EP0771931A1 - Safety device for ladder and ladder incorporating the same - Google Patents

Abstract

The safety mechanism consists of two arms (8) pivoted to the upper ends of the ladder side supports (2a,b) which are opened to allow them to pass round the sides of a pole (1) and closed round the back of the pole by a cord (14) which also acts as a safety line for a person using the ladder. In their non-operative position the arms are folded against the front of the ladder and are turned into the closed position by two levers (16) which connect the arms to the cords, while the latter has two looped ends (15a,b) passing through lugs (18) on a cross-piece (19) equipped with rollers (12) which press against the front of the pole when the ladder is in use.

Description

The present invention relates to a ladder safety device and a ladder equipped with such a device.

To maintain overhead cables, in particular electrical or telephone lines, it is sometimes necessary to carry out interventions at the top of the posts which support these cables.

When the post is a simple smooth mast, a ladder is used, generally telescopic, which is pressed against the upper part of the post.

However, this operation is not without certain dangers, all the more so since some posts can rise quite high.

Safety devices for ladders are already known which allow a ladder to be locked to a pole by means of adjustment operations, which are generally long and complicated.

However, these devices are not entirely satisfactory since their handling is not easy, which encourages users of ladders not to use them.

In addition, we know the lifelines which are ropes to which we can tie to prevent a fall.

The present invention aims to provide a device for blocking a ladder against a mast which solves the problems mentioned above.

This device finds its application in many other fields than that of the maintenance of overhead cables, such as for example the maintenance of trees and more generally any activity in which a ladder must be pressed against a substantially vertical cylindrical support.

The present invention relates to a safety device for a ladder, characterized in that it comprises in combination two pivoting arms mounted at the top of the ladder, capable of assuming an open position, or rest position, in which they leave between them sufficient space for the passage of a pole and a closed position, or working position, in which these arms are clamped against said pole, a cord connecting said arms to the lower part of the ladder to exert a force on the arms which tends to cause them to close when this rope is pulled down, said rope serving as a lifeline by comprising a self-locking sliding handle to which a harness can be connected or a belt worn by the user of the ladder.

It is understood that, thanks to the invention, the user can apply the upper end of the ladder against the post, while the arms are in the open position, after which it suffices to pull on the rope to close the arms around the pole and fix the bottom of the rope to the ladder to ensure the ladder is held in place for the first time.

The user then hooks his harness or his belt to the self-locking handle of the lifeline and climbs the ladder, while the self-locking handle slides along the rope which serves as a lifeline.

If, as a result of a false movement, the user of the ladder falls or becomes unbalanced, he then exerts a traction on the lifeline through his harness, and it causes an increase clamping forces of the arms against the post, which has the effect of ensuring a perfect connection between the upper part of the ladder and the post.

In a preferred embodiment, the arms in the open position are brought completely onto the face of the ladder which is not applied against the post so as to limit the space requirement of the upper part of the ladder when it is positioned against the pole or against a tree.

This embodiment is particularly advantageous because it makes it possible to reduce the size of the ladder, which may be advantageous for storing it or for working on a mast located in branches.

This embodiment also makes it possible to use the ladder against a wall, in the manner of a traditional ladder, without having to disassemble the locking device.

In a preferred embodiment, the arms pass from their open position to their closed position when the rope is pulled towards the lower part of the ladder, while springs, of preferably helical, act on the arms to constantly bring them back to the open position.

In this way, the pivoting arms are not likely to move to come against the face of the ladder which is directed against the post when the ladder is positioned.

In a particular embodiment of the invention, the arms are articulated in the vicinity of one of the uprights of the ladder, around a substantially vertical axis when the ladder is in the position of use.

Thus, the movement of the arms passing from one position to the other takes place in a substantially horizontal plane when the ladder is in the position of use.

Preferably, the rope is connected to each arm at a point on this arm located approximately 10 cm from its pivot axis.

In a particular embodiment of the invention, a slightly curved bearing surface is located substantially at the height of the two arms and allows the ladder to be pressed against the post by centering the latter in the central part of the span d 'support.

In a preferred variant of this embodiment, the bearing surface comprises rollers capable of rolling along the post to facilitate the positioning and possibly the deployment of the ladder, the bearing surface already being applied against the post.

The present invention also relates to a ladder provided with a safety device as described above.

• la figure 1 est une vue en élévation d'un utilisateur monté sur une échelle selon l'invention appliquée contre un poteau,
• la figure 2 est une vue en perspective de la partie supérieure de l'échelle,
• les figures 3, 4, 5 et 6 sont des vues de dessus de l'échelle au cours de la mise en place des bras autour du poteau,
• la figure 7 est une vue de côté d'une poignée auto-bloquante engagée sur la corde, et
• la figure 8 est une vue de face de la partie inférieure de l'échelle.

In order to better understand the invention, we will now describe an embodiment given by way of non-limiting example with reference to the accompanying drawing in which:

• FIG. 1 is an elevation view of a user mounted on a ladder according to the invention applied against a post,
• FIG. 2 is a perspective view of the upper part of the ladder,
• FIGS. 3, 4, 5 and 6 are top views of the ladder during the positioning of the arms around the post,
• FIG. 7 is a side view of a self-locking handle engaged on the rope, and
• Figure 8 is a front view of the bottom of the ladder.

In Figure 1, there is shown a vertical post 1, against which a ladder 2 according to the invention is supported by its upper part 3. A user 4 is climbing to the top of the ladder.

In Figure 2, we see how the ladder 2 is gripped to the pole 1.

At its upper part 3, the ladder comprises a safety device 5 which comprises two tubes of rectangular section 6 each engaged at the top of one of the uprights 2 a , 2 b of the ladder and tightened by collars 6 a , 6 b .

Sleeves 7 are welded to the outer lateral face of the tubes 6 in a direction such that said sleeves 7 are substantially vertical when the ladder is pressed against the post 1, as seen in FIG. 1.

Each sleeve 7 receives the vertical branch of an arm 8, able to pivot in said sleeve.

A pin 9 axially retains each arm in the corresponding sleeve.

Each arm 8 is thus able to pivot in a substantially horizontal plane, as will be explained with reference to FIGS. 3 to 6.

Torsion springs, not shown, are fixed on the one hand to the lower end of each arm, on the other hand to the corresponding tube and ensure the return of the arms to the closed position shown in FIG. 3.

The horizontal branch of each arm 8 ends in a curved part, the curvature of which is directed towards the ladder so as to effectively clamp the post 1 by immobilizing it in an area situated substantially at equal distance from the two sleeves 7.

The safety device 5 also includes a bearing surface 10 which is constituted by a curved bar 11 which is substantially V-shaped, the two branches of which support rollers 12 capable of rotating freely around the bar 11.

The ends of the bar 11 are welded to the tubes 6.

As can be seen in FIG. 2, the ladder is applied against the post by its bearing surface 10, and more precisely by its rollers 12, which, by being able to roll along the post, facilitate the positioning of the ladder and possibly its deployment avoiding wear of the bearing surface 10 against the post, which is especially advantageous when the post is made of cement.

It is understood that the V shape of the bar 11 and the curved ends of the arms 8 lead to the centering of the post relative to the scale.

A cord 13, knotted at 14 so as to comprise two strands 15 a and 15 b , is connected to each of the arms 8 by means of links 16 which are each articulated on an axis 17 welded below each arm, to a distance of about 10 cm from the corresponding sheath 7.

Each strand 15 a , 15 b of the rope is guided in an eyelet 18 which is produced on a rod 19 parallel to the curved bar 11, welded at its ends to the two tubes 6 and in its middle to the curved bar 11.

In the position shown in FIG. 2, it is understood that when the rope 13 is pulled down, the two arms 8 are tightened around the post 1.

In FIG. 3, the safety device is shown with its arms 8 retracted, that is to say that the arms 8 are in the open position and are folded down on the side of the ladder opposite to the post 1.

In this position of the arms 8, the ladder can be applied against the post 1 by its rollers 12, which facilitate the sliding of the upper part of the ladder against the post.

To move from the closed position shown in Figure 2 to the open position of Figure 3, each arm 8 pivots about 320 ° in the direction of its opening, that is to say, relative to Figure 2 , counterclockwise for the arm corresponding to the amount 2 a and clockwise for the arm corresponding to the amount 2 b .

During this pivoting, each strand 15 a , 15 b of the cord 13 is wound around the vertical branch of the corresponding arm 8.

Thanks to the presence of the rods 16, the strands 15 a and 15 b wound around the vertical branches of the arms 8 do not overlap, which makes it possible to avoid friction of the rope on itself, friction which could lead to wear of the rope and blockage of the arms 8.

Once the ladder is correctly positioned, traction is exerted on the rope 13, which causes the arms 8 to pivot.

Given the fact that each strand 15 a , 15 b of the rope 13 is wound directly on the vertical branch of the corresponding arm 8, the torque exerted by the rope on each arm is relatively low compared to the traction exerted on the rope, but sufficient to allow the deployment of said rope, and in particular thanks to the rods 16 which eliminate any risk of friction of the rope on itself.

After having pivoted about half a turn, the arms 8 reach the position shown in FIG. 5.

The strands 15 a and 15 b of the rope are then fully unwound and stretch between the connecting rod 16 and the corresponding eyelet 18.

The pivoting of the arms 8 is interrupted when the latter reach their closed position in which they are tightened around the post 1.

It can be noted that at this stage of the positioning of the arms, the rods can avoid causing the strands 15 a , 15 b to rub against the post, which is advantageous in particular when it is a post in concrete.

To immobilize the arms in the closed position, the user stretches the rope 13 along the ladder and attaches it to the bottom of the ladder.

It should be noted that, according to the invention, it is not necessary for the rope to be perfectly stretched between the two ends of the ladder, but it is sufficient for it to be attached to the lower part of the ladder so as not to ascend with the user when the latter climbs the ladder and prevent the arms from opening to return to their open position.

The rope can therefore be a little loose, the arms then not being tightly tightened against the post but kept in a position in which they enclose the post against the bearing surface.

To block the rope at the bottom of the ladder, one can use a blocker 20 secured to one of the bars of the ladder, as seen in FIG. 8.

The blocker 20 prevents the rope from going up but allows it to slide down.

The ladder is thus applied against the pole with its arms surrounding said pole.

It should be noted that the operations described so far are carried out by the user from the ground, which protects him from any risk of falling.

To use the ladder, the user puts on a harness or a belt (not shown) which he connects to a self-locking handle 21, shown in FIG. 7, which is engaged on the rope 13 so as to be able to climb freely along this rope and to hang on said rope when it is pulled down.

In FIG. 7, there is shown in broken lines a mechanism for blocking the self-locking handle on the cord 13.

It is understood that when the carabiner 22 drives the latch 23 downwards, the jaw 24 encloses the rope 13, which immobilizes the self-locking handle 21 on said rope 13.

Thus, the user can climb freely along the ladder, using the rope as a lifeline.

In the event of a fall or imbalance, the self-locking handle stops on the rope and the user, who is thus held by the rope, exerts on this rope a traction which accentuates the tightening of the arms 8 around the post 1 .

The rope 13 can then exert maximum torque on the arms 8 because the links 16 and the strands 15 a , 15 b extend substantially perpendicular to the horizontal branches of the arms 8.

In this way, the ladder remains in position, allowing the user to recover.

As already explained, we see that it is not necessary for the user to tension the rope perfectly before climbing the ladder. It is sufficient for the arms of the safety device to surround the pole so that the action of the rope on the arms, in the event of the user falling, causes the upper part of the ladder to be securely attached to the pole .

It is understood that the embodiment which has just been described has no limiting character and that it can receive any desirable modifications without departing from the scope of the invention.

In particular, only a pole of electrical wires has been described here, but it is clear that the invention could apply to any substantially cylindrical support against which a ladder is brought to bear.

Claims (8)

Safety device for a ladder, characterized in that it comprises in combination two pivoting arms (8) mounted at the upper part (3) of the ladder (2), capable of assuming an open position in which they leave between them sufficient space for the passage of a pole (1) and a closed position in which these arms are clamped against said pole (1), a rope (13) connecting said arms to the lower part of the ladder (2) for exert on the arms (8) a force which tends to cause their closure when this rope is pulled down, said rope serving as a lifeline by including a self-locking sliding handle (21) to which a worn harness can be connected by the scale user. Device according to claim 1, characterized in that the arms (8) in the open position are brought completely onto the face of the ladder which is not applied against the post (1) so as to limit the size of the upper part (3) of the ladder (2) when positioned against the post (1) or against a tree. Device according to either of Claims 1 and 2, characterized in that the arms (8) pass from their open position to their closed position when the rope (13) is pulled towards the lower part of the ladder ( 2), while springs, preferably helical, act on the arms (8) to constantly return them to the open position. Device according to any one of Claims 1 to 3, characterized in that the arms (8) are articulated in the vicinity of one of the uprights of the ladder each around a substantially vertical axis when the ladder (2) is in position for use. Device according to claim 4, characterized in that the rope (13) is connected to each arm (8) at a point on this arm located approximately 10 cm from its pivot axis. Device according to any one of Claims 1 to 5, characterized in that it has a slightly curved bearing surface (10) substantially at the height of the two arms (8), thanks to which the ladder (2) can lean against the post (1). Device according to claim 6, characterized in that the bearing surface (10) comprises rollers (12) able to roll along the post (1) to facilitate the establishment and possibly the deployment of the ladder ( 2). Ladder, characterized in that it includes a safety device according to any one of claims 1 to 7.

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