Fire escape – ladder – or scaffold – Convertible – Ladder
Reexamination Certificate
1999-08-02
2001-04-24
Stodola, Daniel P. (Department: 3634)
Fire escape, ladder, or scaffold
Convertible
Ladder
C182S163000, C182S228600
Reexamination Certificate
active
06220389
ABSTRACT:
FIELD OF THE INVENTION
The invention relates to a folding ladder, the ladder elements of which can be telescopically extended by means of pull-out sections movable thereon, whereby the pull-out sections can be fixed by means of a locking mechanism in several positions on the respectively associated ladder element on one of its rungs—constructed as a hollow-profile section—which locking mechanism has a locking bolt, which can be guided into the hollow-profile section of the rung under the action of an adjusting spring and handle and can be locked in this position, and whereby furthermore the locking bolt fixed on the handle is axially movably supported in a guide element mounted on the ladder element.
BACKGROUND OF THE INVENTION
Such a folding ladder is already known from the Offenlegungsschrift DE 44 03 001 A1. The guide element for the locking bolt is in this design constructed on a flange piece, which is riveted or screwed to the respective ladder element.
The purpose of the invention is to design a folding ladder of the type described in detail above in such a manner that such a guide element can be secured in a simple manner on the provided ladder element without having to use an expensive rivet or screw connection. However, such a mounting is at the same time also supposed to offer suitable permanent security against a self-release of the connection.
SUMMARY OF THE INVENTION
The purpose is attained according to the invention in such a manner that the guide element can be fastened on the ladder element by means of a bayonet fitting. A mounting of the guide element designed in this manner can be created with one single manipulation. The elements of the bayonet fitting can be co-provided without any difficulties and additional expense during the manufacture of the guide element and of the ladder element, as will become apparent by the details identified more closely below.
Thus, it is for example advantageous when the bayonet fitting consists of a guide flange provided on the front side on the guide element and a counter flange, which concentrically surrounds in the ladder element a guide hold for the guide element, whereby the guide flange can have at least three holding element, which can be guided through surface-complementary holding recesses of the counter flange, and, after an axial rotation of the guide flange against the counter flange, rests on its front surface not facing the guide element, whereby an annular flange of the guide element, abutting the ladder element, determines the axial introduction of the guide flange into the ladder element.
The counter flange consists thus alone of the receiving recesses, which enlarge the guide hole in the ladder element radially outwardly, and it is thus not a separate structural part, but instead merely a defined surface section of the ladder element. During the introduction of the guide hole into the web of the ladder element, it is automatically and without additional input manufactured at the same time.
The guide flange does not present an obstacle during the movement of the pull-out section on the ladder element, when, as this is common, the web of the pull-out section is guided spaced from the web of the ladder element, which as a rule is already desired for different reasons. Thus, the ends of the rungs project at all times slightly over the web of the pull-out section, to which it is in most cases flanged or connected in a different manner so that this projection requires already a certain spacing between the webs. The ladder elements are therefore equipped with guide edges, which determine the spacing between the respective pull-out sections.
It is advantageous when a position-securing lock is available for the bayonet lock, for example, an eyelet piece with an axis-parallel first pin hole for a locking pin is provided on the circumference of the guide element, which locking pin is driven into a second pin hole in the ladder element, which second pin hole is axially aligned with the first one. The second pin hole is designed such that the locking pin can only be driven in when a secure bayonet fitting has been created, which means, when the guide element, after the introduction of the guide flange into the counter flange, has been rotated accordingly.
In detail, the locking bolt is best constructed pipe-shaped and connected, preferably pinned, to the handle so that it can be changed through a direct manual operation between its axial positions corresponding to locking or unlocking. Furthermore, it is possible to provide a lock against rotation between the guide element and the locking bolt (and thus also the handle).
However, it is particularly advantageous thereby when the lock against rotation is not complete and unreleasable but instead permits a—however, limited—rotation of the locking bolt (and this only in its position when it is removed from the rungs). It can thereby advantageously consist of a crosspin fastened in the guide element and an axis-parallel guide groove in the locking bolt, through which guide groove extends the crosspin. The guide groove has in a preferred embodiment a preferably acute-angled laterally bent section. Such an arrangement offers the advantage that the locking bolt, when it is unlocked, can be moved by a slight rotation into a stable unlocking position so that it need not be held during the adjustment of the respective pull-out section.
An arrangement has been created with the invention, in which the guide element can be mounted quickly and safely on the ladder element, and, moreover, in which care is taken in a simple manner that the unlocking of the locking bolt can be transitioned into a stable position ready for use so that the locking bolt loaded by the adjusting spring on the one hand does not hinder the adjustment of the associated pull-out section and on the other hand does not need to be manually held during such an adjustment. The folding ladder can therefore be manufactured expediently and can be handled comfortably.
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patent: 5062499 (1991-11-01), Tu
patent: 5074377 (1991-12-01), Krause
patent: 44 03 001 (1994-08-01), None
Flynn, Theil, Boutell & Tanis, P.C.
Krause-Werk GmbH & Co. KG
Stodola Daniel P.
Thompson Hugh B.
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