JP2000282771A - Ladder with overturning preventive mechanism - Google Patents

Abstract

PROBLEM TO BE SOLVED: To develop a ladder with an overturning preventive mechanism, which can simply and positively fix its front end to a columnar body such as an electric light pole when abutted on the same, and can be easily attached to and detached from the columnar body by operating a lower portion of the ladder. SOLUTION: There is provided a ladder A constituted of a ladder main body 1 and an overturning preventive mechanism B provided for an upper end of the ladder main body 1. The overturning preventive mechanism B comprises a pair of pinching members 2 for pinching the periphery of a columnar body 3, and an opening mechanism C for opening/closing the pinching members 2. Since the columnar body 3 is pinched by the pinching members 2, once the overturning preventive mechanism B of the ladder main body 1 is fixed to the columnar body 3, the overturning preventive mechanism B is not detached from the columnar body 3 even if the operator carries out work while leaning out of the ladder main body 1, whereby the ladder is prevented from overturning.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a ladder that can be easily and reliably fixed to a pillar when the ladder is leaned against a pillar such as a telephone pole. The present invention relates to a ladder with a fall prevention mechanism that can be released from below from below.

[0002]

2. Description of the Related Art For example, when a ladder has to be leaned on a telephone pole and work must be performed on the ladder, another worker must support the ladder from below so that the ladder does not fall down during the work. Must.

[0003] In the conventional ladder, the uppermost stage of the ladder which comes into contact with the telephone pole is provided with a simple bar-like horizontal bar constituting a step, or a modified rubber member is provided on the step. Is only a thing. In the former case, the contact part with the utility pole is slippery at the point contact, and in the latter case, it is a linear contact.Because it is possible to obtain the frictional resistance by the rubber member, the worker is better than the former, When the user leans on the ladder to work on the upper part, the rubber member overcomes the frictional force with the utility pole and shifts in the direction that the rubber member rotates around the utility pole, and in extreme cases, the ladder falls down It is something.

Therefore, if the upper end of the ladder in contact with the utility pole is fixed to the utility pole, a fall accident can be prevented. However, since the fixed portion is located at an extremely high point at the tip of the ladder, the fixed portion is located above the ladder from above the ground. It was extremely difficult to easily attach and detach the parts.

[0005]

SUMMARY OF THE INVENTION The present invention has the following advantages. (1) The tip portion can be easily and securely fixed to a pillar when leaned against a pillar such as a telephone pole. The development of a ladder with a fall prevention mechanism that can be easily performed on the ground from underneath.

[0006]

A ladder (A) with a fall prevention mechanism according to claim 1 comprises a ladder main body (1) and a ladder main body.
(1) is a ladder (A) configured with a fall prevention mechanism (B) provided at the upper end portion, the fall prevention mechanism (B) is a columnar object (3)
And a closing mechanism (C) for opening and closing the holding member (2). "

According to this, the columnar object (3) is held by the holding member (2).
To prevent the ladder body (1) from overturning.
Once (B) is fixed to the pillar (3), the fall prevention mechanism (B) does not come off from the pillar (3) even when the worker leans out of the ladder body (1) and works. There is no such thing as falling down.

[0008] Claim 2 is a further limited version of the ladder (A) with the overturn prevention mechanism according to claim 1, wherein the "clamping member (2)".
Is constituted by a fixed-side holding member (2a) and an opening / closing-side holding member (2b) whose one end is rotatably supported by the fixed-side holding member (2a). Occasionally open / close side holding member
(2b) A one-way clutch that can rotate in the closing direction, but does not rotate the opening / closing side holding member (2b) in the opening direction, and can rotate the opening / closing side holding member (2b) in the opening direction in the released state. (4) is provided. "

According to this, since the one-way clutch (4) is used for the opening / closing mechanism (C), if a force is applied to the opening / closing-side holding member (2b) during use of the ladder (A), the direction is changed. Whatever direction the opening / closing side holding member (2b) does not turn in the opposite direction even if it turns to the fixed side holding member (2a) side, it is a direction always tightened, The opening / closing mechanism (C) does not loosen during use of the ladder (A), and the columnar object (3) is securely captured, and the ladder (A) does not fall out and fall.

A third aspect of the present invention is a further limitation of the ladder (A) having the overturn prevention mechanism according to the first or second aspect, wherein the overturn prevention mechanism (B) includes a fixed side holding member (2a). The lever (5), which is movably mounted and contacts and rotates with the pillar (3) when the tip of the ladder body (1) leans against the pillar (3), is attached to the opening / closing side holding member (2b). Linked ".

According to this, when the ladder main body (1) is leaned against the column (3), first, the column (3) comes into contact with the lever (5) located in front of the fixed side holding member (2a). Fixed side holding member (2a)
Move to the side. In conjunction with this movement, the opening / closing-side holding member (2b) connected to the lever (5) is pulled and rotates toward the fixed-side holding member (2a). As a result, the opening / closing side holding member (2b)
Holds the columnar object (3) from the outside, and the fixed holding member (2a) and the opening / closing side holding member (2b) firmly hold and fix the columnar object (3) from inside and outside. Once clamped, the clamped state is fixed by the action of the one-way clutch (4). Therefore, the lever
The tip of the ladder (A) can be fixed to the pillar (3) simply by leaning the long ladder (A) on the pillar (3) by the action of (5).

A fourth aspect of the present invention describes in detail the "opening / closing mechanism (C)" of the ladder (A) with an overturn prevention mechanism according to the first to third aspects. The rotating cylinder portion (7), which is rotatably arranged with respect to the side holding member (2a) and forms a part of the opening / closing side holding member (2b), and forms a part of the fixed side holding member (2a) A fixed tubular part (9) in which a one-way clutch (4) is housed, the one-way clutch (4), and a rotating tubular part (7), and the rotating tubular part (7) and the one-way clutch (4) It consists of an operating shaft (8) that moves in the axial direction inside.The operating shaft (8) has a large-diameter portion (10) that can be inserted into and removed from the one-way clutch (4), and a small-diameter Part (11) is formed,
When the large-diameter portion (10) is inserted by inserting and removing the operating shaft portion (8), the one-way clutch (4) enlarges the inner diameter and allows only the rotation of the opening / closing side holding member (2b) in the closing direction. When the small diameter portion (11) is inserted, the inner diameter is reduced to allow rotation in both the open and close directions. "

According to this, the one-way clutch operation of the one-way clutch (4) only by moving the operating shaft portion (8) in the axial direction with respect to the one-way clutch (4) (operation of rotating only in one direction and not reversely rotating). And its release is possible.
Therefore, if a string (12) is attached to the operating shaft (8), or if a string is attached to the `` lever member (13) or (13a) '' for operating the operating shaft (8) described later, Ladder (A)
By pulling the string (12) on the ground from below, the operating shaft (8) can be inserted and removed from the one-way clutch (4),
The work of releasing the fall prevention mechanism (B) can be performed by work on the ground from under the ladder (A).

Claim 5 is a further limitation of the opening / closing mechanism (C). "An opening / closing side holding member (2b) is provided between the fixed side holding member (2a) and the opening / closing side holding member (2b). A spring member (6) for applying a force to the normally open side is provided. "

According to this, when the one-way clutch (4) is released and the opening / closing-side holding member (2b) becomes free, it is automatically opened by the action of the "spring member (6)", and the lower part of the ladder (A) is opened. , The release work on the ground becomes easy.

A sixth aspect of the present invention relates to another mechanism for operating the operating shaft (8), wherein the operating shaft (8) is a lever member (13) or a lever member (13) attached to the fixed side holding member (2a). (13a).
If the string (12) is attached to (13) or (13a) ", the operating shaft (8) can be operated with a small force.

[0017] Claim 7 is a further limitation of the ladder (A) with an overturn prevention mechanism according to any one of claims 1 to 6, wherein the columnar member includes a fixed-side holding member (2a) and an opening / closing-side holding member (2b). Pads (14) and (15) for increasing frictional resistance are provided on the contact surface with (3). "

According to this, the frictional resistance of the sandwiched portion is increased by the action of the pads (14) and (15), so that the sandwiched portion becomes less slippery and safety is enhanced.

An eighth aspect of the present invention is a further improvement of the ladder (A) having the overturn prevention mechanism according to the first to seventh aspects.
(B) is attached to the ladder main body (1) so that it can be turned upside down. '' By doing so, the fall prevention mechanism (B) is stored in the ladder main body (1) during storage. The ladder body (1) can be woken up when used, and the ladder body (1) does not become bulky when stored even if it is newly equipped with a fall prevention mechanism (B).

[0020]

DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention will be described below in detail with reference to illustrated embodiments. The ladder body (1) is used by leaning against a tall columnar object such as a telephone pole, and it varies from long to short, depending on the application. This will be described as an example, but is not limited to this.

A tumbling prevention mechanism (B) is provided at the upper end of the ladder body (1). The fall prevention mechanism (B) includes a pair of holding members (2) for holding the outer periphery of the columnar object (3), and a holding member.
And an opening / closing mechanism (C) for opening and closing (2). In the present embodiment, the holding member (2) includes a fixed-side holding member (2a),
One end is rotatable by the opening / closing mechanism (C).
And an opening / closing side holding member (2b) supported by the opening / closing side.

The fixed-side holding member (2a) is a plate-shaped fixed-side main body.
(20) and a fixed cylindrical portion (9) welded and fixed to the upper surface of one end of the fixed side main body (20), the uppermost step (1a) of the ladder main body (1) and the vertical member ( 1b) directly on the reinforcing member (1c) provided at the corner portion, or the
6) is mounted via. On the surface of the fixed side body (20) opposite to the ladder body (1), a fixed side recess (21) into which the columnar object (3) is fitted is formed, and a curved plate is formed on the inner periphery thereof.
One pad (14) is attached via (22).

The opening / closing mechanism (C) comprises a one-way clutch (4) housed in the fixed cylinder (9) and an operating shaft (8). Is the opening / closing side clamping member (2b)
The rotary cylinder part (7) which constitutes a part of is mounted.
The rotating cylinder (7) is fixed via a stationary body (20).
It is arranged on the opposite side (lower side) of (9), and the fixed side body
The working shaft (8) is inserted into the communicating part through a through hole (23) formed in the (20), and moves in the axial direction with respect to the one-way clutch (4). It has become.

A large-diameter portion (10) and a small-diameter portion (11) are formed in a portion where the operating shaft (8) is inserted into and removed from the one-way clutch (4). Large diameter part (1
(0) is inserted, the inner diameter of the one-way clutch (4) is enlarged to allow only the rotation of the opening / closing side holding member (2b) in the closing direction, and when the small diameter portion (11) is inserted, the inner diameter is increased. The opening and closing side holding member (2b) is allowed to rotate only in the opening direction or in both the opening and closing directions.

A stopper (24) is attached to the top end of the operating shaft portion (8), and a stopper (25) provided on the upper surface of the fixed cylindrical portion (9). A coil spring (26) is provided. The coil spring (26) constantly urges the operating shaft (8) in the pulling direction, so that the large diameter portion (10) of the operating shaft (8) is located in the one-way clutch (4), and therefore the small diameter ( 11)
Is located at the escape position, and the one-way clutch (4) is always operated so that the opening / closing-side holding member (2b) rotates only in the closing direction.

Next, a description will be given of the rotary cylinder part (7) which constitutes a part of the opening / closing side holding member (2b). The rotating cylinder (7) is disposed on the back side of the fixed side body (20) as described above, is inserted into the through hole of the holding plate (28), and the outer flange of the rotating cylinder (7).
(20a) is held between the holding plate (28) and the fixed-side main body (20), and is configured to rotate.

The lower part of the operating shaft (8) is
A non-rotating pin (17) slidably inserted into (7) and inserted transversely through the rotary cylinder (7) into a slit (27) formed in the lower part of the operating shaft (8). ) Is inserted,
The operating shaft (8) is formed so as to rotate together with the rotary cylinder (7).

Accordingly, the rotating cylinder (7) rotates about the operating shaft (8) together with the operating shaft (8) with respect to the stationary body (20), and the operating shaft (8) is It will slide further to (7). The operating shaft (8) is located at the lower end of the operating shaft (8).
A cord (12) for pulling in the axial direction is attached. The lever member that moves the operating shaft (8) in the axial direction is
(13) or (13a) ”will be explained again.

The opening / closing side holding member (2b) is provided with the rotary cylinder (7).
And the open / close side clamping arm (2
9), the opening / closing side recess (30) is formed on the surface of the opening / closing side holding arm (29) on the fixed side holding member (2a) side corresponding to the fixed side recess (21). The pad (15) is provided via a curved plate (31).

Further, between the opening / closing side holding arm (29) and the fixed side body (20), the opening / closing side holding arm (29) is always open side (that is, the opening / closing side holding arm (29) is fixed side). A spring member (6) that pulls the spring member (in a direction away from the main body (20)) is provided.

Next, the lever (5) will be described. One end of the lever (5) is rotatably attached to the fixed body (20) via a fulcrum shaft (32), and the free end is connected to the fixed body (2).
It is disposed so as to cross the front of the fixed side recess (21) at a position below the pad (0) so as not to be hooked on the pad (14). The lever (5) and the opening / closing side holding arm (29)
It is connected via a connecting member (33), and is arranged such that when the lever (5) moves, the opening / closing side holding arm (29) also moves via the connecting member (33).

The uppermost step (1) of the ladder body (1)
The member disposed between the vertical members (1b) above the a) is a rubber attachment (34), and the contact surface with the columnar object (3) is formed in a concave curved shape. It is formed so as to easily follow the columnar object (3).

Next, the operation of the present invention will be described. First, the opening / closing side holding arm (29) is kept open, the ladder main body (1) is extended, and its tip is leaned against the columnar object (3). Then, the attachment (34) comes into contact with the side surface of the columnar object (3), and at the same time, the lever (5) is pushed by the side surface of the columnar object (3) and moves to the fixed side recess (21) side, and the pad (14) ) Below to reach the concavely curved bottom of the pad (14).

Then, the open / close side holding arm (29) connected via the connecting member (33) moves to the fixed side concave portion (21) side,
Close the space between the fixed side recess (21) and the opening and closing side recess (30),
The pillar (3) is sandwiched between the inside and the outside by both pads (14) and (15). The rotation of the opening / closing side holding arm (29) in the closing direction is due to the one-way clutch operation of the one-way clutch (4).
The one-way clutch (4) does not rotate any longer even if it tries to open in addition to (9), and the tightened state is not released because the position is maintained.

As described above, since the columnar object (3) is sandwiched between the inside and the outside by the pads (14) and (15), even if a force is applied to the ladder (A), the columnar object (3) ) And both pads (1
4) Even if force is applied in a direction that rotates (15), both pads
(14) The rotation is prevented by the frictional force and the tightening force of (15), and the upper end portion of the ladder (A) is firmly fixed to the columnar object (3).

In this state, the worker climbs on the ladder (A) and performs high-place work on the pillar. During this time, the worker leans out of the ladder (A) and works, as described above. (14) (1
Since the columnar object (3) is gripped in 5), the ladder (A) does not fall down, of course, and does not shake.
Therefore, there is no need for the operator to support the ladder (A) under the ladder (A).

When the work on the pole is completed, the worker moves to the ladder (A).
Get off and pull the string (12) connected to the operating shaft (8) on the ground under the ladder (A). Then, the operating shaft (8) is pulled against the coil spring (26), the small diameter portion (11) is pulled into the one-way clutch (4), the inner diameter of the clutch is enlarged, and the operating shaft (8) is expanded. ) Is released, and the opening / closing side holding arm (29) is pulled by the pulling action of the spring member (6).
Rotates together with the rotating cylinder (7) and the operating shaft (8) in the opening direction to release the holding of the columnar object (3). After that, the ladder (A) is removed from the pillar (3), and the work is completed by folding.

Next, a first embodiment of the "lever member (13)" will be described with reference to FIG. In the above embodiment, the string (12) is directly connected to the operating shaft (8) without using the lever member (13), and the string (12) is pulled to directly operate the operating shaft (8). In this case, the tension of the string (12) is directly applied to the fixed body (20) through the operating shaft (8), and a large moment is applied to the mounting base of the fixed body (20). And may cause the mounting base to flex or bend in some cases.

Then, one end of the lever member (13) is connected to the fixed side main body.
(20) is rotatably attached to a fulcrum (44), the other end is attached with the string (12), and a roller (46) provided in the middle is attached to the stopper (24) of the operating shaft (8) or As shown in the figure, the engaging flange (45) protruding from the side surface of the operating shaft (8) is in contact with the operating shaft (8). Thus, when the string (12) attached to the lever member (13) is pulled, the operating shaft (8) is pushed down by the principle of leverage, and the large diameter part (10) is moved from the one-way clutch (4). Withdrawal,
The small diameter portion (11) enters and enters the release state as described above.
In this case, since the "lever member (13)" is used, not only can the string (12) be pulled with a smaller force, but also the force applied to the fixed body (20) is reduced.

FIG. 9 is the reverse of FIG. 8, in which the lever member (13a) is brought into contact with the stopper (24) of the operating shaft (8), and is provided on the upper surface side of the fixed body (20). Pivoted to the fulcrum (44a),
The stopper (24) is pushed from above. The effect is shown in FIG.
Is the same as

Next, a case will be described in which the fixed-side holding member (2a) is attached to the uppermost step (1a) via the elevating member (16) so as to be able to be turned upside down. In this case, the raising / lowering operating member (16) is firmly fixed to the uppermost step (1a) by the rivet (16a). Further, a fixed-side holding member (2a) is pivotally connected to a rotation support shaft (40) protruding from a casing (16b) of the raising / lowering operation member (16).

On the other hand, a moving pin (43) is provided adjacent to the rotation support shaft (40) and moves in parallel with the rotation support shaft (40), and is slidably supported by the support member (43a). And
The moving pin (43) has a handle portion (43b) protruding therefrom, and protrudes outside from a slide through hole (16c) formed in the casing (16b). A coil spring (43c) is provided between the handle portion (43b) and the support member (43a) to urge the moving pin (43) toward the fixed side holding member (2a). I have. The tip of this moving pin (43) is
It is designed to protrude / retract from a through hole (16d) formed in the facing surface of the fixed-side holding member (2a) of 6b).

On the other hand, the casing (1) of the fixed side holding member (2a)
On the surface facing 6b), locking holes (2a1) and (2a2) are drilled on a circle of a certain radius around the rotation support shaft (40),
The angle (θ) formed by the straight line connecting the locking holes (2a1) (2a2) and the rotation support shaft (40) is, when the fixed side holding member (2a) is caused,
It is substantially horizontal and ready for use, and is set at an angle along the ladder body (1) when it is folded down, that is, at an angle of 75 °.
In this embodiment, the raising and lowering member (16) is a fixed-side holding member.
The movable pin (43) is installed on both sides of (2a). The movable pin (43) is inserted into and removed from the fixed-side holding member (2a) from both sides to maintain a horizontal use position or a folded storage position during use.

In use, when the handle (43b) is held and the moving pin (43) is moved in a direction to deflect the spring (43c), the tip of the moving pin (43) is held in a folded and stored state. It is pulled out from the locking hole (2a2) and further immerses into the casing (16b) through the through hole (16d) to release the locked state. Thereby, the fixed side holding member (2a) can be raised from the ladder main body (1a).

A locking hole that raises the fixed-side holding member (2a) from the ladder body (1a) and raises the horizontal holding state.
When the (2a1) and the through hole (16d) match, the handle (43
When the hand is released from b), the tip of the moving pin (43) protrudes from the through hole (16d) due to the elastic force of the spring (43c), and the locking hole
(2a1) and locked in the locking hole (2a1). Thereby, when the ladder main body (1a) is leaned against the columnar object (3), the fixed side holding member (2a) is held so that it can be used substantially horizontally. And in this state, the ladder (A)
Is attached to the column (3).

After using the ladder (A), the ladder (A) is removed from the pillar (3) by the method described above, and then the handle (4) is used.
3b) and move the pin in the direction to flex the spring (43c).
(43) is moved, and the tip of the moving pin (43) is pulled out from the locking hole (2a1) holding the horizontal use state. Subsequently, the fixed side holding member (2a) is pulled down, and when the locking hole (2a2) for holding the folded storage state matches the through hole (16d), the handle portion is
When the hand is released from (43b), the tip of the moving pin (43) protrudes from the through hole (16d) by the elastic force of the spring (43c) and is inserted into the locking hole (2a2), and the locking hole (2a2 ).

Thus, the folded and stored state is maintained. In addition, when the ladder (A) is long, after use, it is folded or folded in three, and is stored.
a) is stored in the ladder main body (1) in a folded storage state, so that this does not interfere.

Although there are various lock methods, a pin fixation can be employed here as a simple method. Although not shown, a method is used in which a fixing pin is inserted at a place where a fixing pin hole formed in the holding member is aligned with a fixing operation hole, and both are fixed. When not using the fall prevention mechanism, pull out the fixing pin and fold and store the fall prevention mechanism along the ladder main body. Thus, even if the overturn prevention mechanism is provided, the ladder does not become bulky as described above.

Reference numeral (48) denotes a hook attached to the tip of the ladder main body (1), which is used by hooking on an overhead wire stretched between pillars (3) such as telephone poles. An opening / closing member (49) for opening and closing the opening of at least one hook (48) is provided, and by pulling a string (50) attached to the opening / closing member (49) from under the ladder (A). The opening / closing member (49) is pulled down to open the opening of the hook (48).

[0050]

As described above, according to the method of the present invention, when the ladder is leaned against the pillar, the pillar is clamped by the clamping member of the overturn prevention mechanism. Even when working, the ladder does not fall off the pillar and fall down. Therefore, it is not necessary for another worker to support the ladder during the work, and the labor can be saved.

In addition, by using a one-way clutch for the opening / closing mechanism, the opening / closing-side holding portion always rotates only in the direction of tightening the opening / closing-side holding portion to the fixed-side holding member side while the ladder is in use, so that the columnar object can be securely mounted. The ladder does not fall down during use.

Further, by using a lever located in front of the fixed-side holding member and connected to the opening-and-closing-side holding member, the ladder main body is automatically held on the pillar by simply leaning the ladder body on the pillar. Since no special operation is required for the clamping operation, the operation is very simple.

The one-way clutch can operate and release the one-way clutch by inserting and removing an operating shaft having a large-diameter portion and a small-diameter portion. Simply pulling the string from under the ladder enables the work to release the fall prevention mechanism.

If a spring member is provided between the fixed side holding member and the opening / closing side holding member, the spring member constantly applying a force to the opening side of the opening / closing side holding member. The opening / closing-side holding member is opened to facilitate the release operation from below the ladder on the ground.

When the lever is used for operating the operating shaft, the operating shaft can be operated with a small force.

Further, by arranging a pad for increasing frictional resistance on the contact surface between the fixed-side holding member and the columnar member of the opening / closing-side holding member, the frictional resistance of the holding portion can be increased. Is less slippery and more secure.

[Brief description of the drawings]

FIG. 1 is a front view of a ladder of the present invention.

FIG. 2 is a side view of FIG. 1;

FIG. 3 is a bottom view of the overturn prevention mechanism of a portion (X) in FIG. 1;

FIG. 4 is a rear view of FIG. 3;

FIG. 5 is a side view of FIG. 3;

FIG. 6 is an enlarged sectional view of an operation state of the opening / closing mechanism according to the present invention.

FIG. 7 is an enlarged sectional view of a release state of the opening / closing mechanism according to the present invention.

FIG. 8 is an enlarged sectional view of an operating state of the opening / closing mechanism using a lever according to the present invention.

FIG. 9 is another enlarged cross-sectional view of the operating state of the lever-operated opening / closing mechanism according to the present invention.

10 is a side view of the overturning prevention mechanism of part (X) shown in FIG.

FIG. 11 is a rear view of FIG. 10;

FIG. 12 is a bottom view of FIG. 10;

FIG. 13 is a sectional view of a tilting operation member of the overturn prevention mechanism of FIG. 10;

14 is a vertical sectional view of FIG. 13;

[Explanation of symbols]

 (A) Ladder (B) Fall prevention mechanism (C) Opening / closing mechanism (1) Ladder main body (2) Holding member (2a) Fixed side holding member (2b) Opening / closing side fixing member (3) Columnar object (4) One-way clutch ( 5) Lever (6) Spring member (7) Rotating cylinder (8) Operating shaft (9) Fixed cylinder (10) Large diameter part (11) Small diameter part (12) String (13) Lever member (14) Pad (15) Pad (16) Lifting member

Claims (8)

[Claims] 1. A ladder comprising a ladder main body and a tipping prevention mechanism provided at an upper end portion of the ladder main body, wherein the tipping prevention mechanism includes a pair of holding members for holding an outer periphery of a columnar object, and a holding member. A ladder with a fall prevention mechanism, characterized by comprising an opening and closing mechanism for opening and closing members. 2. The holding member comprises a fixed-side holding member and an opening / closing-side holding member one end of which is rotatably supported by the fixed-side holding member. A one-way clutch is provided, which can rotate in the closing direction, but does not rotate the opening / closing side holding member in the opening direction, and can rotate the opening / closing side holding member in the opening direction in the released state. The ladder with a fall prevention mechanism according to claim 1. 3. The overturn prevention mechanism has a lever that is rotatably attached to a fixed-side holding member and that rotates when the tip end portion of the ladder body leans against the columnar object and rotates in contact with the columnar object. The ladder with a fall prevention mechanism according to claim 1 or 2, wherein members are connected. 4. An opening / closing mechanism, which is rotatably disposed with respect to the fixed-side holding member, forms a rotating cylinder portion that forms a part of the opening-and-closing side holding member, and forms a part of the fixed-side holding member, It comprises a fixed cylinder part in which a one-way clutch is housed, the one-way clutch, and an operating shaft part that rotates together with the rotating cylinder part, and moves in the rotating cylinder part and the one-way clutch in the axial direction, The operating shaft has a large-diameter part and a small-diameter part that can be inserted and removed from the one-way clutch.The one-way clutch has an enlarged inner diameter when the large-diameter part is inserted by inserting and removing the operating shaft. The opening / closing side holding member is allowed to rotate only in the closing direction, and when the small diameter portion is inserted, the inner diameter is reduced to allow the opening / closing side holding member to rotate only in the opening direction or in both the opening and closing directions. 4. The method according to claim 1, wherein Ladder with debt prevention mechanism. 5. A spring member for constantly applying a force to the opening / closing side holding member to the open side between the fixed side holding member and the opening / closing side holding member. ~ 4
A ladder with a fall prevention mechanism according to item 1. 6. The ladder with a fall prevention mechanism according to claim 1, wherein the operating shaft portion is operated by a lever member attached to the fixed-side holding member. 7. A fall prevention device according to claim 1, wherein a pad for increasing frictional resistance is provided on a contact surface between the fixed side holding member and the columnar member of the opening / closing side holding member. Ladder with mechanism. 8. The ladder with an overturn prevention mechanism according to claim 1, wherein the overturn prevention mechanism is attached to the ladder main body so as to be able to be turned upside down.