Fall arrester for a climbing protection system

The fall arrester (10) is part of a climbing protection system for preventing a user of a ladder, a platform or the like from falling. The fall arrester (10) is movable along a guide rail (12) and has a rotatably mounted pawl (18) which, in the event of a fall, runs against catching stops (16) in the guide rail (12). A connecting element (40) is attached to the pawl (18) and the user can be secured to the connecting element (40) by a lanyard. The connecting element (40) is hinged to the pawl (18). The connecting element (40) can be hinged to the pawl (18) such that the connecting element (40) is coupled releasably rotation-resistant to the pawl (18) and the coupling (50, 52) is released in the event of a predetermined force on the connecting element (40). The connecting element can be formed as a damping element (40) which deforms in the event of a predetermined force.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application is a national stage application of International Application No. PCT/EP2006/067469, filed on Oct. 16, 2006, whose benefit is claimed.

TECHNICAL FIELD

The invention relates to a fall arrester which is part of a climbing protection system for preventing a user of a ladder, a platform or the like from falling.

The fall arrester is movable along a guide rail and has a rotatably mounted pawl which, in the event of a fall, runs against catching stops in the guide rail, whereby the fall arrester is arrested in the guide rail. A connecting element is attached to the pawl and the user can be secured to the connecting element by a lanyard.

The connecting element can be formed as a deformable damping element.

STATE OF THE ART

In a fall arrester of this type known from DE-U-298 05 788, the damping element is formed in one piece with the pawl.

A fall arrester in which the rotatably mounted pawl is coupled in a positive-locking way to a fastening element is known from DE-A-102 24 681, wherein the fall arrest force which occurs when the secured person falls releases the positive locking, with the result that the pawl can swivel by elastic force against the catching stops in the guide rail and the fall arrester arrests in the guide rail.

A fall arrester is known from DE 203 14 230 in which the pawl is formed in one piece with the body of the fall arrester and a suspended latch on which the lanyard is fastened is hinged to the body. The suspended latch is U-shaped. When the fall arrester engages with the guide rail in the event of a fall, the U-shape of the suspended latch is bent open and the fall arrest force is thereby damped.

An arresting gear for a climbing protection system is known from DE-A-34 26 551 in which the connecting element is a steel ring dented roughly in the shape of a kidney which is stretched in the event of a fall. Fall energy is reduced by the stretching and the fall arrest force is thereby damped.

A damping device for a safety harness is known from DE-A-26 37 593 which contains a section folded repeatedly in a zigzag which likewise absorbs part of the fall energy in the event of a fall and thereby damps the fall arrest force.

Technical Object

The object of the invention is to create a fall arrester which locks securely in the event of a fall and in which the arrest cannot be released by any oscillating movement of the person secured to it.

Technical Solution

According to the invention, this object is achieved by the connecting element being hinged to the pawl.

Advantageous Effects

The hinge connection transmits any oscillating movements of a person suspended from the connecting element to the pawl to only a small extent, if at all, with the result that the latter cannot release itself from its arrested state.

The connecting element can be simultaneously formed as a damping element. The connecting element is preferably a damping element with a non-rectilinear shape. In the event of a fall, the damping element is deformed into a more rectilinear shape by the fall energy, whereby the fall arrest force is damped. The damping element can be U-shaped for example, wherein the end of one leg of the U is hinged to the pawl while the end of the other leg of the U has a lug from which the person to be secured can hang by the lanyard. When the fall arrester locks in place in the rail in the event of a fall, the U-shaped damping element is stretched and bent open into a straight shape, whereby the fall arrest force is damped. The damping element preferably consists of a single- or multi-folded or cold-rolled flat steel bar. The intensity of the fall arrest force can be limited by the dimensioning of the flat steel bar. In the event of a fall, a maximum of 6 kN can act on the person. To limit the fall arrest force to approximately 4 kN, the flat steel bar has a cross-section of 8×10.5 mm-material 1.4301 steel.

The pawl is hinged at one end, its upper end, in the body of the fall arrester. Its other end, the lower end, is formed as a pawl tooth. The pawl is pre-stressed by a spring, with the result that the pawl tooth is pressed against the catching stops in the rear of the guide rail.

Although the connecting element is hinged to the pawl in the normal state, i.e. as long as there is no fall, the connecting element is preferably prevented from rotating relative to the pawl. This can be achieved for example by having, projecting at the connecting element, a toothed tip which lies under a finger jutting out from the pawl and is extended beneath the finger only by the forces occurring in the event of a fall, whereby the connecting element is then released for a rotation at the pawl. If, in this embodiment, the secured person climbs up or down a ladder, then the fall arrester hangs from the lanyard and the lug in the connecting element or the other connection point is chosen such that the elastic force is then overcome by the weight of the fall arrester hanging from the lanyard, with the result that the pawl is swivelled back into the fall arrester. The torque which is exerted on the pawl by the elastic preload is thus smaller than the torque produced by the weight of the fall arrester, when the fall arrester is held at the lug. The point at which the connecting element is hinged to the pawl is selected such that the torque which is produced by the weight of a person hanging from the connecting element acts in the same direction as the torque of the elastic preload and the pawl additionally presses against the catching stops.

The arrangement of the points of rotation and the length of the lever arms are moreover preferably chosen such that the pawl is also then withdrawn from the arrested position if the user leans away from the ladder or guide rail (backward pull), with the result that the lanyard runs approximately horizontally. The fall arrester is preferably unlocked when the connecting line between the point of rotation of the pawl and the stop point, i.e. the lug in the connecting element, forms an angle of a few degrees with the horizontal. This is expedient in order to prevent the fall arrester from being arrested when climbing down. The person introduces a force of up to approximately 600 N into the connection means in the process.

The point of rotation at which the connecting element is hinged to the pawl can lie e.g. approximately in the centre between the point of rotation of the pawl and the lug of the connecting element, wherein the line connecting these three points is inclined downwards from the horizontal by approximately 5 degrees when the fall arrester runs in a vertical guide rail and the pawl is withdrawn.

It is not necessary to form the hinge between the connecting element and the pawl such that it is locked in the normal state. In the above-described embodiment the locking can be dispensed with, although it is then still possible only to descend with backward pull. Through the backward pull a torque is exerted, via the connecting element, on the pawl that overcomes the torque produced by the elastic preload. No backward pull is necessary when climbing up, since the pawl is bevelled, with the result that the catching stops can be overridden.

The advantages achievable by the invention manifest themselves in particular in the embodiment in which the connecting element is formed as a damping element which deforms in the event of a fall. In the case of a single-piece pawl with damping element, as known from DE-U-298 05 788, the geometric arrangement of pivot pins of the pawl and lug is optimal per se for the carabiner of the lanyard and in the event of a fall arrests the fall arrester very quickly and securely in the guide rail. However, as a result of the fall the damping element is bent open downwards in the form of a swan's neck, with the result that the geometric lever ratios (larger lever arm) change (deteriorate) to such an extent that the pawl can very easily be unlocked again (with a small horizontal pull). In the case of the fall arrester according to the invention with a two-part hinged pawl, the geometric ratios in the normal state are identical to those of a fall arrester according to DE-U-298 05 788, but completely different after the fall: because of the two-part formation of the hinged pawl, the lever ratios are also almost identical after the damping element has been bent open in the form of a swan's neck, i.e. by the damping element being hinged at the top to the pawl, the bent-open damping element swivels upwards approximately into the horizontal in the event of a horizontal backward pull and thus there is a much smaller lever arm. The damping element can thus be moved upwards freely at a certain angle, without unlocking the pawl in the process.

However, from a certain angle or if there is a sufficiently strong backward pull or upward pull, with the fall arrester according to the invention, the pawl can also be unlocked again and the fall arrester can continue to be moved in the rail. This is not possible in the case of a fall arrester according to DE-A-102 24 681, since there the two components, pawl (arresting member) and brake-activation element, are completely uncoupled in the event of a fall.

WAY(S) OF CARRYING OUT THE INVENTION

According toFIGS. 1 to 4, the fall arrester10is guided in a guide rail12. The guide rail12is normally arranged vertically. The guide rail has the C-profile known from EP-A-0 168 021 which is open towards the front, i.e. towards the user, wherein the opening edges of the C-profile serve as a guide flange14. Catching stops16projecting into the inside of the guide rail12are pressed out in the rear of the guide rail.

The fall arrester10has a body20, oblong overall, extending in the direction of the guide rail with a pawl18rotatably mounted therein. Two pairs of rollers22,24are provided at the front end of the body20. The inner pair of rollers22runs on the inside of the guide flange14, while the outer pair of rollers24runs on the outside of the guide flange14. The rollers22,24are mounted on journal bearings which are fastened rigidly to the body20. The inner rollers22remain at a distance from the outer rollers24that is somewhat greater than the material thickness of the guide flange14. Two similar pairs of rollers26,28are provided at the rear end of the body20, wherein the inner pair of rollers26again runs on the inside of the guide flange14, while the outer pair of rollers28runs on the outside of the guide flange14. Yet another inner pair of rollers29is provided between the two inner pairs of rollers22and26.

The body20of the fall arrester10has a slit-shaped opening30in which the pawl18is mounted rotatably on a pin32for pivoting around a horizontal axis A. The opening30is closed for a short distance31on the underside of the fall arrester10by the third inner pair of rollers29. The tooth34of the pawl18projects from the fall arrester10into the inside of the C-profile of the guide rail until it meets the catching stops16which project inwards from the rear of the rail. The pin32is located in the upper region of the pawl.

The pawl18is subject to the action of a pressure spring36which presses against the pawl18above the pin bearing, with the result that the tooth34projects as far as possible. To this extent, the design and use of the carriage10corresponds to the carriage according to DE-U-298 05 788 and DE-U-299 20 850 to which reference is made for details.

A damping element40is hinged to the pawl18on the side facing the user and slightly below the pin32. The damping element40acts as connecting element and has a lug42from which a lanyard or other safety harness of the user can be suspended. To form the joint between the pawl18and the damping element40, the pawl is recessed on both sides at44near the pin32approximately in the shape of a semi-circle, with the result that the material thickness of the pawl18is approximately halved in this region. The damping element40is U-shaped overall, and the end of one leg of the U is incised, and this incision sits on the pawl18in the region of smaller thickness. The damping element40is fastened to the pawl18by a pivot pin46for pivoting movement around a horizontal axis A1, that is spaced from the axis A. The shape of the recesses44and the shape of the end of the first leg of the U are matched to each other such that the damping element40has a swivel range of approximately 45 degrees downwards from the horizontal.

In the normal state, as shown inFIGS. 1 and 3, the two U-legs of the damping element are aligned approximately parallel and the damping element40rests tightly against the pawl18. In this state, the damping element40is secured to the pawl18by a toothed tip50which is held below a projecting finger52of the pawl18so that the damping element40and pawl18co-rotate around the axis A. The lug42to which the lanyard is attached is also located at the end of the second U-leg.

In the event of a fall, the pawl18is first pressed through the damping element40by the elastic preload in one direction around the axis A into the position shown inFIG. 5in which the pawl18engages with a catching stop16. The fall arrest force is conducted into the damping element40via the lanyard attached to the lug42. The toothed tip50is extended below the finger52by the fall arrest force and the damping element40is bent out of its initial U-shape state into a different state wherein it has a largely stretched shape. The fall arrest force is thereby damped. Since the toothed tip50is now no longer held fast by the finger52, the damping element40can swivel freely at the pawl18. In the event of a fall, the second U-leg is first pulled downwards, as shown inFIG. 6. It may happen that, due to an elastic rebound of the system, the damping element40shoots upwards (FIG. 7). Because, in its bent-open shape, the damping element40is no longer rigidly connected to the pawl18, but rather only hinged to it, such a movement of the damping element40cannot lead to the pawl18releasing itself from the catching stop16.

REFERENCE LIST