IES63852B2

IES63852B2 - Tear-open webbing in particular for catching-system fall-cushioners

Info

Publication number: IES63852B2
Authority: IE
Inventors: Heiner Schickhardt
Original assignee: Schickhardt C J Gmbh Co Kg
Priority date: 1993-11-02
Filing date: 1994-11-02
Publication date: 1995-06-14
Also published as: GB9422046D0; IES940857A2; GB2283505A; DE9316676U1

Abstract

A tear-open webbing (1) for catching-system fall-cushioners, comprises at least two webbing layers (2, 3) which are connected to each other along a tearing length by means of binder threads (4). The webbing layers (2, 3) are connected to each other in such a fashion that the number of binder threads (4) increases along the tearing length in the tearing direction of the tear-open webbing (1).

Description

The invention concerns a tear-open webbing, in particular for catching-system fall-cushioners, comprising at least two webbing layers which are connected to each other along a tearing length by means of binding threads.

Tear-open webbings of this type are utilized in situations where shock-loads must be cushioned.

A principle area of application for tear-open webbings is fall-cushioners which are safety harnesses constituting components of catching-systems by means of which people working at relatively large heights can be secured in the event of a fall. Fall-cushioners are tear-open webbings comprising two adjacent band-like webbing layers which are woven or sewn together. Towards this end one of the webbing layers, on its free, unsewn or unwoven end, can serve as a safety strap which can be connected to a secure anchor point, for example, to a building. The free end of the second webbing layer can, in this case, assume the function of a catching strap and can be connected to a safety belt attached to the person being secured.

In the event that the person being secured falls, the fall-cushioner effects a gradual breaking of the fall.

Starting from an initial breaking at first engagement of the fall-cushioner, the fall is continuously slowed through the » tearing of the mutually connected fall-cushioner webbing layers until the fall is completely stopped. In this fashion the energy of the fall is absorbed by the loading of the binding threads, binding the fall-cushioner webbing layers to each other, to beyond their breaking limit.

In order to avoid injury to the person being secured, the magnitude of the breaking action of the fall-cushioner must be limited. This is particularly the case for the initial breaking force which occurs during response of the fall-cushioner and which leads to a stopping force on the person falling in the safety belt. The magnitude of the maximum allowable breaking force is specified by national and international standards and is designated, for example, through DIN 32766 5kN and according to EN 355 6kN.

Tear-open webbing has been utilized in the art of fallcushioners whose webbing layers are connected to each other by binding threads, the number of which is constant over the entire tearing length. Experience has shown that, with this type of conventional tear-open webbing, the initial breaking force often exceeds the maximum value determined to assure an injury-free stopping of the secured person.

The underlying purpose of the invention is to create a 2θ securely functioning tear-open webbing, the breaking action of which, in particular the initial breaking action, guarantees an injury-free stopping and catching of the secured individual.

This purpose is achieved in accordance with the invention in •5 that, with a tear-open webbing of the above mentioned kind, the webbing layers are connected to each other by means of binding threads, the number of which increases along the tearing length in the tearing direction of the tear-open webbing. The utilization of a tear-open webbing of this type allows for a softer catching of the falling person. During the initial response of the fall-cushioner, a relatively low number of binding threads resist the tearing apart of the webbing layers. As a result thereof only a relatively small fraction of the fall energy is initially absorbed during the first response of the fall-cushioner and a hard abrupt interruption of the falling motion is avoided. Accordingly the person in the safety belt who is falling is not subjected to a hard shocking load when the fall-cushioner responds. Towards this end the gentle response described above can be achieved using tear-open webbings with webbing layers which are sewn to each other as well as with tear-open webbings with woven layers.

In addition to as soft a breaking shock as possible during the initial response of the fall-cushioner, a gentle action on the person being cushioned requires as uniform a deceleration as possible. A particularly attractive breaking force dependence is given when the number of binding threads holding the webbing layers together increases in a stepwise fashion in the direction of the tear. This is realized in an advantageous embodiment of the invention in that the tearing length exhibits at least two sections of equal length, whereby the sections following each other in the direction of the tear each have a larger number of binding threads than the respective previous section.

In a preferred embodiment of the invention the number of binding threads in the tearing direction of the tear-open webbing increases in each section by a constant number. The constant stepwise increase in the active binding threads provides for a particularly gentle braking of the fall motion. An optimum braking dependence results when the tear-open webbing exhibits 8 sections along its tearing length.

In order to effect a uniform distribution of the absorption of the falling energy over the surface of the tear-open webbing, the binding threads advantageously run largely in the tearing direction and are arranged to be distributed over the entire width of the tear-open webbing.

The invention is described and further explained below with respect to the schematic representation of an embodiment. Ίθ The figure shows a tear-open webbing 1, which comprises an upper webbing layer 2 as well as a lower webbing layer 3.

The two webbing layers, 2, 3 are woven to each other; binder threads 4, running in the lengthwise direction of the web, effect their connection.

The extension of the upper webbing layer 2 serves as a safety strap and is provided, at its free end 5 with a spring hook 7 which can be hung onto a secure anchor point, for example, onto a building. The extension of the lower webbing layer 3 functions, in the fall-cushioner shown, as a catching belt which, by means of a spring hook 8, can, for example, be connected to a body belt attached to the person being secured.

The binder threads 4, provided for in the breaking region, initially serve to keep the webbing layers 2, 3 together. In the event of a fall of the secured person, as soon as the secured person, in the safety belt, falls forces act on the tear-open webbing 1 under the action of which the binder threads 4 are loaded beyond their breaking limit. Up to the point of breakage, the binder threads 4 absorb the falling energy of the falling person. In this fashion the energy absorption takes place solely in the forward region I of the tear-open webbing 1. Accordingly, only the binder threads 4 in the forward region I of the tear-open webbing 1 are torn under the action of the catching load and the webbing layers 2, 3 of the fall-cushioner are only separated in this region from each other during breaking of the fall. The backward region II of the tear-open webbing serves the purpose of a safety reserve. The binders threads 4 remain intact in this region.

Claims

1. Tear-open webbing (1), in particular for catching-system fall-cushioners, comprising at least two webbing layers (

2. , 3) which are connected to each other along a tearing 5 length by means of binder threads (4), characterized in that the webbing layers (2, 3) are connected to each other by binder threads (4) the number of which increases along the tearing length in the tearing direction of the tear-open webbing (1). 10 2. Tear-open webbing according to claim 1, characterized in that the tearing length exhibits at least two sections of equal length, whereby, in the tearing direction, a larger number of binder threads (4) is associated with each subsequent section than in the respective preceding 15 section.

3. Tear-open webbing according to claim 2, characterized in that the number of binder threads (4) of the tear-open webbing (1) increases, in the tearing direction, by the same number in each respective section.

4. Tear-open webbing according to claim 2 or 3, characterized in that the tearing length exhibits eight sections.

5. Tear-open webbing according to one of the preceding claims, characterized in that the binder threads (4) run 25 largely in the tearing direction and are distributed over the entire width of the tear-open webbing (1).