FR2701402A1 - Descender with improved braking - Google Patents

Abstract

Descender or figure-of-eight for climbing, characterised by the presence of an accentuated rope braking distance permitting more effective control of the rope by the second (safety device) and thus affording improved safety (security).

Description

The subject of the present invention is a descender, or eight-shaped ring. This safety device is widely used in modern climbing, as well as in certain exposed works, either to control a rappelling, or to ensure the safety of a climber by his teammate (the insurer)
It is this second use which tends to become the most important, and which will particularly interest us.

In its current form, the descender is a piece of light alloy with high resistance, having the shape of an eight with unequal loops The small loop is fixed by a carabiner to the bau -drier of the insurer (or possibly to a fixed mooring )
The rope connecting the two team members makes a circuit around the large loop, so as to create an energetic friction. Thanks to this friction, the importance of which it can measure, the insurer can, without excessive effort, control the weight of the climber, including in the event of a fall. This control is carried out by exerting a traction on the rope, generally with one hand which we will call the active hand of the as-belayer This moderate traction is strongly amplified by the friction effect of the rope on the descender, which allows it to withstand high stress.

This device is very simple, robust and inexpensive, and its effectiveness is sufficient as long as the weight of the climber does not exceed that of the insurer. On the other hand, there may be a problem if the climber is noticeably heavier, a case which is encountered more and more frequently, especially in practice as a couple, or with children. If the climber falls, the traction to be performed on the rope may then be too great for the strength of the belayer. This could burn your hand and be unable to stop the fall.

The object of the present invention is to remedy this drawback by slightly modifying the shape of the descender.

This modification consists in providing the latter with a V-shaped niche in which the insurer can very easily engage the rope in the event of significant stress (fall of the climber in particular). its friction on the descender, a bit like improving the grip of a belt by using a pulley with a trapezoidal groove. We can even, if desired, go to an almost total jamming of the rope.

The general shape of the descender must be designed so that the gesture that the insurer must make to introduce the rope into the niche in Rrso a natural gesture, practically identical to that which it must do with a traditional descender.

Other advantages and characteristics will emerge more clearly from the description which follows of an embodiment of the invention, given by way of nonlimiting example, and represents in the appended drawings in which: 1 is a front view of a traditional descender
showing the rope circuit.

FIG. 2 is an identical view of a descender according to the invention.

FIG. 3 is a cross-sectional view a of the same
- ashtray, particularly showing the V-shaped niche - Figure 4 is a sectional view b, longitudinal with respect to
V-shaped
The classic descender of Figure I is composed as we have seen:
-a small loop i in which one engages the soft-latch (not shown3 allowing to moor the device, for example on the harness of the insurer.

 -a large loop 2 around which the rope 3 describes a circuit which, in the event of significant stress (controlled descent or fall) appears according to the figure.

The upper part of the rope goes towards the climber, the ground -licitation exerted by this one being represented by the force FI. The lower part goes towards the active hand of the insurer, which exerts a traction F2.

The formula used in particular in belt mechanics teaches us that the ratio F1 / F2 is an exponential function of the cumulative winding angle of the rope on the descenter. This angle being very important here (greater than 360 degrees) the ratio is therefore high, which leads to a moderate force FZ.

To completely balance the force Fi, you must of course add a force F3, which is the reaction of the mooring of the descender by its small loop. F2 being weak, F3 is therefore only slightly less than Fi.

When the insurer must let the rope slip without creating braking (especially when the climber is climbing) it changes the configuration of the circuit by bringing the rope to the position shown in broken lines (ref. 4)
This gesture has the effect of reducing the angle of winding of the rope on the descender, and therefore of reducing friction. The insurer then also ceases to exercise traction.

In the event of an accidental fall of the climber, the belayer must quickly bring the rope back to the previous position (item 3) and restore traction to resist the effort of falling.

This gesture must be made energetically. It is in this type of situation that the FI / F2 ratio, although quite high, can turn out to be insufficient if the climber is too heavy in relation to the strength of the insurer. The latter may then be unable to prevent the rope from sliding, which can go as far as a burn in his active hand, and an uncontrolled fall of the climber.

On the descender according to the invention represented by FIGS. 2, 3, and 4, we note:
-A break in the inner circumference of the large loop forming a slight notch 5, in which the rope comes naturally to engage when it is brought into braking position.

 -In the extension of this notch, a V-shaped slot 6 in which the rope engages in the same position, between the two bosses 7, 7 '.

It is clear that, according to the angle formed by the walls 16, 16 'of the slot 6, it is possible to obtain more or less significant braking of the rope, possibly going as far as jamming. According to a preferred development of the invention, this angle may vary gradually, being fairly open towards the inside of the loop, and closing more and more when one goes outside. The insurer can thus, by playing on the more or less accentuated winding of the rope, switch from medium braking (position 8 in Figure 4) to very vigorous braking (position 9 in Figure 4) which can go to total blockage. The risk of inadvertent sliding of the rope and burns for the insurer is thus eliminated, which greatly improves safety.

As we have seen previously, the rope must be able to move very quickly from the free sliding position to the braking position (equivalent to positions 4 and 3 in Figure 13 respectively. For this, the boss 7 'must be connect in a gentle slope on the large loop of the descender. In order not to overly weigh it down 7 it is interesting that the large loop has, in zone 10, a sensi
- slightly helical, particularly visible in Figures 3 and 4.

Claims (3)

1- Descender device used in climbing, or for tra  -vail in exposed situation, presenting the general shape  classic of an eight-shaped ring, characterized by the presence  an accentuated braking zone of the main rope  -cipally in a niche with oblique walls 6 2- Device according to claim 1, characterized in that  the walls 16.1E 'of the slot 6 are of gradual slope,  thus allowing the user to obtain a variation im  - significant braking by playing on the orientation of the horn  -from two positions 8 and 9, therefore on its introduction  more or less accentuated in niche 6. 3- Device according to one of the preceding claims, charac  - terrified by the fact that loop 2 of the descender on the  which winds up the rope has a slight notch 5,  located opposite slot 6 and constituting the start of  this one, and in which the rope engages so  natural when brought in by the user  braking position. 4- Device according to one of the preceding claims, charac  -terized in that the passage of the rope from the position of  sliding 4 to that of braking 3 is facilitated by a  partially helical in a zone 10 of the bou  -clope 2 of the descender on which the rope is wound.