are retractable, with a level of fixed rail grade below it. At the junction of the base rail 28 and the vertical rod 1, there is a latch mechanism, also called a "lifting mechanism", which has an unlocking knob 50 that is unlocked for its upper level rails, which is installed on the base. On the underside of the crosspiece 28. On both ends of each of the above-mentioned crosspieces, there are provided loops 3, 3', 3" which are sleeved by the vertical telescopic sleeves 1, 1 ', 1". The main features of the case are as follows:

1 The lower part of the ladder has a stationary fixed stop rail grade (base rail), which becomes the basis of the entire ladder, and the upper crosspieces are all retractable ladder rail grades, see Figure ί and Figure 2, The two ends of the basic grade rail 28 are provided with an anti-pinch ring 36, and the inner ring 36 has a raised portion inside, and the height of the raised portion is significantly higher than the height of the loop of the other horizontal retractable rails. The outer upper portion of the ring 36 forms a partial ring wall missing 362 for the operator to protect the hand when it is held by the operator, so as not to be crushed by the upper ladder rail assembly that suddenly slides down from above. Figure 3 is a cross-sectional view taken along line A- of Figure 2; The base level rail 28 has a height difference h between the upper plane 363 of the collar 36 and the upper level 281 of the crosspiece 28 that is a safety gap, such that the upper level 281 of the rail 28 when the ladder is collapsed There is a sufficient horizontal distance between the lower planes of the first horizontal rung 2" adjacent to the upper one. There is a horizontal distance h between the guards against the gripper (referring to the crosspiece 2" after the two crosspieces 2〃 and 28 are close together. ). Referring to Fig. 3, the upper upper horizontal surface 363 of the inner ring 36 wall is provided with a vertically upward unlocking projection 361 which is used to strike the downwardly exposed unlocking of the lower side 2 of the upper rail 2 The lower end 234 of the button 23 (see Fig. 4), so that all the steps above it are interlocked to unlock, which becomes the initial impact point of the unlocking of the entire ladder. The unlocking protrusion 361 is stationary and fixed. It is provided on all the horizontal rails. They are arranged in the same position from the bottom to the top (except the first level), but they are movable, as shown in the ejector 22 in Fig. 4, they are Arranged at the ends of each level of the crosspiece

2 Also shown in Fig. 4 is a chain unlocking mechanism provided on each of the intermediate rails 2' and 2", which includes a corner-shaped button member 23 accommodated in the inner cavity of each level of the rails and a button with a corner shape The member 23 is rotated correspondingly up and down to push up the ejector pin .22 of the upper-order crosspiece button member 23, and the cross pin 21 and the compression spring 24. Fig. 5 shows a perspective view of the overall shape of the button member 23. Key parts of the interlocking unlocking mechanism. Figure 6 shows a perspective view of the second stage rail 2' and the third level rail 2" that accommodate all parts of the chain unlocking mechanism. An annular U-shaped groove is formed in the surrounding wall of the ring 3, and an elastic block 31 is surrounded by the inverted-shaped groove for fitting with the telescopic sleeve 1 of the vertical rod during assembly. Two through holes are formed in the upper plane 281 at the transition of the ring 3 and the crosspiece 2 for passage when the jack 22 in Fig. 4 is passed. Similarly, two through holes (not shown) are also formed in the lower plane thereof for the passage of the lower leg 234 of the link unlocking mechanism button member 23 as shown in Fig. 4. A corner-shaped button member 23 in the cavity of the middle rails 2' and 2", its pivot point 233 is placed on the bottom surface of the rail cavity in a resting state, and the dial 232 is active. Embedded in the dial of the cross pin 21. The crosspieces 2' and 2" of the button member 23 of the inner cavity thereof include a dial 232 and a lower leg 231 which are integrally connected by an angle bar. Both the dial 232 and the lower leg 231 are doubled, and the corner fulcrum 233 of the angle bar is a short post.

3 An unlocking button for realizing the interlocking start action of the chain is provided on the base rail level 28 at the lower portion of the ladder. The unlock button is provided on the lower horizontal side of the lower base level rail 28 of the ladder.

Unlocked for the entire ladder chain is the unlocking stop button 33 on the stationary fixed stop rail 28 which serves as the base rail at the lower part of the ladder, which is push-pull (see Figure 7). The push-pull unlocking button 33 includes a pull-out unlocking button 331 and a spring seat 332. The unlocking push-pull button assembly 33 has a cylindrical portion which is a spring seat 332, and the spring 34 is received in the spring seat. Within 332. The spring 34 keeps the catch button 33 in a state of being in close contact with the lower plane 282 of the crossbar 28. A positioning and fixing boss 38 is disposed between the push-pull step button assembly 33 and the joint plane 282 of the crosspiece 28. The dial 35 and the cross pin 21 are screwed perpendicularly to each other through the screw hole 211. The screw hole 211 accommodates the dial 35. When operating, first pull out the unlock push-pull button 33 vertically downwards to fix the positioning. The boss 38 extends downward beyond the lower plane 282 of the crosspiece and then pushes the spring 24 inwardly, so that the cross pin 21 moves inward and the lock is opened. At this time, the adjacent horizontal rung 2" descends and falls to the top surface of the ring 36 of the lower base rail 28 (see Fig. 4). At this time, the top surface of the ring 36 The 361 collides with the lower end 234 of the button member 23 on the lower bottom surface of the fallen upper rung 2", thus triggering the start of the interlock unlocking. The step of operating the push-pull button 33 is to first pull the unlock button 331 downward and then to the inside of the ladder, which causes the dial 35 to move the cross pin 21 to perform unlocking. , ― : · As can be seen from Fig. 2 and Fig. 6, the arrangement described in the present case encloses the telescopic sleeve 1 at both ends of each crosspiece, and the rings of 1 ', 1 " are all closed loops 3, 3'. 3 ", it has no slits, no screws are required for installation, so the structure is simple and the appearance is better. The loop of Figure 2 is different from the loop of Figure 6, the loop 36 of Figure 2 is for the base rail 28 located in the lower portion of the ladder. The loop of Figure 6 is for the middle rail 2' and 2 〃in use. The loop 3 shown in Fig. 8 is a loop for the highest grade rail. Although the three rings are different, they have a common feature, that is, the crosspiece has an elastic projecting contact point 31 which cooperates with the vertical sleeve 1 on the ring wall of the ring 3. It is formed by cutting the inverted U-shaped groove 312 on the wall surface of the ring at both ends of the crosspiece. The inverted U-shaped groove 312 is surrounded by the cantilever protrusion 31, and the upper end of the cantilever protrusion 31 is oriented. The inner protruding oblique shape has a slope 311. + on the telescopic sleeve 1, and 1 ', 1" of the vertical rod, there are holes 16 or pits corresponding to the elastic contact point cantilever block 31, which are engaged with each other when the two are moved into position with each other during assembly. The reason for this setting is that the telescopic sleeve 1 of the first vertical rod and the second vertical rod is made of metal aluminum alloy, and the ring 3 on the telescopic sleeve 1 is made of nylon, considering the materials of both. Differently, such a design can ensure a good mounting fit between two parts made of different materials. It is generally sufficient to arrange a pair of elastic inward contact points in a certain diameter direction of the ring 3 to face each other. The cantilever protrusion 31 representing it can of course also be set more. Figure 9 shows the ladder damping device of the case: the telescopic sleeve of each of the two vertical bars 1, 1 ', 1 A damping device is fixed in the lower-end port, which comprises a bearing block 5 and a friction ring 4 embedded in the inwardly-retracting groove 51 at the lower end of the bearing block 5, and a pin 7 for bearing the block 5 and the telescopic sleeve 1 The lower end phase is traversed and fixedly connected. This type of friction ring is included in the expansion sleeves 1, 1 ', 1" of each level. The friction rings 4, 4', 4" will maintain a uniform speed during the movement, which also increases the safety. The inner circumference of the friction ring 4, 4', 4" of the lower end of the telescopic sleeve 1, 1 , 1" is concave. This arrangement is also intended to increase safety. The second embodiment is identical to the first embodiment except that the push-pull unlocking button 33 shown in Fig. 7 is different. In the second embodiment, the unlock button is a single push type unlock button. As shown in FIG. 10, it includes a locking cross pin 21 in the base rail 28, a pin shank fixed perpendicularly to the cross pin 21, and a push button 39 unlocked by the ladder is disposed on the side façade of the crosspiece 28. It can be seen from Figure 11 that the push button 39 and the pin shank 391 are an integral part. In Fig. 12, the end of the pin shank 391 is provided with a recess 39'2 which is fitted into the mating pin 211 in the intermediate pin groove of the cross pin 21. Figure 13 shows a slot pin 211 disposed in the intermediate pin slot of the cross pin 21. FIG. 14 shows a state in which the push-pull unlock button 39 is mounted on the side elevation of the base rail 28. Figure 15 shows how the telescopic ladder of the present invention is gathered. It can be seen from the figure that after the ladder is closed, there is a safe gap distance h between the basic grade rail 28 and its upper rung 2", which brings safety to the operation of the staff, There will be a case where the free-falling step damages the human hand. The handshake pad 29 is used by the staff to grasp the different views when carrying the ladder.

Claims

Rights request

An anti-pinch safety telescopic ladder comprising a telescopic vertical rod that is sleeved by a multi-stage sleeve, which are a first vertical rod and a second vertical rod; a horizontally extending crosspiece between the second vertical rods; a latching mechanism at the junction of the crosspiece and the vertical rod, the latching mechanism including a locking knob device; a sleeve on each end of each crosspiece a ring for holding a vertical rod telescopic sleeve, characterized by;

1 The lower part of the ladder has a stationary fixed base rail (28), and both ends are provided with an anti-clamping end piece ring (36), and the outer part of the end piece ring (36) forms a safety-deficient part of the ring wall. (362), and a partially raised wall on the inner ring wall surface, and a vertical upward direction on the top horizontal surface of the raised portion of the ring (36) to achieve the interlocking action when the ladder is closed a protrusion (361), the base rail (28) has a sufficiently secure anti-pinch in the horizontal direction between the first horizontal rail (2") adjacent to the upper side of the ladder when the ladder is collapsed Spacing distance

2 The middle crosspieces (2') and (2") are provided with a chain unlocking mechanism including a corner-shaped button member accommodated in the internal cavity of the crosspieces (2') and (2") ( 23) and the associated ram (22) which can move up and down on the upper plane of the crosspieces (2') and (2") and the horizontally movable horizontal pin (21) and the horizontal cross pin (21) Always opposite springs (24);

3 An unlocking button for performing the chain unlocking start action is provided on the base rail (28) located at the lower part of the ladder.

2. The telescopic ladder according to claim 1, wherein: the crosspiece has a resilient contact point on the ring wall of the ring that cooperates with the vertical telescopic sleeve, and the elastic contact point It is formed by cutting the inverted U-shaped groove on the wall surface of the ring at both ends of the crosspiece to form an elastic protrusion (31) surrounded by the "U"-shaped groove, and the upper end of the elastic protrusion (31) is An oblique projection that protrudes inward, having a slope (33), and a hole (16) or a recess corresponding to the elastic projection (31) as a resilient contact point on the telescopic sleeve of the vertical rod, during assembly When the two move axially into position with each other, they snap together to form a connection.

3. The telescopic ladder according to claim 1, characterized by: at each of the base rails (28) above the ladder, except for the uppermost first stage, the crosspieces (2') and (2) There is provided a chain unlocking mechanism, which comprises a corner-shaped button member (23) accommodated in the inner cavity of the crosspiece and a top rod (22) movable up and down through the upper plane of the crosspiece and is executed therewith a horizontal pin (21) of the latching action; an upper hole of the middle rail (2') and (2〃) is provided with a small hole for the ejector rod (22) to pass up and down, and the On the lower bottom surface of the middle crosspieces (2') and (2"), there are small holes through which the ejector pins (22) in the next horizontal crosspiece can pass upward; the end of the outer end of the cross pin (21) It can be pierced in a corresponding pin hole formed on the wall surface of the telescopic sleeve, and the end of the cross pin (21) is always abutted against a compression spring (24); the ejector pin (22) has a square shape and a bottom thereof It is always against the corner (231) of the button member (23) by gravity.

4. The telescopic ladder according to claim 3, wherein: a corner-shaped button member (23) in the cavity of the middle rail (2') and (2") has a pivot point (233) is placed on the underside of the inner chamber of the crosspiece (2) in a resting state, and the dial (232) is movably embedded in the dial of the cross pin (21).

5. The telescopic ladder according to claim 3 or 4, characterized in that: the crosspiece (2') and (2) the button member (23) of the inner cavity thereof comprises a dial (232) And the lower legs (231) are integrally connected by an angled rod, they are all doubled, and the angular fulcrum (233) of the angled rod is a short column.

6. The telescopic ladder according to claim 1, wherein: the unlocking button for performing a serial unwinding on the base rail level (28) at the lower portion of the ladder is a push-pull type, which includes An unlocking button (33) for pulling and pushing, a dial (35) and a spring (34); a positioning fixing is provided between the pushing plane of the pushing button (33) and the crosspiece (28) The boss (38); the dial (35) and the cross pin (21) are screwed perpendicularly to each other through the screw hole (351); the unlocking button (33) has a cylindrical portion forming a spring seat (331) It accommodates the dial (35) and the spring (34); the spring (34) keeps the push-pull button (33) in close contact with the lower plane (282) of the crossbar (28).

7. The telescopic ladder according to claim 1, wherein: the unlocking button for performing a chain unlocking on the base level rail (28) at the lower portion of the ladder is a single push type unlocking button (39). The utility model comprises a push handle (391) which is integrally fixed with the vertical reinforcement. The end of the push handle (391) is provided with an open groove (392), and the groove pin (211) which is arranged in the middle of the horizontal pin (21). With the mating connection, the inner end of the cross pin (21) always opposes the spring (24).

8. The telescopic ladder according to claim 1, wherein: the lower end ports of each of the two stages of the two vertical rods are provided with a damping device, which includes a bearing block (5) And the friction ring (4) in the recess (51) is inwardly contracted into the lower end of the load bearing block (5), and a pin (7) traverses the bearing block (5) to the lower end of the telescopic sleeve.

9. The telescopic ladder according to claim 8, wherein: the inner ring of the friction ring (4) at the lower end of the telescopic sleeve (1) has a concave shape.

10. The telescopic ladder of claim 1 wherein the loops that enclose and secure the telescoping sleeves of the vertical rod are: an integrally closed loop without an opening. ·